桑树群体结构的研究 Ⅱ.桑树的栽植密度和群体结构

1982—1985年调查分析了新一之濑的不同密度桑园的群体结构,结果表明:一、春季叶面积指数高达10左右时,没有黄、落叶发生,夏伐后不同密度桑园的叶面积指数达4.5左右时,枝条基部均有黄落叶出现。二、桑园的消光系数(K值)大多变动在0.3—0.7之间,且中、下层比较稳定。三、第五年的桑园底层相对照度仍随密度的增加而减弱,这再次说明,增加栽植密度是提高光能利用率的一个重要措施。江、浙两省的速成丰产桑园以亩栽2,000株为宜,普通桑园也不应少于1,000株。

Studies on the stand structure of mulberry trees: I. Relationhips between stand struc-ture and planting densities. Sci. Seric.

The mulberry stand structure (New Ichinose variety) was investigated during 1982-1985. The results outlined as follows. After the Summer-prunnig, as long as LAT was reached to 4.5 the leaves on the lower blanches became yellow and fallen occured, while in the spring the LAT even reachd to about10, we had not observed any leave yellowing and droping. The extinction coefficients, K, of mulberry stands varied between 0.3 to 0.7, depending on planting densities and the seasons, and it was rather constant accounted for the mid-bosal canony of the stands. The fact that the relative irradiance in the bottom of 5-year-old mulberry stands was decreased with the increase of planting densities demonstrates that the utilization rate of Solar energy can be increased by increasing planting density. The reasonable planting density for high productive mulberry yields in a short time in provinces of Jiangsu and Zhejiang, China, should be 2.000 plants per mu and not less than 1,000 plants per mu for ordinary ones.