Plants growth, water relations and photosynthesis of two bean genotypes <i>Phaseolus vulgaris</i> L. treated with NaCl and fluridone

Abstract

Phaseolus vulgaris has a great variability regarding the tolerance to salinity. In this work, we used fluridone as a tool to study the herbicide’s effect on two salt stressed bean genotypes since fluridone alters photosynthetic pigments and blocks normal abscisic acid biosynthesis under salinity. Plants from two bean genotypes were subjected to different NaCl concentrations during three days. Thereafter, half of these plants were treated by fluridone and then were harvested three days later. Growth, water relations, stomatal conductance and photosynthesis were reduced after NaCl application. In general, differences were highly significant for salt treatments up to 60 mM. Decreases in photosynthetic rates under salinity were attributed partly to reduce stomatal conductance (r² = 0.87**), partly to membrane alterations (r² = 0.69**) and partly to reduced photosynthetic pigment concentrations (r² = 0.56**). Thus, when plants of both genotypes were subjected to fluridone, they showed higher sensitivity to a subsequent salinity than stressed plants that had not been exposed to the inhibitor; the negative effects were most evident with 60 mM NaCl concentration and in the presence of 90 mM NaCl, almost all physiological activities were suppressed. The superiority of the genotype Tema against Djadida genotype was attributed to quantitative rather than qualitative physiological response differences.

Keywords: Salinity, fluridone, bean, growth, photosynthesis, stomatal conductance

African Journal of Biotechnology Vol. 12(24), pp. 3811-3821