Growth and Yield of Lettuce (Lactuca sativa var. crispa) in Varying Irrigation Water Salinity and Leaching Fractions

Abstract

This study aimed to determine the response of yield and yield parameters of the ‘Cospirina’ lettuce plant, known to be moderate salinity tolerant, to different levels of salt water applications and different leaching rates in the Eastern Mediterranean Region of Hatay Province, Türkiye. Lettuce was irrigated at three different irrigation water salinity levels (EC0 = 0.5 dS m^-1-control, EC2 = 2 dS m^-1, EC4 = 4 dS m^-1) and four different leaching fractions (LF0 = 0%, LF1 = 10%, LF2 = 20%, LF3 = 30%). Irrigation water salinity was adjusted by adding different amounts of NaCl salt to the tap water (EC0, control) with an EC value of 0.5 dS m^-1. Plant water consumption (PWC) increased as the leaching fraction increased but decreased as salinity increased. PWC ranged from 7.32 – 10.5 L for EC0, 7.0 – 8.46 L for EC2, and 5.0 – 6.46 L for EC4. The mean water use efficiency (WUEy) was calculated as 31.43 g L^-1, 32.12 g L^-1, and 34.77 g L^-1 in EC0, EC2, and EC4, respectively. Lettuce yield decreased with increasing soil salinity and the leaching fraction. Yield ranged from 182 g plant^-1 (EC4LF0) to 282 g plant^-1 (EC0LF2). When soil salinity increased from 0.82 dS m^-1 (EC0) to 1.31 dS m^-1 (EC2) and 2.09 dS m^-1 (EC4), yields decreased by 10% and 28%, respectively. Increasing salinity significantly decreased the root length, root width, leaf number, number of commercial leaves, leaf width, leaf length, and biomass, while commercial head length and commercial head diameter remained unaffected.