摘要
为了探明弱光条件下小麦光合速率降低的原因,为黄淮海麦区小麦生产中合理施氮和高产高效栽培提供理论依据,通过田间试验研究了拔节期至成熟期弱光胁迫(透光率为50%的黑色遮阳网遮阴)和氮素水平[N0,0 kg(N)×hm^(-2);N1,120 kg(N)×hm^(-2);N2,240 kg(N)×hm^(-2)]对冬小麦旗叶光合特性及产量的影响。结果表明:冬小麦拔节期至成熟期长期遮阴,导致旗叶叶绿素含量、PSⅡ荧光光化学猝灭系数(q P)和实际光化学量子产量(ΦPSII)在3个施氮水平下均显著增加,其中以N2施氮水平下增幅最大,同时显著降低了叶绿素a/b和荧光非光化学猝灭系数(q N),进而提高了旗叶光化学效率,降低了热能耗散,提高光能利用率。在开花期至灌浆中期,由于光能不足造成小麦旗叶净光合速率Pn降低,而在灌浆后期,遮阴处理较正常光照能维持较高的叶绿素含量和光能转化效率,从而Pn高于正常光照。在相同光照条件下,随施氮量增加,小麦旗叶净光合速率Pn、叶绿素含量、PSⅡ荧光光化学猝灭系数(q P)和实际光化学量子产量(ΦPSⅡ)显著提高,这有利于植株充分利用光能,增强光合作用。弱光导致穗数、穗粒数及千粒重显著降低(P<0.05),穗粒数降低幅度最大(13%~46.8%),千粒重降低幅度最小(3.4%~8.5%),穗数的降低幅度为8.6%~22.5%,严重影响氮肥的增产效应。遮阴和施氮水平间交互显著影响了叶绿素含量、穗粒数和产量,但对其他指标影响并不显著。综合而言,增施氮肥缓解了弱光胁迫对光合作用的不利影响,遮阴条件下施氮处理(N1、N2)净光合速率Pn较对照(N0)增幅为11.5%~27.4%,其中以N2[240 kg(N)×hm^(-2)]水平增幅最大。在不同施氮水平下,遮阴处理均提高了光能转化效率,但遮阴显著降低了植株光合速率及产量构成因素,导致产量显著降低(P<0.05)。
During the later stage of wheat development, low-light stress caused by cloudy and rainy weather conditions severely influences wheat yield in some wheat(Triticum aestivum L.) production areas in North China. In crop production, in order to get high yield, too much nitrogen fertilizer application has resulted in waste of resources and pollution of the environment. Several studies on the effects of shading or nitrogen application rate on wheat growth have been reported, but little studies have been on the interactive influence of shading and nitrogen rate on photosynthetic characteristics and chlorophyll fluorescence of wheat. Thus, a field experiment was conducted to determine the effects of shading and nitrogen application rate on photosynthetic characteristics of flag leaves and yield of winter wheat during jointing and maturity stages. Wheat plants were planted under diffident treatments including two light levels [S0(no shading) and S1(50% full radiation from jointing to mature stages, produced by black sun-shade net of 50% light transmittance)] and three N fertilizer rates [N0(0 kg×hm^(-2)), N1(120 kg×hm^(-2)) and N2(240 kg×hm^(-2))]. The chlorophyll content, net photosynthetic rate(Pn) and chlorophyll fluorescence parameters of wheat at flower stage(April 23), middle(May 11) and later(May 20) grain-filling stages were investigated, and yield and its components were determined. The results indicated that shading significantly increased chlorophyll content, PSⅡ fluorescence photochemical quenching coefficient(q P) and actual photochemical quantum yield(ΦPSⅡ) of flag leaves of wheat. It, however, significantly decreased chlorophyll a/b ratio and fluorescence of non-photochemical quenching coefficient(q N). Thus shading treatment increased photochemical efficiency and reduced heat dissipation of flag leaves, which was helpful for better utilization of light energy. Due to energy shortage, Pn under S1 was lower than that under S0 at the period from flowering stage to mid-grain-filling stage. Because of higher chlorophyll content and efficiency of light energy conversion in S1, Pn was higher than that under S0 at late-grain filling stage. With increase in N application rate, Pn, chlorophyll content, q P and ΦPSⅡ increased significantly, which enhanced the full use of light energy and improved photosynthetic rate. Shading significantly decreased spike number, kernel number per spike and 1000-grain weight, which severely negated the increase in production due to nitrogen fertilizer application. The comprehensive effect of shading and nitrogen significantly influenced chlorophyll content, kernel number per spike and grain yield, but had no significant effect on other indicators. In conclusion, more nitrogen application alleviated the adverse effects of weak light stress on photosynthesis. Compared with the control(N0), Pn for nitrogen treatments(N1 and N2) increased by 11.5%-27.4%, especially, N2(240 kg×hm^(-2)) treatment having the best effect among all treatments. At diffident nitrogen levels, although shading treatment improved light energy utilization of wheat, it significantly reduced plant photosynthesis and yield components, and finally led to significant reduction of yield.
出处
《中国生态农业学报》
CAS
CSCD
北大核心
2016年第9期1177-1184,共8页
Chinese Journal of Eco-Agriculture
基金
农业部公益性行业科研专项(201203096)
现代农业(小麦)产业技术体系(MATS)
河南省高等学校重点科研项目(15A210031)
国家科技支撑计划项目(2015BAD26B00)资助~~
关键词
冬小麦
遮阴
施氮水平
光合速率
叶绿素荧光
产量
Winter wheat
Shading
Nitrogen application rate
Photosynthetic rate
Chlorophyll fluorescence
Yield