Effect of nitrogen supply on photosynthesis in young clonal tea

The relationship of maximum light-saturated photosynthetic rate (P_max) and photochemical efficiency at low irradiance (q) of young clonal tea (Cammellia sinensis L.) to leaf nitrogen (LN) was investigated. Three levels of N (0, 52.5 and 105 ppm) were supplied through nutrient solutions. Both P_max and q increased with increasing N. While the response of P_max was observed immediately after application of N treatments, the response of q was observed after one month. P_max was positive above a threshold leaf N content (LN) of 2% and reached a plateau around 2.9% LN. q was very low at LN below 2.8%. As LN increased above 2.8%, q increased rapidly and reached a plateau around 3.2% LN.