Different Rootstocks Of Tomato Grafted Seedlings Resistant To Cold Physiological Mechanism

Grafting plays important role in tomato cultivation. Recent years, researches were mainly focused on selection of rootstocks, grafting methods and anti-disease ability of grafted tomato plants, but the mechanisms of grafting of fruit qualities and seedling chilling tolerance of tomato is still unclear. In our country, the listing of the off-season tomatoes are mostly cultivated under the low temperature condition and that leads to unstable production, higher price and poor quality. In other words, the low temperature condition is the main limited factors on cultivating tomatoes in winter and spring. Selection of rootstock is very important to the study of tomato grafting. Tomatoes and eggplants both belong to Solanaceae. Therefore, using eggplants as rootstock would realize full benefit of the rootstock and scion. That improves the tomato plants’ anti-disease ability, extend the fruit-bearing stage and increase the production. Therefore, the grafted tomato plants mainly include eggplant rootstock and tomato rootstock in the current production. Through previous studies, we know that the section of rootstock has an influence on the fruit quality. Usually, we choose the varieties with good resistance and low fruit quality as rootstock. However, the vegetable growers usually do not accept the expensive and insufficient rootstocks. In order to overcome the grafted tomato plants’restriction of fruit quality and production cost, the experiment used the common varieties of tomatoes (Yuhong No.6. Hezuo903) as scion and selected locally produced eggplants (Xia Weiy、the king of Jin Longfen) and the eggplants produced in the Northeast (Shenqie No.1. Yuqie No.11) with resistance to low temperature as rootstocks to graft respectively. In this paper, the physiological mechanisms of fruit qualities and seedling chilling tolerance in tomato influenced by Grafting will be investigated by the physiological and biochemical changes of grafted tomato seedling under chilling stress. The results of this study were as follows:1. Under low temperature stress, the chilling to tolerance of grafted tomato seedlings was higher than own-rooted tomato seedling. Compared with own-rooted tomato seedling, the grafted tomato seedlings had lower chilling injury index, electrolytic leakage (%) and MDA contents in leaves and higher chlorophyll and proline content and the activities of superoxide dismutase (SOD), ascorbate peroxidase (AsA-POD) in leaves under low temperature stress. In addition, the grafted seedlings with higher chilling tolerance had lower electrolytic leakage (%), MDA contents, higher proline content and higher activities of SOD, AsA-POD in leaves than those of grafted seedlings with lower chilling tolerance.2. Under low temperature stress, the chilling to tolerance of grafted tomato seedling was higher than own-rooted tomato seedling. The chilling resistance of grafted tomato seedling is not only related to the rootstock but to the scion. The experimental investigation shows that the grafted tomato seedling that using Xiaweiyi and Jinlongfenwang as rootstock have better chilling resistance, and obviously, the own-rooted tomato seedling is the worst one. And the chilling resistance of grafted tomato seedling that using Yuhong No.6as scion was better than that using Hezuo903. In addition, the decreases on the contents of chlorophyll, the activities of SOD and POD, and the increase on MDA contents in the leaves of both own-rooted and grafted tomato seedlings indicated an injury on the protective system against active oxygen and induced lipid peroxidation under low temperature stress. However, the activity of protective system against active oxygen in grafted tomato seedlings was higher than own-rooted tomato seedling. The activity of protective system against active oxygen in tomato seedling grafted on Yuhong No.6with higher chilling tolerance was higher than tomato seedling grafted on Hezuo903with lower chilling tolerance. This study suggested that the enhancement of chilling tolerance in grafted watermelon seedlings was related to the increase of antioxidants and antioxidative enzyme activities.3. Through experimentation of effects of different rootstocks grafting on quality of tomato fruit, the results showed that selecting Xiaweiyi as grafted tomato seedlings has the best chilling tolerance. Compared with two kinds of own-root seedlings, using Xiaweiyi and Jinlongfenwang as grafted tomato seedlings has better chilling tolerance. And if the rootstocks are same, the experimentation also proves that using Yuhong No.6as scion has a better chilling tolerance than using Hezuo903as scion.