Research Of Moisture Control On Tobacco Plug Seedlings

In order to nurture seedlings strongly, use water and fertilizer rationally, by studying the different water content of the substrate on the seedlings in different periods,the results were as follows:1.Tobacco seeds germination need to absorb a lot of water, In the matrix of 93% relative water content, the maximum germination and germination rate were 84% and 92.5%. Substrate is lower than 60% relative water content, seed germination slow germination and germination rate significantly reduced. Tobacco out of the optimum seedling substrate water content was90-95%.2.Cross the roots of tobacco seedlings, in the matrix of 90% relative water content, leaf area, plant height, shoot dry weight maximum, respectively 2.36cm2,0.45 cm,0.0494g; relative water content in the matrix of 80%, the stem diameter, root dry weight, chlorophyll a and b content, net photosynthetic rate, maximum root activity and NR activity were 0.148cm, 0.0052 g,0.6138 mg/g,0.1986 mg/g,10.65 mg/d2-h,49.16 ugTTC/g-h,294.39μg/g-h. Relative water content in the matrix 80%, SOD activity and MDA content were 92.16 U/g-h and 11.29 mmol·g-1, in the matrix of 90% relative water content, SOD activity and MDA content were 92.16 U/g-h and 10.50 mmol·g-1, subject to water stress is less important. Therefore, to determine the optimal substrates for this period of relative water content was about 85%.3.The vertical arm of the tobacco seedlings in the matrix of 80% relative water content, the leaf area, plant height, shoot dry weight, chlorophyll b contents were maximum, respectively 35.87 cm2,4.16 cm,0.2717 g,0.2265 mg/g; In the matrix of 70% relative water content, the stem diameter, root dry weight, chlorophyll a content, and the rate of net photosynthesis, root activity and NR activity reached the maximum, respectively,0.243 cm, 0.0284 g,0.6642 mg/g,21.63 mg/d2-h,77.15μgTTC/g-h,468.16μg/g-h. In the matrix of 70% relative water content, SOD activity and MDA content were 93.01 U/g-h and 9.06 mmol·g-1, in the matrix of 80% of relative water content, SOD activity and MDA content were 87.09 U/g·h and 8.75 mmol·g-1, subject to water stress was less important. Therefore, to determine the optimal substrates for this period of relative water content was about 75%. 4.Into a seedling, in the matrix of 70% relative water content, the chlorophyll a and b content, the maximum net photosynthetic rates, root activity and the maximum NR activity were 0.8143 mg/g and 0.2818 mg/g,29.42 mg/d2-h,93.61μgTTC/g-h,491.31μg/g-h. In the matrix of 60% relative water content, the root dry weight, was 0.0593 g. In the matrix of 60% relative water content, SOD activity and MDA content were 88.41 U/g-h and 11.35 mmol·g-1, In the matrix of 70% relative water content, SOD activity and MDA content were 67.72 U/g-h and 9.02 mmol·g-1, subject to water stress is less important. Therefore, to determine the optimal substrates for this period of relative water content was about 65%.5.Tobacco seedlings which water controlled, will be better adapt to the environment, seedling faster and survival rate is higher.12 days after transplanted, the survival rate of treated tobacco seedlings, the maximum leaf area and root activity are 11.63%,7.79% and 10.88% higher than the contrast group.