氮素缓解春小麦花后高温早衰的荧光特性研究

[目的]为了研究高温条件下氮素对春小麦荧光特性影响机制,阐明氮素调控光反应中心的内在机理,从而制定缓解高温危害的氮肥运筹措施.[方法]于2019年和2020年开展田间试验,采用裂区试验设计,主区为5个施氮量,依次为0(N0)、75 kg·hm-2(N1)、150 kg·hm-2(N2)、225 kg·hm-2(N3)、...

Fluorescence Characteristics Study of Nitrogen in Alleviating Premature Senescence of Spring Wheat at High Temperature After Anthesis

【Objective】 The aim of this study was to investigate the influence mechanism of nitrogen on the fluorescence characteristics of spring wheat under high temperature, and to clarify the internal mechanism of nitrogen regulation of light reaction center, so as to formulate the nitrogen fertilizer operation measures to alleviate the harm of high temperature.【Method】 The experiment was carried out in 2019 and 2020, using the split-plot trial design. The main zones were 5 nitrogen application, including 0 (N0), 75 kg·hm^-2(N1), 150 kg·hm^-2(N2), 225 kg·hm^-2 (N3), and 300 kg·hm^-2(N4), and the sub-zones were temperatures of 25℃±2℃ (CK) and 35℃±2℃(HT). The interrelationships between nitrogen application and leaf nitrogen content, chlorophyll, PSⅡreaction center activity parameters, PSⅡJ phase variable fluorescence (V_J), PSⅡenergy allocation rate, PI, F_v/F₀, and F_v/F_m at high post-flower temperatures were analyzed. 【Result】 The results showed that the effects of nitrogen application and temperature on leaf nitrogen, chlorophyll a, chlorophyll b, ABS/RC, DI₀/RC, V_J, φE₀ and φD₀ and yield were significant. With the increase of nitrogen application, the yield increased first and then decreased, and reached at the highest yield under N3 with normal and high temperature treatments, which was 9.03 t·hm^-2(CK) and 8.37 t·hm^-2(HT). The difference between high temperature and normal temperature was obvious under different temperature treatment with the same nitrogen application, and the chlorophyll a, ABS/RC, ET₀/RC, TR₀/RC, PI, F_v/F₀, F_v/F_m and yield decreased after high temperature treatment, which indicated that the effects of high temperature on fluorescence parameters and PSⅡactivity had negative effect. Under the treatments of different nitrogen application at the same temperature, the chlorophyll content and ABS/RC, ET₀/RC, PI, F_v/F₀, F_v/F_m of spring wheat increased first and then decreased, while the DI₀/RC and V_J decreased first and then increased, and reached the peak at N3(225 kg·hm^-2), indicating that the effects of nitrogen application on chlorophyll fluorescence parameters and PSⅡactivity had compensatory effect, and the appropriate nitrogen application amount could effectively enhance its activity. The effects of temperature on ABS/RC, TR₀/RC, ET₀/RC, F_v/F₀ and F_v/F_m was not significant, but the interaction between nitrogen application and temperature reached significant level (P<0.05) and extremely significant level (P<0.01). 【Conclusion】 To sum up, the effects of nitrogen application and temperature on the fluorescence characteristics and yield of spring wheat was interactive, in which the dominant factor was temperature, while the amount of nitrogen application had a compensatory effect on it. A reasonable amount of nitrogen application could effectively increase the nitrogen content, chlorophyll content and PSⅡreaction center activity of wheat flag leaves, increase the capture, absorption, transformation and maximum photochemical efficiency of light energy by plants, and reduce the energy dissipation rate, so as to resist the damage caused by high temperature stress to the photosynthetic system of spring wheat. According to this test condition, the nitrogen application amount of N3 could effectively resist high temperature stress and increase the yield of spring wheat. The yield of high spring wheat could provide theoretical basis and technical support for high and stable yield of local spring wheat.