弱光胁迫对南瓜幼苗光合特性的影响

Effects of Low Light Stress on Photosynthetic Characteristics of Pumpkin Seedlings

为探讨南瓜耐低温弱光的特性,以4个不同品系(组合)的南瓜幼苗为材料,研究不同弱光条件对南瓜叶片胞间CO_(2)浓度、蒸腾速率、气孔导度、叶片光合速率、叶绿素初始荧光(Fo)、叶绿素最大荧光(F_(m))和PSⅡ最大光化学量子产量(F_(v)/F_(m))的影响。结果表明,弱光条件下叶片胞间CO_(2)浓度提高,随着弱光程度的增加,叶片的蒸腾速率、气孔导度呈先增后减趋势,NY-1和JB-1在遮光40%时,蒸腾速率和气孔导度达到最高值,NY-1×JB-1随着遮光程度的增加,蒸腾速率下降。光合速率10-32、JB-1呈现递增趋势,NY-1呈现递减趋势,NY-1×JB-1为先增后减趋势。10-32、NY-1、JB-1的Fo表现为显著降低的趋势,NY-1×JB-1的Fo呈现先升后降的趋势。10-32、NY-1×JB-1随着遮光程度的增加Fm表现为先升后降的趋势,在遮光40%时有最大值,遮光80%时最低;NY-1、JB-1随着遮光程度的增加Fm都表现为下降趋势。10-32、NY-1、JB-1、NY-1×JB-1随着遮光强度的增加,F_(v)/F_(m)均表现上升。说明以上指标可作为衡量南瓜耐低温弱光性的指标,可为南瓜耐弱光品种筛选提供参考依据。

In order to investigate the characteristics of low temperature and weak light tolerance of pumpkin,four different strains(combinations)of pumpkin seedlings were used as materials to study the effects of different low light conditions on intercellular CO_(2) concentration,transpiration rate,stomatal conductance,leaf photosynthetic rate,initial chlorophyll fluorescence(F^(o)),maximum chlorophyll fluorescence(F_(m))and maximum photochemical quantum yield of PSⅡ(F_(v)/F_(m))of pumpkin leaves.The results showed that intercellular CO_(2) concentration increased under low light conditions.The transpiration rate and stomatal conductance of leaves increased firstly and then decreased with the increase of low light intensity.The transpiration rate and stomatal conductance of NY-1 and JB-1 reached the highest values when the shading degree was 40%.The transpiration rate of NY-1×JB-1 decreased with the increase of the shading degree.The photosynthetic rate of 10-32 and JB-1 showed an increasing trend,while that of NY-1 showed a decreasing trend,and that of NY-1×JB-1 showed an increasing trend firstly and then a decreasing trend.F_(o) of 10-32,NY-1 and JB-1 showed a trend of significant decrease,and F_(o) of NY-1×JB-1 showed an increasing trend firstly and then a decreasing trend.F_(m) of 10-32,NY-1×JB-1 showed a trend of first increase and then decrease with the increase of shading degree,with the maximum value at 40%shading and the lowest value at 80%shading.F_(m) of NY-1 and JB-1 showed a decreasing trend with the increase of shading degree.The F_(v)/F_(m) of 10-32,NY-1,JB-1 and NY-1×JB-1 increased with the increase of shading degree.The above indexes can be used to evaluate the low temperature and low light tolerance of pumpkin and provide reference for the selection of low light tolerant varieties of pumpkin.