种子萌发期紫花苜蓿秋眠级与耐热性的关系

The relationship between heat-tolerance and fall dormancy of Medicago sativa cultivars at seed germination stage

为了探明高温胁迫对不同秋眠级紫花苜蓿种子萌发的影响,在25和35℃条件下,对14个不同秋眠级紫花苜蓿品种种子进行萌发试验,以发芽率、发芽指数、活力指数、胚根鲜重和发芽势为指标,结合协方差分析、模糊隶属函数和聚类分析统计方法,对各紫花苜蓿品种萌发期耐热性进行分析和综合评价。结果表明:高温胁迫对不同秋眠级紫花苜蓿的种子萌发有影响,高秋眠级品种赛迪10的耐热最强,其发芽指数、活力指数、胚根鲜重、发芽势和发芽率在14个参试品种中最高,分别为67.78、66.70、0.98g、99.33%和92.89%;聚类分析的结果表明,14个品种萌发期耐热性可划分为3类,耐热性较强的品种为标秆、WL903、1075、三得利、赛迪10和赛阔,耐热性较弱的品种为Power、猎人河和阿尔冈金,其余品种耐热性一般;在种子萌发阶段,高秋眠级类型的紫花苜蓿品种表现较强的耐热性,低秋眠级类型的品种耐热性较弱。种子活力指数可作为评价紫花苜蓿萌发期耐热性强弱的有效指标。

To explore the influence of heat stress on the seed germination of Medicago sativa cultivars with different fall dormancy, five germination characteristics （germination rate, germination index, vigor index, fresh weight of radicle and germinability） have been tested to evaluate the thermotolerance of alfalfa eultivars with 14 different fall dormancy during germination stage. Using covariance,the membership functions and cluster analy sis,the results showed that the thermotolerance of different cuhivars was significantly different at seed germina- tion stage under heat stress. ＂Sardil0＂,a high fall dormancy cultivar,has the strongest heat tolerance,with high est germination index, vigor index, fresh weight of radicle, germinability and germination rate as 67.78,66.70,0. 98 g,99.33% and 92.89~ respectively. Cluster analysis divided these 14 cultivars into three thermotolerance categories ： cultivars with highest thermotolerance, including ＂Biaogan＇,＇WL903＇,＇1075＂, and ＂Sanditi＇; cultivars with the lowest thermotolerance,including ＂Sardi10＂and＇Sequel＇,and ＇Power＇,＇Hunter River＂ and ＂Algonquin＇. The other are cultivars have medium thermotolerance. Non-fall dormancy cultivars showed stronger thermotolerance at the stage of germination than fall dormancy cultivars. The vigor index was an effective thermotolerance index of alfalfa at seed germination stage in this study.