Effects of applying uniconazole alone or combined with manganese on the photosynthetic efficiency, antioxidant defense system, and yield in wheat in semiarid regions

Abstract In arid and semiarid regions, wheat productivity depends on natural precipitation, however deficit and unpredictable precipitation leads to reduced production. Uniconazole application can significantly reduce the accumulation of reactive oxygen species (ROS) by enhancing the anti-oxidant enzymes activities and improve the wheat production in semiarid regions. The objective of the current study was to test the hypothesis, whether uniconazole applied alone or in combination with manganese could improve the wheat productivity by enhancing the photosynthetic efficiency and antioxidant defense system. Uniconazole was applied as seed soaking at the concentrations of 0 (CK), 15 (SU1), 30 (SU2), and 45 (SU3) mg L –1 , and in the second experiment with manganese at the concentrations of 0.06 g L –1 (Mn), 0.06 g L –1 manganese + 15 mg L –1 uniconazole (SMU1), 0.06 g L –1 manganese + 30 mg L –1 uniconazole (SMU2), and 0.06 g L –1 manganese + 45 mg L –1 uniconazole (SMU3), respectively. Uniconazole applied alone or in combination with manganese significantly reduced the ROS accumulation by enhancing the anti-oxidant enzymes activities. Treatments SMU2 and SU2 improved significantly the photosynthetic efficiency, soluble protein content, and leaf area plant –1 and thus increased the grain yield. Treatments SMU2 and SU2 significantly enhanced the anti-oxidant enzymes activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX), while reduced the accumulations of MDA, proline, and ROS. The chlorophyll a and b contents, net photosynthetic rate, soluble protein content, and anti-oxidant enzymes activities were significantly negatively correlated with ROS, MDA, and proline contents. Uniconazole application in combination with manganese treatments significantly improved the wheat production. Uniconazole application in combination with manganese at the concentration of 30 mg L –1 and 0.06 g L –1 or uniconazole applied alone at a concentration of 30 mg L –1 significantly enhanced the anti-oxidant defense system and winter wheat production in semiarid regions.