Root morphology mediates yield and fruit quality responses of cherry tomato to a Eu3⁺-VTB450 photoconversion film

Crop yield and quality are influenced by root morphology, but the impact of root morphology on cherry tomatoes under Ethylene–vinyl acetate copolymer (EVA) film mulching (EUV treatment) with Eu3⁺-VTB450 light converter remains unclear. In this study, “Meiying No. 2” cherry tomato was selected as the experimental material, and a one-factor randomized block field experiment with conventional EVA film mulching (CK) and EUV treatment was conducted to investigate the effects of EUV treatment on the yield and quality of the crop. The results showed that EUV treatment induced reconstruction of the light spectral composition, resulting in a 17.0% and 13.5% increase in blue light and red–orange light proportions, respectively (P < 0.05). Compared with CK, EUV treatment improved root development, SPAD values, chlorophyll fluorescence parameters, and gas exchange parameters of cherry tomatoes at each growth stage, with agronomic traits improved to varying degrees. The contents of lycopene, soluble sugar, soluble solids, soluble protein, and vitamin C in fruits increased by 20.4%, 15.9%, 36.6%, 36.5%, and 13.4%, respectively, and the harvest yield increased by 33.1%. Furthermore, partial least squares path modeling revealed that EUV treatment optimized root growth by regulating the light spectral composition, which in turn enhanced plant photosynthesis and growth, ultimately leading to comprehensive improvements in yield and quality. In conclusion, this study systematically investigated the effects of EUV on the growth physiology of cherry tomatoes, while providing novel solutions for light quality regulation in horticultural plants. EUV treatment enhanced the ratio of blue light to red-orange light. EUV treatment optimized root morphological structure. EUV improved photosynthetic characteristics of cherry tomatoes. Root morphology mediated the yield and quality improvement.