| Elymus sibirucus is the perennial plant of the Elymus,due to its good palatability and high nutritional value,has favored by livestocks.In addition,it has strong stress resistance and can adapt to the growth environment of high-altitude areas.So,it has become one of the main fine pastures on the Qinghai-Tibet Plateau.Because of unique geographical location,Qinghai-Tibet Plateau has created rich germplasm resources of E.sibirucus,which provides a certain material basis for its low-shattering germplasm selection and evaluation.However,currently there are shortage of good E.sibirucus varieties and lack of shatter-resistant materials suitable for the Qinghai-Tibet Plateau.Therefore,this study used 15 E.sibirucus resources in different ecological areas as materials,and selected anti-shattering materials by evaluating their shattering rate;Based on the analysis of its comprehensive phenotypic traits and growth and physiological characteristics,the main factor that control shattering and the optimal harvesting time of E.sibirucus was determined,which provided a practical basis for the popularization and application of E.sibirucus on the Qinghai-Tibet Plateau.The main results are as follows:(1)The seed shattering rate of germplasm continued to increase from the first day after milk stage,and reached the highest on the 15 th day after milk ripening,with an average of 49.45%;The number of spikelets is the most critical phenotypic factor affecting the shattering rate,and it has a positive correlation with the shattering rate.The awn length and the inflorescence width are also factors that affect the shattering rate of E.sibirucus,and have a negative correlation with the shattering rate;The highshattering germplasm has a higher shattering rate than the low-shattering germplasm.The abscission zone development of high-shattering germplasm is early than low shattering,and the development of the seedstalk is earlier than spikelet pedicel.(2)The hydrolase activity,abscisic acid content and water content are the key physiological factors affecting the shattering of E.sibirucus.Among them,there is a positive correlation between enzyme activity and shattering rate.The highest polygalacturonase content after seed maturity is about 22.17 mg/h/g,and the highest cellulase content is about 974.56 μg/min/g.High-shattering germplasm has higher enzyme activity than low-shattering germplasm,the seedstalk has higher enzyme activity than spikelet stalk;Abscisic acid content is positively correlated with shattering rate,the content of abscisic acid gradually increases from the first day after milk stage,and reaches the highest value of 132.58 μg/L on the 19 th day after milk stage,the content of abscisic acid at the seedstalk is higher than that of spikelet pedicel.There is a negative correlation between water content and shattering rate.Seed water content and spikelet water content decrease from 56.37% and 58.60% on the1 st day after milk stage to 23.67% and 35.23% on the 22 nd day after milk stage.(3)With the maturation of the E.sibirucus seeds,germination rate and starch content gradually increase,which is positively correlated with the shattering rate.The dynamic changes of inflorescence length,number of spikelets,seed number per inflorescence,seed weight per inflorescence,electrical conductivity and soluble sugar content gradually decrease,all of which had a negative correlation with the shattering rate.The germplasm with low shattering has higher germination rate and electrical conductivity,the germination rate is as high as 95.67% on the 16 th day after milk stage,and the electrical conductivity is 40.55μs/cm;According to the dynamic changes of the seed shattering rate and various growth physiological indicators,the 16 th day after milk stage was selected as the optimal harvesting period for E.sibirucus,which has high seed vigor and low shattering rate. |
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