玉米叶气孔特征对氮素和水分的响应及其与叶气体交换的关系

Responses of leaf stomatal traits to nitrogen and water and their relationship with leaf gas exchange in corn

采用二因素三水平的盆栽试验,研究了玉米叶气孔特征[气孔密度、气孔长、气孔宽、气孔面积、气孔孔径面积指数(SPI)和理论最大气孔导度(g_(smax))]对氮肥和水分的响应及其与叶光合气体交换参数的关系,以揭示叶生理功能对水氮响应的结构基础。结果表明:(1)施氮显著增加玉米叶上表面的气孔密度、气孔长、气孔宽、气孔面积、SPI和g_(smax),充足施氮处理(N2)的增加幅度分别为6.6%、12.5%、10.0%、12.3%、35.9%和31.6%;施氮亦显著增加下表面的气孔密度、气孔长、SPI和g_(smax),N2处理的增加幅度分别为14.4%、4.7%、25.5%和20.9%。随水分供应增加,下表面的气孔密度降低,上、下表面的气孔长和气孔面积增加,充分供水处理(W2)的下表面气孔密度降低6.9%,上、下表面气孔长分别增加5.3%、4.1%,上、下表面气孔面积分别增加7.2%、7.1%;氮处理对气孔特征的影响要大于水分处理。(2)不同处理间上、下表面的气孔大小(气孔长、气孔宽或气孔面积)与气孔密度间无相互制约关系。(3)光合速率和气孔导度主要决定于上、下表面的气孔大小和SPI,g_(smax)可以解释光合速率和气孔导度变异的49.7%和39.7%。蒸腾速率主要受上、下表面气孔大小的影响,而瞬时水分利用效率主要受上表面气孔密度、上下表面气孔大小和SPI的影响。

A pot experiment with two-factor and three-level complete random design was used to study the responses of stomatal traits[stomatal density,length,width,area,stomatal SPI index(SPI)and theoretical maximum stomatal conductance(g_(smax))]to nitrogen and water and their relationship with photosynthetic gas exchange in corn leaves to elucidate the structural basis of leaf gas exchange under different nitrogen and water availabilities.The results indicated that:(1)N application increased stomatal density,length,width,area,SPI and gsmax on the adaxial surface,and the increase percentage for ample N use treatment(N2)was 6.6%,12.5%,10.0%,12.3%,35.9%and 31.6%,respectively.N application also enhanced stomatal density,stomatal length,SPI and gsmax on the abaxial surface,and the increased percentage for N2 treatment was 14.4%,4.7%,25.5%and 20.9%,respectively.Irrigation significantly decreased stomatal density on the abaxial side with a 6.9%decrease for ample irrigation treatments(W2).Irrigation also increased stomatal length and area on both surfaces,with 5.3%and 4.1%increase of stomatal length and 7.2%and 7.1%increase of stomatal area on the adaxial and abaxial surfaces for W2 treatment.The influence of N use on stomatal traits was larger than irrigation.(2)No trade off relationship between stomatal size(stomatal length,width or area)and stomatal density was found for both leaf surfaces.(3)Photosynthetic rate and stomatal were mainly determined by stomatal size and SPI.gsmax explained 49.7%of photosynthetic rate variance and 39.7%of stomatal conductance variance.Transpiration rate was mainly determined by stomatal size on both sides,and instantaneous water use efficiency was mainly determined by adaxial stomatal density,stomatal size and SPI on both sides.These results demonstrated the physiological basis of N and water availabilities affecting leaf gas exchange from the angle of stomatal anatomy.