This article examines the effect of LED lights between the plants compared to LED lights from above on the growth and quality of tomatoes in greenhouses with low natural light. The main goal of this research is to improve the quality and performance of tomatoes in unfavorable light conditions. This study becomes more important especially in regions with cloudy weather conditions and low light, such as high latitudes, because these regions face a lack of light in the autumn and winter seasons, which significantly reduces tomato production and color sensitivity. 

Source of the article on Nature

The research method was such that the research was conducted in a greenhouse located in the north of Iran and the Dutch variety of tomato "Sakhiya RZ F1" was used. Three types of lighting, including light from above, light between plants, and a combination of both methods were used to compare the different effects of lighting on yield, growth, and nutritional quality of tomatoes under limited light conditions. Various parameters such as the number and weight of fruits, the content of vitamin C and lycopene, as well as the expression of genes responsible for the production of these compounds were investigated. 

Performance findings showed that interplant lighting increased tomato yield by an average of 28.46%, which was significantly greater than the 12.12% increase from overhead lighting. The combination of lighting from above and between the plants also provided the best result in improving the overall yield of the crop (38%) and led to the maximum increase in the total weight of the fruits in the greenhouse. == In the impact on nutrients, inter-plant lighting caused a significant increase in lycopene and vitamin C content of tomatoes; This method resulted in a 31.3% increase in lycopene content and a 123.4% increase in vitamin C content. The combination of overhead and interplant lighting showed the greatest effect in improving vitamin C content, while interplant lighting alone had the best results in increasing lycopene. These results indicate that the position of light in the plant can have a significant effect on the nutritional composition of tomato. 

Genetic analysis also showed that interplant lighting increased the expression of key genes related to lycopene, phytoene, and vitamin C metabolism, such as Psy1, LCY-β, and VTC2 genes; This increase in gene expression was correlated with the increase in tomato production and indicates the positive effect of interplant lighting on plant metabolic processes. In fact, interplant lighting not only helped to grow more fruits, but also improved the nutritional and antioxidant properties of tomatoes.

Compared to other studies, the findings suggest that interplant lighting has more advantages than other lighting methods, including overhead lighting; Especially in situations where the shading of the upper leaves prevents the effective photosynthesis of the lower leaves. These results are in high agreement with previous studies that have shown that inter-plant lighting can help improve the performance of plants in low light conditions and lead to an increase in photosynthesis and maintaining the nutritional quality of the product.

Advantages and challenges are also worth mentioning; Interplant lighting helps to better distribute light throughout the plant and improve photosynthesis, and can maintain the photosynthetic and hormonal efficiency of the lower leaves and prevent their premature deterioration. However, there are also challenges such as the need to adjust the position of the lights during plant growth. Nevertheless, the results show that this method can significantly improve the performance and quality of greenhouse products.

In conclusion, this research showed that the use of LED light between plants can effectively improve the yield and quality of tomatoes in low light conditions. This method is especially effective in industrial greenhouses and in areas with cloudy weather and can help increase production and improve the nutritional quality of products. Interplant lighting is suggested as a sustainable strategy to improve greenhouse production due to the uniform distribution of light throughout the plant. This research shows the importance of using LED light in improving the quality and performance of greenhouse products, especially in low light conditions, and it can be used as an effective solution to deal with the challenges of insufficient light in agricultural production.