温室栽培西瓜单叶光合作用对主要生态因子的响应

Photosynthetic responses of greenhouse-grown watermelon to major ecological factors

在早春茬塑料日光温室条件下,以两个温室型品种为试材研究了西瓜单个叶片光合作用对主要生态因子的响应特性．结果表明：温室西瓜单叶的饱和光强和CO_2饱和点均较大田条件下的低,两个品种间光补偿点和表观量子产额有较大差异,黄皮西瓜品种宝冠的光补偿点和表观量子产额明显高于花皮品种新金兰的,但两个品种间饱和光强差异不大,均在1200μmol/(m^2·s)左右．两个品种CO_2饱和点和补偿点差异不大,分别为1050～1250μL/L和20～22μL/L,但宝冠的羧化效率和RuBP再生速率(分别为0．1060和47．3)明显高于新金兰的(分别为0．0684和32．9)；两个品种西瓜单叶光合作用的适宜温度范围略有差异,宝冠的光合适温(25～35℃)低于新金兰的(30～40℃)．宝冠西瓜单叶光合作用的适宜大气湿度范围为50%～70%,低于日光温室环境的正常大气湿度,新金兰光合作用更适宜在低湿的空气环境中进行．

Photosynthetic responses of individual leaves from two watermelon cultivars grown in plastic greenhouses in early spring were studied at fruiting stage, under controlled curvatte environment. The light compensation points, light saturation points, apparent quantum yield, CO2 compensation points, CO2 saturation point, carboxylation efficiency, and maximum RuBP regeneration rate were calculated by solving the equations describing the corresponding curves. The results showed that and the yellow skinned cultivar, Baoguan, had higher LCP and AQY than strip skinned Xinjinlan. Little difference was found between the two cultivars concerning the LSP, CCP and CSP which ranged around 1 200 μmol/（m^2·s）, 20-22 μL/L and 1050-1250 μL/L. However, Baoguan was found to have notably higher CE and Jmax （0.1060 and 47.3 respectively） than Xinjinlan （0.0684 and 32.9）. According to the study, the CCP was 21±2 μL/L and the CSP was 1000-1300 μL/L in greenhouse watermelon. It was found that the suitable leaf temperature for photosynthesis was different for the two cultivars. The optimum temperature range for photosynthesis of Baoguan（25-35℃） was slightly lower than that of Xinjinlan （30-40℃）. The optimum air humidity for photosynthesis of Baoguan was 50%-70%, which is significantly lower than that in a normal plastic greenhouse. The photosynthetic rate of Xinjinlan was higher under lower air humidity.