摘要

Non-dormant alfalfa (Medicago sativa L.) has been cultivated successfully in the east central regions of China as a short-term component of a forage-grain rotation system, but it remains unclear how shoots of alfalfa with different levels of fall dormancy develop in this system. Five alfalfa cultivars with contrasting fall dormancy were sown in the field in Nanjing, China, in October 2012 and 2013, and were harvested three times in the following year. The number and dry weight of shoots that originated from crown (crown shoots) and axillary buds (axial shoots) were recorded at each harvest. The results were analyzed for dormant, semi-dormant and non-dormant cultivars over 2years. At the first spring harvest, axial shoots accounted for an average of 18.3% of dry weight per plant and became the dominant shoot type during later harvests. Crown shoots accounted for 81.7% of plant dry weight in first harvest and the majority of dry weight per plant totaled over three harvests in all fall dormancy types. Fall dormancy had little effect on the relative proportion of crown and axial shoots in dry weight per plant, and the number of crown and axial shoots. Non-dormant cultivars produced heavier individual crown and axial shoots, resulting in greater dry weight per plant at each harvest. Our results show that non-dormant cultivars used in our study produce greater dry weight per plant under a short-term cultivation system, primarily because they have greater dry weight of individual crown and axial shoots.

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