Influence of short-term irradiation during pre- and post-grafting period on the graft-take ratio and quality of tomato seedlings

Abstract

The objective of this study was to evaluate influence of short-term irradiation during pre- and post-grafting period on the graft-take ratio and quality of tomato seedlings. Irradiation by six light qualities, darkness, white fluorescent lamps (WFL), red LED, far-red LED, blue LED, and natural light, were used to treat seedlings for 10 days before grafting. And Irradiation by five light qualities, darkness, WFL, red LED, far-red LED, and blue LED, were used to treat seedlings for 10 days after grafting, during healing and acclimatization periods. When short-term irradiation was applied before grafting, the graft-take ratios (27.8–66.7%) were considerably low in all light treatments as compared with natural light (96.7%). The graft-take ratio of red LED was not statically different with WFL treatment, but higher than far-red and blue LED treatments. The lowest graft-take ratio (27.8%) was observed in darkness treatment. Changing light intensity before grafting was the cause of reduced graft-take ratios in this study. There was no significant difference among natural light, WFL, and red LED treatments in growth parameters, except for leaf chlorophyll level, leaf width, and fresh weight of root, but decreased in seedlings treated with far-red LED, blue LED, and darkness. Graft-take ratios (68.5–100.0%) were enhanced when short-term irradiation was applied after grafting. The maximum (100%) graft-take ratio was recorded in red LED treatment, but was not statistically different with the WFL treatment. The lowest graft-take ratio was also observed in the darkness treatment. Plant growth responses to red LED were also similar with those to WFL after grafting. However, when short-term irradiation was applied after grafting, the lowest values of plant growth were observed in far-red LED treatment. The plant growth parameters were similar in seedlings treated with darkness and blue LED, but lower than red LED and WFL treatments. The root morphology was improved in seedlings treated with red LED after grafting by increasing total root surface, total root length, and number of toot tips. Seedling quality increased at 35 days after transplanting in the red LED treatment by increased plant growth parameters, especially compactness and root morphology, as compared with other treatments.