Nitrogen Stress Effects on Growth and Nitrogen Accumulation by Field‐Grown Tomato

Abstract

There are few growth studies evaluating within‐season effects of N on vegetative growth and N accumulation of tomato ( Lycopersicon esculentum Mill.). Growth analysis of field‐grown tomato for a number of Florida locations and management systems is presented here. Severe N stress resulted in fewer and smaller, but thicker, leaves. With increasing N, average leaf area index (LAI) increased from ≈0.75 to ≈3, but radiation use efficiency (RUE) typically increased less then 30%. Lower RUE under N‐limited conditions reflected a decrease in N concentration of the most recently matured leaves from 40 mg g −1 to as little as 15 mg g −1 . Over the life of well‐fertilized crops, leaf N concentrations dropped from 55 to 65 mg g −1 during initial growth to 20 to 35 mg g −1 at final harvest. Corresponding N concentrations for fruit and for stems were 30 to 35 mg g −1 and 15 to 25 mg g −1 . Severe N stress affected leaf and stem N concentrations most drastically, whereas N in fruits was less variable. With lower N supply (N < 180 kg ha −1 ) under careful management, nitrogen use efficiency (NUE) for field‐grown tomato was ≈0.4 Mg fresh fruit (kg N) −1 and average crop N accumulation increased from 37 to 210 kg N ha −1 as N fertilization increased from 0 to 333 kg N ha −1 . As a fraction of the fertilizer N applied N fertilizer recovery ranged from 0.36 to 0.74 and 0.61 to 0.96 for drip‐irrigated and subirrigated crops, respectively.