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Acta Prataculturae Sinica ›› 2024, Vol. 33 ›› Issue (6): 76-88.DOI: 10.11686/cyxb2023353

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Evaluation of physiological characteristics and cold resistance of 10 alfalfa varieties under low temperature stress

Min WANG1(), Li LI2, Rong JIA3, Ai-ke BAO1()   

  1. 1.Key Laboratory of Grassland Livestock Industry Innovation,Ministry of Agriculture and Rural Affairs,College of Pastoral Agriculture Science and Technology,Lanzhou University,Lanzhou 730020,China
    2.Institute of Grassland,Xinjiang Academy of Animal Science,Urumqi 830000,China
    3.China Huaneng Group Clean Energy Technology Research Institute Co. ,LTD,Beijing 102209,China
  • Received:2023-09-20 Revised:2023-11-06 Online:2024-06-20 Published:2024-03-20
  • Contact: Ai-ke BAO

Abstract:

This research elucidated the physiological responses of 10 alfalfa (Medicago sativa) varieties from diverse regions to low temperature stress in order to identify highly cold-resistant varieties. Twelve physiological indexes of the alfalfa seedlings were measured under low temperature conditions of 4 °C, and the cold tolerance was assessed using correlation analysis, principal component analysis and membership function evaluation methods. Simultaneously, the cold resistance of the 10 alfalfa varieties was verified by a semi-lethal temperature (LT50). The key findings were: 1) Under a low temperature of 4 °C, the leaf transpiration rate of the 10 alfalfa varieties exhibited varying degrees of reduction compared to the control group. Decreased transpiration was accompanied by an increase in relative conductivity, as well as in the levels of proline (Pro), soluble sugar, soluble protein (SP), superoxide dismutase (SOD) and peroxidase (POD) activity. 2) The multivariate cold tolerance ranking of the 10 alfalfa varieties using the membership function method was as follows: Longmu 801 (highest)>Zhaodong>Bara 520 YQ>Gongnong 1>Baimu 401>Aohan>Challenger>Dongnong 1>Knights and finally, Xinmu 4. Further measurement of the LT50 for the leaves of each variety confirmed that Longmu 801 and Xinmu 4 were the varieties with the lowest and highest LT50 values respectively, thus corroborating the result of the membership function evaluation. 3) Regression analysis was used to establish an evaluation model for the cold resistance of alfalfa seedlings, and its multiple-parameter evaluation value (D) was: 0.138+0.178×SP+0.203×POD+0.170×Pro, highlighting SP, POD, and Pro as pivotal physiological indicators of cold resistance in alfalfa seedlings. Overall, this research provides fundamental insights into the mechanism of low-temperature adaptation in alfalfa seedlings and will facilitate the selection of cold-resistant alfalfa varieties.

Key words: alfalfa, cold resistance, low temperature stress, comprehensive evaluation