Rootstock Performance of Cherry Tomatoes Grown in Soil Cultivation: Evaluation of Growth, Yield, and Photosynthesis

Grafted seedlings have widely been used in fruit vegetables such as tomatoes in order to increase productivity by acquiring resistance to environmental stress and soil-borne diseases. This study was conducted to assess the performance of rootstocks by comparatively analyzing the growth, yield, and photosynthetic efficiency, by measuring chlorophyll fluorescence, in cherry tomatoes grown in soil cultivation. The cherry tomato variety ‘Nonari’ was used as the scion. The domestic rootstock cultivars ‘Powerguard’, ‘IT173773’, ‘20LM’, and a control cultivar ‘B-blocking’ were grafted with the scion. When using the rootstock cultivar ‘20LM’ grafted with cherry tomato ‘Nonari’, the yield was 15% higher than the yield using the control rootstock cultivar, and the performance index based on the absorption (PI_ABS ), which is an index of plant vitality, was as much as 3.260 higher with ‘20LM’ than with the control rootstock even in the low temperature period. The rootstock ‘20LM’ maintained the plant vigor with balanced growth until the late harvest because its photosynthetic efficiency was high even when exposed to cold stress in the early stage. The growth strength of the non-grafted cherry tomato decreased to 7.3mm at 80 days after planting. The grafted cherry tomatoes had greater cold stress tolerance than the non-grafted cherry tomatoes because they had stronger roots. In contrast, the non-grafted cherry tomato plants were damaged by cold, which inhibited growth and led to a decrease in fruit yield. When ‘Powerguard’ and ‘IT173773’ were grafted with the scion, the yield was low, which might have been due to the low photosynthetic efficiency in the late harvest stage; the chlorophyll fluorescence OJIP transients (OJIP curves) of the plants with ‘Powerguard’ and ‘IT173773’ rootstocks were lower than those of the other grafted plants. There was a significant relationship between plant growth, yield, and chlorophyll fluorescence. Therefore, photosynthetic efficiency can be used to screen the performance of rootstocks.