断根和剪枝对盆栽苹果叶片光合蒸腾及WUE的影响

Effects of Root Pruning and Shoot Pruning on Water Use Efficiency of Apple Leaves

以 5年生盆栽苹果 (MalusdomesticaBorkh/MalushupenensisRhed)为试材 ,研究了断根和剪枝等处理对叶片净光合速率 (Pn)、蒸腾速率 (Tr)、气孔导度 (Gs)、水分利用效率 (WUE)的影响及引起WUE变化的原因。结果表明 ,断根明显提高了WUE ,处理后第 2～ 42天逐渐升高。同时 ,断根后Tr、Gs明显下降 ,而Pn和羧化效率 (CE)迅速恢复 ,并在第 7天以后明显高于对照 ;新根总数及叶片玉米素核苷 (ZR)浓度则于第 2 8天后恢复至对照水平。剪枝使Pn、CE、Tr、Gs及叶片ZR浓度升高 ,但WUE只在 2 8d后稍高于对照。断根结合剪枝后第 2天 ,Pn、CE、Tr及Gs下降 ;2 1d后Pn和CE高于对照 ,而Tr及Gs与对照相近 ,WUE在后期稍有升高。分析认为 ,断根通过降低气孔导度极显著地提高了叶片WUE ,剪枝则通过提高CE而使WUE升高。

The effect of root pruning and shoot pruning on net photosynthetic rate(Pn), transpiration rate(Tr), stomatal conductance(Gs), leaf water use efficiency (WUE), and the reason causing the changes in WUE were explored in potted five year old apple( Malus pumila Mill/ Malus hupenensis Rhed) trees. The results showed that root pruning increased WUE obviously from the second day to the 42th day after treatment. In the mean time, Tr and Gs decreased obviously, but Pn and carboxylation efficiency(CE) recovered rapidly and was higher than control on the seventh day of treatment. The total number of new roots and the concentration of zeatin riboside(ZR) in leaf restored to the control level after 28 days of treatment. Shoot pruning increased Pn?CE?Tr?Gs and the concentration of ZR, but WUE heighten a little over control after 28 days of treatment. Pn?CE?Tr and Gs all decreased on the second day after both root and shoot pruning, then on the 21th day, Pn and CE was higher than control, Tr and Gs went up to the control level, so the WUE had a little rise in the late stage of treatment. It is proposed that root pruning increased WUE by decreasing Gs significantly and shoot pruning increased WUE by increasing CE.