Effect of Irrigation Levels and Grafting on Growth and Photosynthetic Activities of Greenhouse "Dafnis" Tomato

In this study, the possibility of growing greenhouse tomato cv. Dafnis with saving water consumption through grafting on different rootstocks was investigated by studying photosynthesis and plant growth. The experiment was carried out in the form of split plots based on completely randomized design in which the main-plot was irrigation levels (irrigation intervals of 3, 6 and 9 days) and the sub-plot consisted of 9 different grafting combinations. After grafting and establishment of tomato plants in greenhouse, the plants were exposed to the irrigation levels for 4 months and all were irrigated up to field capacity. Photosynthesis parameters were measured in four stages and shoot and root dry weights were determined at the end of the experiment. Based on the results, photosynthetic parameters were reduced by the intensity and duration of drought stress. The experimental results showed that the rate of photosynthesis was the same in all grafting combinations 36 days after the start of irrigation levels. However, after 72 days, the rate of photosynthesis in the “Emperador” rootstock was higher than in the control. The chlorophyll fluorescence indices were not sensitive to show the effects of drought stress and the role of rootstocks. Cherry tomato rootstock, in addition to having an extensive root system than the other rootstocks, resulted in more shoot growth at all levels of irrigation, although the least reduction in root weight was observed in the local eggplant rootstock of Yazd. In general, it can be concluded that the photosynthesis in this experiment was more affected by the interaction of environmental factors and grafting and the rootstocks used did not play a significant role in this regard. Furthermore, root and shoot growth traits were more affected by genetic potential of rootstock, and photosynthetic activities of the plant had a minor influence on them.