保水剂对烤烟光合特性日变化的影响

【目的】探讨保水剂对烤烟光合特性的影响,在保水剂不同施用量条件下,对烤烟净光合速率及其生理生态因子日变化进行研究。【方法】利用LI-6400便携式光合测定系统测定烤烟光合指标日变化,并采用Excel2007和SPSS13.0对试验数据进行方差分析、相关分析和通径分析。【结果】4个处理的净光合速率(Pn)、气孔导度(Gs)和蒸腾速率(Tr)日变化均为单峰曲线,峰值多出现在9:00或11:00,没有"午休现象";随保水剂施用量的增加,烟叶的光合能力总体上逐渐增强;未施保水剂的烟株净光合速率主要受蒸腾速率和大气相对湿度的影响,施用保水剂的烟株净光合速率主要受气孔导度和大气相对湿度的影响。【结论】保水剂可以增强烟叶的光合能力;4个处理以保水剂施用量为45kg.hm-2的光合能力最强;延边雨季为土壤提供了充足的水分,这是烤烟成熟期没有"午休"现象的主要原因;保水剂主要是通过调节烟叶的气孔导度,进而影响其净光合速率。

Effects of Water Retention Agent on Diurnal Changes of Photosynthetic Characteristics in Flue-cured Tobacco

Objective]In order m understand the effects of water retention agent on photosynthetic characteristics in flue-cured tobacco,diurnal changes of photosynthetic rate and its physio-ecological factors were researched under different water retention agent application rates.Method]Diurnal changes of photosynthetic indexes were determined by the LI-6400 portable photosynthesis system.The data were analyzed by Excel2007 and SPSSI3.0 with variance analysis,correlation analysis and path analysis.Result]The results indicated that the net photosynthetic rates (Pn),stomatal conductance (Gs) and transpiration rates (Tr)diurnal changes in four treatments all appeared as single peak curves,the majority of peaks appeared at 9:00 or 11:00,and they all didn't show midday depression.Overall the photosynthetic capacity of tobacco leaf gradually strengthened with water retention agent application rate growing.The net photosynthetic rate of tobacco in the control was affected by transpiration rate and atmospheric relative humidity (RH).The net photosynthetic rate of tobacco in water retention agent treatment was affected by stomatal conductance and atmospheric relative humidity.Conclusion]Water retention agent could enhance the photosynthetic ability of the flue-cured tobacco leaf.When the water retention agent application rate was 45 kg·ha~(-1),the photosynthetic ability of the flue-cured tobacco was the strongest in four treatments,Rainy season of Yanbian provided enough water for soil which was the main cause of no midday depression phenomenon at maturing stage.Water retention agent influences the net photosynthetic rate mainly by regulating stomatal conductance (Gs) of the flue-cured tobacco.