Effects of nitrogen application rate and harvest time on Leymus chinensis seed yield

Low germination, low tillering, and even seed failure occurring during sheepgrass (Leymus chinensis) cultivation can be at least partially remedied by applying additional nitrogen fertilizer; further, sheepgrass harvest timing for maximum seed yield warrants further research. Hence, this study was conducted to investigate the effects of nitrogen application rate 0, 150, 300 kg·(hm²·a)⁻¹ and harvesting time (25, 30, 35, 40 and 45 days after blooming) on sheepgrass seed yield, in order to determine the optimal nitrogen application rate and harvesting time for sheepgrass in Xinjiang. Our results showed that: 1) Nitrogen application rate and harvesting time significantly affected seed germination rate, yield, and yield components. There were no significant changes in seed germination rate, yield, or yield components when harvest was performed at 35 days after blooming, compared with harvest at 40 or 45 days after blooming. In the first sampling, seed germination rate in the 150 kg·(hm²·a)⁻¹ treatment increased by 31.25% and 12.50% compared with the 0 and 300 kg·(hm²·a)⁻¹ treatments, respectively. 2) Nitrogen application and harvesting time increased total nitrogen and phosphorus in all organs of sheepgrass plants. We recommend 150 kg·(hm²·a)⁻¹ and 35 days after blooming as the appropriate nitrogen application rate and optimum harvesting time, respectively, for the production of sheepgrass seed in Xinjiang.