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Acta Prataculturae Sinica ›› 2022, Vol. 31 ›› Issue (9): 129-138.DOI: 10.11686/cyxb2021379

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The effect of last cutting time on the antioxidant system and cold resistance of alfalfa root-neck

Wei-dong CHEN1(), Yu-xia ZHANG1,2(), Qing-xin ZHANG1, Ting-yu LIU1, Xian-guo WANG3, Dong-ru WANG4   

  1. 1.Agricultural College,Inner Mongolia University for Nationalities,Tongliao 028041,China
    2.Inner Mongolia Autonomous Region Forage Crop Engineering Technology Research Center,Tongliao 028000,China
    3.College of Grassland Science and Technology,China Agricultural University,Beijing 100193,China
    4.Seed Industry Development Section,Hohhot Agriculture And Animal Husbandry Technology Promotion Center,Hohhot 010000,China
  • Received:2021-10-19 Revised:2021-12-06 Online:2022-09-20 Published:2022-08-12
  • Contact: Yu-xia ZHANG

Abstract:

This research explored the effect of different last cutting time on the cold resistance of alfalfa (Medicago sativa) cultivar ‘Gongnong No.1’ in the Horqin sandy land habitat and the relationship between the last cutting time and changes in the antioxidant system under low temperature stress. The experiment included last cutting times of August 25, September 5, September 15, September 25, October 5, October 15, October 25, and November 5. The crowns were excavated in early winter and subjected to low temperature freezing stress treatments of -10, -15,c-20, -25, and -30 ℃, with low temperature storage (4 ℃) as the control. Measurements after low temperature storage included the relative electrical conductivity, malondialdehyde (MDA) content, and superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) activities. The semi-lethal temperature was calculated from the relative conductivity following a logistic regression equation, and the correlations between the semi-lethal temperature and the antioxidant properties were analyzed. It was found that the semi-lethal temperature for alfalfa last mowed on August 25, September 5, September 15, September 25, October 5, October 15, October 25, and November 5 was, respectively, -18.03, -17.61, -17.03, -16.59, -15.80, -15.82, -16.83, -16.34,c-17.12 ℃; The semi-lethal temperature of alfalfa root neck and the POD and CAT activities under -10 ℃ low-temperature freezing stress were significantly negatively correlated (P<0.05); The semi-lethal temperature and SOD activities under -15, -20, and -25 ℃ low temperature stress were significantly or extremely significantly negatively correlated. There was also a significant or very significant positive correlation between semi-lethal temperature and MDA content under low temperature freezing stress of -15, -20, -25, and -30 ℃. For the different last cutting times, the cold resistance of alfalfa ranked uncut>August 25>November 5>September 5>October 15>September 15>October 25>October 5>September 25. The last cutting time regulates the SOD, POD, and CAT enzyme activities in the root neck of alfalfa. An appropriate last cutting time results in lowered active oxygen levels, a reduced degree of membrane lipid peroxidation, and improved cold resistance. Therefore, it is recommended to carry out the last mowing of alfalfa stands before September 5 or after November 5 in the Horqin sandy area.

Key words: alfalfa, last cutting time, cold resistance, antioxidant properties