Effects Of Straw Mulching On Soil Improvement Of Tobacco Field And Quality Of Flue-cured Tobacco Leaves

Field experiments were carried out in Luohe district Henan province from 2006 to 2007. Effects of plastic film mulching and different straw mulching treatment on physical, chemical and biological characters of tobacco farmland soil were studied, proper method of mulching was proposed. The main results showed that:1. Effects of different kind of mulching on the soil temperature and water ratio. Compared with the contrast, mulching could adjust the soil temperature effectively. Furthermore, increasing temperature effect of mulching and decreasing temperature effect of straw mulching were significant. During the early growing period of flue-cured tobacco, the increasing temperature effect of mulching was helpful to the growth of flue-curd tobacco. Otherwise, during the later growing period of flue-curd tobacco, decreasing temperature effect of straw mulching was helpful to the growth of flue-cured tobacco.Compared with other treatments, the straw complete mulching treatment enable the whole stage of flue-cured tobacco and various soil layer to keep a relative high water ratio. During the early growing period of flue-cured tobacco, the soil water ratio of the contrast was the lowest, and of plastic film mulching treatment was between the straw complete mulching treatment and straw strip-like mulching treatments. With the tobacco growing, the soil water ratio of plastic mulching treatment and of contrast become closer and lower. However, the soil water ratio of straw complete mulching was still higher than that of contrast, and of straw strip-like mulching was between them.2. Effects of different kind of mulching on the physical, chemical and biological character of soil.During the early growing period of flue-cured tobacco, the content of organic matter, humus, available nitrogen, available phosphorus and available potassium in plastic film mulching soil was higher than other treatments. With the tobacco growing, the content of organic matter, humus, available nitrogen, available phosphorus and available potassium in soil of straw mulching treatments were higher than that of the straw strip-like mulching treatment and of contrast. The different of the soil total nitrogen content in treatments were not significant. Straw mulching could increase the quantity of microorganism and enhance the activity of them significantly. During the early growing period of flue-cured tobacco, the quantity of germ and actinomycetes in the soil of the plastic mulching treatment was the greatest. After transplanted 60 days, the quantities of the germs and actinomycetes in the soil of the treatment that was mulched straw 15 days before transplanted was the greatest. Meanwhile, the straw strip-like mulching treatments'was higher than the straw complete mulching treatment's, during the every growing period of flue-cured tobacco, the fungi quantity of the treatment which was mulched straw 15 days before transplanted was the greatest. However, the quantity of the bacteria,fungi,actinomycetes in the contrast soil was the lowest.Straw mulching could enhance the activity of urease,invertase and neutral phosphatase in soil. During the whole growing period of flue-cured tobacco, the activity of urease,invertase in straw strip-like mulching soil was the highest. The contrast's was the lowest. During the rosette stage, the activity of neutral phosphatase in the plastic film mulching was the highest, after this period, it lower than every straw mulching treatments'.3. Effects of different kind of munching on growth and physical characters of flue-cured tobacco.After transplanted 30 days, the stem length, stem girth, number of productive leaves and biggest area of leaves were all greater than other treatments. After transplanted 45 days,the stem length and the biggest area of leaves of the straw strip-like mulching treatments were the highest. During the later growing period of flue-curd tobacco, the advantage of three straw mulching treatments was obvious, the biggest area of leaves of them was different from that of plastic mulching treatment and contrast, and meanwhile, straw mulching could improve the enlargement of the leaves during the later stage of tobacco.After transplanted 30 days, the activity of SOD in the leaves of the plastic mulching treatments was high, and the content of MDA was lower relatively. The activity of SOD of the treatments which were mulched complete straw 15 days before transplanted was low, and the content of MDA in the treatment which was mulched straw when transplanted was low relatively. With the tobacco growing, the activity of SOD in every straw mulching treatment was higher than that in the plastic mulching treatment and in contrast. After transplanted 80 days, the order of decreasing range of MDA content was CK>T1>T2>T4>T3.After transplanted 50 to 80 days, the chlorophyll content of the contrast and of the plastic mulching treatment was lower than that of the straw mulching treatment. Compared with the straw mulching treatments, the content of Straw strip-like mulching treatment was lower, which suggested that the chlorophyll content of naked and plastic mulching treatments degraded fast relatively, which affected the photosynthesis of tobacco during the later stage. However, the chlorophyll of straw complete mulching treatment degraded slowly relatively, which was not beneficial to process of becoming yellow. The quantity of chlorophyll content and changing discipline in the Straw strip-like mulching treatments satisfied the demands of excellent tobacco more.4. Effect of different kind of mulching on the quality of flue-cured tobacco.Comparing the output, output values and benefit of tobacco among treatments, we found that the output of plastic mulching treatment was the highest, but the average price and proportion of the high middle class leaf were low relatively. The output values of straw strip-like mulching was highest, mainly because the economic characters of its average price and the proportion of high middle class leaf was superior to other treatment. The output value of straw complete mulching treatment was lower than that of straw strip-like mulching treatment, but higher than that of plastic mulching treatment.Compared with the plastic mulching treatments, the total sugar and total nitrogen content of straw mulching treatments decreased, while the content of K and nicotine increased. The nicotine in middle leaves was close to 2.5%, which was proper relatively. The nicotine,total nitrogen content of plastic film mulching treatment was higher than that of contrast and of straw mulching treatments.Compared the important aroma components content of middle leaves in different kind of mulching treatments, the order showed that T3>T1>T3>T4>CK, which suggested that straw strip-like mulching was more beneficial to the forming of the aroma.5. The proper kind of mulchingThe result showed that straw mulching was helpful to tobacco growth of later stage, furthermore, the output value and economic benefit of it was superior to the plastic mulching. The treatment which was mulched straw 15 days before transplanted was better than the treatment which was mulched straw when transplanted. The strip-like treatment which was mulched straw 15 days before transplanted was the best, the output and quality of them was the best. This kind of treatment should be applied in process of the tobacco producing.