黑河中游边缘绿洲不同水分条件对青贮玉米叶片光合特性及产量的影响

Effect of Different Water Conditions on Photosynthetic Characteristics of Silage Maize in Marginal Oasis Regions of Middle Reach of Heihe River Basin

在甘肃河西走廊中部黑河中游临泽北部边缘绿洲区,运用开放式气体交换LI-6400便携式光合作用测定系统和PAM-2100型便携式叶绿素荧光仪,研究了不同土壤水分条件下青贮玉米的气体交换特征及叶绿素荧光参数。结果表明,不同土壤水分条件下,青贮玉米均出现光合下调,即"光合午休"现象,引起"光合午休"的原因主要为非气孔因素,光系统Ⅱ光化学效率(Fv/Fm)明显降低,表现为光抑制。不同土壤水分条件下,青贮玉米的Pn、Tr均随着土壤水分的降低而降低,WUE却增加,方差分析表明,高水分条件的Pn和WUE与低水分条件的Pn和WUE均存在显著差异,而其他各处理的Pn和WUE之间无显著差异。随着土壤水分的下降,青贮玉米的地上生物产量逐渐降低,但差异性不显著。这说明高的水分条件并不能消除青贮玉米的光抑制现象,反而显著降低其水分利用效率,低水分条件在降低地上生物产量不显著的情况下显著提高了水分利用效率。

In order to discuss the mechanism of photosynthesis regulation of silage maize under different soil water conditions.A LI-6400 portable photosynthesis system and portable chlorophyll fluorometer PAM-2100 were used to study the characteristics of gas exchanges and cholorophyll fluorescence of silage maize under different soil water conditions in the marginal oasis regions of northern part of Linze in middle reach of Heihe river basin in the middle region of Hexi corridor in northwestern China.The results showed that there was midday depression of photosynthesis of silage maize under different soil water conditions,and the main factor which resulted in depression of photosynthesis was non-stomatal factor,and the diurnal changes in Fv/Fm exhibited an obviously decline,it exhibits a photoinhibition.With soil water reduced,the Pn,of silage maize all gradually decreased,but WUE increased,ANOVN showed the Pn and WUE in high water condition had significant difference with that of low water condition,but the Pn and WUE all had not significant difference in other Treatments.The above-ground biomass yield reduced with soil water decreased,but they had not significant difference.These results suggested the photoinhibition phenomenon of silage maize is not avoided in high water condition,but water use efficiency is decreased significantly.The low water condition is advantageous in enhancing water use efficiency of silage maize while above-ground biomass yield reduced little.