修枝对复合农林系统内作物光合特性及生长的影响

以论证修枝作为复合农林系统优化措施的可行性为目的,对复合农林系统内的杨树进行4种不同强度的修枝处理,分别为P1(修掉树冠高度的1/6)、P2(修掉树冠高度的2/6)、P3 (修掉树冠高度的3/6) 、P4(修掉树冠高度的4/6),以CK(不修枝)为对照,研究了修枝对复合农林系统内冬小麦、夏玉米的净光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)、细胞间隙CO2浓度(Ci)、气孔限制值(Ls)等光合生理特性以及农艺性状、产量构成因素的影响.结果表明:(1)修枝能有效增加作物光合速率、蒸腾速率,同一时刻修枝强度越大光合速率、蒸腾速率越大,下午时这种促进作用小于上午与中午.(2)修枝能显著促进小麦、玉米增高、增粗、增重,且越到后期修枝对作物生长的促进作用越明显.另外,修枝对玉米生长的促进作用大于小麦.(3)修枝能使林下作物大幅增产;修枝后玉米主要通过增加穗数,小麦主要通过增加粒重和穗粒数增产;修枝后玉米增产幅度大于小麦,小麦产量表现优于玉米,小麦比玉米更适合复合农林系统.

Effects of different pruning intensity on photosynthetic characters, growth and yield of crops in agroforestry

The effects of pruning on winter wheat and summer maize were investigated to demonstrate whether pruning could act as an optimization measure for agroforestry system. Contrasted to no pruning(CK), four different pruning intensity P1(1/6 height of crown cut down),P2(2/6 height of crown cut down),P3(3/6 height of crown cut down) and P4(4/6 height of crown cut down) were applied to poplar in agroforestry and the agronomic characters, yield components and photosynthetic characters, such as net photosynthetic rate (Pn),transpiration (Tr), stomatal conductance(Gs), intercellular CO2 concentration(Ci) and stomatal limitation(Ls) of winter wheat and summer maize were tested. The results showed that net photosynthetic rate and transpiration rate of crops increased after pruning,which was less remarkable in the afternoon than in the morning. The height,ground diameter and aboveground biomass of winter wheat and summer maize both increased remarkably, and that of summer maize was higher than that of winter wheat. The yield of crops also increased substantially after pruning, and that of wheat mainly came from thousand grain weight and the number of grain per spike, but that of maize mainly came from spike number. The increased yield of maize was higher than that of wheat, but the total yield was lower than that of wheat. So winter wheat was more suitable for agroforesty system than summer maize.