Photosynthesis, fluorescence, and nutrition of Zhonglan No. 2, a new alfalfa cultivar

BACKGROUND The years after planting play an important role in the above‐ground biomass and nutritive value of alfalfa. Zhonglan No. 2 (Medicago sativa L. cv. Zhonglan No. 2) is a new breeding alfalfa cultivar characterized by high drought tolerance and high yield. To determine the optimum time for utilization of Zhonglan No. 2, we examined growth traits, chlorophyll content, photosynthetic and fluorescence parameters, and composition and nutritive values at the late vegetative and early flowering stages of the first stubble in the second, third, fourth, sixth, and eleventh years after planting. RESULTS In general, the height and leaf area decreased with increasing number of years after planting. At the late vegetative stage, the fourth‐year alfalfa exhibited higher stomatal conductance (Gs) and intercellular CO2 concentration (Ci), and better water use efficiency, and at the early flowering stage, the fourth‐year alfalfa had the highest (P