LETTUCE YIELD RESPONSE TO SALINITY OF SPRINKLE IRRIGATION WATER
Abstract
The objective of this work is to study the effect of saline water on the yield of lettuce (Lactuca sativa L., var. longifolia Lam., cv. Nevada), under an experimental design known as double sprinkler line source (DLS), in two different soil types. A saline gradient was created, shown by an electrical conductivity from 1 up to 8 dS/m, and a precise distribution of the salt with a minimal experimental area was obtained. Experiments were carried out in the Campus of Gambelas, University of Algarve, Fare, South Portugal. Lettuce yields were expressed in ton/ha and in fresh weight per plant. It is concluded the main several aspects: 1 - A steep yield reduction from 1 up to 2 dS/m; 2 - A slow yield reduction from 2 up to 5 dS/m; 3 - From 5 up to 8 dS/m yield is very low and near constant. Regression curves had r(2) values not lower than 0.80.