渗透胁迫对烤烟体内钾素累积的影响

以烤烟K326为材料，研究了PEG渗透胁迫对烤烟体内钾素累积的影响。结果表明：旺长期内短时间低渗透胁迫强度刺激了烟株中K^ 的累积，胁迫时间延长或胁迫强度增加时，K^ 累积速率逐渐降低，甚至导致体内钾的损失。钾累积量的这种变化与渗透胁迫导致的根细胞膜结构的破坏及质膜选择透过性功能的降低有关。胁迫程度较高或时间较长时，细胞膜的相对透性增加，导致根中的K^ 大量外流。这说明短时间的低渗透胁迫不会明显降低烟叶的含钾量，但烤烟对干旱的御胁迫性及胁变修复性较小，烤烟生育期内特别是对水分变化最敏感的旺长期应有合适的水分供应，以提高烟根的吸钾速率、降低钾的外流损失。

Effect of osmotic stress on K content of flue-cured tobacco

Effect of osmotic stress on K content of flue-cured tobacco was studied with solution culture experiment. The results showed that:In grand growth period, low external osmotic potential caused by PEG-6000 solution stimulated K accumulation in leaves, stem and roots. High osmotic stress resulted in an increased membrane permeability to K and rapid efflux of K from the roots. Loss of K increased as a function of time. Tobacco plant was very susceptible to drought stress in grand growth stage. Keeping a optimum soil moisture was prerequisite to not only raising K~+ uptake, but also reducing K~+ efflux from roots.