苹果树腐烂病发生与叶片营养成分的关系

Relationship between occurrence of apple Valsa canker and leaf nutrients

【目的】明确苹果树腐烂病发生程度与树体营养之间的关系,为苹果树腐烂病的防治提供理论指导。【方法】在陕西省苹果主产县白水县选取苹果树腐烂病发生程度不同的24个果园,调查苹果树腐烂病发生程度,测定发病叶片氮、磷、钾元素含量,研究苹果树腐烂病发生与叶片营养成分的关系。【结果】树体营养水平与苹果树腐烂病发生程度有明显相关性:单因子回归分析显示,当叶片K含量<9mg/g时,叶片K含量与腐烂病的发生程度呈极显著的负相关关系;多元回归分析显示,N、P、K元素间平衡与腐烂病发生程度关系密切,病情指数与N/K和P/K均呈极显著正相关关系。增施钾肥能提高叶片钾含量,使病斑扩展明显变慢,表明提高钾含量能够提高寄主抗腐烂病菌扩展能力。【结论】从控制苹果树腐烂病角度认为,果园叶片钾含量至少应该≥9mg/g,氮钾比小于2.5,磷钾比小于0.25。

【Objective】The potential relationship between tree nutrition and occurrence of Valsa canker was investigated to provide information for disease control.【Method】24orchards with different severities of Valsa canker in main apple growing area at Baishui County,Shaanxi Province were selected to measure contents of elements(N,P,and K)in apple leaves and analyze the relationship between disease occurrence and leaf nutrients.【Result】There were significant relationships between occurrence of apple canker and nutrients levels.Significantly negative correlation was found between disease indexes and potassium contents(<9mg/g)in leaves based on single factor regression analysis.Multiple factors linear regression analysis showed high correlation between disease indexes and nitrogen-phosphorate-potassium balance.The disease index had extremely positive correlation with N/K and P/K ratios.Adding potassium slowed the spread of canker,indicating that potassium could increase resistance of apple tree to the pathogen.【Conclusion】To control Valsa canker in apple orchards,not less than 9mg/g leaf potassium,N/K ratio of<2.5and P/K ratio of<0.25were suggested.