Crescimento da alface americana em função dos ambientes, épocas e graus-dias

Abstract

This research was conducted in a protected (AE) and a natural environment (AN), and aimed to evaluate the development and to quantify the effect of the meteorological elements and degree-days on the growth of the lettuce crop in two different seasons. The research was conducted at the ";;Empresa Estadual de Pesquisa Agropecuária da Paraíba";; - EMEPA, during the periods of 30/05 to 08/08/2007 (Winter) and 10/09 to 22/11/2007 (Spring) using cabbage lettuce ";;Irene";;. Average air temperatures in AE were higher than the temperatures in AN, for both experiments. Values of the average relative humidity of air obtained in AN were always higher than AE. The higher values of degree-days in AE resulted in the reduction of the crop cycle and the total dry phytomass of the lettuce. The protected environment had a micro-climate favorable to the crop growth, anticipating the harvest of the lettuce by a week, in the two cultivation seasons, and the winter offered the best energy conditions for the growth and development of this cultivar.