自然条件下半干旱雨养春小麦生育后期旗叶光合的气孔和非气孔限制  

Stomatal or non-stomatal limitation of photosynthesis of spring wheat flag leaf at late growth stages under natural conditions in semiarid rainfed regions

作　　者：杨泽粟[1,2] 张强[1] 郝小翠[3] 

机构地区：[1]中国气象局兰州干旱气象研究所/甘肃省气候变化与减灾重点实验室/中国气象局干旱气候变化与减灾重点开放实验室,兰州730020 [2]兰州大学大气科学学院,兰州730000 [3]西北区域气候中心,兰州730020

出　　处：《中国生态农业学报》2015年第2期174-182,共9页Chinese Journal of Eco-Agriculture

基　　金：国家重点基础研究发展计划(973计划)项目(2013CB430206);国家公益性行业(气象)科研专项(GYHY201106029)资助

摘　　要：为探究半干旱地区雨养春小麦旗叶的光合作用限制因素、不同生育期差异及其适应策略,分析了大田条件下春小麦旗叶在抽穗期和灌浆期光合生理特征的动态变化规律,探讨了自然条件下光合作用的气孔与非气孔限制特征。结果表明:净光合速率日变化趋势在抽穗期和灌浆期分别为单峰型和双峰型,峰值相当,为18.5μmol(CO2)·m-2·s-1左右。气孔导度具有与净光合作用几乎相似的日变化规律,胞间CO2浓度大致为上午下降、下午回升。胞间CO2浓度变化除受光合作用消耗和气孔限制共同作用外,下午时段叶肉导度增大,也影响胞间CO2浓度变化。在抽穗期和灌浆期,春小麦旗叶光合作用速率与气孔导度相关性十分显著,相关系数分别达0.916(P=0.000)和0.945(P=0.000)。并且2个生育期均出现明显的光合气孔限制,抽穗期达0.64,灌浆期为0.53。其中,抽穗期气孔导度对饱和水汽压差响应十分敏感,下午出现较为明显的气孔限制;灌浆期中午出现较为明显的光合"午休"现象,其主要原因是半干旱区较大饱和水汽压差和强烈辐射致使气孔关闭,气孔限制达到极大值,并且非气孔限制因素也较为突出。抽穗期至灌浆期,由于气孔对饱和水汽压差敏感性的下降以及"午休"策略,光合气孔限制逐渐减小,是春小麦在半干旱地区维持较高光合速率和保证产量的重要自适应机制。Rainfed agriculture is a critical production mode in arid and semiarid regions, which accounts for 30% of the earth＇s surface. Spring wheat is one of the main crops in the semiarid region of the Loess Plateau in China. It is therefore important to investigate the photosynthetic characteristics of spring wheat（Triticum aestivum L.） in the semiarid region of the Loess Plateau. Previous studies have mainly focused on the responses of photosynthesis to environmental factors, with few researches on photosynthetic limitations under natural conditions in the semiarid regions of Northwest China. Exploration of photosynthetic limitations of flag leaves of spring wheat under natural conditions could contribute to current understanding of the principles of stomatal regulation in semiarid regions. It can also provide a theoretical basis for water use efficiency at the leaf-scale. In order to investigate stomatal and non-stomatal limitations of photosynthetic rates of flag leaves of spring wheat at different growth stages under natural conditions in semiarid areas, a field experiment was conducted in 2012 during the heading and filling stages of spring wheat. Physiological char-acteristics such as photosynthetic rate（Pn）, stomatal conductance（gs） and intercellular CO2 concentration（Ci） were measured by the LI-6400 portable photosynthesis analyzer. Then environmental factors such as photosynthetically active radiation（PAR）, vapor pressure deficit（VPD）, air temperature（Ta） and air relative humidity（RH） were simultaneously recorded. The study firstly analyzed diurnal variations in environmental factors and photosynthetic characteristics of flag leaves of spring wheat. Analyzed next was the response of photosynthetic characteristics to environmental factors, finally followed by discussion on stomatal and non-stomatal limitations at heading and filling growth stages. Results showed that PAR, Ta, and VPD had unimodal type of diurnal curve at both growth stages, while RH had uni-trough type of diurn

关 键 词：春小麦 抽穗期 灌浆期 胞间CO2浓度 气孔限制 光合特征 半干旱区 雨养区 

分 类 号：Q945.79[生物学—植物学] S512.12[农业科学—作物学]