氮素缓解春小麦花后高温早衰的荧光特性研究

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

【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)、300 kg·hm^(-2)(N4),副区为温度,分别为25℃±2℃(CK)和35℃±2℃(HT)。分析花后不同温度处理下施氮量与叶片含氮量、叶绿素、光系统Ⅱ(PSⅡ)反应中心活性参数、PSⅡJ相可变荧光(V_(J))、PSⅡ能量分配率、PI、F_(v)/F_(0)和F_(v)/F_(m)之间的相互关系。【结果】施氮量与温度对叶片含氮量、叶绿素a、叶绿素b、ABS/RC、DI_(0)/RC、V_(J)、φE_(0)、φD_(0)和产量的影响显著。2年结果表明,随着施氮量的增加,产量均呈先增后降的趋势,且在施氮量为N3(225 kg·hm^(-2))时产量最高,2年平均产量分别为9.51t·hm^(-2)(CK)和8.73 t·hm^(-2)(HT)。同一氮肥处理下,高温与常温间各指标差异明显,高温处理后叶绿素a、ABS/RC、ET_(0)/RC、TR_(0)/RC、PI、F_(v)/F_(0)、F_(v)/F_(m)和产量均有所降低,说明高温对荧光参数和PSⅡ活性的影响具有负效应。同一温度处理下,随着施氮量增加,春小麦叶绿素含量、ABS/RC、ET_(0)/RC、PI、F_(v)/F_(0)和F_(v)/F_(m)等均呈先增后降趋势,DI0/RC和V_(J)呈先降后增趋势,且在N3时达到峰值,说明施氮量对叶绿素荧光参数和PSⅡ活性的影响具有补偿效应,适宜的施氮量可以有效增强其活性。温度对ABS/RC、TR_(0)/RC、ET_(0)/RC、F_(v)/F_(0)和F_(v)/F_(m)的影响不显著,而施氮量与温度对ABS/RC、TR_(0)/RC、ET_(0)/RC、F_(v)/F_(0)和F_(v)/F_(m)的交互影响达到显著(P<0.05)或极显著(P<0.01)水平。【结论】施氮量和温度对春小麦荧光特性和产量的影响存在交互作用,其中主导因素为温度,而施氮量对其存在补偿效应。合理的施氮量能有效增加小麦旗叶氮含量、叶绿素含量和PSⅡ反应中心活性,提高植物对光能的捕获、吸收、转化及最大光化学效率,并降低能量耗散率,从而抵御高温胁迫对春小麦光合系统造成的损伤。本试验条件下,选用宁春50号,采用N3(225 kg·hm^(-2))的施氮量能有效抵御高温胁迫,并提高春小麦的产量,可为当地春小麦高产稳产提供理论依据和技术支撑。

【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,including0(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)/F_(0),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 andφD0 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,ET_(0)/RC,TR_(0)/RC,PI,F_(v)/F_(0),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,ET_(0)/RC,PI,F_(v)/F_(0),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,TR_(0)/RC,ET_(0)/RC,F_(v)/F_(0) 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.