Com o objetivo de avaliar a influência de doses de sulfato de zinco sobre a da alface- americana (Lactuca sativa L.), foram
conduzidos três experimentos distintos entre os meses de maio e julho de 2002, no municÃpio de Três Pontas - MG. Utilizou-se o
delineamento de blocos ao acaso, com cinco doses de sulfato de zinco (0; 0,9; 1,8; 2,7 e 3,6 kg ha-1) e 4 repetições, aplicadas em três
diferentes épocas via foliar (14, 21 e 28 dias após o transplante). Foram avaliadas as caracterÃsticas massa fresca total e comercial
(g planta-1), circunferência da cabeça comercial (cm) e comprimento do caule da cabeça comercial (cm). As caracterÃsticas massa fresca
total e comercial evidenciaram efeitos significativos independentes para as doses de sulfato de zinco e épocas de aplicação Para massa
fresca total, a dose de 2,01 kg ha-1 de sulfato de zinco proporcionou o maior rendimento. Em relação à época de aplicação, essa
caracterÃstica apresentou o maior rendimento (988 g planta-1) quando a pulverização foi realizada aos 14 dias. Em termos de massa
fresca comercial, a dose de 2,09 kg ha-1 propiciou o maior rendimento, sendo a aplicação aos 14 dias, estatisticamente superiores, com
rendimentos de 593 g planta-1. Para circunferência de cabeça, a dose de 2,63 kg ha-1 de sulfato de zinco proporcionou o maior retorno.
Não se observou efeitos significativos dos tratamentos para comprimento do caule.
With the objective of evaluating the influence of doses of zinc sulphate on yield and quality of iceberg lettuce (Lactuca
sativa L.), three distinct trials were carried out at Três Pontas, State of Minas Gerais, Brazil, from May to June of 2002. The
experimental design was randomized blocks with five doses of zinc sulphate (0, 0.9, 1.8, 2.7 and 3.6 kg ha-1), applied to the foliage at
three different application times (14, 21 and 28 days after transplanting), and four replicates. The characteristics total and commercial
fresh mass (g plant-1), commercial head circumference (cm) and stem length of commercial head (cm) were evaluated. The total and
commercial fresh mass characteristics evidenced independent significative effects to the doses of zinc sulphate and application times.
For total fresh mass, the dose of 2.01 kg ha-1 of zinc sulphate was estimated to present the highest yield. In relation to application
time, this characteristic was estimated to present the highest yield (988 g plant-1) when the pulverization was realized at 14 days. The
dose of 2.09 kg ha-1 was estimated to achieve the highest yield for commercial fresh mass, the application at 14 days being statistically
superior, with a yield of 593 g plant-1. For head circumference, the dose of 2.63 kg ha-1 of zinc sulphate was estimated to bring showed
the highest return. No significant effects were observed for stem length.
