利用日光诱导叶绿素荧光估算高温干旱复合胁迫下夏玉米生理生态参数

Estimation of physiological and ecological parameters of summer maize under combined stress of heat and drought using solar-induced chlorophyll fluorescence

高温和干旱会对农业生产活动及陆地生态系统产生严重威胁,并最终对经济和社会发展产生不利影响。本研究以夏玉米为研究对象,开展高温干旱复合胁迫田间试验,首先对比分析各胁迫处理下夏玉米形态和生理生态响应特征,之后引入日光诱导叶绿素荧光(SIF),探究各胁迫处理下夏玉米冠层SIF值日变化和不同生育阶段变化特征,最终揭示SIF值与生理生态参数之间的关联性。结果表明,高温、干旱以及高温干旱复合胁迫均会抑制夏玉米株高和叶面积,造成产量下降。在生理生态参数方面,各胁迫处理下夏玉米叶片含水量(LWC)和叶绿素含量的变化规律基本一致,随各胁迫程度的加重总体均呈现逐渐下降趋势。夏玉米冠层SIF值在日尺度上呈现“单峰”型变化特征,在不同生育阶段呈现逐渐下降趋势。基于2/3的冠层SIF值与对应LWC、叶绿素含量之间构建的线性模型的R^(2)值分别为0.837和0.509(P<0.05);且基于上述线性模型和1/3的冠层SIF值估算的LWC和叶绿素含量估算值与实测值之间拟合的R^(2)值分别为0.827和0.726(P<0.05),验证了利用SIF值估算高温干旱复合胁迫下夏玉米生理生态参数(LWC和叶绿素含量)的可靠性。

Heat and drought will pose a serious threat to agricultural activities and terrestrial ecosystems,and have a negative impact on economic and social development ultimately.In this study,summer maize was taken as the research object to carry out field experiments under combined stress of heat and drought.Firstly,the morphological and ecophysiological response characteristics of summer maize under various stresses were compared and analyzed.Then solar-induced chlorophyll fluorescence(SIF)was introduced to investigate the diurnal variation of SIF values and the variation characteristics at different growth stages of summer maize under different stress treatments.Finally,the correlation between SIF values and physiological and ecological parameters was revealed.The results showed that heat,drought and combined stress of heat and drought inhibited plant height,leaf area and yield of summer maize.In terms of physiological and ecological parameters,the changes of leaf water content(LWC)and chlorophyll content of summer maize under different stress treatments were basically consistent,presenting a gradually downward trend on the whole.On daily scale,the canopy SIF values of summer maize showed a"single peak"variation,and gradually decreased at different growth stages.In the correlation analysis,the R^(2) values fitting between 2/3 canopy SIF values and LWC and chlorophyll content were 0.837 and 0.509,respectively(P<0.05).The R^(2) values fitting between the measured value and the estimated value of the remaining 1/3 LWC and chlorophyll content were 0.827 and 0.726,respectively(P<0.05),which further verified the reliability of estimating physiological and ecological parameters(LWC and chlorophyll content)of summer maize under combined stress of heat and drought based on SIF value.