Response of waxy maize (Zea mays L. var. ceratina Kulesh) leaf photosynthesis to low temperature during the grain-filling stage

Low temperature (LT) during the grain-filling stage is an important factor that affects the source-sink relationship and leads to yield loss in maize (Zea mays L). In this study, field and pot trials were conducted to investigate the effects of LT during the grain-filling stage on leaf photosynthesis, antioxidant system, hormones, and grain yield of waxy maize cultivars Suyunuo 5 (S5) and Yunuo 7 (Y7). The results showed that LT treatment inhibited the chlorophyll biosynthesis and reduced the photosynthetic pigment levels during grain-filling stage. Ribulose-1,5-bisphosphate carboxylase and phosphoenolpyruvate carboxylase activities, photosynthetic rate, transpiration rate, and stomatal conductance decreased under LT treatment during the grain-filling stage. Furthermore, LT treatment increased the contents of malondialdehyde and reactive oxygen species, and decreased the activities of catalase, superoxide dismutase, peroxidase, and ascorbate peroxidase in the ear leaves, which accelerated the oxidative damage of leaf. The LT treatment also raised abscisic acid content and reduced indole acetic acid content in the ear leaves during grain-filling stage. The results of field and pot trials were verified by each other, but the field effect was greater than that of pot. Overall, LT treatment reduced the waxy maize dry matter accumulation after silking by affecting the physiological and biochemical processes of leaves, and ultimately decreased grain yield.