Seasonality of nutrients in the leaves of apple trees cultivars Red Delicious and Benoni

The nutrient accumulation or depletion curves are good indicators of plant nutrients demand for each developmental stage. They are also useful tool to evaluate orchard nutritional status and to estimate the amount of soil nutrient removal. This investigation aimed at evaluating the seasonality of macro-nutrients contents of apple trees during the agriculture year 2007. Therefore, leaf samples from the apple trees cultivar Red Delicious and Benoni were collected at fortnightly intervals form 1st may to 1st October and evaluated for macronutrients (N, P, K, Ca, and Mg). Red Delicious had higher foliar concentration of N, Ca and Mg and lower levels of P and K than Benoni leaves. In General concentration of N, P, K decreased and those of ca and Mg increased from first to last sampling in both the cultivars of apple. The distinct period of stability for N, and P and K contents occurred from July15- August 15 and July 1 to august 1 respectively. However, Ca content of leaves showed least variation from July 1 to august 15 while stability period for leaf Mg was recorded from June 15-july 15. Thus proper diagnosis of macro nutrients apple leaves should be sampled in the, month of July or in the first fortnight of august.