EFFECT OF MUSKMELON LEAF AGE ON PHOTOSYNTHESIS RATE AND OTHER PHYSIOLOGICAL PARAMETERS AT DIFFERENT LIGHT DENSITY

There are only 2-6 leaves on a healthy seedling of muskmelon at seedling stage. So, investigating the photosynthesis characteristic of each leaf becomes necessary for establishing a seedling growth model. The experiment was performed in a commercial greenhouse. The research compared light response curves and photosynthesis model parameters of cotyledon and leaf at different age. The results showed that rates of photosynthesis vary with foliage age and typically increase from un-full expansion and then decline from full-leaf expansion until senescence occurs. Photosynthesis model parameters are different for different leaves and different leaf ages. Light response curves of leaf photosynthesis showed that maximum photosynthesis rate, light compensation point, light saturation point, and respiration decreased with leaf age.