关键词: 杨树林, 杨树林, 细根生物量, 垂直分布, 季节变化, 碳储量, 土壤因子

Abstract: This paper aims to study the effects of young fruit thinning combined with pruning on the growth and fruiting of longan trees. Twelve 6-year-old fruiting trees of longan‘Shixia’were used as materials, and a L9(34) orthogonal design was adopted to test the effects of different factors, including retractive pruning, initial rate of fruiting branches and initial number of fruit per panicle, on shoot ratio, fruit dropping rate, fruiting branch rate, the number of fruits per panicle, yield, mature period and fruit quality when fruit ripening, and the combination of advantageous factors and levels was also screened. The research results showed that there were remarkable differences between the treatments and control in shoot growth, fruit development and mature quality (P<0.01), along with the specific performance as follows: the decreased fruit drop rate (P<0.01), earlier maturity, a certain ratio of new shoots, improved unit yield, increased fruit weight and TSS content, and cleaner bright yellow green for fruit color (P<0.01). Higher initial rate of fruiting branches were among the treatments, higher rate of those when ripening, and the fruit color of the trees with retractive pruning treatment tended to be saturated yellow green. The more the initial fruit amount per panicle, the more slowly the fruit development, the higher the fruit dripping speed, the later the fruit ripening and the higher number the fruit per panicle. Furthermore, the single fruit mass and TSS content of aril were all the highest, which matured on the trees with treatment at a middle level of initial fruit amount of 60 per panicle. The variance analysis of the orthogonal test showed that there were significant differences (P<0.05) between the levels of the factor initial number of fruit per panicle in the number of ripening fruit per panicle and the factor retractive pruning in the h° value, and the results of visual analysis showed that the optimal combination to obtain the balance between the growth and fruiting of longan trees as well as the yield and quality of longan fruits was: fruiting branches of 50%-60%, about 60 fruits per panicle and reasonable retractive pruning. Therefore, this study can provide a feasible instruction for longan production.