Análise técnica e econômica da produção de alface americana irrigada por gotejamento

Abstract

Lettuce is one of the vegetables mostly consumed by the Brazilian population, being the states of São Paulo and Minas Gerais the main producers and consumers. With the aim of reducing the difficulties faced by the producers on cultivating the crisphead lettuce, specifically those related to the lack of technical information about the right time to irrigate and the quantity of water to be applied, allied to the process’s economical analysis, a study was carried out in order to determine the effect of various depths on the yielding and economical efficiencies of the crisphead lettuce. The experiment was conducted at the Universidade Federal de Lavras, from March to May 2008 in greenhouse. The experiment was done according to a randomized block design, with five treatments and four repetitions. The treatments, which constituted of five evaporation factors, namely W1, W2 ,W3, W4 and W5, having the respective values of 0.30 EVm; 0.60EVm; 0.90EVm; 1.20EVm; 1.50EVm, were done based upon an evaporated depths of a reduced pan installed inside a greenhouse. Raider-plus crisphead lettuce, was transplanted on 0.3 X 0.3 m spacing, and irrigated through dripping with self-compensating drippers having a 1.76 L h-1 discharge, and spaced by 0.3 m from each other. The results showed that, the highest water application effectiveness (563.07 kg.ha-1 .mm-1) was achieved by applying a 74.53 mm irrigation depth, which corresponded to a 30% water reposition; the maximum commercial productivity, 35.308 kg.ha-1, was estimated by applying a 204.3 mm depths, which corresponded to water reposition factor of 101%; when considering the water factor price (R$ 0.67 mm-1) as well as the crisphead lettuce price (R$ 0.90 kg-1), the optimal economical depths was that of 203.9 mm, that resulted on a commercial productivity practically equal to the physical maximum.