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Acta Prataculturae Sinica ›› 2020, Vol. 29 ›› Issue (11): 141-150.DOI: 10.11686/cyxb2020007

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Effects of nitrogen application rate on chlorophyll fluorescence characteristics and dry matter accumulation in switchgrass (Panicum virgatum) leaves

HE Hai-feng1, YAN Cheng-hong1, WU Na1, LIU Ji-li2,3,*, CHANG Wen-wen2   

  1. 1. College of Agriculture, Ningxia University, Yinchuan 750021, China;
    2. College of Resources and Environmental Science, Ningxia University, Yinchuan 750021, China;
    3. Key Laboratory of Resource Evaluation and Environmental Regulation in Dry-land Region of Ningxia, Yinchuan 750021, China
  • Received:2020-01-07 Revised:2020-03-16 Online:2020-11-20 Published:2020-11-20
  • Contact: *E-mail: tim11082003@163.com
  • Supported by:
    国家自然科学基金项目(31860344,31560361)资助

Abstract: The effect of nitrogen fertilizer application rate on chlorophyll fluorescence characteristics and dry matter accumulation of switchgrass (Panicum virgatum) is of great significance for the improvement of light use efficiency and biomass yield of switchgrass in saline-alkali land. In this research, the patterns of variation in chlorophyll fluorescence parameters and dry matter accumulation in switchgrass were studied in field conditions with a range of nitrogen application treatments: no nitrogen (0 kg·ha-1, N0), low nitrogen application (60 kg·ha-1, N60), medium nitrogen application (120 kg·ha-1, N120) and high nitrogen application (240 kg·ha-1, N240), and the comprehensive effect of nitrogen application on chlorophyll fluorescence and dry matter accumulation in switchgrass was evaluated using a multivariate Grey relational analysis procedure. It was found that: under N60, N120 and N240 treatments, the PSⅡ maximum photochemical efficiency (Fv/Fm), PSⅡ actual photochemical quantum efficiency (ΦPSⅡ), potential activity (Fv/Fo), photochemical quenching (qP), non photochemical quenching (NPQ) and biomass yield were significantly higher, and the heat dissipation of quantum ratio (Fo/Fm) was significantly lower than for the N0 treatment during the flowering and seed maturation stages of switchgrass development. During the flowering period of switchgrass, the PSⅡ potential activity (Fv/Fo) was initially increased and subsequently decreased across the range of nitrogen application rates, with a maximum observed value of 3.13 at N120 (increased 16.26% compared with N0). The effect of nitrogen application rate on dry matter accumulation differed between the crop growth stages. Dry matter accumulation was high during jointing and booting periods, reached its maximum at the seed filling stage, and decreased slightly thereafter. The maximum observed dry matter accumulation (378.13 g·hole-1) occurred under the N240 treatment during the post-flowering stage and was, respectively, 24.33%, 20.09% and 7.24% higher than that of the N0, N60 and N120 treatments. Grey relational analysis showed that the association between the weighted correlation index and the ideal fertilization level was the highest under the N240 treatment. In summary, the N240 treatment in this study in the Yinbei saline-alkali area of Ningxia optimized the photochemical activity of PSⅡ and dry matter accumulation of switchgrass.

Key words: nitrogen application, switchgrass (Panicum virgatum), chlorophyll fluorescence, grey relational analysis