稃的有无对大赖草种子扩散与萌发特性的影响

对大赖草Leymus racemosus（Lam．）Tzvel．]带稃种子和去稃种子的扩散性、萌发率、活力及吸水性和失水性的差异进行了比较。结果表明：在静止空气中带稃种子的降落速度显著小于去稃种子，分别为3．96和4．81m·s-1；而在风速1和4m·s-1的水平气流中带稃种子的扩散距离（15．26和11．86cm）均显著大于去稃种子（27．80和21．60cm）。培养20d后，带稃种子和去稃种子的萌发率分别为99％和97％，差异不显著；在自然条件及60℃高温条件下，带稃种子和去稃种子的活力无显著差异。带稃种子的吸水饱和时间和吸水量均显著大于去稃种子，而其失水速率小于后者但二者差异不显著。研究结果显示：稃对大赖草种子萌发和活力均无显著影响，但可增加种子的风媒扩散能力、有效保持种子含水量并能降低种子失水速率，对大赖草适应干旱的沙漠环境具有重要作用。

Effect of with or without lemma on dispersal and germination characteristics of Leymus racemosusseed

The dispersal characteristics, germination Leymus racemosus （Lam.） Tzvel. seeds with or without rate, vigor, water absorption and water loss of lemma were studied. The results show that in still air, fall speed of seeds with lemma is significantly smaller than that of without lemma with a fall speed of 3.96 and 4.81 m · s-1, respectively. While in horizontal airflow of wind speed 1 and 4 m · s-1 dispersal distance of seeds with lemma （15.26 and 11.86 cm） is significantly farther than that without lemma （ 27.80 and 21.60 cm）. After cultured for 20 d, germination rate of seeds with or without lemma is 99% and 97%, respectively, with no significant difference. And also, there is no significant difference in vigor between seeds with or without lemma under natural condition or high temperature condition of 60 ℃. Water absorption saturation time and water absorption quantity of seeds with lemma all are significantly bigger than those of seeds without lemma, but water loss rate of the former is smaller than that of the latter with no significant difference. It is suggested that the lemma has no significant influence on germination and vigor of L. racemosus seed, but can enhance the anemophily dispersal ability, effectively keep water content in seed and reduce water loss rate of seed, so the lemma has an important role in adapting of L. racemosus to arid desert habitat.