Evaluation of Grafted Tomatoes with Different Levels of Resistance of Rootstocks to TYLCV by Analyzing the Growth Characteristics, Leaf-macronutrient Content, and Chlorophyll Fluorescence

The grafting technique has widely been used with fruits and vegetables in an effort to increase productivity for long-term cultivation. For long-term cultivation, the result is increased vigor provided by the rootstock, which allows the scion to grow longer, even in the presence of a virus. This study was conducted to evaluate the performance of rootstocks having different TYLCV-resistance levels by comparatively analyzing the growth, yield, nutrient concentration in the petiole sap, and chlorophyll fluorescence in tomatoes grown via a hydroponics system. The domestic cultivars ‘HSF4’ and ‘BWM’ were used as the TYLCV-susceptible rootstocks, and ‘21LM’ and ‘21A701’ were used as the TYLCV-resistant rootstocks. The tomato variety ‘Red250’ was used as the TYLCV-resistant scion and the non-grafted control plants. The tomato plants were infected overall with TYLCV at ten weeks after transplanting. Grafted tomatoes on the TYLCV-resistant rootstocks ‘21A701’ and ‘21LM’ were vigorous, and the yields were 7,999g and 7,754g respectively, correspondingly higher by 25% and 22% than those using the TYLCV-susceptible rootstock ‘BWM’. Moreover, the growth strength of ‘21A701’ was highest compared to the others. The NO₃-N concentration of ‘21A701’ was highest at 1,211mg·L^-1, and that of ‘BWM’ was lowest at 835mg·L^-1 at 36 weeks after transplanting. The K⁺ concentration of ‘21A701’ was highest at 4,050mg·L^-1, and the non-grafted case was lowest at 3,350mg·L^-1. The maximum quantum yield of the primary PSⅡ photochemistry (F_V/F_M) and the performance index based on the absorption (PI_ABS) of ‘21LM’ were highest at 0.803 and 2.990, respectively. The non-grafted samples were lowest at 0.739 and 1.422, respectively. The grafted plants on the TYLCV-resistant rootstocks had high vigor of the root system and greater mineral and water uptake levels, leading to an increased yield, likely due to the high concentrations of nutrients reaching the leaves and the high photosynthetic efficiency. The use of TYLCV-resistant rootstocks was required to improve the yields up to the late harvest stage. We concluded that tomato grafting onto TYLCV-resistant rootstocks can increase the uptake of mineral nutrition and the photosynthetic efficiency, thereby affecting plant growth and the fruit yield.