| Threat of drought is the main meteorological factor of agricultural production. Using the crops of drought resistant germplasm resources is an important element of biological water saving, to investigate the feasibility of biological water saving of tomato grafted by drought-tolerant rootstock. These experiment had collected 32 line of tomato rootstocks to identify them under water stress. On this basis, we selected several rootstock of different drought resistance from lines of rootstock to graft tomato, and researched the physiological responses of grafting tomato under water stress, discussed the mechanism of drought resistance, and its effect on fruit yield and quality. The main results are as follows:1. 32 tomato rootstocks as test material, we measured the changes of root fresh weight, stem fresh weight, leaf fresh weight, leaf water potential, root activity both before and after soil dehydration treatment then through comprehensive comparative analysis. It was found that with the prolonging time of soil dehydration, the average value of drought damage index of tomato rootstock seedlings increased, while the coefficient variances were reduced. However, after watered the changes were just the opposite. In the drought damage index regression model there were only root fresh weight, leaf water potential before soil dehydration treatment and the relative added value of root fresh weight had been selected. According to the result from analyzed variable factors of the model by the methods of system clustering, tomato rootstock materials all can be divided into three classes. With the exception of the relative added value of root fresh weight, other factors had the same results. So root fresh weight and leaf water potential of seedlings before soil dehydration treatment are determined to be used as convenient indicators of tomato drought tolerance, and screening out that 606, ???-T, 060813 and 0301112 are drought tolerant tomato rootstock materials.2. Used the split plot design on the test 2 and 3, the main treatment were grafting composed of the ungrafted tomato of ?Jingpeng 1‘(J), the grafted tomato of ?606‘(J/T) with drought-tolerant rootstock and?112‘(J/S) with drought-sensitive rootstock, and the deputy treatment were soil moisture composed of 80%, 60% and 40% soil relative water content. The test 2 was with water stress on grafted tomato seedlings with different drought resistance rootstock, the growth and As A-GSH cycle of grafted tomato with different drought resistance rootstock were studied under water stress. The results showed that the growth and proline, soluble sugar, soluble protein content and SOD, POD, C AT, APX, DHAR, GR activity of both leaves and roots of tomato seedling with different grafting treatment was expressed as J/T>J/S>J under the condition of different soil moisture content. The As A+DHA, As A content and As A/DHA, GSH+GSSG, GSH of grafting treatment were higher in J/T, then followed with J/S and lower in J. With the increase of water stress, the parameters of As A-GSH cycle were increased, indicating that water stress caused oxidative stress on tomato leaves and roots. However, at the same time the As A-GSH cycle defense system was stimulated, and improved APX, DHAR, GR and other enzymes activity, in order to maintain the plant ascorbic acid and glutathione levels and mitigation of drought damage to plants. In the grafting treatment J/T had a better growth advantage and could accumulate more osmotic adjustment substance to reduced cell potential and membrane damage, then used the protective enzymes system of the plant, accelerated AsA-GSH cycle, scavenging reactive oxygen species and free radicals to maintain normal physiological activities of the plant.3. The test 3 was studied on the fruit yield, quality and water-gas exchange parameters of tomato. The results showed that the yield of grafted tomato was significantly higher than the ungrafted tomato and the yield of J/T was 17.05%, 5.86% higher than J, J/S. Simultaneously, the vertical diameter, transverse diameter, firmness, content of vitamine C and lycopene of tomato fruit and the content of tomato leave pigments, photosynthetic rate, leaf water potential, transpiration rate and water use efficiency of J/T were also significantly higher than J and J/S. The yield of tomato had significant differences under different soil moisture content which showed that 80%>60%>40%, contrary to the fruit quality indicators such as soluble solid, soluble protein, vitamine C and lycopene. The content of tomato leave pigments, photosynthetic rate, leaf water potential and transpiration rate were decreased as the water stress increased, while the water use efficiency of 60% was higher than 40% and 80%. The experiment demonstrates that the more possible way to realize biological water saving to a certain extent for tomato was grafting with drought-tolerant rootstock of ?606‘.4. With the tomato growth period go on, water stress prolonging, in addition to deputy treatment of soil moisture treatment with 80%, the relative water content of tomato leaves were significantly decreased in different treatments, in the main area of grafting treatment where J/T was higher, J/S followed and J lower. However, the relative conductivity, MDA content, O2-. and H2O2 content of tomato leaves in different treatment were showed that had significantly increasing with prolonged of water stress, and in the grafting treatment were showed that J/T<J/S<J. Before the fruit expand season(5-15) the SOD, POD, CAT activity of tomato leaves in different treatments were showed an increasing trend, while the fruit set season the highest activity, and then it was gradually decreased, and the activity of different grafting treatment were expressed as J/T higher, J/S followed and J lower. With prolonged of water stress time, the Fv/Fm, PSII and qP of tomato leaves in different treatments were decreased, among grafting process which were expressed as J/T higher, J/S followed and J lower. |
PDF Full Text Request