Effects of photo-selective nets and air humidity coupling on tomato resistance to Botrytis cinerea

•Low air humidity inhibited the mycelial growth of B. cinerea, and both red and blue nets could effectively delay the formation time of pathogen infection structure and reduce the disease incidence.•Under high air humidity, the reduction of net photosynthetic rate of infected plants was mainly caused by non-stomatal restriction, while the changes of light quality by red net reduced the damage of pathogen to tomato photosynthetic structure and improved the photosynthetic capacity of tomatoes.•The coupling of low air humidity and red photo-selective net inhibited the infection process of B. cinerea, alleviated the disease severity, improved the photosynthetic capacity, and maintained the fruit quality and yield of tomatoes. Light quality and air humidity play a vital role in plant-pathogen interactions, which profoundly affect the occurrence of crop disease. However, the effect of light quality and air humidity coupling on the interactions between tomato and Botrytis cinerea remains unclear. In this study, 2 humidity levels and 3 colors of photo-selective nets were used to determine the infection process of B. cinerea and the response of plants to pathogen infection. Results showed that low air humidity inhibited the mycelial growth of B. cinerea, and red and blue nets could effectively delay the formation time of pathogen infection structure and reduce the disease incidence. Under high humidity, the reduction of net photosynthetic rate of infected plants was caused by non-stomatal restriction, whereas the changes in light quality by red net reduced the damage of pathogen to tomato photosynthetic structure and improved the photosynthetic capacity of tomatoes. Low air humidity and red net coupling (LR) treatment slowed down the decline of Fv/Fm, ΦPSⅡ and qP; inhibited the increase of malonaldehyde and reactive oxygen contents; increased the activities of antioxidant enzymes in tomato plants; and promoted the quality and yield of fruits. The LR treatment inhibited the infection process of B. cinerea, alleviated the disease severity, improved the photosynthetic and antioxidant capacities, and maintained the fruit quality and yield of tomatoes.