干旱胁迫下钾对烤烟生长及抗旱性的生理调节

严重干旱胁迫条件下烟株的生长明显受阻，产量下降。增施钾肥可提高烟叶中钾的含量，增加干物质积累，并能使叶片中的各种化学物质充分转化、含量协调，从而提高了干旱条件下烤烟的产量，并能改善品质。钾素的生理调节机理是增强烤烟叶片的保水力，降低失水速率和蒸腾速率。细胞膜在干旱条件下保持其完整性，表现为叶片的相对电导率和伤害率下降。另外，干旱胁迫下钾素能够增强烟株对超氧化物歧化酶（ＳＯＤ）活性的调节，有利于消除活性氧自由基，减轻了干旱胁迫对细胞膜的伤害，从而增强烤烟的抗旱能力，并使恢复供水后的烟株迅速恢复生长。

Adjusting effect of potassium on growth and drought resistance of flue cured tobacco under drought stress conditions

The adjusting mechanism of potassium fertilization on growth and development,yield formation and drought resistance physiology of flue cured tobacco were studied under different soil water content conditions in pot experiments.The results showed that growth of tobacco plant was obviously hindered and the yield reduced sharply under the deep drought stress.The enhancing of potassium fertilizer level could promote potassium content and accumulative quantity of dry matter in tobacco leaves,make chemical constituents more coordinate,increase yield and improve quality under the drought condition.The adjusting mechanism of potassium were to increase water holding ability of leaves due to lower loss water rate(LWR)and transpiration rate(TR)under drought stress.It was demonstrated that potassium could also strengthen tobacco plant to adjust superoxide dismutase(SOD)activity,eliminate free radical of active oxygen,mitigate the injury of drought stress to plasm membrane by lowing relative eletric conductivity and injury rate of cell membrane.Therefore potassium could strengthen drought resistance of the tobacco plant and made it recover growth more quickly after resupplying soil water.