低钾胁迫对生菜光合作用以及内、外叶片钾含量与可溶性糖含量的影响

摘要：为探明缺钾生菜外形正常而生长缓慢的原因,研究了不同程度钾缺乏对生菜的影响。以“巴达维亚”生菜为材料,通过营养液量的管理方法,设置4个梯度的钾供给量,分别为常规用量对照组以及1/2、1/4、1/8钾供给量,分析钾缺乏处理下生菜叶片的钾含量和可溶性糖含量以及光合作用的变化。结果表明：1/2和1/4处理中生菜的净光合速率、气孔导度、胞间二氧化碳浓度和蒸腾速率与CK相比均无显著差异,1/8处理则均较CK显著降低。1/2、1/4、1/8处理下生菜内、外叶片钾含量均逐渐降低,可溶性糖含量均逐渐上升;随着叶片钾含量的降低,外、内叶钾含量比值和外、内叶可溶性糖含量比值均有所上升,这表明生菜在遭受钾缺乏时,将更多功能性物质分配于外叶以维持其正常功能,而内叶由于分配较少导致生长缓慢。

Effects of Potassium Defi ciency Stress on Photosynthesis and Potassium Content and Soluble Sugar Content in Inner and Outer Leaves of Lettuce

Abstract: The effect of potassium defi ciency on lettuce was studied in order to fi nd out the reason of its normal appearance and slow growth. With ''Batavian'' lettuce as the material, four gradients of potassium supply were set through nutrient solution management method, which were the normal amount (CK) and the 1/2, 1/4, 1/8 amount of normal potassium supply, respectively. The changes of potassium content, soluble sugar content and photosynthesis of lettuce leaves under potassium defi ciency treatment were analyzed. The results showed that the net photosynthetic rate, stomatal conductance, intercellular carbon dioxide concentration and transpiration rate of lettuce in 1/2 and 1/4 treatment were not signifi cantly different from those of CK, while those of 1/8 treatment were signifi cantly lower than those of CK. Under 1/2, 1/4, 1/8 treatments, the potassium content in the inner and outer leaves of lettuce gradually decreased, and the soluble sugar content gradually increased. With the decrease of potassium content in leaves, both the ratio of potassium content in outer and inner leaves and the ratio of soluble sugar content in outer and inner leaves all increased, which indicated that when lettuce suffered from potassium defi ciency, more functional substances were allocated to the outer leaves to maintain its normal function, while the inner leaves grew slowly due to less distribution.