Low and fluctuating root-zone temperatures constrain tomato productivity during winter greenhouse cultivation, yet the advantages of dynamic regulation over fixed-temperature control remain unclear. In this study, cherry tomato plants were subjected to an unregulated control (CK), three constant root-zone temperatures (15, 20, and 25 °C), and dynamic temperature treatment (DT). The experiment was conducted in a commercial winter greenhouse, where cherry tomato plants were grown in coconut coir and monitored from 70 to 145 days after transplanting, with five plants per treatment; root-zone temperature was regulated by circulating water through pipes embedded in the cultivation troughs. DT maintained root-zone temperature within 14.9–22.2 °C while reducing cumulative pump operating time by 11.45–21.23% relative to the fixed-temperature treatments. DT sustained high root activity during reproductive development, promoted dry-matter allocation to fruits, accelerated fruit expansion, and achieved the highest total and fourth-truss yields. In leaves, DT improved PSII photochemical performance, as indicated by increased PI_ABS and Φ_PSII and reduced DI₀/RC. It also maintained relatively low POD and SOD activities, comparatively high CAT activity during fruit expansion, and lower MDA accumulation, indicating reduced oxidative pressure and membrane lipid peroxidation. Transcriptomic responses were strongly stage-dependent, with the most pronounced changes occurring during fruit setting and expansion. Differentially expressed genes were mainly associated with auxin response, electron transfer, protein-disulfide reduction, cellular redox homeostasis, and phosphorylation-related processes. WGCNA further identified trait-associated modules linked to mitochondrial electron transport and oxidative phosphorylation, including eight candidate genes associated with respiratory complexes I, III, IV, and V. Collectively, dynamic root-zone temperature regulation improved the temporal matching between thermal supply and crop developmental demand, thereby sustaining root activity, optimizing leaf photochemical and redox status, and promoting dry-matter allocation to fruits. Transcriptomic and WGCNA analyses integrally indicate that mitochondrial electron transport and oxidative phosphorylation may participate in the leaf response to dynamic root-zone temperature regulation.

This study investigated the effects of far-red (FR, 740 nm) and ultraviolet-A (UV-A, 370 nm) supplementation on the growth and nutritional quality of pak choi (Brassica rapa ssp. chinensis ‘Xiawang’) under different light intensities. Plants were grown under a white LED background light (6500 K) at two light intensities (100 and 400 μmol·m⁻²·s⁻¹) either without (T100 and T400) or with an additional 40 μmol·m⁻²·s⁻¹ of FR or UV-A radiation (T100FR, T100UV-A, T400FR, and T400UV-A). The results demonstrated a significant interactive effect between light intensity and FR/UV-A supplementation. Under low light intensity (T100), both FR and UV-A significantly enhanced biomass accumulation, the net photosynthetic rate, and the content of soluble proteins, soluble sugars, and cellulose. Under a high light intensity (T400), FR and UV-A primarily promoted morphological development (leaf expansion and thickening), photosynthetic performance, and carbohydrate accumulation. Specifically, FR notably promoted petiole elongation while reducing photosynthetic pigment content, whereas UV-A markedly increased the vitamin C content while decreasing nitrate accumulation. In conclusion, both FR and UV-A supplementation effectively improve the growth and quality of pak choi, but, through light-intensity-dependent mechanisms. FR acts mainly via morphological and photosynthetic optimization, whereas UV-A acts as a physiological and nutritional regulator. These findings highlight the complementary roles of FR and UV-A, providing practical guidance for optimizing spectral strategies in controlled environment agriculture (CEA).