This study aimed to investigate the combined effects of nitrogen level （high and ordinary） and high temperature stress （37 ℃, 4 d） at the late panicle ini- tiation stage on yield, SPAD value and soluble sugar con...This study aimed to investigate the combined effects of nitrogen level （high and ordinary） and high temperature stress （37 ℃, 4 d） at the late panicle ini- tiation stage on yield, SPAD value and soluble sugar content of Ganxin 203, an early rice cultivar. The results showed that under both high and ordinary nitrogen levels, high temperature stress reduced the seed-setting rate, yield per stem, SPAD value and soluble sugar content of Ganxin 203; under both high and ordinary tem- peratures, high nitrogen level increased the seed-setting rate, yield per stem and soluble sugar content of Ganxin 203; the seed-setting rate, yield per stem and yield per plant of Ganxin 203 under high temperature and high nitrogen level were higher than those under high temperature and ordinary nitrogen level. It suggests that ap- propriate high nitrogen level contributes to weakening the negative effects of high temperature stress on rice yield.展开更多
Controlled experiment of Leymus chinensis seedlings grown in the environmental growth chambers at 3 soil moisture levels and 3 temperature levels was conducted in order to improve the understanding how leaf photosynth...Controlled experiment of Leymus chinensis seedlings grown in the environmental growth chambers at 3 soil moisture levels and 3 temperature levels was conducted in order to improve the understanding how leaf photosynthetic parameters will respond to climatic change. The results indicated that soil drought and high temperature decreased the photochemical efficiency of photosystem(F v/F m), the overall photochemical quantum yield of PSII(yield), the coefficient of photochemical fluorescence quenching(q\-P), but increased the coefficient of non-photochemical fluorescence quenching(q\-N). Severe soil drought would decrease F v/F m and yield by 3.12% and 37.04% under 26℃ condition, respectively, and 6.60% and 73.33% under 32℃ condition, respectively, suggesting that higher temperature may enhance the negative effects of soil drought. All the soil drought treatments resulted in the decline in leaf nitrogen content. There was no significant effect of temperature on leaf nitrogen level, but higher temperature significantly reduced the root nitrogen content and the ratio of root nitrogen to leaf nitrogen, indicating the different strategies of adaptation to soil drought and temperature. It was also implied that higher temperature would enhance the effect of soil drought on leaf photosynthetic capacity, decrease the adaptability of Leymus chinensis to drought.展开更多
Many kinds of high temperature superconductor （HTS） power machines such as HTS cable, HTS fault current limitcr and HTS magnet are cooled by liquid nitrogen. The level of liquid nitrogen should be monitored and cont...Many kinds of high temperature superconductor （HTS） power machines such as HTS cable, HTS fault current limitcr and HTS magnet are cooled by liquid nitrogen. The level of liquid nitrogen should be monitored and controlled to ensure the thermal stability and the dielectric strength as well. To measure the level, capacitance method and differential pressure method are usually used. However, each method has installation difficulties and measurement errors for unsteady state operation with varying system pressure. A new liquid level meter using a 2G HTS conductor is described, which has similar structure with the liquid helium level meter with NbTi filament. The level meter is fabricated with a parallel connected heater, which helps the separation of the superconducting region and normal region, considering the critical temperature, large heat capacity of conductor and cooling characteristics. The level of liquid nitrogen can be obtained from the measured voltage signal along the 2G HTS conductor. Design, fabrication and test results of the new liquid nitrogen level meter are presented.展开更多
A field study to evaluate the impact of different tillage regimes and nitrogen levels on yield and yield components of maize (Zea mays L.), was conducted during autumn 2014 at Students Farm, Department of Agronomy, Un...A field study to evaluate the impact of different tillage regimes and nitrogen levels on yield and yield components of maize (Zea mays L.), was conducted during autumn 2014 at Students Farm, Department of Agronomy, University of Agriculture, Faisalabad. The experiment was laid out in RCBD (Randomized Complete Block Design), with split plot arrangement having three replications. The experiment was comprised of three tillage regimes (Minimum, Conventional and Deep) and three nitrogen levels viz: 100, 200 and 300 kg•ha<sup>-1</sup>. Urea was used as a source of nitrogen, sulphate of potash as a source of potassium and triple super phosphate as a source of phosphorous. The amount of phosphorous and potash was constant in all the treatments i.e. 125 kg•ha<sup>-1</sup> and 100 kg•ha<sup>-1</sup> respectively. Results of present study are summarized as yield parameters are significantly affected by different nitrogen levels and tillage regimes. Maximum number of plants at harvest (7.93), number of grain rows per cob (17.70), number of grains per row (34.31), number of grains per cob (678.58), and cob weight (187.50 g) were observed in deep tillage at 200 kg•ha<sup>-1</sup> nitrogen application. 1000-grain weight (275.52 g), biological yield (15.66 t•ha<sup>-1</sup>), grain yield (6.16 t•ha<sup>-1</sup>) and dried stalk yield (9.91 t•ha<sup>-1</sup>) were observed maximum in deep tillage at 200 kg•ha<sup>-1</sup> nitrogen application. Harvest index significantly affected by tillage regimes and maximum harvest index (39.58%) were recorded in deep tillage which was statistically at par with conventional tillage (38.83%). It was concluded that higher grain yield of maize can be obtained by deep tillage with the application of 200 kg•ha<sup>-1</sup> nitrogen application under the prevailing conditions of Faisalabad.展开更多
The experiment of Glutamate Dehydrogenase (GDH) activity in various plant parts under different nitrogen levels in frame culture during the whole period of growth was carried out on campus of Northeast Agricltural Uni...The experiment of Glutamate Dehydrogenase (GDH) activity in various plant parts under different nitrogen levels in frame culture during the whole period of growth was carried out on campus of Northeast Agricltural University in 1993. The result showed that GDH activity in leaf blades under four nitrogen applied levels rose rapidly to the acme from the seedling to foliage rapid growth stage, then diminished rapidly to the lower level at the latter stage of foliage rapid growth. This level was kept to harvest. GDH activity in roots at each growth stage under all nitrogen levels exhibited little disparity and did not show ostensible regularity of changes. GDH activity in leaf blades was stimulated with nitrogen, however, it reduced with nitrogen fertilizer applying further. GDH activity in leaf blades was the biggest compared with crowns, petioles and roots, which suggested that it could represent the highest enzyme activityof the whole plant.展开更多
Arbuscular mycorrhizal fungi(AMF)and Bacillus play a crucial role in promoting the growth and defense of exotic plants,and their interaction may further enhance plant invasions.Soil nitrogen level is an important fact...Arbuscular mycorrhizal fungi(AMF)and Bacillus play a crucial role in promoting the growth and defense of exotic plants,and their interaction may further enhance plant invasions.Soil nitrogen level is an important factor that affects the interaction.However,the effect of the interaction on the growth and defensive ability of exotic plants under different nitrogen levels remains unclear.In this study,a pot experiment was conducted using Rhizoglomus intraradices(RI)and Bacillus megaterium(BM),one of the dominant AMF and Bacillus in the rhizosphere of Flaveria bidentis,with three soil nitrogen levels(0,3.75 and 7.5 g m^(−2))and four inoculation treatments(uninoculated,inoculation with RI,inoculation with BM and co-inoculated with RI and BM).Significant correlations were observed between microbial inoculations and indicators of plant growth and defense across varying soil nitrogen levels.Co-inoculation notably enhanced both plant growth and defense compared to single inoculations,especially under the nitrogen concentration of 3.75 g m^(−2).Specifically,compared to single inoculation,co-inoculation increased the biomass of F.bidentis by 8.27%and 16.4%,as well as the flavonoids concentration by 21.89%-30.95%and phenolic acids concentration by 54.22%-60.93%,respectively.These enhancements in growth and defensive compound production likely promote the competitive ability of F.bidentis and its resistance to biotic and abiotic stresses,thereby contributing to its successful invasion.展开更多
[Objective] The study aimed at investigating the effects of different geographic sites,soil chemical characteristics and nitrogen application levels on nitrogen accumulation and distribution in different organs and ut...[Objective] The study aimed at investigating the effects of different geographic sites,soil chemical characteristics and nitrogen application levels on nitrogen accumulation and distribution in different organs and utilization efficiency for mid-season hybrid rice.[Method] By using mid-season rice varieties II-you 7 and Yuxiangyou203 as the experimental materials,field experiment was conducted at seven ecological sites in four provinces or cities in Southwestern China in 2009.A total of four nitrogen application levels were set as follows：by using 75 kg/hm2 of P2O5 and 75 kg/hm2 of K2O as the base fertilizer,extra 0,90,150 and 210 kg/hm2 of nitrogen fertilizer（in which,base fertilizer,base-tillering fertilizer and base-earing fertilizer respectively accounted for 60%,20% and 20%.） was applied,respectively.In the split-plot design,fertilizer was considered as the main factor while rice variety was taken as the secondary factor.A total of eight treatments were set with three replications.[Result] Highly significant differences of grain yield were found among seven locations,two varieties,four nitrogen application levels,interactions of site × variety and site × nitrogen application level,but the interaction of variety ×nitrogen application level had no significant influence on rice yield.There were highly significant effects of site,varieties and nitrogen application level on dry matter production,nitrogen content,nitrogen utilization efficiency.Highly significant negative correlations between uptake efficiency and utilization efficiency for nitrogen were found;and multiple stepwise regression analysis showed that nitrogen uptake-utilization efficiency were significantly influenced by different ecological sites,chemical quality of soil and the levels of nitrogen application.[Conclusion] The research will provide theoretical and practical basis for the highly efficient application of nitrogen in mid-season hybrid rice cultivation.展开更多
It was shown from the experiment that glutamine synthetase activity (GSA) in both leaf blades and roots under different nitrogen levels rose rapidly to reach its peak from seedling stage to foliage rapid growth stage ...It was shown from the experiment that glutamine synthetase activity (GSA) in both leaf blades and roots under different nitrogen levels rose rapidly to reach its peak from seedling stage to foliage rapid growth stage and declined to its lowest level at the latter stage of root rapid growth, and then increased slightly. GSA in leaf blades had positive correlation with nitrogen level during the whole period of growth. GSA in roots showed the same tendency as it in leaf blades at the early middle stage of growth, but at the latter stage of growth, no positive correlation was established. GSA in leaf blades was the strongest compared with crowns, petioles and roots, and could represent the highest enzyme activity of the whole plant. GSA had quadratic curvilinear correlation with root yield and sugar production. GSA in leaf blades had significant positive correlation with α-NH2-N at the foliage rapid growth stage.展开更多
The experiment of glutamate synthase activity (GOGATA) in both leaf blades and roots under different nitrogen levels was carried out at Northeast Agricultural University in 1993. The result showed that GOGATA rose rap...The experiment of glutamate synthase activity (GOGATA) in both leaf blades and roots under different nitrogen levels was carried out at Northeast Agricultural University in 1993. The result showed that GOGATA rose rapidly to reach its peak from seedling stage to foliage rapid growth stage, and then declined gradually. GOGATA was enhanced with increasing nitrogen levels and had significant positive correlation with nitrogen levels at the middle stage of growth GOGATA in leaf blades was the strongest compared with crowns, petioles and roots, thus, it could represent the highest enzyme activity of the whole plant. GOGATA had quadratic curvilinear correlation with root yield and sugar production. GOGATA in leaf blades had significant positive correlation with α-NH 2-N at the foliage rapid growth stage while GOGATA in roots existed this relation at the latter stage of growth. GOGATA in roots had significant negative correlation with sugar content at harvest.展开更多
[Objective] This study aimed to investigate the effects of different fertilizer levels on lodging and yield of rice. [Method] A total of four treatments were designed and applied with 6, 9, 12 and 15 kg of nitrogen fe...[Objective] This study aimed to investigate the effects of different fertilizer levels on lodging and yield of rice. [Method] A total of four treatments were designed and applied with 6, 9, 12 and 15 kg of nitrogen fertilizer, respectively. After seedling transplanting, the biological characteristics of rice at different growth stages in each treatment and the biological and economic characteristics of rice after lodging were determined for statistical analysis. [Result] Application with 15 kg of nitrogen fertilizer had significant promotion effect on the increase of rice yield; compared with the control (6 kg of nitrogen fertilizer), rice yield in three experimental treatments (9, 12 and 15 kg of nitrogen fertilizer, respectively) increased by 50.74%, 89.11% and 94.48%, respectively; lodging-resistance mechanical strengths of the three experimental treatments were 103.97%, 132.01% and 89.83% of the control, respectively; rice lodging resistance of treatment C (12 kg of nitrogen fertilizer) was the strongest, with the highest yield. [Conclusion] This study provides reference data and technical support for the rational fertilization of rice production.展开更多
We conducted field trials of rice grown in sandy soil and clay soil to determine the effects of nitrogen application levels on the concentration of NH4＋-N in surface water, loss of ammonia through volatilization from...We conducted field trials of rice grown in sandy soil and clay soil to determine the effects of nitrogen application levels on the concentration of NH4＋-N in surface water, loss of ammonia through volatilization from paddy fields, rice production, nitrogen-use efficiency, and nitrogen content in the soil profile. The concentration of NH4＋-N in surface water and the amount of ammonia lost through volatilization increased with increasing nitrogen application level, and peaked at 1-3 d after nitrogen application. Less ammonia was lost via volatilization from clay soil than from sandy soil. The amounts of ammonia lost via volatilization after nitrogen application differed depending on the stage when it was applied, from the highest loss to the lowest： N application to promote tillering 〉 the first N topdressing to promote panicle initiation （applied at the last 4-leaf stage） 〉 basal fertilizer 〉 the second N topdressing to promote panicle initiation （applied at the last 2-leaf stage）. The total loss of ammonia via volatilization from clay soil was 10.49-87.06 kg/hm2, equivalent to 10.92%-21.76% of the nitrogen applied. The total loss of ammonia via volatilization from sandy soil was 11.32-102.43 kg/hm2, equivalent to 11.32%-25.61 % of the nitrogen applied. The amount of ammonia lost via volatilization and the concentration of NH4＋-N in surface water peaked simultaneously after nitrogen application; both showed maxima at the tillering stage with the ratio between them ranging from 23.76% to 33.65%. With the increase in nitrogen application level, rice production and nitrogen accumulation in plants increased, but nitrogen-use efficiency decreased. Rice production and nitrogen accumulation in plants were slightly higher in clay soil than in sandy soil. In the soil, the nitrogen content was the lowest at a depth of 40-50 cm. In any specific soil layer, the soil nitrogen content increased with increasing nitrogen application level, and the soil nitrogen content was higher in clay soil than in sandy soil. In terms of ammonia volatilization, the amount of ammonia lost via volatilization increased markedly when the nitrogen application level exceeded 250 kg/hm2 in the rice growing season. However, for rice production, a suitable nitrogen application level is approximately 300 kg/hm2. Therefore, taking the needs for high crop yields and environmental protection into account, the appropriate nitrogen application level was 250-300 kg/hm2 in these conditions.展开更多
Long-term excessive nitrogen(N)application neither increases nor enhances grain yield and N use efficiency(NUE)of maize,yet the mechanisms involving root morphological and physiological characteristics remain unclear....Long-term excessive nitrogen(N)application neither increases nor enhances grain yield and N use efficiency(NUE)of maize,yet the mechanisms involving root morphological and physiological characteristics remain unclear.This study aimed to elucidate the mechanisms underlying stagnant grain yield under excessive N application by examining root morphological and physiological characteristics.A 10-year N fertilizer trial was conducted in Jilin Province,Northeast China,cultivating maize at three N fertilizer levels(zero N,N0;recommended N,N2;and high N level,N4)from 2019 to 2021.Two widely cultivated maize genotypes,‘Xianyu 335’(XY335)and‘Zhengdan 958’(ZD958),were evaluated.Grain yield,N content,root morphology,and physiological characteristics were analyzed to assess the relationships between N uptake,N utilization,plant growth,and root systems under different N treatments.Compared to N0,root biomass,post-silking N uptake,and grain yield improved significantly with increased N input,while no significant differences emerged between recommended N and high N.High N application enhanced root length and root surface area but decreased root activity(measured by TTC(2,3,5-triphenyltetrazolium chloride)method),nitrate reductase activity,and root activity absorbing area across genotypes.Root length and root to shoot ratio negatively affected N uptake(by-1.2 and-24.6%),while root surface area,root activity,nitrate reductase activity,and root activity absorbing area contributed positively.The interaction between cultivar and N application significantly influenced NUE.XY335 achieved the highest NUE(11.6%)and N recovery efficiency(18.4%)through superior root surface area(23.6%),root activity(12.5%),nitrate reductase activity(8.3%),and root activity absorbing area(6.9%)compared to other treatments.Recommended N application enhanced Post N uptake,NUE,and grain yield through improved root characteristics,while high N application failed to increase or decreased NUE by reducing these parameters.This study demonstrates that root surface area,root activity,nitrate reductase activity,and root activity absorbing area limit NUE increase under high N application.展开更多
In order to research effects of the nitrogen top-dressing levels on carbon-nitrogen metabolism and yield of Desmodium styracifolium, a field experiment was conducted on the research farm of Guangxi University in 2007....In order to research effects of the nitrogen top-dressing levels on carbon-nitrogen metabolism and yield of Desmodium styracifolium, a field experiment was conducted on the research farm of Guangxi University in 2007. Some physiological indexes and yield ofD. styracifolium were compared among five nitrogen top-dressing levels （0, 37.5, 75.0, 112.5 and 150.0 kg N. hm-2）. Results showed that the nitrogen top-dressing could significantly increase the contents of chlorophyll, soluble protein, sucrose and nitrogen as well as nitrate reducase activity. However, there were no significant differences in most of these indexes under high nitrogen levels. Consistently, there was no significant difference in yield among nitrogen top-dressing levels of 75 kg N.hm-2, 112.5 kg N. hm-2 and 150 kg N-hm-2. Therefore, the optimum nitrogen top-dressing level ofD. styracifolium was 75 kg N. hm-2.展开更多
The effects of nitrogen on physiological and biochemical characteristics of potato cultivar Zihuabai under NaCl stress were studied in culture condition.The results show that,under NaCl stress,the contents of proline,...The effects of nitrogen on physiological and biochemical characteristics of potato cultivar Zihuabai under NaCl stress were studied in culture condition.The results show that,under NaCl stress,the contents of proline,chlorophyll and protein and root system vitality first increase and then decrease with the increase of nitrogen level,and reach the top under 4.17 mmol/L NH4NO3 level.Wherein,the contents of chlorophyll,protein and root system vitality are respectively 69.88%,13.07% and 59.29% higher than that of the control under 4.17 mmol/L NH4NO3 level;the activities of superoxide dismutase（SOD）and peroxidase（POD）increase generally under NaCl stress with the increase of nitrogen level,and reach the peaks [111.83 U/g and 25.467 U/（g·min）],which are 37.73% and 35.46% higher than that of control,at 6.25 mmol/L NH4NO3 level.展开更多
Water and nitrogen （N） are considered the most important factors affecting rice production and play vital roles in regulating soil microbial biomass, activity, and community. The effects of irrigation patterns and N...Water and nitrogen （N） are considered the most important factors affecting rice production and play vital roles in regulating soil microbial biomass, activity, and community. The effects of irrigation patterns and N fertilizer levels on the soil microbial community structure and yield of paddy rice were investigated in a pot experiment. The experiment was designed with four N levels of 0 （NO）, 126 （N1）, 157.5 （N2）, and 210 kg N ha^（-1） （N3） under two irrigation patterns of continuous water-logging irrigation （WLI） and water- controlled irrigation （WCI）. Phospholipid fatty acid （PLFA） analysis was conducted to track the dynamics of soil microbial communities at tillering, grain-filling, and maturity stages. The results showed that the maximums of grain yield, above-ground biomass, and total N uptake were all obtained in the N2 treatment under WCI. Similar variations in total PLFAs, as well as bacterial and fungM PLFAs, were found, with an increase from the tillering to the grain-filling stage and a decrease at the maturity stage except for actinomycetic PLFAs, which decreased continuously from the tillering to the maturity stage. A shift in composition of the microbial community at different stages of the plant growth was indicated by principal component analysis （PCA）, in which the samples at the vegetative stage （tillering stage） were separated from those at the reproductive stage （grain-filling and maturity stages）. Soil microbial biomass, measured as total PLFAs, was significantly higher under WCI than that under WLI mainly at the grain-filling stage, whereas the fungal PLFAs detected under WCI were significantly higher than those under WLI at the tillering, grain-filling, and maturity stages. The application of N fertilizer also significantly increased soil microbial biomass and the main microbial groups both under WLI and WCI conditions. The proper combination of irrigation management and N fertilizer level in this study was the N2 （157.5 kg N ha^（-1）） treatment under the water-controlled irrigation pattern.展开更多
基金Supported by Special Scientific Research Fund of Meteorological Public Welfare Profession of China(GYHY201406025GYHY201006025)+2 种基金Special Fund for Agroscientific Research in the Public Interest of China(201403002)Young Talent Project of China Meteorological AdministrationJiangxi"555"Ganpo Yingcai Project~~
文摘This study aimed to investigate the combined effects of nitrogen level （high and ordinary） and high temperature stress （37 ℃, 4 d） at the late panicle ini- tiation stage on yield, SPAD value and soluble sugar content of Ganxin 203, an early rice cultivar. The results showed that under both high and ordinary nitrogen levels, high temperature stress reduced the seed-setting rate, yield per stem, SPAD value and soluble sugar content of Ganxin 203; under both high and ordinary tem- peratures, high nitrogen level increased the seed-setting rate, yield per stem and soluble sugar content of Ganxin 203; the seed-setting rate, yield per stem and yield per plant of Ganxin 203 under high temperature and high nitrogen level were higher than those under high temperature and ordinary nitrogen level. It suggests that ap- propriate high nitrogen level contributes to weakening the negative effects of high temperature stress on rice yield.
文摘Controlled experiment of Leymus chinensis seedlings grown in the environmental growth chambers at 3 soil moisture levels and 3 temperature levels was conducted in order to improve the understanding how leaf photosynthetic parameters will respond to climatic change. The results indicated that soil drought and high temperature decreased the photochemical efficiency of photosystem(F v/F m), the overall photochemical quantum yield of PSII(yield), the coefficient of photochemical fluorescence quenching(q\-P), but increased the coefficient of non-photochemical fluorescence quenching(q\-N). Severe soil drought would decrease F v/F m and yield by 3.12% and 37.04% under 26℃ condition, respectively, and 6.60% and 73.33% under 32℃ condition, respectively, suggesting that higher temperature may enhance the negative effects of soil drought. All the soil drought treatments resulted in the decline in leaf nitrogen content. There was no significant effect of temperature on leaf nitrogen level, but higher temperature significantly reduced the root nitrogen content and the ratio of root nitrogen to leaf nitrogen, indicating the different strategies of adaptation to soil drought and temperature. It was also implied that higher temperature would enhance the effect of soil drought on leaf photosynthetic capacity, decrease the adaptability of Leymus chinensis to drought.
基金Project supported by the Second Stage of Brain Korea 21 Projects
文摘Many kinds of high temperature superconductor （HTS） power machines such as HTS cable, HTS fault current limitcr and HTS magnet are cooled by liquid nitrogen. The level of liquid nitrogen should be monitored and controlled to ensure the thermal stability and the dielectric strength as well. To measure the level, capacitance method and differential pressure method are usually used. However, each method has installation difficulties and measurement errors for unsteady state operation with varying system pressure. A new liquid level meter using a 2G HTS conductor is described, which has similar structure with the liquid helium level meter with NbTi filament. The level meter is fabricated with a parallel connected heater, which helps the separation of the superconducting region and normal region, considering the critical temperature, large heat capacity of conductor and cooling characteristics. The level of liquid nitrogen can be obtained from the measured voltage signal along the 2G HTS conductor. Design, fabrication and test results of the new liquid nitrogen level meter are presented.
文摘A field study to evaluate the impact of different tillage regimes and nitrogen levels on yield and yield components of maize (Zea mays L.), was conducted during autumn 2014 at Students Farm, Department of Agronomy, University of Agriculture, Faisalabad. The experiment was laid out in RCBD (Randomized Complete Block Design), with split plot arrangement having three replications. The experiment was comprised of three tillage regimes (Minimum, Conventional and Deep) and three nitrogen levels viz: 100, 200 and 300 kg•ha<sup>-1</sup>. Urea was used as a source of nitrogen, sulphate of potash as a source of potassium and triple super phosphate as a source of phosphorous. The amount of phosphorous and potash was constant in all the treatments i.e. 125 kg•ha<sup>-1</sup> and 100 kg•ha<sup>-1</sup> respectively. Results of present study are summarized as yield parameters are significantly affected by different nitrogen levels and tillage regimes. Maximum number of plants at harvest (7.93), number of grain rows per cob (17.70), number of grains per row (34.31), number of grains per cob (678.58), and cob weight (187.50 g) were observed in deep tillage at 200 kg•ha<sup>-1</sup> nitrogen application. 1000-grain weight (275.52 g), biological yield (15.66 t•ha<sup>-1</sup>), grain yield (6.16 t•ha<sup>-1</sup>) and dried stalk yield (9.91 t•ha<sup>-1</sup>) were observed maximum in deep tillage at 200 kg•ha<sup>-1</sup> nitrogen application. Harvest index significantly affected by tillage regimes and maximum harvest index (39.58%) were recorded in deep tillage which was statistically at par with conventional tillage (38.83%). It was concluded that higher grain yield of maize can be obtained by deep tillage with the application of 200 kg•ha<sup>-1</sup> nitrogen application under the prevailing conditions of Faisalabad.
文摘The experiment of Glutamate Dehydrogenase (GDH) activity in various plant parts under different nitrogen levels in frame culture during the whole period of growth was carried out on campus of Northeast Agricltural University in 1993. The result showed that GDH activity in leaf blades under four nitrogen applied levels rose rapidly to the acme from the seedling to foliage rapid growth stage, then diminished rapidly to the lower level at the latter stage of foliage rapid growth. This level was kept to harvest. GDH activity in roots at each growth stage under all nitrogen levels exhibited little disparity and did not show ostensible regularity of changes. GDH activity in leaf blades was stimulated with nitrogen, however, it reduced with nitrogen fertilizer applying further. GDH activity in leaf blades was the biggest compared with crowns, petioles and roots, which suggested that it could represent the highest enzyme activityof the whole plant.
基金supported by the National Key Research and Development Program of China(2022YFC2601100)the National Natural Science Foundation of China(grant nos.31972343 and 32272562)the Hebei Natural Science Foundation(grant no.C2022201032).
文摘Arbuscular mycorrhizal fungi(AMF)and Bacillus play a crucial role in promoting the growth and defense of exotic plants,and their interaction may further enhance plant invasions.Soil nitrogen level is an important factor that affects the interaction.However,the effect of the interaction on the growth and defensive ability of exotic plants under different nitrogen levels remains unclear.In this study,a pot experiment was conducted using Rhizoglomus intraradices(RI)and Bacillus megaterium(BM),one of the dominant AMF and Bacillus in the rhizosphere of Flaveria bidentis,with three soil nitrogen levels(0,3.75 and 7.5 g m^(−2))and four inoculation treatments(uninoculated,inoculation with RI,inoculation with BM and co-inoculated with RI and BM).Significant correlations were observed between microbial inoculations and indicators of plant growth and defense across varying soil nitrogen levels.Co-inoculation notably enhanced both plant growth and defense compared to single inoculations,especially under the nitrogen concentration of 3.75 g m^(−2).Specifically,compared to single inoculation,co-inoculation increased the biomass of F.bidentis by 8.27%and 16.4%,as well as the flavonoids concentration by 21.89%-30.95%and phenolic acids concentration by 54.22%-60.93%,respectively.These enhancements in growth and defensive compound production likely promote the competitive ability of F.bidentis and its resistance to biotic and abiotic stresses,thereby contributing to its successful invasion.
基金Supported by Construction of Southwestern Rice Innovation System,Science and Technology Project on Food Production (2006BAD02-A05)Agriculture Science Technology Achievement TransformationFund (2006GB2F000256)+2 种基金Sichuan Provincial Foundation for Lead-ers of Disciplines in ScienceProject of Rice Breeding Technology ofSichuanProgram Promoted by Sichuan Financial Administration~~
文摘[Objective] The study aimed at investigating the effects of different geographic sites,soil chemical characteristics and nitrogen application levels on nitrogen accumulation and distribution in different organs and utilization efficiency for mid-season hybrid rice.[Method] By using mid-season rice varieties II-you 7 and Yuxiangyou203 as the experimental materials,field experiment was conducted at seven ecological sites in four provinces or cities in Southwestern China in 2009.A total of four nitrogen application levels were set as follows：by using 75 kg/hm2 of P2O5 and 75 kg/hm2 of K2O as the base fertilizer,extra 0,90,150 and 210 kg/hm2 of nitrogen fertilizer（in which,base fertilizer,base-tillering fertilizer and base-earing fertilizer respectively accounted for 60%,20% and 20%.） was applied,respectively.In the split-plot design,fertilizer was considered as the main factor while rice variety was taken as the secondary factor.A total of eight treatments were set with three replications.[Result] Highly significant differences of grain yield were found among seven locations,two varieties,four nitrogen application levels,interactions of site × variety and site × nitrogen application level,but the interaction of variety ×nitrogen application level had no significant influence on rice yield.There were highly significant effects of site,varieties and nitrogen application level on dry matter production,nitrogen content,nitrogen utilization efficiency.Highly significant negative correlations between uptake efficiency and utilization efficiency for nitrogen were found;and multiple stepwise regression analysis showed that nitrogen uptake-utilization efficiency were significantly influenced by different ecological sites,chemical quality of soil and the levels of nitrogen application.[Conclusion] The research will provide theoretical and practical basis for the highly efficient application of nitrogen in mid-season hybrid rice cultivation.
文摘It was shown from the experiment that glutamine synthetase activity (GSA) in both leaf blades and roots under different nitrogen levels rose rapidly to reach its peak from seedling stage to foliage rapid growth stage and declined to its lowest level at the latter stage of root rapid growth, and then increased slightly. GSA in leaf blades had positive correlation with nitrogen level during the whole period of growth. GSA in roots showed the same tendency as it in leaf blades at the early middle stage of growth, but at the latter stage of growth, no positive correlation was established. GSA in leaf blades was the strongest compared with crowns, petioles and roots, and could represent the highest enzyme activity of the whole plant. GSA had quadratic curvilinear correlation with root yield and sugar production. GSA in leaf blades had significant positive correlation with α-NH2-N at the foliage rapid growth stage.
文摘The experiment of glutamate synthase activity (GOGATA) in both leaf blades and roots under different nitrogen levels was carried out at Northeast Agricultural University in 1993. The result showed that GOGATA rose rapidly to reach its peak from seedling stage to foliage rapid growth stage, and then declined gradually. GOGATA was enhanced with increasing nitrogen levels and had significant positive correlation with nitrogen levels at the middle stage of growth GOGATA in leaf blades was the strongest compared with crowns, petioles and roots, thus, it could represent the highest enzyme activity of the whole plant. GOGATA had quadratic curvilinear correlation with root yield and sugar production. GOGATA in leaf blades had significant positive correlation with α-NH 2-N at the foliage rapid growth stage while GOGATA in roots existed this relation at the latter stage of growth. GOGATA in roots had significant negative correlation with sugar content at harvest.
文摘[Objective] This study aimed to investigate the effects of different fertilizer levels on lodging and yield of rice. [Method] A total of four treatments were designed and applied with 6, 9, 12 and 15 kg of nitrogen fertilizer, respectively. After seedling transplanting, the biological characteristics of rice at different growth stages in each treatment and the biological and economic characteristics of rice after lodging were determined for statistical analysis. [Result] Application with 15 kg of nitrogen fertilizer had significant promotion effect on the increase of rice yield; compared with the control (6 kg of nitrogen fertilizer), rice yield in three experimental treatments (9, 12 and 15 kg of nitrogen fertilizer, respectively) increased by 50.74%, 89.11% and 94.48%, respectively; lodging-resistance mechanical strengths of the three experimental treatments were 103.97%, 132.01% and 89.83% of the control, respectively; rice lodging resistance of treatment C (12 kg of nitrogen fertilizer) was the strongest, with the highest yield. [Conclusion] This study provides reference data and technical support for the rational fertilization of rice production.
基金supported by the National Natural Science Foundation of China (Grant No.30671223)the 11th 5-year Major Project of National Science and Technology Support Plan (GrantNo. 2006BAD02A03)
文摘We conducted field trials of rice grown in sandy soil and clay soil to determine the effects of nitrogen application levels on the concentration of NH4＋-N in surface water, loss of ammonia through volatilization from paddy fields, rice production, nitrogen-use efficiency, and nitrogen content in the soil profile. The concentration of NH4＋-N in surface water and the amount of ammonia lost through volatilization increased with increasing nitrogen application level, and peaked at 1-3 d after nitrogen application. Less ammonia was lost via volatilization from clay soil than from sandy soil. The amounts of ammonia lost via volatilization after nitrogen application differed depending on the stage when it was applied, from the highest loss to the lowest： N application to promote tillering 〉 the first N topdressing to promote panicle initiation （applied at the last 4-leaf stage） 〉 basal fertilizer 〉 the second N topdressing to promote panicle initiation （applied at the last 2-leaf stage）. The total loss of ammonia via volatilization from clay soil was 10.49-87.06 kg/hm2, equivalent to 10.92%-21.76% of the nitrogen applied. The total loss of ammonia via volatilization from sandy soil was 11.32-102.43 kg/hm2, equivalent to 11.32%-25.61 % of the nitrogen applied. The amount of ammonia lost via volatilization and the concentration of NH4＋-N in surface water peaked simultaneously after nitrogen application; both showed maxima at the tillering stage with the ratio between them ranging from 23.76% to 33.65%. With the increase in nitrogen application level, rice production and nitrogen accumulation in plants increased, but nitrogen-use efficiency decreased. Rice production and nitrogen accumulation in plants were slightly higher in clay soil than in sandy soil. In the soil, the nitrogen content was the lowest at a depth of 40-50 cm. In any specific soil layer, the soil nitrogen content increased with increasing nitrogen application level, and the soil nitrogen content was higher in clay soil than in sandy soil. In terms of ammonia volatilization, the amount of ammonia lost via volatilization increased markedly when the nitrogen application level exceeded 250 kg/hm2 in the rice growing season. However, for rice production, a suitable nitrogen application level is approximately 300 kg/hm2. Therefore, taking the needs for high crop yields and environmental protection into account, the appropriate nitrogen application level was 250-300 kg/hm2 in these conditions.
基金supported by the National Key Research and Development Program of China(2023YFD2301702)the earmarked Fund for China Agriculture Research System(CARS-02)the National Natural Science Foundation of China(31971852).
文摘Long-term excessive nitrogen(N)application neither increases nor enhances grain yield and N use efficiency(NUE)of maize,yet the mechanisms involving root morphological and physiological characteristics remain unclear.This study aimed to elucidate the mechanisms underlying stagnant grain yield under excessive N application by examining root morphological and physiological characteristics.A 10-year N fertilizer trial was conducted in Jilin Province,Northeast China,cultivating maize at three N fertilizer levels(zero N,N0;recommended N,N2;and high N level,N4)from 2019 to 2021.Two widely cultivated maize genotypes,‘Xianyu 335’(XY335)and‘Zhengdan 958’(ZD958),were evaluated.Grain yield,N content,root morphology,and physiological characteristics were analyzed to assess the relationships between N uptake,N utilization,plant growth,and root systems under different N treatments.Compared to N0,root biomass,post-silking N uptake,and grain yield improved significantly with increased N input,while no significant differences emerged between recommended N and high N.High N application enhanced root length and root surface area but decreased root activity(measured by TTC(2,3,5-triphenyltetrazolium chloride)method),nitrate reductase activity,and root activity absorbing area across genotypes.Root length and root to shoot ratio negatively affected N uptake(by-1.2 and-24.6%),while root surface area,root activity,nitrate reductase activity,and root activity absorbing area contributed positively.The interaction between cultivar and N application significantly influenced NUE.XY335 achieved the highest NUE(11.6%)and N recovery efficiency(18.4%)through superior root surface area(23.6%),root activity(12.5%),nitrate reductase activity(8.3%),and root activity absorbing area(6.9%)compared to other treatments.Recommended N application enhanced Post N uptake,NUE,and grain yield through improved root characteristics,while high N application failed to increase or decreased NUE by reducing these parameters.This study demonstrates that root surface area,root activity,nitrate reductase activity,and root activity absorbing area limit NUE increase under high N application.
基金Supported by Scientifi c Research Foundation of Guangxi University (x061106)
文摘In order to research effects of the nitrogen top-dressing levels on carbon-nitrogen metabolism and yield of Desmodium styracifolium, a field experiment was conducted on the research farm of Guangxi University in 2007. Some physiological indexes and yield ofD. styracifolium were compared among five nitrogen top-dressing levels （0, 37.5, 75.0, 112.5 and 150.0 kg N. hm-2）. Results showed that the nitrogen top-dressing could significantly increase the contents of chlorophyll, soluble protein, sucrose and nitrogen as well as nitrate reducase activity. However, there were no significant differences in most of these indexes under high nitrogen levels. Consistently, there was no significant difference in yield among nitrogen top-dressing levels of 75 kg N.hm-2, 112.5 kg N. hm-2 and 150 kg N-hm-2. Therefore, the optimum nitrogen top-dressing level ofD. styracifolium was 75 kg N. hm-2.
基金Supported by National Key Technology Research and Development Program(2007BAD49B03-1)~~
文摘The effects of nitrogen on physiological and biochemical characteristics of potato cultivar Zihuabai under NaCl stress were studied in culture condition.The results show that,under NaCl stress,the contents of proline,chlorophyll and protein and root system vitality first increase and then decrease with the increase of nitrogen level,and reach the top under 4.17 mmol/L NH4NO3 level.Wherein,the contents of chlorophyll,protein and root system vitality are respectively 69.88%,13.07% and 59.29% higher than that of the control under 4.17 mmol/L NH4NO3 level;the activities of superoxide dismutase（SOD）and peroxidase（POD）increase generally under NaCl stress with the increase of nitrogen level,and reach the peaks [111.83 U/g and 25.467 U/（g·min）],which are 37.73% and 35.46% higher than that of control,at 6.25 mmol/L NH4NO3 level.
基金Supported by the National Basic Research Program (973 Program) of China (No.2007CB109305)the National Natural ScienceFoundation of China (No.3197859)
文摘Water and nitrogen （N） are considered the most important factors affecting rice production and play vital roles in regulating soil microbial biomass, activity, and community. The effects of irrigation patterns and N fertilizer levels on the soil microbial community structure and yield of paddy rice were investigated in a pot experiment. The experiment was designed with four N levels of 0 （NO）, 126 （N1）, 157.5 （N2）, and 210 kg N ha^（-1） （N3） under two irrigation patterns of continuous water-logging irrigation （WLI） and water- controlled irrigation （WCI）. Phospholipid fatty acid （PLFA） analysis was conducted to track the dynamics of soil microbial communities at tillering, grain-filling, and maturity stages. The results showed that the maximums of grain yield, above-ground biomass, and total N uptake were all obtained in the N2 treatment under WCI. Similar variations in total PLFAs, as well as bacterial and fungM PLFAs, were found, with an increase from the tillering to the grain-filling stage and a decrease at the maturity stage except for actinomycetic PLFAs, which decreased continuously from the tillering to the maturity stage. A shift in composition of the microbial community at different stages of the plant growth was indicated by principal component analysis （PCA）, in which the samples at the vegetative stage （tillering stage） were separated from those at the reproductive stage （grain-filling and maturity stages）. Soil microbial biomass, measured as total PLFAs, was significantly higher under WCI than that under WLI mainly at the grain-filling stage, whereas the fungal PLFAs detected under WCI were significantly higher than those under WLI at the tillering, grain-filling, and maturity stages. The application of N fertilizer also significantly increased soil microbial biomass and the main microbial groups both under WLI and WCI conditions. The proper combination of irrigation management and N fertilizer level in this study was the N2 （157.5 kg N ha^（-1）） treatment under the water-controlled irrigation pattern.
