Abstract:

Abstract: In order to study the photosynthetic characteristics of wild watermelon, the daily changes of photosynthetic physiology index of cultivated and wild watermelon plants under a clear day and a cloudy day in summer were studied by portable photosynthesis system Li-6400 . 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 due to both the stomatal limitation and non-stomatal limitation.