苹果树形改造对树冠结构和冠层光合能力的影响

为解决乔化密植苹果园树冠郁闭、光照差、产量低、品质差的问题, 于2001～2004年在北京昌平区十三陵农场(东经116°13′, 北纬40°13′, 海拔79 m) 对1986年定植的富士苹果(M alus domestica Borkh.‘Fuji’) 进行树形改造试验, 将三主枝疏散分层形逐步改造为高干开心形。经过3年的改造, 主干高度从0.29 m提高到1.37 m, 主枝数从15.8个减少到4.58个, 冬剪后枝数从2 119.73 ×10³ ·hm^{- 2}减少到814.07 ×10³ ·hm^{- 2} , 叶面积指数从3.98减少到2.31。改造后树冠的叶片和光照分布更加均匀, 低于30%的无效光区从43%减少到24%。通过对冠层光合作用的数值模拟发现, 改造树冠层的光合作用比未改树略有降低, 在整个生长季(5～9月) 改造树的冠层光合能力比未改造树小14.6%, 但平均单叶光合速率却增加40.4%。改造后苹果产量从27.3 t·hm^{- 2}增加到54.5 t·hm^{- 2} , 可溶性固形物从12.83%增加到15.55%。

Influences of Tree Form Reconstruction on Canopy Structure and Photosynthesis of Apple

Tree form reconstruction of ‘Fuji’ apple (Malus domestica Borkh. ‘Fuji’) was carried outfrom 2001 to 2004 in theMing Tombs Farm ( longitude 116°13′east, latitude 40°13′north, altitude of 79 m)in Changp ing of Beijing. The three branch form was reconstructed into open2center system to resolve the p roblem of badly light distribution, yield and quality. By three years of experiment the height of trunk was advanced from 0.29 m to 1.37 m. The number of bough was reduced from 15.58 to 4.58. The number of spurswas reduced from 2 119.7 ×10³ ·hm^-2 to 814.1 ×10³ ·hm^-2 and leaf area index was reduced from 3.98 to2.31. The distribution of leaves and relative light intensity in canopywere uniform in open-center system. Theuseless light space was reduced from 43% to 24%. The simulation showed that photosynthesis rate of canopyin open-center system was reduced by 14.6% compared with control in growth period, but the mean photosynthetic rate was 40.4% higher than control. And the outputwas increased from 27.3 t·hm^-2 to 54.5 t·hm^-2and the soluble sugar of fruit was increased from 12.83% to 15.55%.