THE EFFECT OF DIFFERENT N, P, K RATES ON PHOTOSYNTHESIS RATE AND CHLOROPHYLL CONTENT OF LEAVES OF WALNUT SAPLINGS

Two-year-old (Juglans regia L.) grafted walnuts were used to study the effect of different N, P, K rates on the net photosynthetic rate and chlorophyll content of leaves. The results indicated that the application of N, P, K fertilizer could increase net photosynthetic rate and chlorophyll content in walnut leaves. The best concentration of N to enhance the net photosynthetic rate of walnut leaves was 50 mg N/kg soil, but the best concentration of N to increase the chlorophyll content in walnut leaves was 100 mg N/kg soil. The best concentration of P and K were 100 mg element/kg soil.