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 germplasm. To clarify the appropriate seed harvest time and the effects of germplasm, seed development and after-ripening on seed germination, 20 germplasm of sheepgrass were selected. Moreover, the seed morphological and physical changes as well as the seed germination and dormancy characteristics of sheepgrass during seed development stages were analyzed using a seven—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 germplasm was observed at 35–42 DAP. Thus, 35–42 DAP may 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 six types of germination patterns, including germplasm with increasing germination rates in the developing seed, such as S19 and S13, and germplasm that maintained a consistently low germination rate, such as S10. Moreover, we compared the seed germination rate of eight germplasm during seed development in both 2016 and 2017, and the results indicated that the seed germination patterns of the eight germplasm 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 germplasm where four types of germination patterns were revealed for 10 germplasm 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 sheepgrass with better germination performance.
Highlights
Sheepgrass (Leymus chinensis (Trin.) Tzvel) is a perennial species of Poaceae that is widely distributed in the eastern part of the Eurasian steppe, the northern and eastern parts of the People’s Republic of Mongolia, and the northern and northeastern grasslands of China (Lin et al, 2011)
Morphological changes during seed development in sheepgrass To obtain the basic characteristics of sheepgrass seed development, we closely observed the morphological features of the developing seeds from flowering until maturity
The results showed that the germination characteristics of the developing sheepgrass seeds remained relatively constant during the two different years, suggesting that germplasm may significantly affect the seed germination rate of sheepgrass
Summary
Sheepgrass (Leymus chinensis (Trin.) Tzvel) is a perennial species of Poaceae that is widely distributed in the eastern part of the Eurasian steppe, the northern and eastern parts of the People’s Republic of Mongolia, and the northern and northeastern grasslands of China (Lin et al, 2011). Previous studies on the seed dormancy and germination of sheepgrass have mostly focused on dormancy-breaking methods and the environmental and hormonal effects on germination (He et al, 2016; Zhang et al, 2006). It was reported that the seed dormancy of sheepgrass was significantly affected by the lemma, palea, pericarp/testa, and endosperm of the seed, and their average contribution to seed dormancy was 23.4%, 6.2%, 28.4%, and 42.0%, respectively (He et al, 2016). The dormancy-breaking methods for sheepgrass seed have varied from low temperature treatments to chemical agents, including PEG and GA3 (Gu, Yi & Holubowiecz, 2005; Liu, Wang & Li, 2002; Zhang et al, 2006). Previous studies on the dormancy and germination of sheepgrass seeds mainly examined
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