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

Effects of Different Altitudes Gradient on Seed Size and Germination Characteristics of 3 Grasses Species from Tibet Plateau

以西藏高原3个海拔梯度的野生禾本科植物垂穗披碱草、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、0.11~0.21g和3.34~7.46g;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 gra- mineous species （Elymus nutans, Poa crymophila, Stipa capillacea） from Tibetan plateau. Results showed that thousand seed weight of Elymus nutans,Poa erymophila and Stipa capillaeea 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.