Oregano production under various water depths estimated by means of the class A pan evaporation Produção de orégano com diferentes lâminas de irrigação estimadas a partir da evaporação do tanque classe A

The purpose of this experiment was to analyze the effect of five irrigation water depths on oregano production. Oregano is a plant rich in essential oil, commonly used as seasoning in food preparation. The water depths were estimated based on the class A pan evaporation (CPE): 0 CPE (without water replacement); 25 CPE, 50 CPE, 75 CPE, and 100% CPE. The analyzed variables were fresh and dry weight of leaves and roots, yield, net return, and water use efficiency. The experiment was carried out in Presidente Prudente, São Paulo State, Brazil, from February to May 2006. The best results for all the studied variables were found when 100% CPE was used. A linear positive relation was observed between water increments and fresh and dry weight of both the aboveground part and roots. The use of a water depth corresponding to 100% CPE resulted in the maximum productivity (8,089.7 kg ha-1), and in the highest net annual return (R$57,637.87 ha-1).<br>Foi analisado o efeito de cinco lâminas de irrigação na produção do orégano, planta rica em óleo essencial, muito usada como tempero na preparação de alimentos. As lâminas de água foram baseadas na evaporação do tanque classe A (ECA) sendo: 0 ECA (sem reposição de água); 25 ECA; 50 ECA; 75 ECA e 100$ 57.637,87 ha-1)