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Scientia Silvae Sinicae ›› 2014, Vol. 50 ›› Issue (9): 67-72.doi: 10.11707/j.1001-7488.20140909

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Evaluation of Frost Resistance Ability of Different Walnut Cultivars

Ren Junjie, Zhao Shuang1, Li Meimei1, Qi Guohui1 2, Li Baoguo1 2   

  1. 1. College of Forestry, Agricultural University of Hebei Baoding 071000;
    2. Research Center for Walnut Engineering and Technology of Hebei Lincheng 054300
  • Received:2014-04-02 Revised:2014-05-05 Online:2014-09-25 Published:2014-09-30
  • Contact: 齐国辉

Abstract:

In order to investigate the frost resistance and the mechanism, 6 walnut cultivars, ‘Lvling’,‘Xiangling’, ‘Liaoning NO.1’, ‘Shangsong NO.6’, ‘Zhonglin NO.1’ and ‘Qingxiang’, were used as materials to determine their supercooling point, freezing point and electrolyte leakage rate in leaves and ovaries in April 15th, and to calculate the semi-lethal temperature. Their frost freezing indexes in April 20~21th were investigated. The results showed that the frost freezing indexes of ‘Lvling’, ‘Xiangling’, ‘Liaoning NO.1’, ‘Shangsong NO.6’, ‘Zhonglin NO.1’ and ‘Qingxiang’ were 41.97%, 52.65%, 54.88%, 67.58%, 74.93%, and 98.67%, respectively. The frost freezing indexes of ‘Lvling’ was very significantly lower than those of the other cultivars. The supercooling points in leaves of ‘Lvling’, ‘Xiangling’, ‘Liaoning NO.1’, ‘Shangsong NO.6’, ‘Zhonglin NO.1’ and ‘Qingxiang’ were -4.40℃, -4.27℃, -3.87℃, -3.73℃, -3.53℃ and -3.23℃, respectively, and the freezing points were -3.83℃, -3.27℃, -3.10℃, -3.30℃, -2.47℃ and -2.43℃, respectively. The supercooling points in ovaries were -3.71℃, -3.68℃, -3.53℃, -3.24℃, -2.72℃ and -2.31℃, respectively, and the freezing points were -3.12℃, -2.83℃, -2.61℃, -2.53℃, -1.87℃ and -1.73℃, respectively. The supercooling points in leaves and ovaries, the freezing points in ovaries of ‘Lvling’ and ‘Xiangling’ were very significantly lower than those of the other cultivars. The freezing point in leaves of ‘Lvling’ was very significantly lower than those of the other cultivars. The semi-lethal temperatures in leaves of ‘Lvling’, ‘Xiangling’, ‘Liaoning NO.1’, ‘Shangsong NO.6’, ‘Zhonglin NO.1’ and ‘Qingxiang’ was -3.33℃, -2.96℃, -2.81℃, -2.63℃, -2.31℃ and -2.25℃, respectively, and that of in leaves of ‘Lvling’ was very significant lower than those of the other cultivars. The semi-lethal temperatures in ovaries of the 6 cultivars were -2.62℃, -2.58℃, -2.39℃, -2.05℃, -1.80℃ and -1.07℃, respectively. There was no significant difference in the semi-lethal temperature between ‘Lvling’ and ‘Xiangling’, but theirs were very significantly lower than those of the other cultivars. The analyses of supercooling point, freezing point, electrolyte leakage rate and the frost resistance in the field all indicated that the frost resistance of the 6 cultivars from high to low was ‘Lvling’, ‘Xiangling’, ‘Liaoning NO.1’, ‘Shangsong NO.6’, ‘Zhonglin NO.1’, and ‘Qingxiang’.

Key words: walnut, frost, freezing index, supercooling point, semi-lethal temperature

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