Abstract
The asymmetric warming in diurnal and seasonal temperature patterns plays an important role in crop distribution and productivity. Asymmetric warming during the early growth periods of winter wheat profoundly affects its vegetative growth and post-anthesis grain productivity. Field experiments were conducted on winter wheat to explore the impact of night warming treatment in winter (Winter warming treatment, WT) or spring (Spring warming treatment, ST) on the senescence of flag leaves and yield of wheat plants later treated with night warming during grain filling (Warming treatment during grain filling, FT). The results showed that FT decreased wheat yield by reducing the number of grains per panicle and per 1,000-grain weight and that the yield of wheat plants treated with FT declined to a greater extent than that of wheat plants treated with WT + FT or ST + FT. The net photosynthetic rate, chlorophyll content, and chlorophyll fluorescence parameters of the flag leaves of wheat plants treated with WT + FT or ST + FT were higher than those under the control treatment from 0 to 7 days after anthesis (DAA) but were lower than those under the control treatment and higher than those of wheat plants treated with FT alone from 14 to 28 DAA. The soluble protein and Rubisco contents in the flag leaves of wheat plants treated with WT + FT or ST + FT were high in the early grain-filling period and then gradually decreased to below those of the control treatment. These contents were greater in wheat plants treated with WT + FT than in wheat plants treated with ST + FT from 0 to 14 DAA, whereas the opposite was true from 21 to 28 DAA. Furthermore, WT + FT and ST + FT inhibited membrane lipid peroxidation by increasing superoxide dismutase and peroxidase activities and lowering phospholipase D (PLD), phosphatidic acid (PA), lipoxygenase (LOX), and free fatty acid levels in the early grain-filling period, but their inhibitory effects on membrane lipid peroxidation gradually weakened during the late grain-filling period. Night-warming priming alleviated the adverse effect of post-anthesis warming on yield by delaying the post-anthesis senescence of flag leaves.
Highlights
In the twentieth century, the annual mean temperature in China increased from 0.4 to 0.8◦C, and the mean temperature increases in spring, summer, fall, and winter were 0.33, 0.40, 0.73, and 1.37◦C, respectively
The WT and ST priming treatments reduced the inhibitory effect of FT on grain yield
Liu et al (2016) reported that post-anthesis heat stress and its combination with drought significantly decreased Photosynthetic Rate (Pn), and the primed plants showed a significantly higher Pn than the nonprimed plants under post-anthesis drought and heat stress, suggesting that drought priming enhanced the capacity of the plants to protect photosynthetic activity from exposure to a later stress event. These findings suggest that warming and stresses in an early stage can induce the partial memory of stress-response signals in plants through self-regulation, thereby improving their stress tolerance
Summary
The annual mean temperature in China increased from 0.4 to 0.8◦C, and the mean temperature increases in spring, summer, fall, and winter were 0.33, 0.40, 0.73, and 1.37◦C, respectively. China experienced 17 consecutive warm winters beginning in 1990, and the mean temperature increase in winter was more than two times the average annual increase in global temperature (0.6◦C) (Qin et al, 2010; Gao et al, 2011; Hatfield et al, 2011). High temperature in the post-anthesis period often accelerates wheat maturation and, severely reduces wheat yield and quality (Riaz et al, 2021). Shirdelmoghanloo et al (2016) found that warming in the early post-anthesis period significantly reduces photosynthesis and the antioxidant capacity of flag leaves in wheat, resulting in smaller grain size and weight but barely affecting grain yield. An ambient temperature higher than 25◦C shortens the grainfilling period, affecting grain weight, while an ambient temperature lower than 12◦C causes chilling injuries in wheat
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