A study was conducted at Akron, CO, USA, on a Weld silt loam in 2004 to quantify the effects of water deficit stress on corn (Zea mays, L.) root and shoot biomass. Corn plants were grown under a range of soil bulk den...A study was conducted at Akron, CO, USA, on a Weld silt loam in 2004 to quantify the effects of water deficit stress on corn (Zea mays, L.) root and shoot biomass. Corn plants were grown under a range of soil bulk density and water conditions caused by previous tillage, crop rotation, and irrigation management. Water deficit stress (Dstress) was quantified by the number of days when the water content in the surface 0.3 m deviated from the water content range determined by the Least Limiting Water Range (LLWR). Root and shoot samples were collected at the V6, V12, and R1 growth stages. There was no significant correlation between Dstress and shoot or root biomass at the V6 growth stage. At the V12 and R1 growth stages, there were negative, linear correlations among Dstress and both root biomass and shoot biomass. The proportional decrease of shoot biomass was greater than the proportional decrease in root biomass, leading to an increase in the root:shoot ratio as water deficit stress increased at all growth stages. Determining restrictive soil conditions using the LLWR may be useful for evaluating improvement or degradation of the soil physical environment caused by soil management.展开更多
Sugarcane is used worldwide for sugar, ethanol and energy production. In Brazil, the shift from burned to unburned harvest systems resulted in increases in nitrogen fertilization rates, which can impact root architect...Sugarcane is used worldwide for sugar, ethanol and energy production. In Brazil, the shift from burned to unburned harvest systems resulted in increases in nitrogen fertilization rates, which can impact root architecture and biomass. The expectation is also an increase in sugarcane biomass. The study hypothesized that high N rates applied to sugarcane fields increases root growth and N stored in roots, promoting higher biomass and N accumulated in shoots. Two experiments were set up in Southeastern Brazil, on a Typic Kandiudox (TK) and Rhodic Eutrudox (RE). Four treatments were studied 1) N application in the plant-cane (0 and 120 kg·ha-1 N) and 2) N application in the ratoon (0 and 150 kg·ha-1 N). The shoot biomass and the root density (by the core method up to 0.6 m) were evaluated over the first ratoon crop cycle, and the N content in those compartments was also examined. There was no carry over effect on N applied at planting in root and shoot biomass in the ratoon crop cycle. At the RE site, the ratoon N fertilization increased root density in the superficial soil layer (0 - 0.2 m) and close to the plants (<0.3 m). The effect of N addition on root biomass, and biomass and N accumulated in shoot was limited in both sites. Increasing N rates in unburned sugarcane fields do not consistently increases root and shoot biomass under Brazilian field conditions.展开更多
This paper focused on the water relations of two halophytes differing in photosynthetic pathway, phe- notype, and life cycle： Karelinia caspica （Pall.） Less. （C3, deep-rooted perennial Asteraceae grass） and Atrip...This paper focused on the water relations of two halophytes differing in photosynthetic pathway, phe- notype, and life cycle： Karelinia caspica （Pall.） Less. （C3, deep-rooted perennial Asteraceae grass） and Atriplex tatarica L. （C4, shallow-rooted annual Chenopodiaceae grass）. Gas exchange, leaf water potential, and growth characteristics were investigated in two growing seasons in an arid area of Xinjiang to explore the physiological adaptability of the two halophytes. Both K. caspica and A. tatarica showed midday depression of transpiration, in- dicating that they were strong xerophytes and weak midday depression types. The roots of A. tatarica were con- centrated mainly in the 0-60 cm soil layer, and the leaf water potential （~L） increased sharply in the 0-20 cm layer due to high soil water content, suggesting that the upper soil was the main water source. On the other hand, K. caspica had a rooting depth of about 1.5 m and a larger root/shoot ratio, which confirmed that this species uptakes water mainly from deeper soil layer. Although A. tatarica had lower transpiration water consumption, higher water use efficiency （WUE）, and less water demand at the same leaf water potential, it showed larger water stress impact than K. caspica, indicating that the growth of A. tatarica was restricted more than that of K. caspica when there was no rainfall recharge. As a shallow-rooted C4 species, A. tatarica displayed lower stomatal conductance, which could to some extent reduce transpiration water loss and maintain leaf water potential steadily. In contrast, the deep-rooted C3 species K. caspica had a larger root/shoot ratio that was in favor of exploiting groundwater. We concluded that C3 species （K. caspica） tapes water and C4 species （A. tatarica） reduces water loss to survive in the arid and saline conditions. The results provided a case for the phenotype theory of Schwinning and Ehleringer on halophytic plants.展开更多
Forest plays very important roles in global system with about 35% land area producing about 70% of total land net production. It is important to consider both elevated CO2 concentrations and different soil moisture wh...Forest plays very important roles in global system with about 35% land area producing about 70% of total land net production. It is important to consider both elevated CO2 concentrations and different soil moisture when the possible effects of elevated CO2 concentration on trees are assessed. In this study, we grew Cinnamomum camphora seedlings under two CO2 concentrations （350 μmol/mol and 500μmnol/mol） and three soil moisture levels [80%, 60% and 40% FWC （field water capacity）] to focus on the effects of exposure of trees to elevated CO2 on underground and aboveground plant growth, and its dependence on soil moisture. The results indicated that high CO2 concentration has no significant effects on shoot height but significantly impacts shoot weight and ratio of shoot weight to height under three soil moisture levels. The response of root growth to CO2 enrichment is just reversed, there are obvious effects on root length growth, but no effects on root weight growth and ratio of root weight to length. The CO2 enrichment decreased 20.42%, 32.78%, 20.59% of weight ratio of root to shoot under 40%, 60% and 80% FWC soil water conditions, respectively. And elevated CO2 concentration significantly increased the water content in aboveground and underground parts. Then we concluded that high CO2 concentration favours more tree aboveground biomass growth than underground biomass growth under favorable soil water conditions. And CO2 enrichment enhanced lateral growth of shoot and vertical growth of root. The responses of plants to elevated CO2 depend on soil water availability, and plants may benefit more from CO2 enrichment with sufficient water supply.展开更多
为明确不同氮肥运筹对玉米根冠协调发育的影响,基于长期定位氮肥试验平台,设置4个氮素处理(N3:300 kg N/hm^(2);N2:225 kg N/hm^(2);N1:150 kg N/hm^(2);N0:0 kg N/hm^(2)),2023-2024年以郑单958和先玉3352个玉米品种为试验材料,分析玉...为明确不同氮肥运筹对玉米根冠协调发育的影响,基于长期定位氮肥试验平台,设置4个氮素处理(N3:300 kg N/hm^(2);N2:225 kg N/hm^(2);N1:150 kg N/hm^(2);N0:0 kg N/hm^(2)),2023-2024年以郑单958和先玉3352个玉米品种为试验材料,分析玉米关键生育期根冠特征。结果表明,增施氮肥显著提高玉米产量及地上部和地下部的生物量,但N2与N3处理间产量差异不显著,N3、N2、N1处理成熟期干物质积累量较N0分别增加了106.5%~164.3%、87.4%~125.7%、71.8%~87.4%;根系干重峰值出现在吐丝后15 d左右,N3、N2、N1处理较N0处理分别增加了33.67%~49.67%、17.87%~21.89%、9.69%~18.38%。根冠比动态呈单峰曲线,峰值出现在出苗后45 d左右,随施氮量增加而降低,N2处理较N1、N0处理分别降低11.1%和25.7%,较N3处理增加4.1%。研究结果表明,氮肥投入影响玉米产量的增加,当施氮量超过225 kg N/hm^(2)时,增产效应趋于饱和。合理的氮肥运筹(中氮,N2)通过优化物质分配比例,协调根冠生长,在保障产量提升的同时提高了肥料利用效益,为玉米氮肥精准调控及可持续生产提供了依据。展开更多
草地作为我国陆地生态系统重要的碳库,对我国气候调节和实现碳达峰碳中和具有重要意义。综合以往草地植被碳储量估算的相关文献,本文综述了草地植被碳储量代表性估算方法,并分析了不同估算结果的差异性来源。结果表明:自21世纪以来我国...草地作为我国陆地生态系统重要的碳库,对我国气候调节和实现碳达峰碳中和具有重要意义。综合以往草地植被碳储量估算的相关文献,本文综述了草地植被碳储量代表性估算方法,并分析了不同估算结果的差异性来源。结果表明:自21世纪以来我国草地植被碳储量的估算值之间差异较大,碳储量的估算结果介于0.56~4.66 Pg,均值为2.22 Pg,碳密度估算结果介于216~1148 g C·m^(-2),均值为654.23 g C·m^(-2);草地植被枯落物碳储量占比介于0.1%~8.6%,均值为5.6%,枯落物的忽略会导致碳储量估算总量偏低;采用全球单位碳密度估算方法同其他估算方法之间存在显著性差异(P<0.05);草地植被地上部、地下部和枯落物的含碳率分别为39.3%、36.6%和30.7%,植被地上部含碳率与枯落物含碳率之间呈显著性差异(P<0.05),采用较为普遍的碳转换系数45%会导致草地植被碳储量估算总量偏大;不同草地类型根茎比差异较大,介于0.76~41.80,均值为9.16。综上,草地植被碳储量的估算方法、数据源、重要参数的不同,导致了草地植被碳储量估算总量之间的差异。展开更多
文摘A study was conducted at Akron, CO, USA, on a Weld silt loam in 2004 to quantify the effects of water deficit stress on corn (Zea mays, L.) root and shoot biomass. Corn plants were grown under a range of soil bulk density and water conditions caused by previous tillage, crop rotation, and irrigation management. Water deficit stress (Dstress) was quantified by the number of days when the water content in the surface 0.3 m deviated from the water content range determined by the Least Limiting Water Range (LLWR). Root and shoot samples were collected at the V6, V12, and R1 growth stages. There was no significant correlation between Dstress and shoot or root biomass at the V6 growth stage. At the V12 and R1 growth stages, there were negative, linear correlations among Dstress and both root biomass and shoot biomass. The proportional decrease of shoot biomass was greater than the proportional decrease in root biomass, leading to an increase in the root:shoot ratio as water deficit stress increased at all growth stages. Determining restrictive soil conditions using the LLWR may be useful for evaluating improvement or degradation of the soil physical environment caused by soil management.
文摘Sugarcane is used worldwide for sugar, ethanol and energy production. In Brazil, the shift from burned to unburned harvest systems resulted in increases in nitrogen fertilization rates, which can impact root architecture and biomass. The expectation is also an increase in sugarcane biomass. The study hypothesized that high N rates applied to sugarcane fields increases root growth and N stored in roots, promoting higher biomass and N accumulated in shoots. Two experiments were set up in Southeastern Brazil, on a Typic Kandiudox (TK) and Rhodic Eutrudox (RE). Four treatments were studied 1) N application in the plant-cane (0 and 120 kg·ha-1 N) and 2) N application in the ratoon (0 and 150 kg·ha-1 N). The shoot biomass and the root density (by the core method up to 0.6 m) were evaluated over the first ratoon crop cycle, and the N content in those compartments was also examined. There was no carry over effect on N applied at planting in root and shoot biomass in the ratoon crop cycle. At the RE site, the ratoon N fertilization increased root density in the superficial soil layer (0 - 0.2 m) and close to the plants (<0.3 m). The effect of N addition on root biomass, and biomass and N accumulated in shoot was limited in both sites. Increasing N rates in unburned sugarcane fields do not consistently increases root and shoot biomass under Brazilian field conditions.
基金supported by the National Basic Research Program of China(2009CB825101)the Specialized Research Fund for the Doctoral Program of Higher Education of China(20110008110035)
文摘This paper focused on the water relations of two halophytes differing in photosynthetic pathway, phe- notype, and life cycle： Karelinia caspica （Pall.） Less. （C3, deep-rooted perennial Asteraceae grass） and Atriplex tatarica L. （C4, shallow-rooted annual Chenopodiaceae grass）. Gas exchange, leaf water potential, and growth characteristics were investigated in two growing seasons in an arid area of Xinjiang to explore the physiological adaptability of the two halophytes. Both K. caspica and A. tatarica showed midday depression of transpiration, in- dicating that they were strong xerophytes and weak midday depression types. The roots of A. tatarica were con- centrated mainly in the 0-60 cm soil layer, and the leaf water potential （~L） increased sharply in the 0-20 cm layer due to high soil water content, suggesting that the upper soil was the main water source. On the other hand, K. caspica had a rooting depth of about 1.5 m and a larger root/shoot ratio, which confirmed that this species uptakes water mainly from deeper soil layer. Although A. tatarica had lower transpiration water consumption, higher water use efficiency （WUE）, and less water demand at the same leaf water potential, it showed larger water stress impact than K. caspica, indicating that the growth of A. tatarica was restricted more than that of K. caspica when there was no rainfall recharge. As a shallow-rooted C4 species, A. tatarica displayed lower stomatal conductance, which could to some extent reduce transpiration water loss and maintain leaf water potential steadily. In contrast, the deep-rooted C3 species K. caspica had a larger root/shoot ratio that was in favor of exploiting groundwater. We concluded that C3 species （K. caspica） tapes water and C4 species （A. tatarica） reduces water loss to survive in the arid and saline conditions. The results provided a case for the phenotype theory of Schwinning and Ehleringer on halophytic plants.
基金Project supported by the National Natural Science Foundation of China (Nos. 30170161 and 90102015) and the Doctoral Disciplines Programs Foundation of Ministry of Education of China (No. 20030335043)
文摘Forest plays very important roles in global system with about 35% land area producing about 70% of total land net production. It is important to consider both elevated CO2 concentrations and different soil moisture when the possible effects of elevated CO2 concentration on trees are assessed. In this study, we grew Cinnamomum camphora seedlings under two CO2 concentrations （350 μmol/mol and 500μmnol/mol） and three soil moisture levels [80%, 60% and 40% FWC （field water capacity）] to focus on the effects of exposure of trees to elevated CO2 on underground and aboveground plant growth, and its dependence on soil moisture. The results indicated that high CO2 concentration has no significant effects on shoot height but significantly impacts shoot weight and ratio of shoot weight to height under three soil moisture levels. The response of root growth to CO2 enrichment is just reversed, there are obvious effects on root length growth, but no effects on root weight growth and ratio of root weight to length. The CO2 enrichment decreased 20.42%, 32.78%, 20.59% of weight ratio of root to shoot under 40%, 60% and 80% FWC soil water conditions, respectively. And elevated CO2 concentration significantly increased the water content in aboveground and underground parts. Then we concluded that high CO2 concentration favours more tree aboveground biomass growth than underground biomass growth under favorable soil water conditions. And CO2 enrichment enhanced lateral growth of shoot and vertical growth of root. The responses of plants to elevated CO2 depend on soil water availability, and plants may benefit more from CO2 enrichment with sufficient water supply.
文摘为明确不同氮肥运筹对玉米根冠协调发育的影响,基于长期定位氮肥试验平台,设置4个氮素处理(N3:300 kg N/hm^(2);N2:225 kg N/hm^(2);N1:150 kg N/hm^(2);N0:0 kg N/hm^(2)),2023-2024年以郑单958和先玉3352个玉米品种为试验材料,分析玉米关键生育期根冠特征。结果表明,增施氮肥显著提高玉米产量及地上部和地下部的生物量,但N2与N3处理间产量差异不显著,N3、N2、N1处理成熟期干物质积累量较N0分别增加了106.5%~164.3%、87.4%~125.7%、71.8%~87.4%;根系干重峰值出现在吐丝后15 d左右,N3、N2、N1处理较N0处理分别增加了33.67%~49.67%、17.87%~21.89%、9.69%~18.38%。根冠比动态呈单峰曲线,峰值出现在出苗后45 d左右,随施氮量增加而降低,N2处理较N1、N0处理分别降低11.1%和25.7%,较N3处理增加4.1%。研究结果表明,氮肥投入影响玉米产量的增加,当施氮量超过225 kg N/hm^(2)时,增产效应趋于饱和。合理的氮肥运筹(中氮,N2)通过优化物质分配比例,协调根冠生长,在保障产量提升的同时提高了肥料利用效益,为玉米氮肥精准调控及可持续生产提供了依据。
文摘草地作为我国陆地生态系统重要的碳库,对我国气候调节和实现碳达峰碳中和具有重要意义。综合以往草地植被碳储量估算的相关文献,本文综述了草地植被碳储量代表性估算方法,并分析了不同估算结果的差异性来源。结果表明:自21世纪以来我国草地植被碳储量的估算值之间差异较大,碳储量的估算结果介于0.56~4.66 Pg,均值为2.22 Pg,碳密度估算结果介于216~1148 g C·m^(-2),均值为654.23 g C·m^(-2);草地植被枯落物碳储量占比介于0.1%~8.6%,均值为5.6%,枯落物的忽略会导致碳储量估算总量偏低;采用全球单位碳密度估算方法同其他估算方法之间存在显著性差异(P<0.05);草地植被地上部、地下部和枯落物的含碳率分别为39.3%、36.6%和30.7%,植被地上部含碳率与枯落物含碳率之间呈显著性差异(P<0.05),采用较为普遍的碳转换系数45%会导致草地植被碳储量估算总量偏大;不同草地类型根茎比差异较大,介于0.76~41.80,均值为9.16。综上,草地植被碳储量的估算方法、数据源、重要参数的不同,导致了草地植被碳储量估算总量之间的差异。
