苜蓿秋眠性及其与抗寒性和产量的关系

Alfalfa fall dormancy and its relationship to winter hardiness and yield

秋眠性是苜蓿对日照缩短的一种生长反应,用苜蓿在秋季的再生高度来唯一划分。由于传统苜蓿品种的秋眠性与抗寒性之间存在表型相关,秋眠性被普遍用于抗寒性的预测。但许多研究表明,秋眠性和抗寒性是苜蓿适应不同的环境因素、为了不同的原因、同时而又独立进化的。与非秋眠品种相比,秋眠品种在夏末和秋季生长下降,导致全年刈割次数减少,故全年产草量较低。在深入认识秋眠性和抗寒性之间的遗传独立性的基础上,美国育种家致力于非秋眠而又抗寒、高产的苜蓿品种培育,使得新品种的抗寒性超过其秋眠级所预测的水平。随着我国引进苜蓿品种的增加,国内产业界人士有必要对苜蓿秋眠性的科学内涵及在品种改良和适应性选择的意义上有更进一步的认识。

Fall dormancy (FD) is a response of alfalfa (Medicago sativa) to reduction in day length, and is (determined) solely based on height of fall regrowth. FD is commonly used to predict winter hardiness (WH) of alfalfa varieties because of the close relationship between the two traits in traditional alfalfa varieties. (Nevertheless), there is accumulating scientific proof that FD and WH have evolved together but independently in response to different stimuli and for different reasons. Compared with non-dormant varieties, fall dormant (varieties) generally have lower fall growth, resulting in reduced number of cuttings and season-long forage yield. With increased recognition of the genetic independence of FD and WH, American researchers have been (developing) alfalfa genotypes that have WH and yield much higher than that would be predicted by FD. As the alfalfa industry develops rapidly in China, it is important for people to better understand the scientific meaning of FD and its relevance to alfalfa improvement and adaptation.