Plants show different growth responses to N sources supplied with either NH4^＋ or NO3^-. The uptake of different N sources also affects the rhizosphere pH and therefore the bioavallability of soil phosphorus, particu...Plants show different growth responses to N sources supplied with either NH4^＋ or NO3^-. The uptake of different N sources also affects the rhizosphere pH and therefore the bioavallability of soil phosphorus, particularly in alkaline soils. The plant growth, P uptake, and P availability in the rhizosphere of oat （Arena nuda L.） grown in hydroponics and in soil culture were investigated under supply with sole NH4^＋-N, sole NO3-N, or a combination. Sole NO^- -fed oat plants accumulated more biomass than sole NH4^＋ -fed ones. The highest biomass accumulation was observed when N was supplied with both NH^＋ -N and NO3^- -N. Growth of the plant root increased with the proportion of NO3^- in the cultural medium. Better root growth and higher root/shoot ratio were consistently observed in NO3^- fed plants. However, root vigor was the highest when N was supplied with NO3^- ＋NH4^＋. NH4^＋ supply reduced the rhizosphere pH but did not affect P uptake by plants grown in soils with CaHPO4 added as P source. No P deficiency was observed, and plant P concentrations were generally above 2 g kg^-1. P uptake was increased when N was supplied partly or solely as NO3^--N, similarly as biomass accumulation. The results suggested that oat was an NO3-preferring plant, and NO3^- -N was essential for plant growth and the maintenance of root absorption capacity. N supply with NH4^＋ -N did not improve P nutrition, which was most likely due to the absence of P deficiency.展开更多
为探讨信号分子过氧化氢(H 2 O 2 )对干旱胁迫下裸燕麦生理响应的调控机制,以砂培白燕7号幼苗为材料,研究了喷施0.01 mmol·L -1 H 2 O 2 对17.8%聚乙二醇6000模拟的干旱胁迫下叶片光合特性、活性氧代谢、渗透调节物质积累和幼苗生...为探讨信号分子过氧化氢(H 2 O 2 )对干旱胁迫下裸燕麦生理响应的调控机制,以砂培白燕7号幼苗为材料,研究了喷施0.01 mmol·L -1 H 2 O 2 对17.8%聚乙二醇6000模拟的干旱胁迫下叶片光合特性、活性氧代谢、渗透调节物质积累和幼苗生长的影响。结果表明:喷施H 2 O 2 后,干旱胁迫下的裸燕麦幼苗叶片叶绿素a、叶绿素b、总叶绿素、类胡萝卜素含量和叶绿素a/b较对照(喷H 2 O后干旱胁迫)分别提高了20.0%、12.9%、18.5%、8.1%和24.3%,叶片净光合速率、气孔导度、胞间CO 2 浓度和水分利用效率分别提高了20.6%、25.9%、12.0%和33.8%,蒸腾速率降低了9.7%;喷施H 2 O 2 还使干旱胁迫下裸燕麦幼苗叶片的过氧化氢酶、抗坏血酸过氧化物酶活性和抗坏血酸含量分别提高了113.5%、102.9%和13.8%,而超氧化物歧化酶、过氧化物酶活性及O —· 2 、H 2 O 2 、丙二醛含量和细胞膜相对透性分别下降了21.5%、60.4%、29.3%、38.4%、19.7%和14.2%,可溶性蛋白质、可溶性糖、游离氨基酸和脯氨酸含量分别上升了10.5%、40.3%、13.8%和17.2%,幼苗株高、根长、植株鲜重、植株干重和相对含水量分别提高了14.8%、25.0%、20.1%、11.0%和5.93 %,但谷胱甘肽含量没有显著变化。表明外源H 2 O 2 能够通过降低膜脂过氧化程度和促进渗透溶质积累,改善叶片光合功能和植株水分状况,从而减轻干旱对裸燕麦幼苗生长的抑制,增强裸燕麦的抗旱性。展开更多
基金Project supported by the National Natural Science Foundation Council of China (No.30660086)the Natural Science Foundation of Inner Mongolia of China (No.200607010302)+2 种基金Hong Kong Research Grants Council (No.2465/05M)Hong Kong University Grants Committee (No.AOE/B-07/99)Hong Kong Baptist University Matching Research Fund.
文摘Plants show different growth responses to N sources supplied with either NH4^＋ or NO3^-. The uptake of different N sources also affects the rhizosphere pH and therefore the bioavallability of soil phosphorus, particularly in alkaline soils. The plant growth, P uptake, and P availability in the rhizosphere of oat （Arena nuda L.） grown in hydroponics and in soil culture were investigated under supply with sole NH4^＋-N, sole NO3-N, or a combination. Sole NO^- -fed oat plants accumulated more biomass than sole NH4^＋ -fed ones. The highest biomass accumulation was observed when N was supplied with both NH^＋ -N and NO3^- -N. Growth of the plant root increased with the proportion of NO3^- in the cultural medium. Better root growth and higher root/shoot ratio were consistently observed in NO3^- fed plants. However, root vigor was the highest when N was supplied with NO3^- ＋NH4^＋. NH4^＋ supply reduced the rhizosphere pH but did not affect P uptake by plants grown in soils with CaHPO4 added as P source. No P deficiency was observed, and plant P concentrations were generally above 2 g kg^-1. P uptake was increased when N was supplied partly or solely as NO3^--N, similarly as biomass accumulation. The results suggested that oat was an NO3-preferring plant, and NO3^- -N was essential for plant growth and the maintenance of root absorption capacity. N supply with NH4^＋ -N did not improve P nutrition, which was most likely due to the absence of P deficiency.
