甜瓜光合特性对土壤水分条件的响应

以甜瓜品种‘银帝’和‘玉金香’为材料,设充分供水、轻度亏缺、中度亏缺3种水分处理,研究土壤水分条件对甜瓜开花-果实膨大期光合特性的影响.结果表明:在3个水分处理下,‘银帝’和‘玉金香’的净光合速率(Pn)日变化和气孔导度日变化(Gs)均表现为双峰曲线型,具有明显的光合"午休"现象.轻度和中度水分胁迫下,‘银帝’、‘玉金香’Pn显著降低,随水分亏缺程度加大,甜瓜叶片的蒸腾速率(Tr)呈下降趋势,瞬时水分利用效率(WUE)有所增加,表明轻度和中度水分亏缺能够提高甜瓜的水分利用效率.轻度、中度处理下,甜瓜叶片Pn下降以非气孔限制为主.各处理下甜瓜叶片Ci均呈现"下降-上升-下降-上升"的变化趋势,Ls的变化趋势则与Ci相反.在水分胁迫处理下,‘玉金香’叶片的Pn和WUE均高于‘银帝’,中度亏缺处理下,‘玉金香’日平均Pn和WUE分别比‘银帝’增加15.4%和8.2%,说明‘玉金香’的干旱适应性比‘银帝’强.

Photosynthetic response of melon leaf under soil water deficiency

Photosynthetic response characteristics of melon leaf(cvs.'Yindi'and'Yujingxiang')were researched during the period of flowering-fruit enlargement under the treatments of full-supplied water,light and moderate water deficit.The results indicated that diurnal change on net photosynthetic rate(Pn) of both cultivars appeared double-peak curve with apparent middy depression in the three treatments.The Pnof them significantly reduced under water deficit treatments.With the increase of water deficit degree,the transpiration rate(Tr) appeared a downward trend,but instantaneous water use efficiency(WUE) increased,which showed that the water utilization efficiency of melon was improved under light and moderate water deficit.Their decline of Pnwas contributed to non-stomatal limit under water deficit treatments.The Pnand WUEof'Yujinxiang'were higher than those of'Yindi'under the two kind water deficits.The average dinural Pnand WUEof'Yujinxiang'increased by 15.4% and 8.2%respectively compared with Yindi under moderate deficit,which showed'Yujinxing'had a better adaptation to drought.