MORPHOLOGICAL AND PHYSIOLOGICAL INDICES AND LETTUCE (Lactuca sativa L.) YIELD IN NATURAL AND PROTECTED AMBIENTS

ABSTRACT

The objective of this research was to evaluate and to compare the growth and yield of lettuce. Two experiments were conducted in the experimental area of Physics and Biophysics Department of the Biosciences Institute of Paulista State University, Botucatu Campus (22º54'S; 48º27'W; 850m) in the summer of 1995/96 and winter of 1996, with three plots of 7m x 5m, where two were located in the greenhouse (tunnel type), in the East-West and North-South directions, and the other plot under natural or external conditions. The absolute growth rate in the summer was 5.22 g.week^-1 in the greenhouse, and 3.97 g.week^-1 in the external plot, while in winter these values were 3.02 e 2.8 g.week^-1. The net assimilation rate suffered more influence from greenhouse conditions than from year period. The crop growth rate showed clearly that under greenhouse conditions the growth rate was quicker. According to the yield results, it is concluded that the protected environments had a influence in the two-year periods, with little advantage for the winter.

Key words: growth; dry weight; leaf area; greenhouse