Effect of application of K fertilizer and wheat straw to soil on crop yield and status of soil K in the plough layer under different planting systems was studied.The experiments on long-term application of K fertilize...Effect of application of K fertilizer and wheat straw to soil on crop yield and status of soil K in the plough layer under different planting systems was studied.The experiments on long-term application of K fertilizer and wheat straw to soil in Hebei fluvo aquic soil and Shanxi brown soil in northern China were begun in 1992.The results showed that K fertilizer and straw could improve the yields of wheat and maize with the order of NPK+St〉NPK〉NP+St〉NP,and treatment of K fertilizer made a significant difference to NP,and the efficiency of K fertilizer in maize was higher than in wheat under rotation system of Hebei.In contrast with Shanxi,the wastage of soil potassium was a more serious issue in the rotation system in Hebei,only treatment of NPK+St showed a surplus of potassium and the others showed a wane.K fertilizer and straw could improve the content of water-soluble K,nonspecifically adsorbed K,non-exchangeable K,mineral K,and total K in contrast to NP;however,K fertilizer and straw reduce the proportion of mineral K and improve proportion of other forms of potassium in the two locating sites.Compared with the beginning of orientation,temporal variability character of soil K content and proportion showed a difference between the two soil types;furthermore,there was a decrease in the content of mineral K and total K simultaneously in the two locating sites.As a whole,the effect of K fertilizer applied to soil directly excelled to wheat straw to soil.Wheat straw to soil was an effective measure to complement potassium to increase crop yield and retard the decrease of soil K.展开更多
Lessons learned from past experiences push for an alternate way of crop production.In India,adopting high density planting system(HDPS)to boost cotton yield is becoming a growing trend.HDPS has recently been considere...Lessons learned from past experiences push for an alternate way of crop production.In India,adopting high density planting system(HDPS)to boost cotton yield is becoming a growing trend.HDPS has recently been considered a replacement for the current Indian production system.It is also suitable for mechanical harvesting,which reducing labour costs,increasing input use efficiency,timely harvesting timely,maintaining cotton quality,and offering the potential to increase productivity and profitability.This technology has become widespread in globally cotton growing regions.Water management is critical for the success of high density cotton planting.Due to the problem of freshwater availability,more crops should be produced per drop of water.In the high-density planting system,optimum water application is essential to control excessive vegetative growth and improve the translocation of photoassimilates to reproductive organs.Deficit irrigation is a tool to save water without compromising yield.At the same time,it consumes less water than the normal evapotranspiration of crops.This review comprehensively documents the importance of growing cotton under a high-density planting system with deficit irrigation.Based on the current research and combined with cotton production reality,this review discusses the application and future development of deficit irrigation,which may provide theoretical guidance for the sustainable advancement of cotton planting systems.展开更多
Management intensity critically influences the productivity and sustainability of pasture systems through modifying soil microbes, and soil carbon （C） and nutrient dynamics; however, such effects are not well unders...Management intensity critically influences the productivity and sustainability of pasture systems through modifying soil microbes, and soil carbon （C） and nutrient dynamics; however, such effects are not well understood yet ir the southeastern USA. We examined the effects of grazing intensity and grass planting system on soil C and nitrogen （N） dynamics, and microbial biomass and respiration in a long-term field experiment in Goldsboro, North Carolina, USA. A split-plot experiment was initiated in 2003 on a highly sandy soil under treatments of two grass planting systems （ryegrass rotation with sorghum-sudangrass hybrid and ryegrass seeding into a perennial bermudagrass stand） at low and high grazing densities. After 4 years of continuous treatments, soil total C and N contents across the 0 30 cm soil profile were 24.7% and 17.5% higher at the high than at the low grazing intensity, likely through promoting plant productivity and C allocation belowground as well as fecal and urinary inputs. Grass planting system effects were significant only at the low grazing intensity, with soil C, N, and microbial biomass and respiration in the top 10 cm being higher under the ryegrass/bermudagrass than under the ryegrass/sorghum-sudangrass hybrid planting systems. These results suggest that effective management could mitigate potential adverse effects of high grazing intensities on soil properties and facilitate sustainability of pastureland.展开更多
Conversion of potato from conventional methods to wide bed planting systems may increase water and nitrogen use efficiency in commercial potato production system by reducing the amount of irrigation water and water ap...Conversion of potato from conventional methods to wide bed planting systems may increase water and nitrogen use efficiency in commercial potato production system by reducing the amount of irrigation water and water applied nitrogen fertilizer bypassing the potato root zone. Potato (Solanum tuberosum L) cv. Desiree was tested against different planting system for yield and yield components at Kaghan, a high mountainous Himalayan region ofPakistan. The experiment was carried out at Himalayan Agricultural Research Station (HARS), Kaghan during the summer season of 2005. The results showed that maximum tuber growth (88.7%), number of stems per plant (3.5), plant expansion (45.5 cm), average number of tubers per plant (10.1) and yield per hectare (12.4 t/ha) were significantly different and higher when potatoes were planted on wide bed and covered with soil from one side. Tallest plants (53.4 cm) were observed when potatoes were sown on the ridges. Maximum number of green potatoes (12.5) and injured potatoes (5.3%) were observed when the tubers were planted following local farmers’ method. Keeping in view the soil type, land slopping, we recommend sowing potatoes on relatively plain wide beds and covering it with soil from one side, for potato cultivation in the area.展开更多
[Objectives]To investigate the effects of different planting densities and nitrogen application rates on the yield and quality of the tobacco cultivar Chuxue 80.[Methods]A field experiment was conducted in Hubei Provi...[Objectives]To investigate the effects of different planting densities and nitrogen application rates on the yield and quality of the tobacco cultivar Chuxue 80.[Methods]A field experiment was conducted in Hubei Province,evaluating various combinations of planting density and nitrogen rate for Chuxue 80.[Results]At the maturity stage,the TN1 treatment(5 kg N per 667 m^(2) with a density of 1900 plants per 667 m^(2))demonstrated the most favorable agronomic performance.The TN9 treatment(11 kg N per 667 m^(2) with a density of 1110 plants per 667 m^(2))achieved the highest wrapper tobacco yield and output value.Meanwhile,the TN5 treatment(8 kg N per 667 m^(2) with a density of 1515 plants per 667 m^(2))resulted in the best smoking quality.[Conclusions]The TN9 treatment,with a planting density of 1110 plants per 667 m^(2) and a nitrogen application rate of 11 kg per 667 m^(2),is recommended as the optimal cultivation practice for Chuxue 80 in Hubei Province.展开更多
Hydraulic theory predicts a positive coupling between leaf hydraulic conductance(K_(leaf))and stomatal conductance(g_(s));however,this theory has not been fully supported by observations,and underlying mechanisms are ...Hydraulic theory predicts a positive coupling between leaf hydraulic conductance(K_(leaf))and stomatal conductance(g_(s));however,this theory has not been fully supported by observations,and underlying mechanisms are poorly understood.Partitioning K_(leaf)into inside-xylem(K_(x))and outside-xylem(K_(ox))components offers a refined framework for elucidating the regulation of g_(s) by leaf hydraulics.While optimal planting density may enhance water use efficiency(WUE)through modulation of g_(s),corresponding changes in leaf hydraulic properties and their influence on gas exchange remain unclear.We examined relationships among K_(x),K_(ox),g_(s),leaf photosynthetic rate(A_(N)),and WUE,and analyzed the structural determinants of K_(ox)in cotton grown under eight planting densities:12,18,24,36,48,60,72,and 84 plants m^(–2).Results showed that as planting density increased,K_(leaf)and A_(N) remained stable,whereas K_(ox)and g_(s) declined significantly.Leaf thickness and the volume fraction of inter-cellular air space were key structural factors influencing K_(ox).Neither K_(leaf)nor K_(x)correlated with A_(N) or g_(s);however,K_(ox)exhibited a significant positive correlation with g_(s).Furthermore,K_(ox)was negatively correlated with WUE.These findings indicate that K_(ox)modulates g_(s) to minimize water loss without compromising A_(N),thereby enhancing WUE in cotton across varying planting densities.展开更多
In maize production,the development of density-tolerant and lodging-resistant varieties has made dense planting an effective strategy for achieving high and stable yields,with superior hybrids serving as a prerequisit...In maize production,the development of density-tolerant and lodging-resistant varieties has made dense planting an effective strategy for achieving high and stable yields,with superior hybrids serving as a prerequisite for successful highdensity cultivation.However,the photosynthetic mechanisms underlying improved density tolerance in maize hybrids released across different eras in China remain unclear.This study investigates 40 years of breeding progress toward enhanced photosynthetic traits under varying planting densities and elucidates the physiological and ecological bases of improved density tolerance in maize hybrids.A three-year field experiment was conducted from 2019 to 2021 to compare eight major Chinese hybrids from four decadal cohorts under three planting densities:45,000(D1),67,500(D2),and 90,000(D3)plants ha^(-1).At high density(D3),modern hybrids exhibited a more optimal canopy architecture and superior leaf photosynthetic performance compared to older hybrids,despite a slight reduction in specific leaf nitrogen.Notably,modern hybrids(2000s)were able to maintain higher net photosynthetic rates and photosynthetic nitrogen use efficiency(PNUE)at D3,resulting in the highest grain yield(GY),which was 118.47%greater than that of older hybrids(1970s).Leaf area duration after anthesis,total chlorophyll content,key photosynthetic enzyme activities,and maximum quantum efficiency of PSII photochemistry were all positively correlated with GY.Among these,PNUE showed the strongest correlation with grain yield and thus represents a key indicator for optimizing maize hybrids.Based on these findings,breeders should continue selecting hybrids under high-density and suboptimal conditions,focusing on optimizing population architecture and enhancing photosynthetic capacity while fine-tuning leaf nitrogen status to develop high-yielding,density-tolerant hybrids capable of sustaining long-term increases in maize grain yield.展开更多
Rising global change intensifies water scarcity in China’s vital Yellow River Basin grain region,which mounts the need for precise spatial water management.In this study,we investigated the irrigation water demand fo...Rising global change intensifies water scarcity in China’s vital Yellow River Basin grain region,which mounts the need for precise spatial water management.In this study,we investigated the irrigation water demand for seven major crops in cities at the prefecture level between 2000 and 2019.Using Logarithmic Mean Divisia Index(LMDI)decomposition and k-means clustering,we quantified how yield,area,water use efficiency,and cropping patterns affect water demand and identified five irrigation development clusters.Key water-saving areas were identified by tracking transitions among clusters,and NSGA-II was applied to optimize crop structure.The results revealed that the total irrigation demand in the Yellow River Basin averaged 50.09 billion m3/year,with wheat accounting for 54.7%.The increase in yield and area increased demand by 15.2 and 5.5 billion m3,respectively,which was partly offset by changes in water use efficiency and cropping pattern(−7.0 and−1.8 billion m^(3),respectively).Regions in the upper reaches,particularly within the Lanzhou-Toudaoguai section,were identified as critical for water conservation.Optimization of the cropping structure in key regions can reduce annual irrigation water demand by 280 million m3,which accounts for 4.9%of the total demand in these areas,with minimal impact on crop production.This study provides a spatially explicit basis for targeted water conservation strategies in water-scarce agricultural regions.展开更多
Coordinating light and nitrogen(N)distribution within a canopy is essential for improving rice yield and resource use efficiency.However,limited research has examined light and N distribution in response to planting d...Coordinating light and nitrogen(N)distribution within a canopy is essential for improving rice yield and resource use efficiency.However,limited research has examined light and N distribution in response to planting density and N rate,and their relationships with grain yield,radiation use efficiency(RUE),and N use efficiency for grain production(NUEg)in rice.A two-year field experiment was conducted with two hybrid varieties under three N levels,0 kg ha^(-1)(N1),90 kg ha^(-1)(N2)and 180 kg ha^(-1)(N3),and two planting densities,22.2 hills m-2(D1)and 33.3 hills m^(-2)(D2).Results showed 3.4%higher yield and 4.4%higher NUEg under N2D2 compared with N3D1.The extinction coefficient for N(K_(N))and light(K_(L))and their ratio(K_(N)/K_(L))at heading stage were significantly influenced by N rate,planting density,and their interaction.K_(N)decreased with the increase of N input or planting density.Compared to N1,K_(N)decreased by 43.5 and 58.8%under N2 and N3,respectively,while K_(N)under D2 decreased by 16.0%compared to D1.Higher K_(L)and K_(N)/K_(L)values occurred under low N rates,with opposite trends under high N rates.Increased planting density led to decreased K_(L)and K_(N)/K_(L)values.N2D2 demonstrated higher K_(L)and K_(N),and thus comparable K_(N)/K_(L),compared to N3D1.Correlation analysis revealed K_(L)negatively correlated with RUE,while K_(N)and K_(N)/K_(L)positively correlated with NUEg.These findings indicate that increasing planting density under reduced N input could maintain rice yield while enhancing resource use efficiency through regulation of canopy light and N distribution.展开更多
Livestock farming is a critical pillar of Tajikistan’s national economy and livelihood security.However,significant economic challenges in the country have led to the degradation of grassland ecosystems.This degradat...Livestock farming is a critical pillar of Tajikistan’s national economy and livelihood security.However,significant economic challenges in the country have led to the degradation of grassland ecosystems.This degradation has not only reduced the productivity of grassland ecosystems but also severely impacted their ecological functions.A particularly concerning consequence is the threat to biodiversity,as the survival and persistence of endemic,rare,and endangered plant species are at serious risk,thereby diminishing the value of species’genetic resources.Based on the data from multiple sources such as literature reviews,field observations,and national statistics,this study employed a systematic literature review and meta-analysis to investigate the current status,causes of degradation,and restoration measures for grassland ecosystems in Tajikistan.The results revealed that Tajikistan’s grassland ecosystems support exceptionally high plant species diversity,comprising over 4500 vascular plant species,including nearly 1500 endemic and sub-endemic taxa that constitute a unique genetic reservoir.These ecosystems are experiencing severe degradation,characterized by significantly reduced vegetation cover and declining species richness.Palatable forage species are increasingly being displaced by unpalatable,thorny,and poisonous species.The primary drivers of degradation include excessive grazing pressure,which disrupts plant reproductive cycles and regeneration capacity,habitat fragmentation due to urbanization and infrastructure development,and uncontrolled exploitation of medicinal and edible plants.Climate change,particularly rising temperatures and altered precipitation patterns,further exacerbates these anthropogenic pressures.Ecological restoration experiments suggested that both ecosystem productivity and plant species diversity are significantly enhanced by systematic reseeding trials using altitude-adapted native species.These findings underscore the necessity of establishing scientifically grounded approaches for ecological restoration.展开更多
As a critical global ecosystem,grasslands rely on complex aboveground-belowground interactions that underpin multifunctionality,yet their mechanisms remain poorly understood.Our investigation employed the plateau pika...As a critical global ecosystem,grasslands rely on complex aboveground-belowground interactions that underpin multifunctionality,yet their mechanisms remain poorly understood.Our investigation employed the plateau pika(Ochotona curzoniae),a small herbivore widely distributed throughout the Qinghai-Tibetan Plateau,as a model organism to examine the consequences of disturbance on plant diversity,soil properties,microbial diversity,and multifunctionality of grassland ecosystems.We found that high pika burrow density significantly reduced plant diversity(Shannon-Wiener and Chao1 indices)and aboveground biomass.It also increased soil pH and reduced ammonium nitrogen content.The soil microbial diversity,encompassing both bacteria and fungi,was markedly decreased in areas characterized by a high concentration of burrows.Microbial interaction networks demonstrated greater complexity in areas with high burrow densities,as revealed by the network analysis.Conversely,in regions characterized by low burrow density,a significant negative correlation was observed between the intricacy of soil bacterial networks and the multifunctionality of grassland ecosystems.Structural equation modelling showed that pika disturbance indirectly affected multifunctionality via changes in plant biomass and soil properties-notably,nitrate nitrogen explained 40%of multifunctionality variation under high disturbance.This investigation advances our understanding of complex aboveground-belowground linkages in grassland ecosystems,revealing novel mechanisms through which biodiversity governs ecosystem multifunctionality.Our findings underscore the critical role of small herbivores in shaping grassland ecosystem functions and emphasize the importance of maintaining balanced disturbance regimes to sustain ecosystem multifunctionality.This has immediate implications for global conservation policies on the Qinghai-Tibetan Plateau and analogous ecosystems.展开更多
Non-native plants are increasingly recognized as ecosystem engineers across a wide range of ecosystems.While their impacts on understory composition have been widely documented,consequences for community assembly rema...Non-native plants are increasingly recognized as ecosystem engineers across a wide range of ecosystems.While their impacts on understory composition have been widely documented,consequences for community assembly remain largely unexplored.We investigated the engineering impacts of Sorbaria sorbifolia,a naturalized Rosaceae shrub,on abiotic conditions and understory community assembly in Central European forests.Across 60 plots spanning coniferous and deciduous stands,we quantified light availability,organic layer C/N ratio and thickness,and understory functional diversity along an invasion gradient.Using ordination and linear regression,we found that increasing S.sorbifolia cover reduced light availability,thickened the organic layer,and altered C/N ratio in contrasting,forest-type-specific ways.In coniferous stands,invasion increased C/N and strongly suppressed understory light,whereas in deciduous stands it reduced C/N with weaker shading effects.These changes translate into consistent declines in functional richness and dispersion,particularly in coniferous forests where invasion led to homogenization of the understory.Trait shifts indicated stronger habitat filtering under invasion,with declines in specific leaf area(SLA)and increases in leaf dry matter content and seed mass,reflecting exclusion of light-demanding species and persistence of stress-tolerant taxa and woody seedlings.Remarkably,once S.sorbifolia exceeded~50%cover,positive relationships between habitat properties and understory functional diversity collapsed,replaced by uniform light limitation.This threshold effect highlights S.sorbifolia as an ecosystem engineer,capable of transforming forest structure and regeneration trajectories.Early detection and management are therefore crucial to prevent long-term homogenization and the formation of novel,invasion-driven forest states.展开更多
Arid and semi-arid ecosystems are prone to extensive fires due to specific climatic conditions,sparse vegetation cover,and high density of fine fuels.Understanding the flammability characteristics of land covers is es...Arid and semi-arid ecosystems are prone to extensive fires due to specific climatic conditions,sparse vegetation cover,and high density of fine fuels.Understanding the flammability characteristics of land covers is essential for fire management and designing land restoration programs in arid and semi-arid ecosystems.This study provided a new approach to evaluate the flammability of shrublands and woodlands using flammability indices(FIs)including time to ignition(TI),duration of combustion(DC),and flame height(FH)of plant species and their relative frequencies in the Dalfard Basin of southeastern Iran.The results showed that there was a significant difference in FIs between land covers.Shrublands had higher flammability potential compared with woodlands.Plant moisture content had a negative relationship with TI(P<0.010)and no significant relationship with DC and FH(P>0.050).Artemisia spp.,Astragalus gossypinus Fischer,Amygdalus scoparia Spach,and Cymbopogon jwarancusa(Jones)Schult.had the highest FI.Tree species such as Rhazya stricta Decne.,and Pistacia atlantica Desf.showed greater resistance to fire.Using principal component analysis,the relationship between species and FIs was examined,and TI of wet fuel was the most important FI in relation to species.Structural equation model showed that life form(P<0.001)was the most important flammability driver.Precipitation(P<0.010)and legume species(P<0.010)were significantly related to the flammability in arid land.This study emphasizes the importance of managing high-risk species and using resistant species in vegetation restoration and shows that combining species FIs with their abundance is an effective tool for assessing fire risk and fuel management at the plant community scale.展开更多
The real-time and accurate calculation of electricity indirect carbon emissions is not only the critical component for quantifying the carbon emission levels of the power system but also an effective mean to guide ele...The real-time and accurate calculation of electricity indirect carbon emissions is not only the critical component for quantifying the carbon emission levels of the power system but also an effective mean to guide electricity users in carbon reduction and promote power industry low-carbon transformation.Fundamentally,calculating indirect carbon emissions involves allocating direct carbon emission data from the power source side,indicating that accurate indirect emission results rely on the precise measurement of power source emissions.However,existing research on indirect carbon emissions in large-scale power systems rarely accounts for variations in carbon emission characteristics under different operating conditions of power sources,such as rated/non-rated operating conditions and ramping up/down conditions,making it difficult to reflect source-side and load-side carbon emission information variation during providing ancillary services.Quadratic and exponential functions are proposed to characterize the energy consumption profiles of coal-fired and gas-fired power generation,respectively,to construct a refined carbon emission model for power sources.By leveraging the theory of power system carbon flow,we analyze how variable operating conditions of power sources impact indirect carbon emissions.Case studies demonstrate that changes in power source emissions under variable conditions have a significant effect on the indirect carbon emissions of power grids.展开更多
[Objective] The aim was to promote nutrient cycling and utilization in the mountain＇s system combining fruits and poultry and to control non-point source pollution produced from swine raising and navel orange plantin...[Objective] The aim was to promote nutrient cycling and utilization in the mountain＇s system combining fruits and poultry and to control non-point source pollution produced from swine raising and navel orange planting in headwaters of Dongjiang River. [Method] The quantitative analysis was mainly conducted for the so called ＂raising by planting＂ which is about material cycle in ＂pig-methane-fruit-fish＂ model and energy cascade utilization, based on relationship between excreted amount by livestock and the utilized quantity in Xinlin Farm in Longtang Town, Dingnan County, Jiangxi Province. [Result] Considering N requirement by fruit trees, a navel orange orchard （1 mu） could support about 2.72 pigs, the equipped biogas pool （1.88 m3） could support 1 166.67 kg of duckweeds and a fish pond could support 25.57 grass carps. In contrast, a satsuma orchard （1 mu） could support about 1.96 pigs, the equipped biogas pool （1.35 m3） could support 841.53 kg duckweeds and the fish pond could support 18.44 grass carps. [Conclusion] The results provided scientific references for quantitative allocation of members in ＂pig-methane-fruit-fish＂ model when popularized in headwaters of Dongjiang River.展开更多
Understanding the differences in yield traits of rice among pothole seedling of mechanical transplanting （PSMT）, carpet seedling of mechanical transplanting （CSMT） and mechanical direct seeding （MDS） is of great...Understanding the differences in yield traits of rice among pothole seedling of mechanical transplanting （PSMT）, carpet seedling of mechanical transplanting （CSMT） and mechanical direct seeding （MDS） is of great importance not only for rice scientists but also for rice farmers to develop a high-yield production system under mechanical conditions in a rice-wheat rotation system. However, such traits are yet to be studied among rice varieties ofjaponica-indica hybrid rice （JIHR）,japonica conventional rice （JCR） and indica hybrid rice （IHR）. Field experiments were conducted in 2014 and 2015, where six cultivars of the three rice types JIHR, JCR and IHR were grown individually with PSMT, CSMT and MDS methods, under respective managements for each method to achieve the maximum attainable yield. Results showed that （i） the PSMT significantly increased grain yield of JIHR by 22.0 and 7.1%, of JCR by 15.6 and 3.7% and of I HR by 22.5 and 7.4%, compared to MDS and CSMT on average across the two years, respectively. The highest yield was produced by the combination of JIHR and PSMT; （ii） high yield under PSMT was mainly attributed to large sink capacity and high-efficient dry matter accumulation. With sufficient panicles per hectare, the increase of spikelet number per panicle, especially the increase in spikelet number of the secondary rachis-branches was determined to be the optimal approach for developing a large sink capacity for rice under PSMT. The optimal tillers development, large leaf area index at heading stage, and high leaf area duration, crop growth rate and net assimilation rate during grain-filling phase could be the cause of sufficient dry matter accumulation for rice under PSMT; （iii） moreover, the PSMT favored plant growth as well as enriched the stems plus sheaths during grain-filling phase, as compared with CSMT and MDS. These results suggest that PSMT may be an alternative approach to increasing grain yield in a rice-wheat rotation system in the lower reaches of the Yangtze River in China.展开更多
Rational nitrogen(N) application can greatly increase rice(Oryza sativa L.) yield. However, excessive N input can lead not only to low N use efficiency(NUE) but also to severe environmental pollution.Reducing N applic...Rational nitrogen(N) application can greatly increase rice(Oryza sativa L.) yield. However, excessive N input can lead not only to low N use efficiency(NUE) but also to severe environmental pollution.Reducing N application rate with a higher planting density(RNHD) is recommended to maintain rice yield and improve NUE. The effects of RNHD on fertilizer N fate and rice root growth traits remain unclear. We accordingly conducted a two-year field experiment to investigate the influence of RNHD on rice yield, fertilizer 15N fate, and root growth in a double-rice cropping system in China. In comparison with the conventional practice of high N application with sparse planting, RNHD resulted in similar yield and biomass production as well as plant N uptake. RNHD increased agronomic NUEs by 23.3%–31.9%(P < 0.05) and N recovery efficiency by 17.4%–24.1%(P < 0.05). RNHD increased fertilizer 15N recovery rate by 14.5%–34.7%(P < 0.05), but reduced15 N retention rate by 9.2%–12.0%(P < 0.05). Although a reduced N rate led to significantly reduced root length, surface area, volume, and biomass, these root traits were significantly increased by higher planting density. RNHD did not affect these root morphological traits and reduced activities of nitrate reductase(NR) and glutamine synthetase(GS) only at tillering stage. Plant N uptake was significantly positively correlated with these root traits, but not correlated with NR and GS activities. Together, these findings show that reducing N application with dense planting can lead to high plant N uptake by maintaining rice root growth and thus increase NUE.展开更多
The herbaceous peony(Paeonia lactiflora Pall.)has high ornamental value.Replanting problems occur when seedlings are replanted into previous holes.We studied the root system and soil environment of the'Dongjingnvl...The herbaceous peony(Paeonia lactiflora Pall.)has high ornamental value.Replanting problems occur when seedlings are replanted into previous holes.We studied the root system and soil environment of the'Dongjingnvlang'variety under a continuous planting regime of one,four,and seven years,and a replanting regime of one and four years.Under the condition of continuous planting,with the increase of number of years,pH,ammonium nitrogen,and nitrate nitrogen decreased in the rhizosphere and non-rhizosphere soils,whereas organic matter,available phosphorus and potassium,enzyme activities,and the number of bacteria,fungi,and actinomycetes increased.Under the condition of replanting,with the increase of number of years,fungi and actinomycetes in both soils increased,while pH,organic matter,nutrients,enzyme activities,and bacterial number decreased.pH,organic matter,nutrient content,enzyme activity and the number of bacterial were lower in soil replanted for four years,whereas the abundance of fungi and actinomycetes was higher,altering the soil from“bacterial high-fertility”to“fungal low-fertility”with increasing years of replanting.The activity of antioxidant enzymes and MDA content in roots of peony in replanting were higher than those in continuous planting,while the content of osmotic regulatory substances in replanting was lower than that in continuous planting.The results showed that there were no obvious adverse factors in soil during seven years of continuous planting,and herbaceous peony could maintain normal growth and development.However,soils after four years of replanting were not suitable for herbaceous peony growth.Benzoic acid increased with years of replanting,which potentially caused replanting problems.This study provides a theoretical basis for understanding the mechanism of replanting problems in the herbaceous peony.展开更多
Based on climate data from 254 meteorological stations, this study estimated the effects of climate change on rice planting boundaries and potential yields in the southern China during 1951-2010. The results indicated...Based on climate data from 254 meteorological stations, this study estimated the effects of climate change on rice planting boundaries and potential yields in the southern China during 1951-2010. The results indicated a signiifcant northward shift and westward expansion of northern boundaries for rice planting in the southern China. Compared with the period of 1951-1980, the average temperature during rice growing season in the period of 1981-2010 increased by 0.4＆#176;C, and the northern planting boundaries for single rice cropping system （SRCS）, early triple cropping rice system （ETCRS）, medium triple cropping rice system （MTCRS）, and late triple cropping rice system （LTCRS） moved northward by 10, 30, 52 and 66 km, respectively. In addition, compared with the period of 1951-1980, the suitable planting area for SRCS was reduced by 11%during the period of 1981-2010. However, the suitable planting areas for other rice cropping systems increased, with the increasing amplitude of 3, 8, and 10%for ETCRS, MTCRS and LTCRS, respectively. In general, the light and temperature potential productivity of rice decreased by 2.5%. Without considering the change of rice cultivars, the northern planting boundaries for different rice cropping systems showed a northward shift tendency. Climate change resulted in decrease of per unit area yield for SRCS and the annual average yields of ETCRS and LTCRS. Nevertheless, the overall rice production in the entire research area showed a decreasing trend even with the increasing trend of annual average yield for MTCRS.展开更多
Seed shattering is a common problem in early soybean production system (ESPS) in the Midsouth, which mainly uses maturity group (MG) IV soybeans. Many studies have been conducted on the genetics of soybean shattering ...Seed shattering is a common problem in early soybean production system (ESPS) in the Midsouth, which mainly uses maturity group (MG) IV soybeans. Many studies have been conducted on the genetics of soybean shattering resistance for individual varieties;however, information on the physiology of soybean shattering pattern under specific environmental conditions, which is often critical to soybean growers, is very limited. Field experiments were conducted at Stoneville MS from 2007 to 2009 to investigate the shattering patterns of 80-132 MG IV soybean varieties each year. Results from 2007 and 2008 indicated that, when April-planted MG IV soybeans matured in mid- to late August, pods of most soybean varieties did not shatter within the first three weeks after maturity (WAM) and there was no significant shattering effect on final yields. However, differences in pod shattering among the varieties became apparent in the fourth WAM. Late-planted MG IV soybeans, which matured in early September, had a low shattering rate and could hold seeds up to 6 WAM before reaching a critical shattering point. Most soybean varieties planted in April 2009 did not show significant pod shattering by the end of the fourth WAM. The critical point of shattering was not reached until 6 - 7 WAM. Relatively lower temperatures and abundant rainfall during the late growing season in 2009 may be the main reasons causing delayed shattering in April-planted MG IV soybeans. Results from the May-planting of 2007 and the April-planting of 2009 indicated that soybeans maturing after September have much less problematic shattering. Different weather patterns, especially temperature and rainfall in each year could be essential factors affecting seed shattering patterns.展开更多
文摘Effect of application of K fertilizer and wheat straw to soil on crop yield and status of soil K in the plough layer under different planting systems was studied.The experiments on long-term application of K fertilizer and wheat straw to soil in Hebei fluvo aquic soil and Shanxi brown soil in northern China were begun in 1992.The results showed that K fertilizer and straw could improve the yields of wheat and maize with the order of NPK+St〉NPK〉NP+St〉NP,and treatment of K fertilizer made a significant difference to NP,and the efficiency of K fertilizer in maize was higher than in wheat under rotation system of Hebei.In contrast with Shanxi,the wastage of soil potassium was a more serious issue in the rotation system in Hebei,only treatment of NPK+St showed a surplus of potassium and the others showed a wane.K fertilizer and straw could improve the content of water-soluble K,nonspecifically adsorbed K,non-exchangeable K,mineral K,and total K in contrast to NP;however,K fertilizer and straw reduce the proportion of mineral K and improve proportion of other forms of potassium in the two locating sites.Compared with the beginning of orientation,temporal variability character of soil K content and proportion showed a difference between the two soil types;furthermore,there was a decrease in the content of mineral K and total K simultaneously in the two locating sites.As a whole,the effect of K fertilizer applied to soil directly excelled to wheat straw to soil.Wheat straw to soil was an effective measure to complement potassium to increase crop yield and retard the decrease of soil K.
文摘Lessons learned from past experiences push for an alternate way of crop production.In India,adopting high density planting system(HDPS)to boost cotton yield is becoming a growing trend.HDPS has recently been considered a replacement for the current Indian production system.It is also suitable for mechanical harvesting,which reducing labour costs,increasing input use efficiency,timely harvesting timely,maintaining cotton quality,and offering the potential to increase productivity and profitability.This technology has become widespread in globally cotton growing regions.Water management is critical for the success of high density cotton planting.Due to the problem of freshwater availability,more crops should be produced per drop of water.In the high-density planting system,optimum water application is essential to control excessive vegetative growth and improve the translocation of photoassimilates to reproductive organs.Deficit irrigation is a tool to save water without compromising yield.At the same time,it consumes less water than the normal evapotranspiration of crops.This review comprehensively documents the importance of growing cotton under a high-density planting system with deficit irrigation.Based on the current research and combined with cotton production reality,this review discusses the application and future development of deficit irrigation,which may provide theoretical guidance for the sustainable advancement of cotton planting systems.
基金Supported by the USDA-NRI,USA(No.NRI-2007-03307)the USDA Southern Region SARE Program,USA(No.2012-02978)+2 种基金the China Scholarship Council(No.[2006]3085)the National Natural Science Foundation of China(No.41201259)the Natural Science Foundation of Shaanxi Province,China(No.2013JQ5001)
文摘Management intensity critically influences the productivity and sustainability of pasture systems through modifying soil microbes, and soil carbon （C） and nutrient dynamics; however, such effects are not well understood yet ir the southeastern USA. We examined the effects of grazing intensity and grass planting system on soil C and nitrogen （N） dynamics, and microbial biomass and respiration in a long-term field experiment in Goldsboro, North Carolina, USA. A split-plot experiment was initiated in 2003 on a highly sandy soil under treatments of two grass planting systems （ryegrass rotation with sorghum-sudangrass hybrid and ryegrass seeding into a perennial bermudagrass stand） at low and high grazing densities. After 4 years of continuous treatments, soil total C and N contents across the 0 30 cm soil profile were 24.7% and 17.5% higher at the high than at the low grazing intensity, likely through promoting plant productivity and C allocation belowground as well as fecal and urinary inputs. Grass planting system effects were significant only at the low grazing intensity, with soil C, N, and microbial biomass and respiration in the top 10 cm being higher under the ryegrass/bermudagrass than under the ryegrass/sorghum-sudangrass hybrid planting systems. These results suggest that effective management could mitigate potential adverse effects of high grazing intensities on soil properties and facilitate sustainability of pastureland.
文摘Conversion of potato from conventional methods to wide bed planting systems may increase water and nitrogen use efficiency in commercial potato production system by reducing the amount of irrigation water and water applied nitrogen fertilizer bypassing the potato root zone. Potato (Solanum tuberosum L) cv. Desiree was tested against different planting system for yield and yield components at Kaghan, a high mountainous Himalayan region ofPakistan. The experiment was carried out at Himalayan Agricultural Research Station (HARS), Kaghan during the summer season of 2005. The results showed that maximum tuber growth (88.7%), number of stems per plant (3.5), plant expansion (45.5 cm), average number of tubers per plant (10.1) and yield per hectare (12.4 t/ha) were significantly different and higher when potatoes were planted on wide bed and covered with soil from one side. Tallest plants (53.4 cm) were observed when potatoes were sown on the ridges. Maximum number of green potatoes (12.5) and injured potatoes (5.3%) were observed when the tubers were planted following local farmers’ method. Keeping in view the soil type, land slopping, we recommend sowing potatoes on relatively plain wide beds and covering it with soil from one side, for potato cultivation in the area.
基金Supported by Science and Technology Project of China Tobacco Zhejiang Industrial Co.,Ltd.(2023330000340093).
文摘[Objectives]To investigate the effects of different planting densities and nitrogen application rates on the yield and quality of the tobacco cultivar Chuxue 80.[Methods]A field experiment was conducted in Hubei Province,evaluating various combinations of planting density and nitrogen rate for Chuxue 80.[Results]At the maturity stage,the TN1 treatment(5 kg N per 667 m^(2) with a density of 1900 plants per 667 m^(2))demonstrated the most favorable agronomic performance.The TN9 treatment(11 kg N per 667 m^(2) with a density of 1110 plants per 667 m^(2))achieved the highest wrapper tobacco yield and output value.Meanwhile,the TN5 treatment(8 kg N per 667 m^(2) with a density of 1515 plants per 667 m^(2))resulted in the best smoking quality.[Conclusions]The TN9 treatment,with a planting density of 1110 plants per 667 m^(2) and a nitrogen application rate of 11 kg per 667 m^(2),is recommended as the optimal cultivation practice for Chuxue 80 in Hubei Province.
基金financially supported by the Tianshan Talent Development Program,China for Yali Zhangthe Natural Science Foundation of Xinjiang Production and Construction Corps,China(2024DA002)the Earmarked Fund for XJARS-Cotton,China(XJARS-03)。
文摘Hydraulic theory predicts a positive coupling between leaf hydraulic conductance(K_(leaf))and stomatal conductance(g_(s));however,this theory has not been fully supported by observations,and underlying mechanisms are poorly understood.Partitioning K_(leaf)into inside-xylem(K_(x))and outside-xylem(K_(ox))components offers a refined framework for elucidating the regulation of g_(s) by leaf hydraulics.While optimal planting density may enhance water use efficiency(WUE)through modulation of g_(s),corresponding changes in leaf hydraulic properties and their influence on gas exchange remain unclear.We examined relationships among K_(x),K_(ox),g_(s),leaf photosynthetic rate(A_(N)),and WUE,and analyzed the structural determinants of K_(ox)in cotton grown under eight planting densities:12,18,24,36,48,60,72,and 84 plants m^(–2).Results showed that as planting density increased,K_(leaf)and A_(N) remained stable,whereas K_(ox)and g_(s) declined significantly.Leaf thickness and the volume fraction of inter-cellular air space were key structural factors influencing K_(ox).Neither K_(leaf)nor K_(x)correlated with A_(N) or g_(s);however,K_(ox)exhibited a significant positive correlation with g_(s).Furthermore,K_(ox)was negatively correlated with WUE.These findings indicate that K_(ox)modulates g_(s) to minimize water loss without compromising A_(N),thereby enhancing WUE in cotton across varying planting densities.
基金supported by the National Natural Science Foundation of China(32071960)the National Key Research and Development Program of China(2018YFD0300603)。
文摘In maize production,the development of density-tolerant and lodging-resistant varieties has made dense planting an effective strategy for achieving high and stable yields,with superior hybrids serving as a prerequisite for successful highdensity cultivation.However,the photosynthetic mechanisms underlying improved density tolerance in maize hybrids released across different eras in China remain unclear.This study investigates 40 years of breeding progress toward enhanced photosynthetic traits under varying planting densities and elucidates the physiological and ecological bases of improved density tolerance in maize hybrids.A three-year field experiment was conducted from 2019 to 2021 to compare eight major Chinese hybrids from four decadal cohorts under three planting densities:45,000(D1),67,500(D2),and 90,000(D3)plants ha^(-1).At high density(D3),modern hybrids exhibited a more optimal canopy architecture and superior leaf photosynthetic performance compared to older hybrids,despite a slight reduction in specific leaf nitrogen.Notably,modern hybrids(2000s)were able to maintain higher net photosynthetic rates and photosynthetic nitrogen use efficiency(PNUE)at D3,resulting in the highest grain yield(GY),which was 118.47%greater than that of older hybrids(1970s).Leaf area duration after anthesis,total chlorophyll content,key photosynthetic enzyme activities,and maximum quantum efficiency of PSII photochemistry were all positively correlated with GY.Among these,PNUE showed the strongest correlation with grain yield and thus represents a key indicator for optimizing maize hybrids.Based on these findings,breeders should continue selecting hybrids under high-density and suboptimal conditions,focusing on optimizing population architecture and enhancing photosynthetic capacity while fine-tuning leaf nitrogen status to develop high-yielding,density-tolerant hybrids capable of sustaining long-term increases in maize grain yield.
基金National Natural Science Foundation of China,No.42041007。
文摘Rising global change intensifies water scarcity in China’s vital Yellow River Basin grain region,which mounts the need for precise spatial water management.In this study,we investigated the irrigation water demand for seven major crops in cities at the prefecture level between 2000 and 2019.Using Logarithmic Mean Divisia Index(LMDI)decomposition and k-means clustering,we quantified how yield,area,water use efficiency,and cropping patterns affect water demand and identified five irrigation development clusters.Key water-saving areas were identified by tracking transitions among clusters,and NSGA-II was applied to optimize crop structure.The results revealed that the total irrigation demand in the Yellow River Basin averaged 50.09 billion m3/year,with wheat accounting for 54.7%.The increase in yield and area increased demand by 15.2 and 5.5 billion m3,respectively,which was partly offset by changes in water use efficiency and cropping pattern(−7.0 and−1.8 billion m^(3),respectively).Regions in the upper reaches,particularly within the Lanzhou-Toudaoguai section,were identified as critical for water conservation.Optimization of the cropping structure in key regions can reduce annual irrigation water demand by 280 million m3,which accounts for 4.9%of the total demand in these areas,with minimal impact on crop production.This study provides a spatially explicit basis for targeted water conservation strategies in water-scarce agricultural regions.
基金supported by the Hubei Provincial Science and Technology Project,China(2025CSA039)the National Natural Science Foundation of China(32001467)。
文摘Coordinating light and nitrogen(N)distribution within a canopy is essential for improving rice yield and resource use efficiency.However,limited research has examined light and N distribution in response to planting density and N rate,and their relationships with grain yield,radiation use efficiency(RUE),and N use efficiency for grain production(NUEg)in rice.A two-year field experiment was conducted with two hybrid varieties under three N levels,0 kg ha^(-1)(N1),90 kg ha^(-1)(N2)and 180 kg ha^(-1)(N3),and two planting densities,22.2 hills m-2(D1)and 33.3 hills m^(-2)(D2).Results showed 3.4%higher yield and 4.4%higher NUEg under N2D2 compared with N3D1.The extinction coefficient for N(K_(N))and light(K_(L))and their ratio(K_(N)/K_(L))at heading stage were significantly influenced by N rate,planting density,and their interaction.K_(N)decreased with the increase of N input or planting density.Compared to N1,K_(N)decreased by 43.5 and 58.8%under N2 and N3,respectively,while K_(N)under D2 decreased by 16.0%compared to D1.Higher K_(L)and K_(N)/K_(L)values occurred under low N rates,with opposite trends under high N rates.Increased planting density led to decreased K_(L)and K_(N)/K_(L)values.N2D2 demonstrated higher K_(L)and K_(N),and thus comparable K_(N)/K_(L),compared to N3D1.Correlation analysis revealed K_(L)negatively correlated with RUE,while K_(N)and K_(N)/K_(L)positively correlated with NUEg.These findings indicate that increasing planting density under reduced N input could maintain rice yield while enhancing resource use efficiency through regulation of canopy light and N distribution.
基金supported by the National Key Research and Development Program of China(2025YFE0103800,2023YFE0102600,2024YFE0214200).
文摘Livestock farming is a critical pillar of Tajikistan’s national economy and livelihood security.However,significant economic challenges in the country have led to the degradation of grassland ecosystems.This degradation has not only reduced the productivity of grassland ecosystems but also severely impacted their ecological functions.A particularly concerning consequence is the threat to biodiversity,as the survival and persistence of endemic,rare,and endangered plant species are at serious risk,thereby diminishing the value of species’genetic resources.Based on the data from multiple sources such as literature reviews,field observations,and national statistics,this study employed a systematic literature review and meta-analysis to investigate the current status,causes of degradation,and restoration measures for grassland ecosystems in Tajikistan.The results revealed that Tajikistan’s grassland ecosystems support exceptionally high plant species diversity,comprising over 4500 vascular plant species,including nearly 1500 endemic and sub-endemic taxa that constitute a unique genetic reservoir.These ecosystems are experiencing severe degradation,characterized by significantly reduced vegetation cover and declining species richness.Palatable forage species are increasingly being displaced by unpalatable,thorny,and poisonous species.The primary drivers of degradation include excessive grazing pressure,which disrupts plant reproductive cycles and regeneration capacity,habitat fragmentation due to urbanization and infrastructure development,and uncontrolled exploitation of medicinal and edible plants.Climate change,particularly rising temperatures and altered precipitation patterns,further exacerbates these anthropogenic pressures.Ecological restoration experiments suggested that both ecosystem productivity and plant species diversity are significantly enhanced by systematic reseeding trials using altitude-adapted native species.These findings underscore the necessity of establishing scientifically grounded approaches for ecological restoration.
基金supported by the National Natural Science Foundation of China(32471603)Science and Technology Commissioner Special Project of Qinghai Province(2025-NK-P42)+2 种基金Central Financial Funds for Forestry and Grassland Reform and Development in 2024(2024-TG16)Hainan Tibetan Autonomous Prefecture Science and Technology Program Project(2025-KH01-B)the leading Kunlun talents in Qinghai Province.
文摘As a critical global ecosystem,grasslands rely on complex aboveground-belowground interactions that underpin multifunctionality,yet their mechanisms remain poorly understood.Our investigation employed the plateau pika(Ochotona curzoniae),a small herbivore widely distributed throughout the Qinghai-Tibetan Plateau,as a model organism to examine the consequences of disturbance on plant diversity,soil properties,microbial diversity,and multifunctionality of grassland ecosystems.We found that high pika burrow density significantly reduced plant diversity(Shannon-Wiener and Chao1 indices)and aboveground biomass.It also increased soil pH and reduced ammonium nitrogen content.The soil microbial diversity,encompassing both bacteria and fungi,was markedly decreased in areas characterized by a high concentration of burrows.Microbial interaction networks demonstrated greater complexity in areas with high burrow densities,as revealed by the network analysis.Conversely,in regions characterized by low burrow density,a significant negative correlation was observed between the intricacy of soil bacterial networks and the multifunctionality of grassland ecosystems.Structural equation modelling showed that pika disturbance indirectly affected multifunctionality via changes in plant biomass and soil properties-notably,nitrate nitrogen explained 40%of multifunctionality variation under high disturbance.This investigation advances our understanding of complex aboveground-belowground linkages in grassland ecosystems,revealing novel mechanisms through which biodiversity governs ecosystem multifunctionality.Our findings underscore the critical role of small herbivores in shaping grassland ecosystem functions and emphasize the importance of maintaining balanced disturbance regimes to sustain ecosystem multifunctionality.This has immediate implications for global conservation policies on the Qinghai-Tibetan Plateau and analogous ecosystems.
文摘Non-native plants are increasingly recognized as ecosystem engineers across a wide range of ecosystems.While their impacts on understory composition have been widely documented,consequences for community assembly remain largely unexplored.We investigated the engineering impacts of Sorbaria sorbifolia,a naturalized Rosaceae shrub,on abiotic conditions and understory community assembly in Central European forests.Across 60 plots spanning coniferous and deciduous stands,we quantified light availability,organic layer C/N ratio and thickness,and understory functional diversity along an invasion gradient.Using ordination and linear regression,we found that increasing S.sorbifolia cover reduced light availability,thickened the organic layer,and altered C/N ratio in contrasting,forest-type-specific ways.In coniferous stands,invasion increased C/N and strongly suppressed understory light,whereas in deciduous stands it reduced C/N with weaker shading effects.These changes translate into consistent declines in functional richness and dispersion,particularly in coniferous forests where invasion led to homogenization of the understory.Trait shifts indicated stronger habitat filtering under invasion,with declines in specific leaf area(SLA)and increases in leaf dry matter content and seed mass,reflecting exclusion of light-demanding species and persistence of stress-tolerant taxa and woody seedlings.Remarkably,once S.sorbifolia exceeded~50%cover,positive relationships between habitat properties and understory functional diversity collapsed,replaced by uniform light limitation.This threshold effect highlights S.sorbifolia as an ecosystem engineer,capable of transforming forest structure and regeneration trajectories.Early detection and management are therefore crucial to prevent long-term homogenization and the formation of novel,invasion-driven forest states.
文摘Arid and semi-arid ecosystems are prone to extensive fires due to specific climatic conditions,sparse vegetation cover,and high density of fine fuels.Understanding the flammability characteristics of land covers is essential for fire management and designing land restoration programs in arid and semi-arid ecosystems.This study provided a new approach to evaluate the flammability of shrublands and woodlands using flammability indices(FIs)including time to ignition(TI),duration of combustion(DC),and flame height(FH)of plant species and their relative frequencies in the Dalfard Basin of southeastern Iran.The results showed that there was a significant difference in FIs between land covers.Shrublands had higher flammability potential compared with woodlands.Plant moisture content had a negative relationship with TI(P<0.010)and no significant relationship with DC and FH(P>0.050).Artemisia spp.,Astragalus gossypinus Fischer,Amygdalus scoparia Spach,and Cymbopogon jwarancusa(Jones)Schult.had the highest FI.Tree species such as Rhazya stricta Decne.,and Pistacia atlantica Desf.showed greater resistance to fire.Using principal component analysis,the relationship between species and FIs was examined,and TI of wet fuel was the most important FI in relation to species.Structural equation model showed that life form(P<0.001)was the most important flammability driver.Precipitation(P<0.010)and legume species(P<0.010)were significantly related to the flammability in arid land.This study emphasizes the importance of managing high-risk species and using resistant species in vegetation restoration and shows that combining species FIs with their abundance is an effective tool for assessing fire risk and fuel management at the plant community scale.
基金supported by the Science and Technology Project of China Southern Power Grid Co.,Ltd.(ZBKTM20232244)the Project of National Natural of Science Foundation of China(52477103).
文摘The real-time and accurate calculation of electricity indirect carbon emissions is not only the critical component for quantifying the carbon emission levels of the power system but also an effective mean to guide electricity users in carbon reduction and promote power industry low-carbon transformation.Fundamentally,calculating indirect carbon emissions involves allocating direct carbon emission data from the power source side,indicating that accurate indirect emission results rely on the precise measurement of power source emissions.However,existing research on indirect carbon emissions in large-scale power systems rarely accounts for variations in carbon emission characteristics under different operating conditions of power sources,such as rated/non-rated operating conditions and ramping up/down conditions,making it difficult to reflect source-side and load-side carbon emission information variation during providing ancillary services.Quadratic and exponential functions are proposed to characterize the energy consumption profiles of coal-fired and gas-fired power generation,respectively,to construct a refined carbon emission model for power sources.By leveraging the theory of power system carbon flow,we analyze how variable operating conditions of power sources impact indirect carbon emissions.Case studies demonstrate that changes in power source emissions under variable conditions have a significant effect on the indirect carbon emissions of power grids.
基金Supported by "Control and Treatment of Water Pollution" in National Science and Technology Major Project of China (2009ZX07211-001)~~
文摘[Objective] The aim was to promote nutrient cycling and utilization in the mountain＇s system combining fruits and poultry and to control non-point source pollution produced from swine raising and navel orange planting in headwaters of Dongjiang River. [Method] The quantitative analysis was mainly conducted for the so called ＂raising by planting＂ which is about material cycle in ＂pig-methane-fruit-fish＂ model and energy cascade utilization, based on relationship between excreted amount by livestock and the utilized quantity in Xinlin Farm in Longtang Town, Dingnan County, Jiangxi Province. [Result] Considering N requirement by fruit trees, a navel orange orchard （1 mu） could support about 2.72 pigs, the equipped biogas pool （1.88 m3） could support 1 166.67 kg of duckweeds and a fish pond could support 25.57 grass carps. In contrast, a satsuma orchard （1 mu） could support about 1.96 pigs, the equipped biogas pool （1.35 m3） could support 841.53 kg duckweeds and the fish pond could support 18.44 grass carps. [Conclusion] The results provided scientific references for quantitative allocation of members in ＂pig-methane-fruit-fish＂ model when popularized in headwaters of Dongjiang River.
基金The Special Fund for Agro-scientific Research in the Public Interest(201303102)the Major Independent Innovation Project in Jiangsu Province,China(CX(15)1002)+3 种基金the National Key Research Program of China(2016YFD0300503)the Science and Technology Plan of Jiangsu Province,China(BE2015340)the Research Innovation Program for College Graduates of Jiangsu Province,China(KYLX15_1369)a Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions,China supported this study
文摘Understanding the differences in yield traits of rice among pothole seedling of mechanical transplanting （PSMT）, carpet seedling of mechanical transplanting （CSMT） and mechanical direct seeding （MDS） is of great importance not only for rice scientists but also for rice farmers to develop a high-yield production system under mechanical conditions in a rice-wheat rotation system. However, such traits are yet to be studied among rice varieties ofjaponica-indica hybrid rice （JIHR）,japonica conventional rice （JCR） and indica hybrid rice （IHR）. Field experiments were conducted in 2014 and 2015, where six cultivars of the three rice types JIHR, JCR and IHR were grown individually with PSMT, CSMT and MDS methods, under respective managements for each method to achieve the maximum attainable yield. Results showed that （i） the PSMT significantly increased grain yield of JIHR by 22.0 and 7.1%, of JCR by 15.6 and 3.7% and of I HR by 22.5 and 7.4%, compared to MDS and CSMT on average across the two years, respectively. The highest yield was produced by the combination of JIHR and PSMT; （ii） high yield under PSMT was mainly attributed to large sink capacity and high-efficient dry matter accumulation. With sufficient panicles per hectare, the increase of spikelet number per panicle, especially the increase in spikelet number of the secondary rachis-branches was determined to be the optimal approach for developing a large sink capacity for rice under PSMT. The optimal tillers development, large leaf area index at heading stage, and high leaf area duration, crop growth rate and net assimilation rate during grain-filling phase could be the cause of sufficient dry matter accumulation for rice under PSMT; （iii） moreover, the PSMT favored plant growth as well as enriched the stems plus sheaths during grain-filling phase, as compared with CSMT and MDS. These results suggest that PSMT may be an alternative approach to increasing grain yield in a rice-wheat rotation system in the lower reaches of the Yangtze River in China.
基金supported by the National Natural Science Foundation of China(31601263)the National Key Research and Development Program of China(2018YFD0301103)+2 种基金the China Postdoctoral Science Foundation(2017M622100)the Jiangxi Province Postdoctoral Science Foundation(2017KY11)the Open Foundation of Guangxi Key Laboratory of Rice Genetics and Breeding(160-380-16-2)。
文摘Rational nitrogen(N) application can greatly increase rice(Oryza sativa L.) yield. However, excessive N input can lead not only to low N use efficiency(NUE) but also to severe environmental pollution.Reducing N application rate with a higher planting density(RNHD) is recommended to maintain rice yield and improve NUE. The effects of RNHD on fertilizer N fate and rice root growth traits remain unclear. We accordingly conducted a two-year field experiment to investigate the influence of RNHD on rice yield, fertilizer 15N fate, and root growth in a double-rice cropping system in China. In comparison with the conventional practice of high N application with sparse planting, RNHD resulted in similar yield and biomass production as well as plant N uptake. RNHD increased agronomic NUEs by 23.3%–31.9%(P < 0.05) and N recovery efficiency by 17.4%–24.1%(P < 0.05). RNHD increased fertilizer 15N recovery rate by 14.5%–34.7%(P < 0.05), but reduced15 N retention rate by 9.2%–12.0%(P < 0.05). Although a reduced N rate led to significantly reduced root length, surface area, volume, and biomass, these root traits were significantly increased by higher planting density. RNHD did not affect these root morphological traits and reduced activities of nitrate reductase(NR) and glutamine synthetase(GS) only at tillering stage. Plant N uptake was significantly positively correlated with these root traits, but not correlated with NR and GS activities. Together, these findings show that reducing N application with dense planting can lead to high plant N uptake by maintaining rice root growth and thus increase NUE.
基金supported by grants from the National Natural Science Foundation of China(Grant No.31670663).
文摘The herbaceous peony(Paeonia lactiflora Pall.)has high ornamental value.Replanting problems occur when seedlings are replanted into previous holes.We studied the root system and soil environment of the'Dongjingnvlang'variety under a continuous planting regime of one,four,and seven years,and a replanting regime of one and four years.Under the condition of continuous planting,with the increase of number of years,pH,ammonium nitrogen,and nitrate nitrogen decreased in the rhizosphere and non-rhizosphere soils,whereas organic matter,available phosphorus and potassium,enzyme activities,and the number of bacteria,fungi,and actinomycetes increased.Under the condition of replanting,with the increase of number of years,fungi and actinomycetes in both soils increased,while pH,organic matter,nutrients,enzyme activities,and bacterial number decreased.pH,organic matter,nutrient content,enzyme activity and the number of bacterial were lower in soil replanted for four years,whereas the abundance of fungi and actinomycetes was higher,altering the soil from“bacterial high-fertility”to“fungal low-fertility”with increasing years of replanting.The activity of antioxidant enzymes and MDA content in roots of peony in replanting were higher than those in continuous planting,while the content of osmotic regulatory substances in replanting was lower than that in continuous planting.The results showed that there were no obvious adverse factors in soil during seven years of continuous planting,and herbaceous peony could maintain normal growth and development.However,soils after four years of replanting were not suitable for herbaceous peony growth.Benzoic acid increased with years of replanting,which potentially caused replanting problems.This study provides a theoretical basis for understanding the mechanism of replanting problems in the herbaceous peony.
基金supported by the National Basic Research Program of China(2010CB951502)the Special Fund for Meteorology-Scientific Research in the Public Interest,China(GYHY201106020)
文摘Based on climate data from 254 meteorological stations, this study estimated the effects of climate change on rice planting boundaries and potential yields in the southern China during 1951-2010. The results indicated a signiifcant northward shift and westward expansion of northern boundaries for rice planting in the southern China. Compared with the period of 1951-1980, the average temperature during rice growing season in the period of 1981-2010 increased by 0.4＆#176;C, and the northern planting boundaries for single rice cropping system （SRCS）, early triple cropping rice system （ETCRS）, medium triple cropping rice system （MTCRS）, and late triple cropping rice system （LTCRS） moved northward by 10, 30, 52 and 66 km, respectively. In addition, compared with the period of 1951-1980, the suitable planting area for SRCS was reduced by 11%during the period of 1981-2010. However, the suitable planting areas for other rice cropping systems increased, with the increasing amplitude of 3, 8, and 10%for ETCRS, MTCRS and LTCRS, respectively. In general, the light and temperature potential productivity of rice decreased by 2.5%. Without considering the change of rice cultivars, the northern planting boundaries for different rice cropping systems showed a northward shift tendency. Climate change resulted in decrease of per unit area yield for SRCS and the annual average yields of ETCRS and LTCRS. Nevertheless, the overall rice production in the entire research area showed a decreasing trend even with the increasing trend of annual average yield for MTCRS.
文摘Seed shattering is a common problem in early soybean production system (ESPS) in the Midsouth, which mainly uses maturity group (MG) IV soybeans. Many studies have been conducted on the genetics of soybean shattering resistance for individual varieties;however, information on the physiology of soybean shattering pattern under specific environmental conditions, which is often critical to soybean growers, is very limited. Field experiments were conducted at Stoneville MS from 2007 to 2009 to investigate the shattering patterns of 80-132 MG IV soybean varieties each year. Results from 2007 and 2008 indicated that, when April-planted MG IV soybeans matured in mid- to late August, pods of most soybean varieties did not shatter within the first three weeks after maturity (WAM) and there was no significant shattering effect on final yields. However, differences in pod shattering among the varieties became apparent in the fourth WAM. Late-planted MG IV soybeans, which matured in early September, had a low shattering rate and could hold seeds up to 6 WAM before reaching a critical shattering point. Most soybean varieties planted in April 2009 did not show significant pod shattering by the end of the fourth WAM. The critical point of shattering was not reached until 6 - 7 WAM. Relatively lower temperatures and abundant rainfall during the late growing season in 2009 may be the main reasons causing delayed shattering in April-planted MG IV soybeans. Results from the May-planting of 2007 and the April-planting of 2009 indicated that soybeans maturing after September have much less problematic shattering. Different weather patterns, especially temperature and rainfall in each year could be essential factors affecting seed shattering patterns.
