1. Effects of application nitrogen on carbon and nitrogen metabolism of summer maize grain under post-silking heat stress.
- Author
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WANG Rui, LI Xiang-Ling, GUO Dong, WANG Xin-Bing, MA Wei, LI Cong-Feng, ZHAO Ming, and ZHOU Bao-Yuan
- Abstract
Post-silking heat stress is one of the main stresses affecting grain filling and yield formation of summer maize in the Huang-Huai-Hai plains. At present, it has been confirmed that increasing nitrogen application can alleviate the inhibition of post-silking heat stress on the yield formation of wheat, maize, and rice, but the regulatory pathways and physiological mechanisms remain unclear. In this study, two maize varieties Zhengdan 958 (ZD958) and Xianyu 335 (XY335) were selected in pot experiment. To study the effects of increased nitrogen application on carbon and nitrogen metabolism of maize under heat stress during post-silking stage, two temperature treatments [ambient temperature (CK) and heat stress (HS)], three nitrogen application levels [low nitrogen application rate (LN): 120 kg hm
-2 , middle nitrogen application rate (MN): 240 kg hm-2 , and high nitrogen application rate (HN): 360 kg hm-2 ] were set. The results showed that the dry weight of ZD958 and XY335 cultivars at maturity stage decreased by 10.6%-19.3% after 20 days of post-silking heat stress (35°C) compared with the ambient temperature. However, the decrease of kernel dry weight under heat stress was gradually decreased with the increase of nitrogen application rate, and the decrease rate (10.6%-11.2%) of kernel dry weight under medium nitrogen application rate (MN) and high nitrogen application rate (HN) was lower than that (16.2%-19.3%) under low nitrogen application rate (LN), which indicating that increased nitrogen application could significantly increase maize kernel dry weight under post-silking heat stress. This was mainly due to the increasing application of nitrogen effectively alleviated the inhibitory effect of early post-silking heat stress on maize grain nitrogen metabolism, and significantly increased the activities of key enzymes of nitrogen metabolism such as glutamine synthetase (GS) and glutamate synthetase (GOGAT). At the same time, the activities of sucrose phosphate synthetase (SPS) and sucrose synthetase (SS), which were key enzymes of carbon metabolism, were maintained, and the synthesis of soluble sugar in grains was increased, thus ensuring a larger amount of material for grain filling. In conclusion, increasing nitrogen application can alleviate the inhibition of post-silking heat stress on grain carbon and nitrogen metabolism and promote the accumulation of assimilates in grain and increase the kernel weight and yield, which provides a way for the resistant cultivation of summer maize in the Huang-Huai-Hai plains. [ABSTRACT FROM AUTHOR]- Published
- 2023
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