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The tomato variety 'Micro Tom' is used as an experimental material in a fully artificial light-type plant factory. An LED light with adjustable illumination modes was used as the light source and a pure white LED light was used as the control. Different illumination mode, such as pure red light, pure blue light, mixed red and blue light, and alternating red and blue light were used as supplementary light. The influence of different red and blue supplemental lighting modes on the growth, development, and fluorescence characteristics of greenhouse tomatoes was explored. The results showed that: (1) in all treatments, the growth indicators and fruit weight of the tomato plants increased to a certain extent. The dynamic change of chlorophyll fluorescence was significantly affected by supplementary light. Pure red light supplementation had the greatest effect on the increase in plant height, stem thickness, leaf area, and yield of the tomato plants. Alternating red and blue light supplementation at intervals of 1h or 6h significantly promoted the increase in chlorophyll content and the improvement of PSII photosynthetic performance. (2) During the vegetative growth stage of tomatoes, under pure red light supplementation, the relative growth rate and absolute growth rate of plant height increased by 106.8% and 60% respectively compared to the control. The relative growth rate and absolute growth rate of stem thickness increased by 50% and 80% respectively. 44 days after sowing, the leaf area of the tomato plants under pure red light supplementation increased by 92.1% compared to the control.(3) During the reproductive growth period of tomatoes, compared with the control, 83 days after sowing, the number of fruits set under pure red light supplementation increased by 73.6%. The horizontal and vertical diameters and volume of tomato fruit increased by 34.4%, 35.3%, and 129.6% respectively.(4) Compared with the control, 44 days after sowing, the chlorophyll content in tomato leaves under alternating red and blue light supplementation at intervals of 1h or 6h increased by 30.3% and 31.8% respectively. 83 days after sowing, the performance index (PIABS) of tomato plants after alternating red and blue light supplementation at intervals of 1h or 6h increased by 100% and 30% respectively compared to the control. The electron transfer efficiency (ETo/CS) of PSII after alternating red and blue light supplementation at intervals of 1h or 6h increased by 16% and 23% respectively compared to the control. In summary, pure red light supplementation can effectively promote the growth and development of facility tomatoes. Alternating red and blue light supplementation at intervals of 1h or 6h significantly affects the fluorescence characteristics of tomatoes. In the future, the most suitable supplementary lighting mode can be chosen based on different production objectives. [ABSTRACT FROM AUTHOR]

Harvest 74-560 RZ F1" tomato was cultivated in a plant factory with LEDs. One of the four reproductive stages (flowering stage, expanding stage, color turning stage and harvesting stage) was subjected to low light intensity of 160μmol·m-2·s-1, while the other three stages maintained 1000 μmol·m-2·s-1. The light intensity kept 1000μmol·m-2·s-1 at all the reproductive stages in the control. The growth and fruit quality indices were measured to evaluate the effects of low light on tomato. The results showed that: (1) low light significantly affected the morphology of tomato plants at the flowering stage and expanding stage. Low light at flowering stage resulted in the most prominent overgrowth trend of tomato plants, as well as the least average number of leaves and nodes per plant which respectively decreased by 3.5 and 1.6 compared with the control. Low light at the expansion stage significantly reduced the content of carotenoid and the value of Chla/b compared with the control. The number of fruit set per plant after low light treatment at flowering stage was 53% lower than that of the control, while the number of fruit set per plant was not significantly affected by low light at other reproductive stages. The average yield of the first, second and third ear per plant after low light treatment at flowering or expansion stage was significantly lower than the other treatments. (2) Compared with the control, low light treatments decreased the soluble solid content of tomato fruit (first ear) in varying degrees, among which, the soluble solid content decreased by 25% after low light treatment at flowering stage. The soluble sugar content of tomato fruit decreased by 15% compared with the control, on the contrary, the total acid content increased by 26%, resulting in the lowest sugar/acid ratio of tomato fruit under this treatment. Compared with the control, low light treatments decreased the vitamin C content of tomato fruit in varying degrees, among which, the lowest vitamin C content was detected in tomato fruit subjected to low light treatment at the harvesting stage. This study showed that low light reduced the yield and quality of tomato, and the sensitivity of tomato to low light was different at varied reproductive stages. According to the growth characteristics and responses of tomato subjected to low light at different periods, it is of certain significance to supplement artificial light in order to stabilize the quality and yield of protected tomato. [ABSTRACT FROM AUTHOR]