Assessment of seed shattering and analysis of agronomic traits in Elymus nutans

To understand its germplasm resources and promote breeding in Elymus nutans, variation coefficient, correlation-ship, principal component and cluster analyses were carried out on 15 agronomic traits of 13 accessions from 2015 to 2016. The results showed that the value of the seed shattering rate variation coefficient was the maximal (57.43%) and ear length was the minimum (5.77%) among 15 agronomic traits. PI619516 showed the best shattering resistance (breaking tensile strength, BTS = 70.05 gf) among 13 accessions, while the shattering rate of PI639855 (BTS = 13.99 gf) was the highest. Variation analysis of BTS suggested that PI639852 had the largest variation (CV=45.09%), which indicated there was great genetic differentiation among individuals. Correlative analysis revealed high significantly positive correlation (P<0.01) between length of the second leaf from the inflorescence and flag leaf length, as well as flag leaf width; flag leaf width had a high significantly positive correlation (P<0.01) with flag leaf length. Florets per ear and ear length showed a significantly positive correlation (P<0.05), as well as stem diameter. Breaking tensile strength and ear length were significantly negatively correlated (P<0.05), as well as stem diameter, showing that the larger the ear length and stem diameter, the higher the shattering rate (BTS was smaller). Cluster analysis of BTS showed that 13 accessions were clustered into four groups. Group ⅰ showed the lowest shattering rate. Group ⅱ and ⅲ seed shattering were highest shattering rate. Group ⅳ seed shattering was medium cluster analysis for 15 agronomic traits showed that all accessions were clustered into four groups. The subordinate function analysis showed PI547396 had the best comprehensive performance with subordinate function value of 0.55. These screened materials are important for future breeding programs.