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Acta Prataculturae Sinica ›› 2022, Vol. 31 ›› Issue (9): 76-85.DOI: 10.11686/cyxb2021380

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Effect of water and fertilizer coupling on seed yield and composition of alfalfa grown with underground drip irrigation in Ningxia

Xing WANG1(), Wei HUANG1, Shu-yan YU1, Xiao-yun LI1, Xue-qin GAO1,2, Bing-zhe FU1,2()   

  1. 1.School of Agriculture,Ningxia University,Yinchuan 750021,China
    2.Ningxia Grass Husbandry Engineering Technology Research Center,Yinchuan 750021,China
  • Received:2021-10-19 Revised:2022-01-27 Online:2022-09-20 Published:2022-08-12
  • Contact: Bing-zhe FU

Abstract:

This study investigated the most suitable irrigation and fertilizer rates for alfalfa (Medicago sativa) seed yield under drip irrigation in Ningxia. The alfalfa cultivar used in the experiment was ‘Gannong No.4’ and the experiment was laid out in a two-factor split plot design. There were four irrigation rates (900, 1350, 1800 and 2250 m3·ha-1) in the main plot treatments, and five fertilizer levels (N-P2O5-K2O applied in proportions by weight 0-0-0, 9-45-60, 18-90-120, 27-135-180 and 36-180-240 kg·ha-1, respectively). The results showed that appropriate irrigation and fertilizer applications improved alfalfa seed yield. With successive increments in irrigation and fertilizer alfalfa seed yield initially increased and then decreased. Irrigation had a significant effect on the alfalfa floret number, number of inflorescences per plant, number of pods formed, seeds per pod, pod setting rate and thousand seed weight. A path coefficient analysis showed that the number of inflorescences per plant, reproductive branch number, thousand seed weight and pod setting rate had important determinants of the seed yield of alfalfa. Alfalfa seed yield and irrigation water use efficiency were the highest at an irrigation rate of 900 m3·ha-1 and an N-P2O5-K2O fertilizer rate of 27-135-180 kg·ha-1. According to a regression optimization model, the optimal irrigation rate for alfalfa seed production in the Ningxia Yellow River irrigation area under local soil conditions was 2250 m3·ha-1, and the optimal fertilizer amount was 34 kg·ha-1 of nitrogen fertilizer, 172.68 kg·ha-1 of phosphate fertilizer and 230.28 kg·ha-1.

Key words: water-fertilizer coupling, Medicago sativa, seed yield, subsurface drip irrigation, optimization model