氮磷钾配施对百喜草干物质积累及其动态变化的影响

在1999年N、P、K单施的基础上,于2000年进行了N、P、K的4种配比施肥对百喜草干物质积累动态变化的研究,结果表明,N P K、N P、N K三个组合增产效果显著,干物质积累量分别达到14.61,14.34,13.80 t/hm2,比单施N、P、K和P K的效果好.所有处理的干物质积累量增长与生长时间的关系曲线皆呈"S"型,干物质积累量增长最佳时间为萌动生长后的125 d左右,含N组合在该时间段增长明显快于P K组,N素对百喜草的增产具有主导作用.在百喜草生长期内,N、P、K配比施用中,百喜草干物质积累量(Y)与生长时间(X)的回归方程可用Logistic 生长曲线拟合,相关系数呈极显著水平,可用于施肥对百喜草干物质积累的动态预测.通过对Logistic 生长曲线的分析表明,N的主导效应主要通过显著地增加线性期历时、缩短指数期和衰减期的历时来实现.

Effects of N, P, K and their combinations on dry matter accumulation of Paspalum notatum

On the basis of simple application of N, P and K in 1999, effects of four combined applications of N, P and K on dry matter (DM) accumulation of Paspalum notatum were studied in 2000. The results showed that dry matter accumulation had significant responses to N+P+K, N+P and N+K applications and reached (14.61), 14.34 and 13.80 t/hm~2 respectively. The combined applications were better than the simple application of N, P, K or P+K in terms of DM increase. The relations between dry matter accumulation and growing days could be well simulated by "S" curves. The optimal growth stage of increasing dry matter was around 125 days after germination. The increase in dry matter accumulation was higher with the applications including N than that of the application without N during that stage. Thus N played the most important role in dry matter accumulation. P had better effect on DM accumulation than K. The relations between the amount of dry matter accumulation (Y) and growing days (X) for different N+P+K combinations could be modeled by Logistic (equations) with significant correlation coefficients (P<0.01). The equations can be used to predict the dry matter accumulation under different fertilizer regimes. The analysis by logistic growth curve indicated that the N fertilizer was the key factor to DM accumulation mainly by significantly increasing the days of linear phase of growth and decreasing the days of logarithmic and senescence phase of growth.