低温胁迫对诺丽幼苗叶片光合荧光特性的影响

为了解诺丽抗寒生理特性,比较其抗寒能力,以4个诺丽（Morinda citrifolia L.）种质幼苗为试材,研究不同低温（25、12、9、6、3、0 ℃）及不同时间（1、3、5 d）胁迫对各种质幼苗叶片光合及叶绿素荧光参数等指标的影响,利用隶属函数法对4个诺丽种质耐寒能力进行评价。结果表明：（1）相同时间下随着胁迫温度的降低,4个诺丽种质幼苗叶片的净光合速率（P_n）、气孔导度（G_s）、蒸腾速率（T_r）和电子传递速率（ETR）显著下降,而胞间二氧化碳浓度（C_i）、PSⅡ潜在活性（F_v/F_o）和PSⅡ最大光化学效率（F_v/F_m）则呈降-升-降趋势,不同处理间差异显著;（2）相同温度不同时间处理,除C_i外,各种质其余指标皆随胁迫时间的延长显著下降,6 ℃以下低温处理C_i含量随胁迫时间延长显著增加;（3）温度和时间产生交互作用,相同时间显示低温危害强度效应,相同低温显示低温危害累积效应,影响着各诺丽种质幼苗叶片的光合及荧光指标;（4）隶属函数综合评价结果表明,4个诺丽种质抗寒能力依次为‘NL004’>‘NL003’>‘NL001’>‘NL002’。综合分析表明,参试的4个诺丽种质中,‘NL004’的抗寒适应性最强,‘NL002’最弱,研究结果为诺丽抗寒栽培和育种提供参考。

Effects of Low Temperature Stress on the Photosynthetic Fluorescence Characteristics of Noni(Morinda citrifolia L.)Seedling Leaves

The purpose of this study was to understand the physiological characteristics of cold resistance of Morinda citrifolia L.,and compare the cold resistance ability of different germplasms.Four seedlings of noni germplasms were used as the test materials to study the effects of low temperature(25,12,9,6,3,0℃)and(1,3,5 d)stress on the leaf photosynthesis and chlorophyll fluorescence parameters,and membership function method was used to evaluate the cold tolerance of the four seedlings of noni germplasms.With the decrease of stress temperature at the same time,the net photosynthetic rate(P_n),stomatal conductance(G_s),transpiration rate(T_r)and electron transfer rate(ETR)of the leaves of 4 noni germplasms seedlings decreased significantly,while the intercellular carbon dioxide concentration(C_i),PSⅡpotential activity(F_v/F_o)and PSⅡmaximum photochemical efficiency(F_v/F_m)showed a downward-upward-downward trend,with significant differences among different treatments.With the treatments at the same temperature but different time,except C_i,other indexes of all germplasms decreased significantly with the extension of stress time.while C_i content increased significantly under 6℃with the extension of stress time.The interaction between temperature and time showed the intensity effect of low temperature damage at the same time,and the accumulation effect of low temperature damage at the same low temperature,which affecting the photosynthesis and fluorescence indexes of seedling leaves of various noni germplasms.The comprehensive evaluation results of membership function showed that the cold resistance of 4 noni germplasms was‘NL004’>‘NL003’>‘NL001’>‘NL002’.Comprehensive analysis showed that among the 4 tested noni germplasms,‘NL004’had the strongest cold resistance adaptability and‘NL002’was the weakest.The research results would provide references for cold-resistant cultivation and breeding of noni.