弱光对小麦花后旗叶光合及籽粒灌浆的影响

Effects of Weak Light at Grain Filling Stage on Photosynthetic Characteristics and Grain Filling of Winter Wheat

为给小麦的高产优质栽培提供理论依据,选用优质小麦品种济麦20为试验材料,在大田试验条件下研究了灌浆期弱光对小麦光合及籽粒灌浆进程的影响。结果表明,弱光处理后,旗叶净光合速率和光合色素含量(除叶绿素b)显著降低,灌浆中期弱光处理下小麦旗叶净光合速率降低的主要原因是气孔限制因素,而前期、后期弱光处理是非气孔因素造成的。弱光对旗叶叶绿素a的影响大于叶绿素b。弱光胁迫显著降低小麦产量和粒重,且产量和粒重对不同灌浆时期弱光胁迫的响应不同。灌浆中期弱光胁迫对小麦产量及粒重的形成影响最大,其中弱光胁迫对小穗下位籽粒粒重的影响大于上位籽粒粒重。弱光处理后籽粒粒重的降低主要是平均灌浆速率显著降低所致,而灌浆持续期长短对其影响较小。弱光胁迫下小麦光合同化产物不能满足灌浆需求,是导致其产量及粒重降低的主要原因之一。

The quality wheat cultivar Jimai20 was used to study the effects of weak light at grainfilling satge on the photosynthetic characteristics and grain filling of winter by shading treatment.The results showed that Net photosynthesis rate,and photosynthetic pigment contents excluding Chl b of wheat flag leaves were significantly decreased while shading at three stages.Stomatal limitations is the major reason for reduction of net photosynthesis rate at middle shading and no stomatal limitations is the major reason at early and late shading.The content of Chl a was more sensitive to shading than Chl b.Shading at all three stages caused a significant decrease in both yield and grain weight.Grain yield decreased by 26.1%,30% and 17.4% at early,middle and late shading treatments,respectively.Grain weight and yield were most seriously affected while shading at middle stage.And the decrease of grain weight was mainly in the basal kernels while shading.Decrease of grain filling rate,not decrease of grain filling duration was the major reason for declined grain weight at shading treatments.Shortage of assimilate supply due to inhibition of photosynthetic processes at shading was one of the major factors determining wheat grain filling.