Peer Review #3 of "Germination characteristics among different sheepgrass (Leymus chinensis) germplasm during the seed development and after-ripening stages (v0.2)"

Abstract

Sheepgrass (Leymus chinensis (Trin.) Tzvel) is an important forage grass in the Eurasian steppe. However, little information is available concerning its seed morphological features and germination characteristics during seed development and after-ripening among different germplasms. To clarify the appropriate seed harvest time and the effects of germplasm, seed development and after-ripening on seed germination, 20 germplasms of sheepgrass were selected. Moreover, the seed morphological and physical changes as well as the seed germination and dormancy characteristics of sheepgrass during see d development stages were analyzed using a 7 -d gradient of day after pollination (DAP).The results indicated that the seed water content decreased significantly during 35 -42 DAP and that the highest seed germination rate of most germplasms was observed at 35 -42 DAP. Thus, 35 -42 DAP will be the best time to harvest sheepgrass to obtain the maximum seed germination rate and avoid seed shattering. Furthermore, our results indicated that there were 6 types of germination patterns, including germplasms with increasing germination rates in the developing seed, such as S19 and S13, and germplasms that maintained a consistently low germination rate, such as S10. Moreover, we compared the seed germination rate of 8 germplasms during seed development in both 2016 and 2017, and the results indicated that the seed germination patterns of the 8 germplasms were highly consistent between the two consecutive years, suggesting that germplasm rather than year is the major factor in determining germination during seed development. The effect of after-ripening on seed germination was different among the germplasms, where 4 types of germination patterns were revealed for 10 germplasms and resulted in various dormancy features. A two-factor ANOVA analysis suggested that the germplasm of the sheepgrass has a large influence on seed germination, whether during seed development or after-ripening. Thus, these findings lay the foundation for future studies on seed dormancy and germination and may guide the breeding of new cultivars of