Nitrogen Stress Effects on Growth and Nitrogen Accumulation by Field-Grown Tomato
2000
Scholberg, Johannes | McNeal, Brian L. | Boote, Kenneth J. | Jones, James W. | Locascio, Sal J. | Olson, Stephen M.
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.
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