Função de resposta da alface americana à aplicação de água e nitrogênio.

Abstract

The maiin objective of this experiment, carried out, from September to December/2004, inside a greenhouse at the Federal University of Lavras, in Minas Gerais, was to study the effect of water and nitrogen applications, and interaction between these factors, on economic yield and on yield characteristics of crisphead lettuce. A 4 x 4 factorial experimental design with randomized blocks and three replications was used. Treatments were determined by combinations of four water depths (W1=91.99; W2=142.79; W3=186.34; W4=237.14 mm) and four nitrogen levels (N0=0; N1=80; N2=160; N3=320 kg ha-1). Crisphead lettuce (cv. raider) was grown under daily irrigations applications computed based on the evaporation measured on a reduced pan (EVm). Treatments W1,, W2, W3 e W4, corresponded to, respectively, 0.35EVm, 0.70EVm, 1.0EVm, and 1.35EVm. A 0.30m x 0.30 m plant spacing was observed and irrigation water was applied trough a drip irrigation system with 1.6 L h1 emitters spaced 0.30 m apart. Under the price scenario considered, water at R$ 0.44 mm-1, nitrogen at R$ 2.09 kg-1 and crisphead lettuce at R$ 0.80 kg-1, the maxim profit, and the maxim economical productivity, estimated at 26,959.93 kg ha-1 , was achieved with the application of 205.26 mm of water and 257.14 kg ha-1 of nitrogen.