糜子/绿豆间作模式下施氮量对绿豆叶片光合特性及产量的影响

探讨施氮量对间作条件下绿豆叶片光合特性、氮素特征及产量的影响,以期为西北旱区糜子//绿豆间作模式的合理施氮提供理论依据。试验于2018-2019年在陕西榆林采用裂区设计,主处理设糜子间作绿豆(PM)、绿豆单作(SM)2种种植模式,副处理设0(N0)、45(N1)、90(N2)和135 kg hm^-2(N3)4个氮肥水平。结果表明,施氮处理下间作绿豆叶片净光合速率(Pn)、蒸腾速率(T_r)比不施氮平均增加10.5%~24.5%、15.2%~29.5%,提高了叶片光合特性;PSII最大光化学效率(F_v/F_m)、PSII实际光化学效率(ΦPSII)平均增加2.9%~7.8%、11.7%~28.4%,PSII非光化学淬灭系数(non-photochemical quenching coefficient,NPQ)降低10.3%~17.4%,叶片叶绿素荧光参数得到改善,对弱光的截获和利用能力提高,叶片PSII反应中心活性增强。单株叶面积、单位干质量叶片氮含量(N_mass)和单位面积氮含量(N_area)均随施氮量增加表现为先升高后降低的趋势;Chl a、Chl b含量增加,光合氮利用效率(photosynthetic N-use efficiency,PNUE)则比不施氮有所降低;不同施氮量均显著增加间作绿豆干物质积累量和荚数,百粒重2年平均分别比不施氮增加1.1%~6.9%,产量增加9.3%~19.7%。2年试验间作各处理土地当量比(land equivalent ratio,LER)为1.63~2.07,表现为间作产量优势。由此可知,施氮可改善间作绿豆叶片光合物质生产能力,延缓衰老,有效调节了光合系统对遮阴的适应性反应,且间作叶片光合性能对氮肥的响应要大于单作。糜子/绿豆间作模式LER大于1,可作为西北旱作农业区推广种植模式,在90 kg hm^?2施氮量下间作绿豆叶片光合特性表现最好,产量最高,LER最大,是其适宜施氮水平。

Effects of nitrogen application rate on photosynthetic characteristics and yield of mung bean under the proso millet and mung bean intercropping

To explore the effect of nitrogen(N)on the leaf gas exchange,chlorophyll fluorescence,nitrogen characteristics and yield of mung bean under intercropping with proso millet,the field experiments were conducted in 2018 and 2019 using split-plot design with two cropping patterns[proso millet-mung bean intercropping(PM)and soled mung bean(SM)]and four total N fertilizer application rates[0(N0),45(N1),90(N2),and 135 kg hm^-2(N3)].Under N application,the net photosynthetic rate(Pn)and transpiration rate(T_r)of mung bean in intercropping increased by 10.5%–24.5%and 15.2%–29.5%on average,which improved the photosynthetic characteristics.Maximum photochemical efficiency(F_v/F_m)and actual photochemical efficiency(ΦPSII)increased by 2.9%–7.8%and 11.7%–28.4%,respectively,and PSII non-photochemical quenching coefficient(NPQ)decreased by 10.3%–17.4%.The chlorophyll fluorescence parameters were improved,resulting in enhancing the ability to capture and utilize light energy,and the activity of PSII reaction center was enhanced.Leaf area per plant,N content per unit dry mass of leaves(N_mass)and N content per unit area(N_area)increased first and then decreased with the increase of N application rate.The content of Chl a and Chl b increased.Photosynthetic N-use efficiency(PNUE)decreased compared with N0.N application significantly increased the dry matter accumulation and pods of mung bean in intercropping.Under the treatment of N1,N2,and N3,100-grain weight and yield were increased by 1.1%–6.9%and 9.3%–19.7%,respectively.In the two-year trial intercropping,the land equivalent ratio of each treatment was 1.63–2.07,indicating the yield advantage of intercropping.N application could improve the photosynthetic production capacity of mung bean in intercropping and effectively regulate the adaptive response of photosynthetic system to shading.The response of photosynthetic performance of intercropping to N fertilizer was greater than that of single-plant systems.Under the conditions of this experiment,the proso millet and mung bean intercropping model can increase land productivity,and it can be used as a planting model to promote dry farming in northwestern China.The intercropping mung bean had the best photosynthetic characteristics at 90 kg hm^-2,which showed the highest yield,and the largest land equivalent ratio.