氮素缓解春小麦花后高温早衰的抗氧化特性研究

为研究花后高温胁迫下氮肥对春小麦抗氧化特性的响应机制,阐明氮素缓解高温危害的生理机理及运筹机制,2019年采用裂区设计,主区为0 (N0)、75 (N1)、150 (N2)、225 (N3)和300 (N4) kg·hm-25个施氮量处理,副区为(25±2)℃(CK)和(35±2)℃(HT)2个温度处理,研究不同温度处...

Antioxidative Characteristics Study of Nitrogen in Alleviating Premature Senescence of Spring Wheat at High Temperature after Anthesis

In order to study the response mechanism of nitrogen fertilizer to the antioxidant properties of spring wheat under high temperature stress after anthesis and clarify the physiological mechanism and operational mechanism of nitrogen to alleviate the harm of high temperature, in 2019, the split plot design was adopted with five nitrogen applications including 0 (N0), 75 (N1), 150 (N2), 225 (N3) and 300 (N4)kg·hm^-2 (primary zone) and two temperatures including (25±2)℃(CK) and (35±2)℃(HT) (secondary zone). Carotenoid content, superoxide dismutase (SOD) activity, peroxidase dismutase (POD) activity, catalase dismutase (CAT) activity, malondialdehyde (MDA) content, proline (Pro) content, superoxide anion radical (O^-₂·) content in flag leaf of spring wheat and their relationship with yield were analyzed. The results showed that the application of nitrogen fertilizer could significantly increase the contents of carotenoid, Pro and nitrogen in flag leaf, and improve the activities of SOD, POD, CAT and other enzymes, with the best effect of N3 treatment. Compared with CK, the content of carotenoids and the activities of SOD, POD and CAT in flag leaves decreased after high temperature stress, and the degree of decrease was the smallest under N3. In addition, the contents of MDA and O^-₂· in flag leaf increased significantly after high-temperature stress compared with CK, with the largest increase under the N0 treatment and the smallest increase under the N3 treatment. With the increase of nitrogen application, the 1 000-grain weight and yield of spring wheat showed a trend of increasing first and then decreasing. The yield of N3 treatment was the highest, 8.64 (CK) and 8.09 (HT) t·hm^-2, respectively. Compared with CK, the yields after high-temperature stress was decreased significantly, with a decrease from 7.81% to 33.71%. In conclusion, the carotenoid content and activities of SOD, POD and CAT in flag leaf under high-temperature stress significantly decreased, and the MDA and O-2· contents increased significantly, which led to an increase in the degree of membrane lipid peroxidation and premature aging. A suitable amount of nitrogen application (225 kg·hm^-2) could effectively resist high temperature stress and alleviate premature aging by maintaining high activities (SOD, POD and CAT) and contents of Pro and carotenoid, and reducing the contents of MDA and O^-₂·, which could provide theoretical basis and technical support for high and stable yield of spring wheat.