Effects of Difference Between Day and Night Temperature (DIF) During the Nursery Stage on Morphogenesis, Post-transplant Growth, and Early Yield of Tomato

This study investigated the effects of differential day-night temperature (DIF) regimes during the tomato seedling stage on seedling quality, post-transplant vegetative and reproductive development after transplanting, and early yield performance.Tomato seedlings were grown under four DIF treatments (+5, 0, -5, and -8°C), with growth responses varying substantially across the developmental stages.During early seedling growth, the +5°C DIF treatment promoted rapid leaf expansion and stem elongation.However, +5°C DIF treatment did not show consistently superior growth post-transplant.In contrast, the -5°C DIF treatment resulted in greater leaf area, fresh and dry biomass accumulation, and enhanced stem thickening and root development at the later phase of seedling.These responses indicate that -5°C DIF effectively suppressed excessive elongation while improving the balance between shoot and root growth, resulting in structurally robust seedlings.Carry-over effects of DIF treatments were evident after transplanting.Plants previously grown under -5 and -8°C DIF exhibited markedly accelerated harvest initiation, with >50% of plants producing marketable fruit by 7 weeks after transplanting, whereas no harvestable fruit was observed in the 0 and +5°C DIF treatments at this stage.Among all treatments, -5°C DIF resulted in the highest cumulative early yield.Therefore, the -5°C DIF regime was identified as the most effective environmental management strategy for producing compact, physiologically vigorous tomato seedlings that enhance post-transplant establishment, accelerate fruit harvest, and maximize early-season yield.Although -8°C DIF increased floral initiation, fruit-set efficiency was lower than that of the -5°C treatment.This response is attributed to competition for assimilates among developing sinks and increased variability in harvest progression among individual plants.This finding highlights the practical value of moderate negative DIF as a reliable technique for improving transplant quality and stabilizing early productivity in controlled-environment tomato production systems.