Influence of salicylic acid on the growth of lettuce (<i>Lactuca sativa</i> var longifolia) during reduced leaf water potential

Abstract

Salicylic acid (SA) a signal molecule which is responsible for inducing defense mechanisms in plants and also has a protective role in stress sensitivity. A study was conducted to determine the effect of water deficit stress on the growth of Lactuca sativa L. (Lettuce) using SA (1 mM and 3 mM) during reduced leaf water potential. Plants were subjected to 7 days drought after four weeks of growth. Stressed plants exhibited a lower leaf water potential (ψ_w) of -0.499 MPa as compared with the control (ψ_w of -0.460 MPa). Plants with lower leaf ψ_w exhibited reduction in almost all the parameters studied: 1 mM SA foliar treatment caused increase of 8 % in plant height and 53.16 % in plant biomass. Foliar treatment of 3 mM SA of the relative water content stimulated 13 % increase in the growth as compared to the control plant which was statistically significant at P<0.05. Overall, SA in stressed plant exhibited higher ameliorative capacity which has the beneficial role of mediating defense response in plants under stress.

Keywords: Water stress, Salicylic acid, Growth, Lactuca sativa