叶面喷施钾、钙肥对核桃幼树抗寒性的影响

Effects of leaf surface K and Ca fertilizer on cold resistance of young walnut trees

【目的】探讨喷施不同外源物质处理对核桃抗寒指标的影响情况,为核桃抗寒性研究提供理论参考依据。【方法】以2年生核桃幼树为试验材料,于核桃生长期,对盆栽核桃叶片分别喷施不同浓度(5、10、15、20 mmol·L^(-1))的K_(2)SO_(4)和CaCl_(2)溶液,然后采集喷施后的核桃叶片进行低温胁迫处理,测定了喷施不同浓度的K_(2)SO_(4)和CaCl_(2)溶液后核桃叶片的相对电导率和叶片中可溶性糖、丙二醛(MDA)、脯氨酸含量等抗寒性生理生化指标,比较分析不同处理对各个抗寒指标的影响情况;采用隶属函数法对各处理核桃的抗寒性进行综合性评价。【结果】在低温胁迫下,随着K_(2)SO_(4)和CaCl_(2)浓度的增加,核桃叶片相对电导率均呈现出先降低后升高的趋势,但均低于对照的;除了喷施5 mmol·L^(-1)的K_(2)SO_(4)溶液的核桃叶片中可溶性糖的含量略低于对照的外,其他处理下核桃叶片中可溶性糖的含量与对照的相比都有不同程度的升高;喷施低浓度的K_(2)SO_(4)和CaCl_(2)溶液后,核桃叶片中MDA的含量与对照的相比均有所降低,而当喷施浓度较高时,核桃叶片中MDA的含量与对照的相比均有所升高;喷施不同浓度的K_(2)SO_(4)溶液后,核桃叶片中脯氨酸的含量与对照的相比都有显著提高,喷施浓度分别为5和10 mmol·L^(-1)的CaCl_(2)溶液后,核桃叶片中脯氨酸的含量与对照的相比均略有下降,但其与对照间的差异均不显著(P>0.05),随着CaCl_(2)浓度的继续升高,核桃叶片中脯氨酸的含量又开始升高,且其与对照间的差异显著(P<0.05)。隶属函数分析结果表明,不同处理的核桃幼树抗寒性的强弱顺序为:10 mmol·L^(-1)的CaCl_(2)>5 mmol·L^(-1)的CaCl_(2)>15 mmol·L^(-1)的K_(2)SO_(4)>CK>10 mmol·L^(-1)的K_(2)SO_(4)>20 mmol·L^(-1)的K_(2)SO_(4)>15 mmol·L^(-1)的CaCl_(2)>20 mmol·L^(-1)的CaCl_(2)>5 mmol·L^(-1)的K_(2)SO_(4)。【结论】喷施较低浓度的K_(2)SO_(4)和CaCl_(2)溶液,有利于增强核桃幼树的抗寒性;而喷施浓度过高的K_(2)SO_(4)和CaCl_(2)溶液会影响核桃幼树的正常生长。CaCl_(2)对低温胁迫下核桃幼树抗寒性的影响作用大于K_(2)SO_(4)。

【Objective】The purpose of the research was to explore the effects of spraying different exogenous substances on cold resistance of walnut, and to provide theoretical basis for cold resistance ability of walnut.【Method】K_(2)SO_(4) and CaCl_(2)solutions with different concentrations(5, 10, 15 and 20 mmol·L^(-1)) were sprayed on the two-year-old walnut trees. The treated walnut leaves were collected for low temperature stress treatment. The relative conductivity and the physiological and biochemical indexes of cold resistance such as soluble sugar, malonaldehyde(MDA) and proline content in leaves were measured. By comparing the physiological and biochemical indexes, we evaluated the effect of different treatments on cold resistance of walnut trees.【Result】Under low temperature stress, with the increase of K_(2)SO_(4)and CaCl_(2)concentrations, the relative electrical conductivity of walnut leaves decreased firstly and then increased, but they were lower than those of the control. Except spraying 5 mmol·L^(-1)K_(2)SO_(4), the soluble sugar content of walnut leaves was slightly lower than that of the control, the soluble sugar content of walnut leaves under other treatments was higher than that of the control. When the concentrations of K_(2)SO_(4)and CaCl_(2)was lower, the MDA content of walnut leaves decreased compared with the control. However, when the sprayed concentrations was higher, the MDA content of walnut leaves increased compared with the control. The proline content of walnut leaves increased significantly in all the treatment with K_(2)SO_(4)compared with the control. The proline content of walnut leaves decreased slightly in the treatment of 5mmol·L^(-1)and 10 mmol·L^(-1)CaCl_(2), but there was no significant difference with the control(P > 0.05). With the increase of CaCl_(2)concentration, the proline content of walnut leaves increased significantly(P < 0.05). The order of the effect of different treatments on cold resistance of walnut leaves were 10 mmol·L^(-1)CaCl_(2)> 5 mmol·L^(-1)CaCl_(2)> 15 mmol·L^(-1)K_(2)SO_(4)> CK > 10 mmol·L^(-1)K_(2)SO_(4)> 20 mmol·L^(-1)-1 K_(2)SO_(4)> 15 mmol·L^(-1)CaCl_(2)> 20 mmol·L^(-1)CaCl_(2)> 5 mmol·L^(-1)K_(2)SO_(4).【Conclusion】Spraying low concentrations of K_(2)SO_(4)and CaCl_(2)solution increased the cold resistance ability of walnut tree, but spraying too high concentration hindered the normal growth of walnut trees. The effect of spraying CaCl_(2)solution was better than K_(2)SO_(4)solution on cold resistance of walnut trees.