Study On The Yield And Qualities Formation And Growth Of Flue-cured Tobacco Under Different Magnesium Fertilizer

Field experiments with flue-cured tobacco Yunyan No.87 were conducted in Changning in Hunan in 2005, by using complete random block design with 3 replicates. Three magnesium (Mg) application treatments, i.e. the low rate (150 Mg kg/hm~2), the middle rate (300 Mg kg/hm~2) and the high rate (450 Mg kg/hm~2) were experimented to study the yield and qualities formation and growth of flue-cured tobacco under different magnesium fertilizer application. The main results were as follows:1. The growth and development of tobacco were obviously stimulated by magnesium in this experiment, the agronomic chracteristics of tobacco improved, the top root lengthened, the root system developed vastly and deeply. Height of tobacco lengthened, diameter of stalks larger, the more magnesium application, the more significant the effects, at a range of limited amount magnesium application; Over it, adding the amount of magnesium application, but no effects, even worse.2. With applying magnesium fertilizer, the activities of tobacco root system improved, the content of chlorophyll of tobacco leaves increased obviously, the intensification of photosynthesis and transpiration enhanced.3.The effects of magnesium application on the qualities of tobacco is quite different, It reduced the content of nicotine and total nitrogen, increased the content of total sugar and the ratio of sugar to nicotine, there was a significant positive-correlation between the amount of magnesium application in all stage of tobacco growth and development. Meanwhile, it promoted tobacco plants to absorb more K~+, increased the total of K. in tobacco leaves and the ratio of K to Ca plus Mg, and elevated the combusting quality of tobacco. But over the amount rang of Mg application limited, It led to negative effects on tobacco.4. The accumulation and absorption of tobacco to Mg were significantly enhanced, the correlation between the value of Mg accumulating for tobacco and the amount of Mg application was quite significant, the index of correlation was 0.8945(P<0.01).5. The ability of tobacco to accumulate dry matter was enhanced, the order of the function is middle Mg level>high Mg level>low Mg level.6. The qualities and yield and the rate of high grade leaf of flue-cured tobacco were improved, the efficiency of tobacco production as well. Under the condition this experiment, all of the yield, high grade leaf and the efficiency of tobacco production were middle Mg treatments was the highest, next high Mg treatments, next low Mg treatments. Therefore, the production of flue-cured tobacco Yunyan No. 87 might be to consider the use of Mg seriously, and the optimum amount of Mg application was 150 kg/hm~2-300kg/hm~2.