沙芥和斧形沙芥种子萌发对土壤含水量的适应性

以中国特有种沙芥[Pugionium cornutum(L.)Gaertn.]和濒危种斧形沙芥(Pugionium dolabratum Max-im.)的种子为研究材料,利用自然生境的沙土在室内进行种子萌发人工模拟试验,研究沙芥和斧形沙芥种子萌发、幼苗出土和幼苗生长对土壤含水量的适应性。结果表明:沙芥和斧形沙芥果实适宜萌发的土壤含水量范围均为6%～12%,适宜出苗的土壤含水量范围均为6%～16%。当土壤含水量低于2%时,果实不能萌发;当土壤含水量低于3%时,幼苗不能出土定居;当土壤含水量为6%～12%时,最有利于幼苗的生长。当土壤含水量分别为3%～8%和4%～8%时,沙芥和斧形沙芥植株根冠比最大。因此,沙芥和斧形沙芥种子萌发机制对沙生环境有着极强的适应性;植株将更多的同化物用于根系生长,以吸收更深层次的水分,从而适应含水量低的土壤。

Adaptation of Seed Germination of Pugionium cornutum and P.dolabratum to Sand Moisture Content

Pugionium cornutum is a special species in China and Pugionium dolabratum was listed an endangered species in 1992.Took sand from the natural habitat of P.dolabratum and used for indoor artificial simulation test,we investigated the adaptation of seed germination,seedling emergence and seedling growth in P.cornutum and P.dolabratum to sand moisture content.Results showed the optimal sand moisture content for seed germination was from 6% to 12% for both P.cornutum and P.dolabratum.The optimal sand moisture content for seedling emergence was from 6% to 16%.When sand moisture content was under 2%,seeds could not germinate;when sand moisture content was under 3%,seedling could not emerge and settle.The optimal sand moisture content was from 6% to 12% for P.cornutum and P.dolabratum’s seedling development.From 3% to 8% for P.cornutum and from 4% to 8%,for P.dolabratum have their significantly highest root-top ratio.The seed germination mechanism of P.cornutum and P.dolabratum has strong adaptability to sand environment.In order to adapt to low sand moisture content,seedling allocated more biomass to root to absorb deeper level of water.