种植密度对烤烟叶片生育期光合特性的影响

Effects of planting density on tobacco leaf photosynthetic characteristics

选用K326品种,研究了3种种植密度处理(从大到小依次为D1,D2,D3)对烤烟下、中、上部位叶片光合特性的影响。结果显示:(1)叶片净光合速率(Pn)中、下部叶以D2处理最高,上部叶以D3处理最高;(2)蒸腾速率(Tr)以D1处理最高;(3)单叶水分利用率(WUE)中、下部叶以D2处理在中后期较高,上部叶以D3处理较高;(4)气孔限制值(Ls)D3处理最低,D1和D2处理差异不显著。综上表明,D2处理(18150株.hm-2)可减小Pn的下降率,延缓光合功能的衰退,光合作用和蒸腾作用达到最为协调的状态,有较高的单叶水分利用率(WUE)。

Effects of three planting densities,i.e.D1,D2 and D3 in descending order,on photosynthetic characteristics of tobacco leaves at all stalk positions were studied in field experiments using K326.Results indicated that 1） for leaf net photosynthetic rate（Pn）,D2（18150 plants per hectare） led to the highest level in the middle and lower leaves,while D3 in upper leaves;2） for transpiration rate（Tr）,D1 led to the peak point;3） for water use efficiency,D2 showed higher level in the late growth period in middle and lower leaves,and D3 in upper leaves;and 4） for limiting value of stomata（Ls）,D3 led to bottom level,and no significant difference were found between D1 and D2.In conclusion,D2 treatment could lower decrease scale of Pn,delay decline of photosynthesis,result in higher WUE,and thus optimal photosynthetic characteristics.