Preharvest illumination of cherry tomato reduces ripening period, enhances fruit carotenoid concentration and overall fruit quality

The prevention of certain chronic diseases has been related to tomato (Solanum lycopersicum L.) consumption. The demand for high-quality tomatoes has, therefore, increased rapidly. As a climacteric fruit, tomato will only ripen to full colour postharvest. Trusses of mature-green greenhouse tomatoes of a red (‘Cherry Little Wonder’) and a yellow cultivar (‘Goldilocks’) were illuminated, preharvest, with either red (RL) (peak at 634 nm, 120 ± 20 µmol m–2 s–1) or blue (BL) LED lights (peak at 450 nm, 120 ± 20 µmol m–2 s–1) for 8 h per day for seven consecutive days. These on-plant RL and BL treatments significantly affected fruit colour and pigment concentration. Both light treatments enhanced the accumulation of lycopene, thereby significantly enhancing the nutritive value of the fruit. Similarly to lycopene, the β-carotene concentrations also increased following RL and BL exposure, again more so in the red than the yellow cultivar. Both light treatments also enhanced the speed of colour change by 5 days for the red and by 10 days for the yellow cultivar, resulting in either the desired red or the yellow colour. Our findings could be employed to improve quality and shorten the ripening period of tomato, while mechanisms involved in the biosynthesis and accumulation of these carotenoids require further investigation.部分慢性病的预防与番茄（Solanum lycopersicum L.）的食用密切相关。因此，市场对高品质番茄的需求快速增长。番茄作为跃变型果实，仅能在采后完成全色成熟过程。本实验选取温室栽培的绿熟期番茄果穗，涉及红色品种‘Cherry Little Wonder’与黄色品种‘Goldilocks’，于采前每日采用红光（RL，峰值波长634 nm，光强120 ± 20 µmol·m⁻²·s⁻¹）或蓝光（BL，峰值波长450 nm，光强120 ± 20 µmol·m⁻²·s⁻¹）LED光源连续照射8小时，共持续7天。上述植株原位的红光与蓝光处理，显著影响了番茄果实的色泽与色素含量。两种光照处理均促进了番茄红素（lycopene）的积累，进而显著提升了果实的营养价值。与番茄红素类似，经红光与蓝光照射后，β-胡萝卜素（β-carotene）的含量也有所提升，且红色品种的提升幅度仍高于黄色品种。两种光照处理还分别将红色品种与黄色品种的转色进程提前了5天与10天，使果实最终达到预期的红色或黄色成熟色泽。本研究结果可用于优化番茄品质、缩短成熟周期，但相关类胡萝卜素的生物合成与积累机制仍有待进一步探究。