干旱胁迫下氮素对小麦幼苗生长及光合生理的影响

Effects of nitrogen on growth and physiological characteristics of wheat seedlings under drought stress

以小麦品种商麦5226和小偃15为材料,设置低氮、中氮和高氮3个氮素水平(0.5、8.0、15.0 mmol/L),PEG-6000模拟干旱处理,测定不同水氮耦合处理下小麦生长指标、光合生理参数和叶绿素含量的变化。结果表明,中度干旱胁迫下,小麦最大根长、净光合速率、叶绿素含量表现为高氮>中氮>低氮,苗高、气孔导度为中氮>高氮>低氮;严重干旱胁迫下,最大根长表现为低氮>中氮>高氮,净光合速率、叶绿素含量均表现为中氮>高氮>低氮;2个干旱处理下,根冠比均表现为低氮>中氮>高氮,胞间CO2浓度为高氮>低氮>中氮。适度氮素处理能增强小麦幼苗生长和光合作用能力,对干旱胁迫具有一定的补偿效应。

The changes of growth indexes,physiological characteristics and chlorophyll content in wheat seedling leaves under different water-nitrogen coupling were determined.The wheat cultivars,namely Shangmai 5226 and Xiaoyan 15,were treated with 3 nitrogen levels low nitrogen,medium nitrogen,high nitrogen(0.5、8.0、15.0 mmol/L)and drought treatment simulated by PEG-6000.The results showed that,under moderate drought stress,maximum root length,net photosynthetic rate and chlorophyll content were high nitrogen>medium nitrogen>low nitrogen,seedling height and stomatal conductance were medium nitrogen>high nitrogen>low nitrogen;under severe drought stress,maximum root length showed low nitrogen>medium nitrogen>high nitrogen,net photosynthetic rate and chlorophyll content were medium nitrogen>high nitrogen>low nitrogen;under two drought treatments,root-shoot ratio was low nitrogen>medium nitrogen>high nitrogen,and intercellular CO2 concentration was high nitrogen>low nitrogen>medium nitrogen.Moderate nitrogen could enhance the growth and photosynthetic capacity of wheat seedlings,indicating that nitrogen had a certain compensatory effect on drought stress.