A METHOD FOR DIAGNOSING THE STATUS OF HORTICULTURAL CROPS .1. MACRONUTRIENTS

Marked responses of horticultural crops (tomato, pepper, navy bean, cu cumber, muskmelon and watermelon) to macro- and micronutrient fertiliz ation have been recorded but little information exists on macronutrien t requirements of these crops in greenhouses. Although he crops differ ed in visual susceptibility to nutrient concentrations in the vegetati ve stage, they differed only slightly in macronutrient uptake. Leaf co ncentration of mobile nutrients N, P, S and K significantly declined ( export) as the biological cycle of cultures elapses. For immobile nutr ients Ca, Mg and Na, leaf concentration significantly increase (import ) with time in all the species studied. Culture conditions and the cha racteristics of the species used led to high values for optimal ranges . Optimal ranges for macronutrients, cannot however be considered as s tatic, since they define a critical area which varies throughout the b iological cycle and which is stablished in terms of nutritional dynami cs in each species.