不同土壤水分条件下施氮水平对紫花苜蓿苗期光合作用的影响  

Effects of Nitrogen Application Rate on Photosynthesis of Alfalfa in Seedling Stage under Different Soil Moisture Conditions

作　　者：王茜 纪树仁 渠晖 沈益新 

机构地区：[1]南京农业大学草业学院,江苏南京210095

出　　处：《中国草地学报》2018年第1期49-54,共6页Chinese Journal of Grassland

基　　金：公益性行业(农业)科研专项(201403048)资助

摘　　要：通过盆栽半控制试验,采用两因素随机区组设计,研究了在3个土壤水分水平(分别为田间最大持水量的50%、70%、90%)下,4个施氮水平(0、90、180和270kg/hm2)对紫花苜蓿净光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)、胞间CO2浓度(Ci)、表观量子效率(AQY)、羧化效率(CE)、光呼吸速率(Rp)、暗呼吸速率(Rd)的影响。结果表明,在土壤水分含量较低时(50%田间最大持水量),90kg/hm2施氮水平的叶片Pn、Tr、Gs、Ci、AQY和CE均达到所有施氮水平的最大值;在土壤水分含量较高时(70%~90%田间最大持水量),180kg/hm2施氮水平可显著增大叶片的Pn、Tr、Gs、Ci、AQY和CE。因此,在土壤水分含量较低时施氮90kg/hm2,较高时施氮180kg/hm2可在扩大气孔开放度,减少气孔阻力,改善叶片组织内CO2的供给状况,提高叶片光能和CO2的利用率,增强光合强度,促进苗期生长等各方面发挥最大的效应。A semi-controlled pot experiment was carried out to clear the effects of nitrogen fertilizer on photosynthesis of alfalfa（Medicago sativa L.）seedlings under different soil moisture conditions.The effects of four nitrogen rates（0,90 kg/ha,180 kg/ha,270 kg/ha）on the photosynthetic parameters（net photosynthetic rate（Pn）,transpiration rate（Tr）,stomatal conductance（Gs）,intercellular concentration of CO_2（Ci）,apparent quantum yield（AQY）,carboxylation efficiency（CE）,photo respiratory rate（Rp）,dark respiration rate（Rd））under three soil moisture levels（50%,70%and 90% of maximum water holding capacity）were analyzed.The results showed that under the lower soil moisture level（50% of maximum water holding capacity）,the highest values of Pn,Tr,Gs,Ci,AQY and CE occurred in 90 kg/ha nitrogen treatment.While with the higher soil moisture contents（70%~90% of maximum water holding capacity）,the Pn,Tr,Gs,Ci,AQY and CE were significantly increased under 180 kg/ha nitrogen treatment.It was concluded that 90 kg/ha nitrogen application under the lower soil moisture levels（50% of maximum water holding capacity）and 180 kg/ha nitrogen application under the higher soil moisture levels（70% and 90% of maximum water holding capacity）could get greatest benefit in several aspects including increasing the opening degree of stoma,accelerating CO_2 into the leaf tissues,improving light and CO_2 use efficiency,as well as increasing photosynthesis and dry matter accumulation.

关 键 词：紫花苜蓿 土壤水分 施氮 互作效应 光合作用 

分 类 号：S541[农业科学—作物学]