不同施氮量烤烟赤星病发生与发病初期氮营养、生理状况关系研究

在石林和寻甸两个不同气候生态区通过田间试验研究了烤烟不同施氮量与打顶时（即赤星病发病初期）健康烟株烟叶中的含氮量以及类黄酮、总酚、可溶性糖和游离性氨基酸含量等部分生理生化指标以及后期赤星病发生三者间的相互关系。结果表明，尽管两个试验点烟株体内的生理生化状况和赤星病发生程度有一定的差异，但施氮量与上述生理生化指标、赤星病发生三者间的关系都有一致的规律，即:随着施氮量增加，烟叶内游离性氨基酸含量和氮累积量增加，类黄酮、总酚和可溶性糖含量下降；烟叶成熟过程中不同时间赤星病发病情况均随施氮量增加而增加，其中，高氮和不施氮处理间差异显著。相关分析表明，烟株赤星病发病初期、中期和后期的发病率和病情指数均与发病初期烟叶内的类黄酮、总酚和可溶性糖含量有显著负相关关系；而与游离性氨基酸含量和氮累积量有显著正相关关系。这表明不同施氮量烟株成熟期赤星病发生的差异在一定程度上与发病初期烟叶中的类黄酮、总酚、可溶性糖和游离性氨基酸含量以及氮累积量的差异有关；同时还表明通过调控施氮量可以较好地控制赤星病病害的发生。

Study on the relationship between the content of nitrogen and some bio-physiological substances at topping and the occurrence of brown spot of tobacco applied with different amount of nitrogen

Relationship among nitrogen application rate, biochemical substrate content, such as flavonoid, phenol, soluble sugar, free amino acid, as well as leaf nitrogen at topping, and leaf brown spot occurrence after topping were studied in two different climatic counties, Shilin and Xundian, respectively. Results showed that the relationship mentioned above was similar in leaves on different positions of the stalk at two experimental sites. Higher nitrogen application rate caused higher accumulation of N and free amino acid content, but less flavonoid, phenol and soluble sugar. In addition, increased severity of leaf brown spot was observed with increasing nitrogen rate treatment.Significant negative correlations existed between the content of flavonoid, phenol, soluble sugar and the occurrence of the brown spot disease, while positive correlation was observed between the content of free amino acid and N in leaf and the occurrence of the brown spot. Result suggested that the different N treatment may cause flavonoid, phenol, soluble sugar, free amino acid content difference at topping, and the brown spot severity difference after topping. Result also recommended that the moderate application of nitrogen rate should be considered for the control of brown spot disease under experimental conditions.