Effects of Main Cultural Factors on the Microstructure of Leaf Tissues

The results showed that the correlation of thickness of leaf,palisade tissue,sponge tissue and upper epidermis with the quality and yield was TN86KY907TN90KY908K26KY8959.So the leaf structure of TN86,KY907 and TN90 was better than others.The thickness of leaf,palisade tissue,sponge tissue,palisade / sponge,palisade/leaf,upper and lower epidermis and width of cell of palisade tissue decreased with the increase in growth density,the delay of topping stage and increase in the remained leaf number.The extent of decline was smaller from lower level to middle level than from middle to higher.The above leaf microstructure parameters was enhanced with increase in N fertilizer,but the extent of increase was larger from lower N to middle N than from middle to higher.The effect of N fertilizer was more obvious than growth density,and topping stage was more obvious than remained leaf number.These leaf micro structure parameters increased with the leaf position upward.Therefore,leaf might have a ideal leaf structure when the plants have the following culture measures: growth density 18 000 plant/hm2,N 300 kg/hm2,topping only once at the time when 50% flower bud growing up to 8～10 cm and 20～21 remained leaf/plant.The leaf key structure feature was largest at the leaf mature stage,middle at pre-leaf mature stage and smallest at post-leaf mature stage.The leaf mature stage of lower,middle and upper position leaf were 3,4,5 weeks after topping,so it would be better to chop harvest the tobacco at 4 weeks after topping.