野生西瓜与栽培西瓜光合特性比较研究

Comparative Study on Photosynthetic Characteristics of Wild and Cultivated Watermelon Plants

探讨野生西瓜的光合特性,为高光效西瓜育种提供参考。以一个来源于新疆的野生西瓜种质和2个栽培西瓜品种(‘黑美人’西瓜、‘子龙’西瓜)为材料,利用Li-6400光合仪,测定生长点下第4片完全展开叶晴天和阴天下的光合生理指标日变化,并进行了比较分析。试验结果表明,晴天下野生西瓜的光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)和胞间CO2浓度(Ci)总体高于同一时刻的栽培西瓜,阴天下却低于栽培西瓜。野生西瓜的光合"午休"很不明显,而栽培西瓜的光合午休十分明显。从晴天到阴天,野生西瓜的光合速率呈明显下降趋势,这可能是由气孔限制因素和非气孔限制因素共同决定的。野西瓜是高光效植物,光合午休不明显。

In order to study the photosynthetic characteristics of wild watermelon,it was significant for breeding high photosynthetic efficiency in watermelon. The daily changes of photosynthetic physiology index of the fourth functional leaves below the top fully expanded leaves of cultivated and wild watermelon plants were studied with portable photosynthesis system Li-6400 under a clear day and a cloudy day in summer. The results showed that net photosynthetic rate （Pn ）,transpiration rate （Tr ）,stomata conductance （Gs ）,and intercellular CO2 concentration（Ci ） of wild watermelon were generally higher than cultivated watermelon at the same clock in clear day,whereas it was lower in cloudy day. Wild watermelon presented slight photosynthesis depression at midday,but cultivated watermelon showed obvious photosynthesis depression at midday. The decrease of net photosynthetic rates of wild watermelon from clear day to cloudy day may be caused by stomatal limitation and non-stomatal limitation. These indicated that wild watermelon had high photosynthetic efficiency with no typical midday depression of photosynthesis in clear day.