干旱胁迫下氮素对猴樟幼苗生长及光合特性的影响

Effects of nitrogen on growth and photosynthetic characteristics of Cinnamomum bodinieri seedlings under drought stress

为研究猴樟(Cinnamomum bodinieri)幼苗对干旱胁迫的响应及外源添加氮素对其抗旱性调控的效应,以1年生猴樟幼苗为试验材料,以霍格兰营养液为氮源,设置缺氮(N_(0))、施氮(N_(1))2个氮素水平,并对其进行干旱处理,分别于停止浇水后0 d(正常水分,W_(0))、3 d(轻度干旱,W_(1))、5 d(中度干旱,W_(2))、8 d(重度干旱,W_(3))进行生长指标、叶绿素含量和光合气体交换参数的测定。结果表明,干旱胁迫会抑制猴樟幼苗的生长及生物量的积累,降低叶片叶绿素含量,诱导气孔关闭,降低胞间CO_(2)浓度,抑制叶片的净光合速率。外源添加氮素能够促进猴樟幼苗的生长,且主要体现为对地上部分生长的促进,并能够提高幼苗叶片叶绿素含量,显著提高干旱胁迫下猴樟幼苗的净光合速率。

To investigate the response to drought stress and the effect of exogenous nitrogen addition on drought resistance,1-yearold Cinnamomum bodinieri seedlings were used as experimental materials,and the Hoagland nutrient solution was used as the nitrogen source.Two nitrogen levels,nitrogen deficiency(N_(0))and nitrogen application(N_(1))were set,and drought treatment was applied.The growth indexes,chlorophyll content and photosynthetic gas exchange parameters were measured at 0 d(normal water,W_(0)),3 d(mild drought,W_(1)),5 d(moderate drought,W_(2))and 8 d(severe drought,W_(3))after stopping watering,respectively.The results showed that drought stress could inhibit the growth and biomass accumulation of Cinnamomum bodinieri seedlings,reduce leaf chlorophyll content,induce stomatal closure,reduce intercellular carbon dioxide concentration,and inhibit the net photosynthetic rate of leaves.Exogenous nitrogen addition could promote the growth of Cinnamomum bodinieri seedlings,mainly reflected in the growth of the above-ground part,and could increase the chlorophyll content of the seedlings,and significantly increase the net photosynthetic rate of the seedlings under drought stress.