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Chinese Journal of Applied Ecology ›› 2020, Vol. 31 ›› Issue (9): 2963-2976.doi: 10.13287/j.1001-9332.202009.026

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Characteristics of light energy utilization of intercropping alfalfa/gramineae forage based on yield effect

LIN Fang1,2, LIU Xiao-jing1*, TONG Chang-chun1, WU Yong1   

  1. 1Pratacultural College, Gansu Agricultural University, Lanzhou 730070, China;
    2School of Life Science and Technology, Xinxiang University, Xinxiang 453000, Henan, China
  • Received:2020-03-17 Accepted:2020-06-23 Online:2020-09-15 Published:2021-03-15
  • Contact: * E-mail: liuxj@gsau.edu.cn
  • Supported by:
    the Science and Technology Innovation Fund of Gansu Agricultural University (GSAU-XKJS-2018-008), the Modern Agriculture Industry Technology System of Gansu Province-Herbivorous Livestock Industry System (GARS-CS-3), the National Natural Science Foundation of China (31460622), and the Grassland Technology Promotion Station of Gansu Province (XMXZGSNDXY201802).

Abstract: Based on field experiments in 2017-2019, we examined the characteristics, yield effect and regulatory mechanism of light energy utilization in alfalfa/gramineous forage grass intercropping. With monoculture of alfalfa, forage triticale (C3 plant), and forage maize (C4 plant) as control, we measured the yield effect, the effect of light energy utilization factor on yield formation, the characteristic difference and mechanism of light energy utilization under alfalfa/triticale and alfalfa/maize intercropping patterns. Results showed that land equivalent ratios of both intercropping patterns were all greater than 1, indicating that land utilization ratio and yield benefit of the two intercropping patterns were higher than that of monoculture, among which alfalfa/triticale intercropping pattern was the most promising one. The contribution of light energy utilization factors to yield was following an order of leaf area index (1.531) > net photosynthetic rate (0.882) > intercellular CO2 concentration (0.282) > transpiration rate (-0.229) > canopy opening (-0.291) > PAR interception rate (-0.681) > stomatal conductance (-0.751). Among them, leaf area index was not only one of the important indices to characterize photosynthetic capacity, but also an important component factor of forage crop yield aiming at harvesting nutrients. Therefore, among all factors of photosynthetic characteristics, net photosynthetic rate was the main factor affecting yield. The net photosynthetic rate of alfalfa, triticale and maize under intercropping showed the same pattern, and being different from that of monoculture. The main ways for intercropping to increase net photosynthetic rate included: triticale and maize increased net photosynthetic rate and yield by enhancing the carboxylation fixation capacity of CO2 and the utilization capacity of strong light, while alfalfa could improve its net photosynthetic rate and promote growth under low light, by increasing the content of chlorophyll b in functional leaves, changing chlorophyll composition and enhancing the collection and transmission of light energy.

Key words: alfalfa, gramineous forage grass, intercropping, yield effect, light energy utilization