Effects of Four Seasons Pruning on Controlling Crown and Yield of Young Trees in Close Planting Chestnut Garden

Six chestnut varieties(Yanming,Timazhenzhu,Zipo,Beijing No.8,Daqinggan and Yanshankuili) were used as materials,the effects of four seasons pruning on the plant height,crown diameter,fruit branch number in crown projection per unit area and yield in close planting chestnut garden were studied from 2005 to 2007.The results showed that four seasons pruning could accelerate the speed of forming,promote bearing,and control the crown effectively.There was obvious difference in the yield between four seasons pruning and only winter pruning in the second year.The tree was compact in the third year,the average yield was 1 293.3 kg/hm2,which increased by 133.9%,that was 2 542.8 kg/hm2 in the forth year,which increased by 133.0%.The control tree only with winter pruning could not complete the shaping in the third year,and it would crown closure in the forth year.The effects of the pruning technique on Yanshankuili was significant.