Planting density influence yield, plant morphology, and physiological characteristics of determinate Suzukoma Tomato

Abstract: The effect of planting densities on yield, plant morphology, and physiological characteristics in determinate-type cooking Suzukoma tomato were examined [high density (HD), medium density (MD), and low density (LD), corresponding to 792, 396, and 264 plants a¹¹]. Although the fruit yield per plant under HD was 0.6 and 0.5-fold lower than that under MD and LD, respectively, the yield per area under HD was 1.2- and 1.5-fold higher than that under MD and LD, respectively, because planting density under HD was 1.5- and 3.0-fold higher than under MD and LD, respectively. There were no differences among planting densities of fruit set ratio, fruit weight, marketable fruit ratio, and soluble solids content. Lateral shoot length at the first cotyledonary node and third to fifth true leaf nodes under HD was shorter than one third of those under LD. Hence, the total numbers of flowers and fruits per plant were the lowest under HD. The extent of reduced photosynthetic rates and SPAD values for the third, fifth, and seventh true leaves under HD were not so larger compared to LD, despite being extremely reduced photosynthesis photon flux density (PPFD) at a low position in the plant community. The causes of decreased lateral shoot length at intermediate nodes under HD compared to LD suggested that the concentrations of isopentenyl adenine riboside (iPR) and trans-zeatin riboside (tZR) in stems, and IAA, iPR, tZR, and trans-zeatin (tZ) in lateral shoots under HD were lower than in those under LD. From these results, it was indicated that yield per area under HD was higher than under LD due to the morhological and physiological change of the plants by light conditions in the plant community.