Studies On The Effects Of Nitrogen Rates And Remained Leaves Number On Physiology And Plant Type Of Flue-cured Tobacco In Guizhou

Nitrogen rates and remained leaves number have affects on the formation of tobacco growth and development of plant type and have great significance to the production and value of output. In order to study the different effects of nitrogen rates and remained leaves number on plant growing development, plant type and value of output. To provide theoretical basis for formulating the directional cultivation technology of control of plant and optimizing the group structure. The test set of nitrogen application amount and remained leaf number was studied. This study used Flue-cured tobacco varieties of K326as material, have had measured and statisticaled plant type, photosynthetic characteristics, physiological, value of output of tobacco.The main results are as follows:The study of photosynthetic characteristics was carried out that photosynthetic pigment contents of tobacco, net photosynthetic rate of tobacco, stomatal conductance of tobacco and transpiration rate of tobacco were declined with time, but the intercellular CO2concentrtion was changed in the opposite. Nitrogen rates and remained leaves number can promote the photosynthetic characteristics of tobacco. In general, photosynthetic characteristics of tobacco that with nitrogen rates at180kg·hm-2and remained leaves number at22leaves of each plant was best.The results of population physiology showed that leaf area and the leaf area index and leaf area duration of each treatment was showed a tendency that increase with transplanting period. Under different nitrogen rates, leaf area, leaf area index, leaf area duration, relative growth rate, net assimilation rate and photosynthetic productivity of tobacco were increased with increase of nitrogen rates. But specific leaf area and leaf weight ratio of tobacco was declined with increase of nitrogen rates. At different levels of remained leaves number that left most of leaves of tobacco, its leaf area duration, leaf area, leaf area index, net assimilation rate and photosynthetic productivity were higher than another two kinds of treatments. Comprehensive analysis showed that:Population physiological characteristics of Nitrogen rates at180kg·hm-2and remained leaves number at22pieces of each plant was best.The results of research suggests that the root length, surface area and volume of tobacco was increased with remained leaves number at the same rates of nitrogen. At the same remained leaves level, three indicators was increased with the rates of nitrogen. In short, the experimental treatment of nitrogen rates at180kg·hm-2and22pieces of each plant was best. Under the same nitrogen level, the root activity of tobacco was increased with the remained leaves number. Under the same remained leaves number, root activity of tobacco increased with the rate of nitrogen at first, however, when nitrogen rates have reached120kg·hm-2, it begain to decrease. Comprehensive analysis showed that: the root activity of tobacco with the best treatment is120kg·hm-2of nitrogen rates and18pieces of each plant.Results of carbon metabolism key enzyme activity showed that under the same number of leaves, the activity of amylase along with the increase of nitrogen rates, but variations of sucrose phosphate synthesis was not obvious. At the same level of nitrogen rates, the variations of amylase activity, sucrose phosphate synthase, sucrose synthase and sucrose content did not conform with the change tendency of remained of leaves number.The study of key enzyme activity of nitrogen metabolism activity was carried out that the increasing of nitrogen rates can promote the protein content and glutamine synthetase activity of tobacco leaves. In brief, the protein content and glutamine synthetase activity of experimental treatment that nitrogen rates with180kg·hm-2was highest. In three kinds of number of remained leaves the highest of protein contents of experimental treatment was22pieces of each plant, but the effects of remained leaves number on glutamine synthetase activity was not significant.Research results economic characters of tobacco showed that the highest yield and output value in four kinds of nitrogen rates is180kg·hm-2, in three kinds of remained leaves number the highest yield and output value of experimental treatments is22pieces of each plant. The yield increased with remained leaves number and nitrogen rates, however, the output increased with nitrogen rates at first, and then begain to decrease, nitrogen rates of120kg·hm-2was the highest. The highest average price is nitrogen rates of60kg·hm-2and remained leaves number of18pieces of each plant. In12kinds of experimental treatments, the largest ratio of high class leaves of tobacco is nitrogen rates of120kg·hm-2and remained leaves number of18pieces of each plant, have reached at20.33%.The study of plant type was carried out that the treatment without nitrogen application and leaves number remained22leaves of each plant that leaf layer height and leaf layer width was best. The growing period of flue-cured tobacco plant type changes low to high. Though the analysis of variance have found that the effect of nitrogen on plant type was not significant, but the ramaind leaves number on the plant type of tobacco was crucial in the formation. The interaction of two factors on the plant type of tobacco did not reach significant level. Leaves number remained14leaves of each plant mainly change cylinder shape to cylinder shape. Leaves number remained18leaves of each plant mainly change long tube to long tube. Leaves number remained22leaves of each plant mainly change drum type to long tube.The reaserch results of plant type showed that in three kinds of plant types which tobacco with drum shape-long cylinder that photosynthetic rate, population growth rate, root growth, nitrogen metabolism key enzyme activity, sucrose content, output value and quality grading were better than the other two kinds of plant types. But tobacco with long cylinder-long cylinder that potassium content, the ratio of sugar to nicotine, potassium, chlorine were highest.tobacco with cylinder-cylinder that nicotine, total nitrogen, chlorine content and amylase activity were highest.Though comprehensive analysis we have foud the effects of nitrogen rates on plant type of tobacco was not significant, however, remained leaves number plays a key role in plant type. Experimental treatment under nitrogen rates of180kg·hm-2and22remained leaves of each plant, its photosynthetic characteristics, population physiology, root index, yield and output value of tobacco was best. But the best fold of tobacco in twelve kinds treatment was nitrogen rates of the60kg·hm-2and18remained leaves of each plant. The ideal plant type was drum shape-long cylinder.