Effects Of Chlorine On Physiological Characteristics And Quality Of Flue-cured Tobacco In Red-yellow Soil Of Sichuan

In XiChang tobacco research Institute, Liangshan Sichuan, Pot and field experiments were carried out to study the effects of different chlorine-applied amount on growth condition, physiological characteristics and quality of flue-cured tobacco. Proper chlorine-applied amount and appropriate chlorine content in upper, middle and lower leaves were put forward. The results were as following:1 Effects of different chlorine application rate on growth condition of flue-cured tobaccoWhen chloride application rate was 0.8-4.0 g per plant, the plant height, stem perimeter, area of the biggest leaf and dry matter accumulation of roots, stem and leaves were all distinctively increased.Before the 60th day after transplanting, the dry matter accumulation of the treatments (0.8-4.0 g per plant chlorine application rate) was higher than that of the treatments (4.8 and 5.6 g per plant's chloride application rate) .Beyond the range, the growth of tobacco was restrained, which was unfavourite to the growth of tobacco plant in early stages. Speed of cell dividing and plant growth were reduced.2 Changes of contents of K+, CFand total nitrogen in tobacco leaves; distribution and accumulation of Cl~- in the growth stageWith increasing of chlorine application rate, potassium and chlorine contents in flue-cured tobacco leaves both increased, but total nitrogen content had a decreasing tendency; distribution of Cl~- content in tobacco leaves at different position was: lower leaves>middle leaves>upper leaves; chlorine content in tobacco leaves at different growth stage was: 60 d>45 d>80 d, which showed a tendency of increasing in the early period and then decreasing in the late period. Potassium content gradually decreased, which showed 45 d>60 d>80 d. From 45 days to 60 days, K/Cl gradually decreased; then it began to increase after 60 days. Vigorous growing stage was the stage of increasing rapidly of chlorine concentration in tobacco leaves. The chlorine accumulation amounts showed significant quadratic curves correlation with the amount of chloride applied. The chlorine accumulation amount of the chloride-applied treatments were obviously higher than that of CK. The chlorine application amount of 4.0 g per plant caused the maximum chlorine accumulationamount in tobacco leaves.When chlorine-applied amount ≥4.8 g per plant, dry matter accumulation amount of tobacco leaves decreased gradually.3 Effects of chlorine application amount on physiological characteristics of flue-cured tobaccoThere was a tendency of decreasing of Nitrate reductase activity with increasing of chlorine application amount. Higher chloride application amount (4.8-5.6 g per plant) was unfavorite to decreasing of its activity in vigorous growing stage (45 d); the progress of carbon and nitrogen metabolism's transformation was delayed; there was a tendency of prolonging with nitrogen metabolism's course in tobacco plant. The chloride application amount of 1.6-4.0 g per plant improved the Invertase activity and strengthened carbon metabolism. Beyond the range of 1.6-4.0 g per plant, the capability of tobacco leaves' making use of carbohydrates was weakened. Peroxidase activities increased with increasing of chloride application amount. There was a relationship between the inhibition of higher chloride to tobacco plant's growth and higher peroxidase activities. With the growing period delay, Glycolate oxidase activities increased gradually; GO activities were positively correlated to the chloride application amount significantly.Lower chloride application amount treatment (0-0.8 g per plant) , chlorophyll content was on a lower level during the full growth period. Proper chloride application amount (1.6-4.0 g per plant) promoted chlorophyll synthesis during the vegetative growing period; chlorophyll content was improved obviously. At later growth stage, the catabolism of chlorophyll was obvious. When chlorine application amount was 4.8-5.6 g per plant, chlorophyll content was still on a higher level at later growth stage.Photosynthetic rate (Pn ) transpiration rate (Tr) and stomatal conductance (Gi) increased and the intercellular CO2 concentration (Ci) decreased with increasing of chloride application amount. When chloride application amount was ≤ 4.0 g per plant, increasing of Gs provided the condition for Pn's improving. When chloride application amount was >4.0 g per plant, decreasing of chlorophyll synthesis amount was the key factor of Pn's decreasing of leaves which was caused by nonstomatal factors.4 Soil chlorine content being suitable for tobacco growthChlorine application amount of 1.6-4.0 g per plant in pot experiment favored to physiology metabolism and growth. Soil chlorine volume being suitable for tobacco...