杉木苗期施氮对二年生生长的影响

Effect of N Supply in Seedlieg Time on the 2 - Yearold Chinese-seedling

为了研究杉木苗期施氮的后期效应,我们在盆栽条件下对一年生杉苗按0.0、0.4、0.8、1.2、1.6、2.0g氮/盆6个水平进行施肥,结果表明:苗期施用氮肥对二年生杉苗的生长仍有十分显著的影响,二年生杉苗的苗高、地径、生物量(干重)积累、分枝数、分枝总长等各项生长指算随施氮水平的变化趋势均与一年生时相似;H/D值、T/R值与根、茎、叶占全苗比重等各项比例在不同的施氮水平之间有著差异,但在一年生和二年生之间无显著差异;当仅以苗高、地径、根长来评价其二年生生长效应时,可以认为苗期施氮无效,但综合生物量枳累和分枝特性指算,施氮的效应显著。

This paper deals with the effect of N supply on the 2 -year-old Chinese-fir seedlings by the seedlingsraising in pot culture at six levels of N ( urea ) supply: 0.0, 0.4, 0.8, 1.2, 1.6 and 2.0 g N/pot. The results are as follows: 1 ) N sapply still have had significant influence over the grow of the seedlings. With N supply levels the change tends of heigh, diameter at butt end, biomass (dried weiht)nuumber of branchisng and total length of braching etc of the seedlings, were simiar to those of the 1-year-old seedlings. 2) Under the N supply levels the H/D rate, T/R rate and the percentage of root, stem and needle were significant difference but there was not significant difference between the years. 3) It was considered there no effect of N supply on the 2-year-old seedlings, which was eveluated by the means of the indices of the height, diameter at butt end and length of root. But there was significant effect of N supply on the 2-year old seedlings according to the indices of biomass, characters of branching.