四种豆科牧草种子萌发和幼苗生长对干旱的响应及抗旱性评价

摘要

The adaption ability of forage seed to meet adversity between germination and seedling stage is key factor to determine the distribution of grassland population and continuation in arid areas. The objective of on comprehensive evaluation of forage seeds drought resistance was to provide support for water regulation and seedling maintenance at natural grassland reseeding, artificial rangeland establishing and mine vegetation restoration in arid and semiarid regions. The study adopted different osmotic potential using Polyethylene glycol (PEG-6000) solution simulated drought conditions in Erdos drought-area steppe, The seed germination, seedling growth and drought resistance assessment of four common legumes that usually used as reseeding or seeding establishment forage, Caragana stenophylla Pojark., Melilotus suavelens Ledeb., Medicago sativa L.cv. Neimeng Zhungeer and Astragalus adsurgens Pall.cv Shadawang were studied. The results showed that slight drought (-0.05 MPa~-0.2 MPa) had a promoting effect on the seed germination of 4 legumes. Except for M. sativa L.cv. Neimeng Zhungeer the simulated drought promoted the seedling root growth and increased the ratio of seedling root:shoot. The relative vitality index was higher for C. stenophylla Pojark and A adsurgens Pall. cv .Shadawang than other forage, but the germination of drought resistance was the lowest for C. stenophylla Pojark in moderate drought condition (-0.4 Mpa~-0.6 MPa). M. sativa L.cv.Neimeng Zhungeer had the highest relative germination indexes in the heavy drought condition (≤-0.8 MPa). Using the comprehensive evaluation of fuzzy membership function method, the drought resistances of the four legumes under seed germination stage ranked M. sativa L.cv. Neimeng Zhungeer > A. adsurgens Pall. cv .Shadawang>M. suavelens Ledeb.>C.stenophylla Pojark, in the seedling growth stage ranked M. suavelens Ledeb.>M. sativa L.cv. Neimeng Zhungeer>C. stenophylla Pojark>A.adsurgens Pall. cv .Shadawang. and the comprehensive assessment rank was M. suavelens Ledeb.>M. sativa L.cv. Neimeng Zhungeer>A.adsurgens Pall. cv .Shadawang>C. stenophylla Pojark.%牧草种子在萌发和幼苗生长期对逆境的适应能力是决定干旱区草地种群分布及延续的关键因素，对牧草种子抗旱性的综合评价，可为干旱、半干旱地区草地补播、人工草地建植和矿山植被恢复进行水分调控及苗期养护等提供支持。采用不同渗透势聚乙二醇（PEG-6000）溶液梯度（0~-1.2 MPa）模拟干旱条件，选择鄂尔多斯干旱草原区补播或建植常用的4种豆科牧草：狭叶锦鸡儿（Caragana stenophylla Pojark.）、黄花草木樨（Melilotus suavelens Ledeb.）、内蒙准格尔苜蓿（Medicago sativa L.cv.Neimeng Zhungeer）和沙打旺（Astragalus adsurgens Pall. cv .Shadawang），研究其种子萌发和幼苗生长特性对模拟干旱的响应及抗旱性评价。结果表明，轻微干旱（-0.05~-0.2 MPa）对4种牧草种子萌发和幼苗生长均有促进作用，除内蒙准格尔苜蓿外，干旱均促进其他3种牧草幼根生长及根苗比的增加；中度干旱条件下（-0.4~-0.6 MPa），狭叶锦鸡儿和沙打旺种子的相对活力指数较高，但前者的萌发抗旱指数最差；在重度干旱条件（≤-0.8 MPa）下，内蒙准格尔苜蓿萌发期各指标相对值均最高。运用模糊数学隶属函数法综合评价，4种牧草种子萌发期抗旱性强弱排序为：内蒙准格尔苜蓿>沙打旺>黄花草木樨>狭叶锦鸡儿。幼苗生长期：黄花草木樨>内蒙准格尔苜蓿>狭叶锦鸡儿>沙打旺。总体评价为：黄花草木樨>内蒙准格尔苜蓿>沙打旺>狭叶锦鸡儿。