干旱胁迫下抗旱高产小麦新品系旱丰9703的渗透调节与光合特性

The Osmotic Adjustment and Photosynthesis of a Wheat Cultivar Hanfeng 9703 with High Yield, Drought Resistance under Drought Stress

以抗旱性强的小麦旱丰 970 3与抗旱性弱的山农 2 15 95 3为试材 ,对扬花期、灌浆期、乳熟期的渗透调节能力、净光合速率和PSⅡ光化学活性等进行了研究。结果表明 ,长期大田干旱胁迫下 ,旱丰 970 3三个生育时期的叶片相对含水量与渗透调节能力均高于山农 2 15 95 3,扬花期的渗透调节能力最强 ,分别比灌浆期、乳熟期高 0 0 7和 0 3MPa ;干旱胁迫降低了两个小麦品种扬花期、灌浆期、乳熟期的净光合速率 (Pn)、最大光化学效率 (Fv Fm)和实际光化学效率 (ΦPSⅡ) ,在乳熟期这种趋势更加明显 ,但抗旱性强的小麦品种下降幅度较小 ,与山农 2 15 95 3相比旱丰 970 3仍具有较高的Pn、Fv Fm和ΦPSⅡ ;干旱加重了乳熟期两个小麦品种的“光合午休” ,但旱丰 970 3仍具有较高的PSⅡ光化学活性 ;干旱胁迫下两品种光合速率最高值比对照提前 2h出现 ,强光下旱丰 970 3的非光化学猝灭 (NPQ)能力较强 ,光抑制程度较轻 ,在傍晚PSⅡ光化学活性能够较快恢复。据此 ,我们认为 ,旱丰 970 3较强的渗透调节能力使叶片的保水能力增强 ,维持了较高的净光合速率和PSⅡ光化学活性 。

The osmotic adjustment, net photosynthetic rate(P n) and photochemical activity of PSⅡ complex at flowering, seed filling and milk ripening stages under drought stress conditions were studied by using two high yield winter wheat (Triticum aestivum L.) cultivars Hanfeng 9703(drought resistant) and Shannong 215953(drought sensitive). Osmotic adjustment (OA) and relative water content of Hanfeng 9703 were higher than those of Shannong 215953 at three different stages. Osmotic adjustment at flowering stage was the highest which was 0 07 and 0 3MPa over that at seed filling stage and milk ripening stage, respectively. Drought stress resulted in the decrease of net photosynthetic rate, maximal photochemical efficiency (F v/F m) and actual photochemical efficiency (Φ PSⅡ) of the two varieties at the three stages, and this trend was more obvious at milk ripening stage. However, P n, F v/F m, Φ PSⅡ of Hanfeng 9703 were higher than those of Shannong 215953. Drought stress enhanced the midday depression of P n in the leaves of the two varieties at milk ripening stage. PSⅡ photochemical activity in the leaves of Hanfeng 9703 were higher than that of Shannong 215953. The peak of P n in the two varieties appeared 2 h earlier under drought stress than under normal conditions. The activity of PSⅡ reaction centers were less suppressed, and the recovery of PSⅡ photochemical activity was faster in Hanfeng 9703 than that in Shannong 215953. According to the above results, we concluded that higher osmotic adjustment of Hanfeng 9703 could maintain higher net photosynthetic rate and PSⅡ photochemical activity which were beneficial for high yield production.