外源Ca2+对高温强光下西葫芦幼苗形态特征、光合特性及荧光参数的影响

选用西葫芦(Cucurbita pepo)品种“阿兰”一代为试验材料，研究了外源Ca²⁺处理对高温强光交叉胁迫下西葫芦幼苗生长特征、光合特性及叶绿素荧光参数的影响.结果表明：高温强光胁迫下，5～20 mmol·L^-1 Ca²⁺处理的西葫芦幼苗具有较高的株高和较大的叶面积，其叶绿素、类胡萝卜素含量及光合速率（P_n）、气孔导度（G_s）、蒸腾速率（T_r）、PSⅡ最大光化学效率(F_v/F_m)、PSⅡ实际光化学效率(Φ_PSⅡ)和光化学猝灭系数(q_P)均较高，而胞间CO₂浓度（C_i）和非光化学猝灭系数（NPQ）较低，其中以10 mmol·L^-1Ca²⁺处理效果最好.说明5～20 mmol·L^-1Ca²⁺处理能有效缓解高温强光对西葫芦光合机构的不可逆伤害，使其保持较快的光合电子传递速率和较高的PSⅡ电子传递活性.Ca²⁺处理浓度超过40 mmol·L^-1时对高温强光胁迫没有缓解效应.

Effects of exogenous Ca2+ on|morphological and photosynthetic characteristics and chlorophyll fluorescent parameters of squash seedlings under high temperature and strong light stress.

Taking squash (Cucurbita pepo L.) variety Alan as test object, this paper studied the effects of exogenous Ca²⁺ on themorphological and photosynthetic characteristics and chlorophyll fluorescent parameters of squash seedlings under the cross-stress of high temperature and strong light. Under the stress, applying 5-20 mmol·L^-1 of Ca²⁺ increased the plant height, leaf area, chlorophyll and carotenoid contents, photosynthetic rate (P_n), stoma conductance (G_s), transpiration rate(T_r), maximal PSⅡ efficiency (F_v/F_m), actual PSⅡ efficiency (Φ_PSⅡ), and photochemical queching coefficient (q_P), and decreased the intercellular CO₂ concentration (C_i) and non-photochemical fluorescence quenching coefficient (NPQ), suggesting that this application of exogenous Ca²⁺could effectively mitigate the damage of high temperature and strong light stress on the squash seedlings leaf, and make it keep more rapid photosynthetic electron transfer rate and higher PSⅡ electron transfer activity. Among the treatments of applying Ca²⁺, 10 mmol Ca²⁺·L^-1had the best effect. When the Ca²⁺application rate exceeded 40 mmol·L^-1, no mitigation effect was observed on the high temperature and strong light stress.