海拔梯度对西藏高原3种禾本科牧草种子大小和萌发特性的影响

摘要

以西藏高原3个海拔梯度的野生禾本科植物垂穗援碱草、冷地早熟禾和丝颖针茅为研究对象,观测分析各类植物的种子大小、萌发特性及相互关系.结果发现:垂穗披碱草、冷地早熟禾和丝颖针茅种子千粒重分别为3.05～4.58、0.11～0.21 g和3.34～7.46 g;垂穗披碱草和丝颖针茅发芽率变幅分别为54.7％～88.0％、60.0％～84.0％,其千粒重、发芽率及发芽速率随海拔升高而降低.早熟禾种子千粒重、发芽率及发芽速率呈单峰变化,海拔4 654m的那曲县采集的种子发芽率最高,达93.4％;分析表明,种子大小与发芽率、发芽速率显著(p＜0.05)正相关,不同牧草呈现不同的拟合曲线.综合表明,海拔决定下的种子大小是影响植物萌发的重要因素.%The paper examined germination characteristics and their relations to seed size of 3 wild gramineous species (Elymus nutans、Poa crymophila、Stipa capillacea) from Tibetan plateau.Results showed that thousand seed weight of Elymus nutans、Poa crymophila and Stipa capillacea were 3.05-4.58 g、0.11-0.21 g and 3.34-7.46 g.respectively;the germination rate amplitude of Elymus nutans and Stipa capillacea were 54.7％-88.0％ and 60.0％-84.0％,respectively,and their thousand seeds weight、germination rate and germination speed declined with the rising of altitude;the variation of thousand seeds weight、germination rate and germination speed of Poa crymophila were unimodal type,the highest germination rate(93.4％) was obtained by Nagqu country with 4654 m.In addition,seed size was significant(p ＜ 0.05) negative with germination rate and germination speed,seed size under altitude is the key factor affecting seed germination.