Growth, Yield and Seed Nutritional Composition of Groundnut (<i>Arachis hypogaea</i> LINN) under Elevated Level of Soil Salinity

Abstract

A field experiment was conducted to investigate the effect of salinity on growth, yield and nutritional composition of Arachis hypogaea L. (groundnut) to evaluate its tolerance level. Plants were irrigated with 0 (control), 25, 50, 100, 150 and 200 mM NaCl solution. Mortality 30% and 50% occurred only at 150 and 200 mM concentrations respectively. Salinity significantly reduced shoot length, collar diameter, leaf area, root length and relative growth rate (RGR). Number of leaves, branches, roots, primary branches and root nodules/plant declined with increasing NaCl concentration. Fresh and dry mass of plant parts were significantly lower under saline soil than in control, which culminated in reduced total biomass. Leaf total chlorophyll decreased significantly from 100 mM NaCl to higher concentrations. Plants grown in saline soil had slightly higher root: shoot ratio than in control. Yield parameters decreased with increasing salt concentration except number of seeds/pod. Number of pods/plant differed from control significantly except at 25 and 50 mM NaCl. Pods produced at 200 mM lacked seeds. Salinity reduced seed mineral content except phosphorus (P), while percentage sodium (Na) increased with increasing salinity. Cl - and Na + accumulated in the seeds of salt-treated plants, which resulted in elevated level of percentage ash. Percentage fibre was not affected while carbohydrate, protein and lipid were reduced by soil salinity but at a non-significant level. Arachis hypogaea can tolerate and produce reasonable yield up to 50 mM NaCl concentration, but not fit for soil above 150 mM NaCl.