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Acta Prataculturae Sinica ›› 2022, Vol. 31 ›› Issue (8): 126-143.DOI: 10.11686/cyxb2021315

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Effects of planting density and nitrogen application on leaf enzyme activity and water-nitrogen utilization of silage maize under ridge furrow rainwater harvesting in Loess Plateau

Da-liang ZHOU(), Wei SHI(), Zi-wei JIANG, Zheng-ye WEI, Huan-huan LIANG, Qian-min JIA   

  1. State Key Laboratory of Grassland Agroecosystem,Key Laboratory of Grass and Animal Husbandry Innovation,Ministry of Agriculture and Rural Areas,Engineering Research Center of Ministry of Education of Grassland Agriculture,College of Grassland Agricultural Science and Technology,Lanzhou University,Lanzhou 730020,China
  • Received:2021-08-25 Revised:2021-11-29 Online:2022-08-20 Published:2022-07-01
  • Contact: Wei SHI

Abstract:

A field experiment was conducted in Huan County, Gansu Province, to explore the effects of planting density and nitrogen application levels on leaf enzyme activity and water-nitrogen use efficiency of silage maize (Zea mays) under ridge furrow rainwater harvesting. Four planting densities (D1: 6×104 plants·ha-1; D2: 7.5×104 plants·ha-1; D3: 9.0×104 plants·ha-1; D4: 10.5×104 plants·ha-1) and four nitrogen application levels (N0: 0 kg·ha-1; N1: 120 kg·ha-1; N2: 240 kg·ha-1; N3: 360 kg·ha-1) were included in the experiment. In summary, it was found: 1) The activities of nitrate reductase (NR), superoxide dismutase (SOD) and catalase (CAT) decreased with increase in plant density. However, the NR, SOD and CAT activity increased with N application and at the grain filling stage were significantly higher under N2 and N3 treatments than in the N0 treatment. 2) The fresh and hay yield increased incrementally with increase in plant density. The average fresh and hay yield of the N3 treatment was numerically highest, but the difference between N3 and N2 treatments was not statistically significant. 3) The precipitation utilization efficiency (PUE) and biomass water use efficiency (WUEB) of D3 and D4 treatments were significantly higher than those of D1 and D2 treatments, and the grain yield water use efficiency (WUEG) of D3 treatment was greater compared to other treatments. Moreover, PUE, WUEB and WUEG of N2 and N3 treatments were significantly higher than those of N0 and N1 treatments. 4) The nitrogen content of D3 and D4 treatments was less than that of D1 treatment, but the nitrogen uptake, nitrogen agronomic efficiency (AEN) and nitrogen use efficiency (NUE) of D3 and D4 treatment were significantly higher than those of treatment D1. With increase in nitrogen application rate, nitrogen content and nitrogen uptake increased, while AEN and NUE initially increased and then decreased as nitrogen application rate increased. There was no significant interaction between planting density and nitrogen application rate for leaf enzyme and water-nitrogen use efficiency in our experiment. Among all the treatments, NUE, WUEG and WUEB were the highest in D3-N2 treatment, and higher yield was obtained. These results indicate that D3-N2 is a suitable agronomic management regime for silage maize production in the Loess Plateau.

Key words: ridge furrow rainwater harvesting, planting density, nitrogen application, enzyme activity, water use efficiency, nitrogen use efficiency