Effects of drought on photosynthate supplying capability of flag leaf in different winter wheats | 干旱对不同冬小麦旗叶光合产物供应能力的影响

صينى. 研究干旱对小麦旗叶光合产物供应能力的影响，揭示小麦抗旱高产的生理机制，为提高小麦的抗旱能力及高产稳产提供理论依据。在防雨池栽培条件下，以旱地冬小麦品种长武134（抗旱性强）和水地冬小麦品种陕253（抗旱性弱）为试材，以适宜水分处理为对照（CK，土壤含水量为田间持水量的70%～75%），研究干旱处理（土壤含水量为田间持水量的50%～55%）对不同冬小麦旗叶光合产物供应速率（净光合速率和蔗糖合成能力）和供应持续期的影响。与对照相比，干旱处理降低了冬小麦灌浆中后期旗叶净光合速率，缩短了净光合速率高值持续期(PAD)，其中长武134降幅较小，净光合速率较高；干旱处理提高了冬小麦灌浆初期旗叶的蔗糖磷酸合成酶(SPS)活性，其中长武134增幅较大，且在灌浆中后期依然能保持相对较高的蔗糖供应能力；干旱处理缩短了冬小麦叶绿素含量缓降期(RSP)，提高了丙二醛(MDA)含量，加速了旗叶的衰老，缩短了光合产物的供应持续期，其中长武134受干旱影响较小；干旱处理降低了冬小麦灌浆中后期主茎穗粒质量积累量及其速率，其中长武134降幅较小。干旱条件下，抗旱品种长武134旗叶在灌浆中后期可维持较高的光合产物供应速率和较长供应持续期，这是其主茎穗粒质量积累量及其速率降幅较小的重要原因。

إنجليزي. Studying the effects of drought on photosynthate supplying capability of flag leaf can partially reveal the physiological mechanisms of drought-resistant wheat cultivars with high grain yield and provide some theoretical basis for improving drought resistance ability and maintaining a high and stable yield of wheat. Under the condition of rain-proof shelter culture, two types of winter wheat (Triticum aestivum L.), dryland cultivar Changwu 134 (drought-resistant) and irrigated cultivar Shaan 253 (drought-sensitive), were applied to study the effects of soil drought (the soil water content was 50%C55% of the field water capacity) on photosynthate supplying rate (net photosynthetic rate and sucrose synthetic rate) and supplying duration of flag leaves. Thereinto, the optimum soil water treatment was served as control (CK,the soil water content was 70%-75% of the field water capacity). Compared with the control, both net photosynthetic rate (Pn) and photosynthetic active duration (PAD) of flag leaves in two winter wheats were significantly decreased during the middle and late grain filling period due to drought stress. In contrast with Shaan 253, however, Changwu 134 had a relatively lower decreased degree and could maintain a higher Pn. Drought also significantly increased the flag leaf sucrose phosphate syntheses (SPS) activity in two winter wheats during the early grain filling period. However, Changwu 134 exhibited relatively higher flag leaf SPS activity when compared with Shaan 253, which might be helpful to preserve a high sucrose supplying capability during the middle and late grain filling period. Moreover, the shortened steady phase of chlorophyll content (RSP) and the increased malondialdehyde (MDA) content in flag leaf might accelerate the aging of flag leaf, which could significantly shorten its photosynthate supplying duration. Furthermore, drought resulted in a significant decrease of accumulation rate and accumulation amount per spike grain mass of main stem during the middle and late grain filling period, but had little influence on Changwu 134. Under drought conditions, drought-resistance wheat-Changwu 134 can maintain a relatively higher photosynthate supplying rate and longer photosynthate supplying duration in comparison with Shaan 253, which could be a key reason for a low decrease of accumulation rate and accumulation amount per spike grain mass of main stem.