Effect Of Different Ecological Factors Oon Growth And Photosynthesis Of Tobacco(Nicotiana Tabacμm L.)

As a crop, tobacco is very sensitive to light, temperature, water and other ecological factors. Finding effective strategy to increase tobacco yield is very beneficial to the economic effectiveness for farmers.Thus, the effects of artificial controlled conditions such as on tobacco growth, metabolism and photosynthesis light quality, light intensity, temperature and water stress were investigated in this paper. The results are showed below.1. Different light quality was obtained by covered four colors of film that was red, yellow, blue and white. The effects of light quality on growth and photosynthesis of flue-cured tobacco were studied. The results are as follows:(1)Red light can promote the growth of flue-cured tobacco, which increased the plant height and stem girth.While yellow light inhibited the growth.(2) Yellow light treatment can promote the accumulation of chlorophyll.(3) Pn, Tr and Gs reduced under the four different light quality.(4) Blue light increased the activities of SOD and PAL as well as the contents of soluble protein and soluble sugar.(5) Red and white light can enhance the activity of PPO.2. The results showed tobacco growth and photosynthesis under65%and35%shade conditions.(1) The weaker the light intensity, the greater height, maximum leaf length and width will be get, whereas the slender stem and fewer leaf numbers will be obtained.(2) The content of chlorophyll increased and photosynthetic efficiency decreased as shading intensity increase in tobacco.(3) Chlorophyll flμorescence showed that shading treatment reduced the degree of photosynthetic apparatus injury, indicating that weakening of the light intensity can protect photosynthetic apparatus of tobacco from damage.(4) Shading treatment decreased the activities of PPO, PAL and POD as well as the contents of soluble sugar and soluble protein, whereas the activity of SOD was increased in tobacco.3. We studied the effects of temperature on tobacco growth and photosynthesis by controlling the temperature in the greenhouse.The results showed that:(1) The height of plant under lower and higher temperature conditions were higher compared to the control, while stem girth, number of leaves, maximum leaf length, and width were lower than that in the control, suggesting that temperature treatment made the plant spindling.Temperature-stress plants showed decreased photosynthetic efficiency and chlorophyll content.(2) The initial fluorescence Fo, Fv/Fm and φPSⅡ reduced μ nder temperature stress, indicating that they suffered photoinhibition.(3) The activities of superoxide dismutase (SOD) and peroxidase (POD) were elevated to removing free radicals, while the activities of PPO and PAL reduced, and the contents of soluble sugar and soluble protein increased under lower and higher temperature treatment.4. By controlling the moisture to the tobacco plant, we studied the effect of mild water stress and poisoning water stress on the seedling growth and photosynthesis. The results are as follows:(1) The height, stem girth, maximum leaf length and width and leaf numbers decreased gradually with the increase of water stress, suggest that the growth of tobacco seedling was inhibited under water stress.(2) After water stress, the leaf chlorophyll content decreased, net photosynthetic efficiency, stomatal conductance(Gs), intercellular CO2concentration(Ci) and transpiration rate decreased; stomatal limit values of the leaves increased, but the water utilizationrate, instantaneous carboxylation efficiency, instantaneous energy utilization decreased.(3) With the increasing of the water stress, Fo, Fv/Fm, φPSⅡ and qP decreased, while the Fm and qN increased. (4) The activities of SOD and POD increased, the contents of soluble sugar and soluble protein also increased, but the activities of PAL and PPO decreased.