Effect of Drip Irrigation and N Application Rates on Biomass Accumulation, Nitrogen Uptake, and Yield of Bell Pepper and Watermelon Crops.

Nutrient uptake by plant roots affects the concentration, movement and distribution of these nutrients within the crop root zone. Under drip fertigation, plant nutrients can be directly applied to the crop root zone, therefore increase the use efficiency of these nutrients, crop growth and yield and reduce the leaching potential of nutrients below the crop root zone. Two field experiments were conducted in a completely randomized block design in spring 2002 at the University of Florida, North Florida Research and Education Center. Bell pepper (Capsicum annum L) and watermelon (Citrullus lunatus Thrunb) crops were grown on plastic mulched soil beds. Treatments included three irrigation levels: 66, 100, and 133% of crop evapotranspiration (ETC) and two rates of N fertilizer: 100 and 125% of the recommended rate. Objectives of the study were to assess the impact of irrigation and N application rates on (i) biomass accumulation, (ii) N uptake, and (iii) crop growth yield. The goal of study was to determine a combination of irrigation and N rates that would optimize crop growth and yield while minimize nutrient leaching. During fruit development, increasing N rate significantly increased biomass and N uptake for both crops. However, increasing irrigation rates reduced biomass and N uptake for bell pepper and had no effect on watermelon crop implying potential nutrient leaching below the bell pepper crop root zone. However, at harvest, biomass accumulation was higher for watermelon crop with the higher irrigation rate. Nitrogen translocated from leaves and stems to the fruits. There was significant interaction between irrigation and N rates on marketable yield of both crops. It appears that current N recommendation (100%) would be adequate for both crops, but irrigation rates should not exceed 66% ETC for bell pepper due to potential leaching of nutrients below the root zone. 1