Fruit quality and carotenoids in fruits of cherry tomato (Solanum lycopersicum) grown under plant factory

Abstract

According to global warming has affected yield and quality of cultivated plants under open-field, especially tomatoes which are susceptible to environmental stresses. Recently, plant factory has been developed to solve the problem concerning poor plant growing environment. However, information about appropriate growing condition management for cherry tomato under plant factory is limited. Thus, this study was to investigate the effect of plant factory environment on fruit quality and carotenoids in fruit of cherry tomato (Solanum lycopersicum) compared to open field and greenhouse conditions. Three cherry tomato varieties, i.e., G1, G2 and Nil Manee (G3) were grown in four growing environments: open-field (E1), greenhouse with 50% shading (E2). Under plant factory system (relative humidity 70 %, 25±2 °C, 12-h photoperiod), three cherry tomato were subjected to different LED wavelengths, i.e., LED ratios red: blue: white (1:1:0.5) (E3) with photosynthetic photon flux densities (PPFD) 323 µmol/m²/s (E3) and red: blue (1:1) with PPFD 229 µmol/m²/s (E4). A complete randomized design with three replications was used in each environment. Fruit quality and carotenoid contents were measured. Combined analysis of variance was performed and the Least Significant Difference (LSD)was used to compare mean differences. The result found that G1 and G3 plants grown under E1 and E2 conditions had higher fruit weight and larger size than those plants grown under E3 and E4. In general, cherry tomato fruit under plant factory produced higher titratable acid than that under E1 and E2 conditions. Moreover, the different growing environments had affected lycopene and beta-carotene contents in cherry tomato fruits. G2 and G3 varieties which contained lycopene and ß-carotene contents more than G1 variety produced the highest both phytochemical under E3, but G1 fruits was not affected by those environments. This study reveals that plant factory growing environment could increase titratable acid lycopene and ß-carotene contents in some, but not all, cherry tomato varieties.