沙冬青种子形态和比叶面积沿降水梯度的变化特征

Variation in seed morphology and specific leaf area of Ammopiptanthus mongolicus along precipitation gradient

种子形态学性状对种子植物繁衍具有重要的调控作用,比叶面积反映植物截获光能的能力,这二大功能性状反映了植物对环境的适应策略及自身调控机制。以天然沙冬青种群为研究对象,沿270-50mm年降水梯度,测量分析了6个分布区内的标准株的种子和叶片。结果表明:6个自然分布区的沙冬青种子长度、宽度、体积、表面积及千粒重均有显著性差异(P<0.05),而种子长宽比差异不显著(P>0.05)。其中种子体积变异程度最大,且种子多项形态指标的协同作用显著,说明种子通过调节大小和性状间的最优组合来适应环境的变化。不同区域的环境因子中仅年平均降雨量对沙冬青比叶面积的影响显著,且随着雨量的增加,比叶面积呈增大趋势,表现出显著的正相关性(P<0.05)。沙冬青种子各性状与比叶面积之间存在负相关关系,但仅种子长度与比叶面积的相关性显著,说明植物的资源营养生长和种子繁殖生长的时期本身不完全同步,两者间的权衡关系体现了沙冬青对外界环境变化的适应策略。

The morphological characters of seeds have important regulation effect on seed plant reproduction.The specific leaf area reflected the ability of plants to intercept light energy.These traits reflect the adaptability of plants to their surrounding environment and their self-regulatory capacity.In this study,the seed morphological characters and specific leaf area of Ammopiptanthus mongolicus natural populations were determined along the precipitation gradient(from 270 to 50 mm)in six experimental plots.The results showed that the length,width,volume,surface area and thousand seed mass of A.mongolicus in the six plots were significantly different(P<0.05),but the difference in length width ratio was not significant(P>0.05).Seed volume variation was the largest,and the synergistic effect of multiple morphological indexes was significant.A.mongolicus.adapted to the changes in the environment by regulating various morphological indexes of its seed and forming optimum functional combinations of the traits.Among the environmental factors in different plots,only the annual average rainfall had a significant influence on the specific leaf area of A.mongolicus.With the increase of rainfall,the specific leaf area increased continuously.It showed a significant positive correlation.Seed traits and specific leaf area were negative correlation,but they had no significant difference excepted for the seed length(P>0.05).This indicates that the vegetative growth and the period of seed propagation growth are not completely synchronous.The response of the functional traits combination of seed and specific leaf area reflect the survival strategy and adaptation mechanism of desert plants to the environmental change.