Among the three cultívars of tea, Assam hybrids had a relatively higher net photosynthetic rate (P^) than the China and Cambod types. Though the leaves selected for chlorophyll (Chl) estimation were physiologically mature and identical, wide range of shades in the colour of leaves was observed. No significant difference between cultívars was notíced in Chl (a + b) content, but distinct difference was obtained among certain dones. Chl atb ratío exhibited significant difference between both the cultívars and dones.
Quadratic relationship between the age of a tea leaf and the net photosynthetic rate (PN) has been found. A progressive increase in PN was recorded for four months. Then the PN slowly declined, yet even seven-month-old tea leaves sustained a low PN. In a tea shoot, the PN increased from the first leaf onwards. Besides the physiological maturity and proximity, photon flux density (PFD) played an important role in reducing the PN. The tea leaf PN was influenced by cultivation procedures which in turn disrupted the quantum of PFD transmitted through the canopy. and R. Raj Kumar, L. Manivel, S. Marimuthu.