不同留苗株数对刺槐苗地径等级的影响

Effects of Different Numbers of Seedlings Left in the Seedbed on Diameter Grade of Robinia pseudoacacia

在辽西半干旱地区,以苗圃地播种获得的刺槐1年生幼苗为对象,研究了刺槐实生苗不同留苗密度对苗木质量的影响.结果表明留苗密度在12万-20万株hm^-2范围内,产出的Ⅰ级苗木的数量最多,达到6万-9万株hm^-2,且Ⅰ和Ⅱ级苗占总留苗株数的百分率达90%以上;留苗密度〈12株hm^-2,Ⅰ和Ⅱ级苗占总留苗株数的百分率能够达90%以上,但产出的Ⅰ级苗木的数量减少;留苗密度〉20株hm^-2,Ⅰ和Ⅱ级苗占总留苗株数的百分率低于90%,且产出的Ⅰ级苗木的数量减少.

In the semi-arid areas of western Liaoning Province,taking 1-year-old Robinia pseudoacacia as obj ects, the effects of Robinia pseudoacacia seedlings with different densities on their qualities were studied.Result shows that GradeⅠemerged the largest number (60 000-90 000 ?hm-2 )while the density being 120 000-200 000 trees ? hm-2;seedlings of GradeⅠ and Grade Ⅱ occupied more than 90% of the total seedlings left in the seedbed ;when the densities of seedlings left in the seedbed are less than 1 2 trees ?hm-2 ,seedlings with GradeⅠand GradeⅡoccu-pied above 90% of the total seedlings left in the seedbed,but the number of seedlings with Grade Ⅰ reduced;when density of seedlings left in the seedbed are greater than 20 trees ?hm-2 ,seedlings with GradeⅠand GradeⅡoccupied less than 90% of the total seedlings left in the seedbed,the number of seedlings with GradeⅠreduced.