燕麦表型可塑性与繁殖分配的研究

在不同的种植密度（种子数／m^2.D1,75;D2,300;D3,525;D4,750;D5,975)下，燕麦（Avena sativa L.）表现出较高的表型可塑性，其单株分蘖数、穗数、小穗数、不孕小穗数、种子数、植物体大小、繁殖体大小、营养体大小、穗粒数、穗粒重和单分蘖重等性状值均随密度的增加而减少，表现出明显的密度依赖性。无效分蘖数及其占分蘖总数的比例、种子单粒重及株高在密度处理间无显著差异，这些性状是非密度依赖的，植物体几何形状的变化模式属异速生长型，繁殖分配比例为一恒定值，对性状间回归分析的结果表明，处子数量和种子大小间不存在负的表型相关，植物单株与单分蘖大小依赖的繁殖输出以及繁殖体与营养体大小间显著的正相关关系都是线笥的，由于单位面积上的繁殖输出随种群密度的增加而增加，因此植物个体繁殖输出的变化不足以补偿因密度变化而造成的差异。

Studies on the phenotypic plasticity and reproductive allocation in Avena sativa L

The phenotypic plasticity and reproductive allocation were investigated in the annual plant Avena sativa L.in relation to sowing density.The number of tillers,spikes,spikelets,sterile spikelets and seeds decreased significantly with increasing density in single plants.So did the biomass of reproductive part,vegetative part and aboveground part of the plant,the number and size of seed per spike and tiller weight.This suggests a density-dependent response in these phenotypic traits.On the other hand,there was no significant difference in unspiked tiller number,mean seed mass and mean height of the plant.So these phenotypic traits were density-independent.The changes of the plant geometric shapes were allometry in growth period and the allocation of the plant to reproductive part was a constant with different densities.The results of regression analyses of phenotypic traits showed that there was no correlation between the seed number per plant and the mean seed mass.A liniar model of size-dependent reproductive output was detected for the plant,and the significant positive relations between reproductive weight and vegetative weight were liniar to single plants and to tillers respectively across different densities.Owing to the increase of the reproductive output per unit area with increasing density,it is clear that the variation of reproductive output per plant cannot compensate for the differentces caused by such large density variation.