土壤水分胁迫下小麦叶片渗透调节与光合作用

Osmotic Adjustment and Photosynthesis of Wheat Leaves under Soil Water Stress

在土壤水分胁迫过程中,抗旱性强的小麦品种昌乐5号、北农2号与抗旱性弱的品种济南13、鲁麦5号相比,渗透调节能力高0.41MPa～0.604MPa;相对含水量少降7%～8%;叶片水势少降0.40MPa～0.41MPa.水分胁迫使叶片光合能力下降,抗旱性强的品种与抗旱性弱的品种相比,其下降的平均百分数为:光合速率前者比后者少降17%～22%;气孔导度少降21%～23%;表观量子产额少降5%～36%;光系统Ⅱ光化学效率少降6%～8%;羧化效率少降10%～21%.说明土壤水分胁迫下,抗旱性强的小麦品种通过渗透调节使光合作用从气孔调节、光化学过程到暗反应都比抗旱性弱的品种下降幅度小.

Under soil water stress, osmotic adjustment ability of wheat cultivars with strong drought-resistant (Changle 5 and Beinong 2) was higher than that of wheat cultivars with weak drought-resistant (Jinan 13 and Lumai 5) , the increasing degree of osmotic adjustment was 0. 41 MPa-0. 604 MPa. While relative water content and water potential of wheat cultivar leaves decreased, the dropping percentage of relative water content and dropping value of water potential of wheat cultivars with strong drought-resistant were 7%-8% and 0. 40 MPa-0. 41 MPa less than that of wheat cultivars with weak drought-resistant. Photosynthetic capacity of wheat cultivars was inhibited under soil water stress. However, inhibition degree of photosynthesis was different between strong drought-resistant cultivars and weak drought-resistant cultivars. Experimental results showed that photosynthetic rate, stomatal conductance, apparent quantum yield, PS Ⅱ photochemical efficiency(Fv/Fm) and carboxylation efficiency of wheat cultivars with strong drought-resistant were 17%-22%, 21%-23%, 5%-36% and 6%-8% and 10%-21% less than that of wheat cultivars with weak drought-resistant, respectively. All the above results showed that the osmotic adjustment could counteract the depression of stomatal conductance, photochemical phase and carbon dioxide assimilation of wheat leaves under soil water stress, and thus helped to maintain the photosynthetic rate at relative higher level.