Author(s)

Mahmoud El-Sharkawy¹, Talaat El-Beshsbeshy¹, Rania Al-Shal¹, Ali Missaoui^2*

¹Soil Science and Water Department, Faculty of Agriculture, Tanta University, Tanta, Egypt.
²Department of Crop and Soil Sciences, Institute of Plant Breeding Genetics and Genomics, University of Georgia, Athens, USA.

Salinity is a major impediment to crop production. This study was undertaken to compare the effect of seaweed extract, humic acid, and potassium sulfate nanoparticles in alleviating salt stress in Alfalfa (Medicago sativa L.). Seeds of ten alfalfa genotypes were germinated in a growth chamber at five salt concentrations (0%, 0.5%, 1.0%, 1.5%, and 2.00%). Salt concentrations above 1% reduced seed germination by more than 70% in most genotypes. One salt tolerant genotype (Mesa-Sirsa) and one salt sensitive (Bulldog 505) were selected and planted in greenhouse pots containing 2 kg of sand and subjected to two salt levels (10 and 15 dS· m^-1). Four treatments consisting of 1) control (Hoagland solution, no-salt), 2) seaweed extract at 4 Kg·ha^-1, 3) humic acid at 28 L· ha^-1, and 4) potassium sulfate at 300 Kg· ha^-1. Plant biomass was reduced under both salt concentrations in both genotypes, with a greater magnitude in the salt sensitive genotype. Application of seaweed extract resulted in higher relative water content and proline under both salt concentrations (10 and 15 dS·m^-1) in the salt sensitive genotype, and lower electrolyte leakage in both salt tolerant and salt sensitive genotypes, under both salt concentrations. Seaweed extract also resulted in higher catalase and SOD activities in both genotypes under 10 dS·m^-1. Catalase and SOD activities were associated with significantly (p < 0.01) reduced electrolyte leakage and increased shoot dry weight. Overall, seaweed extract seemed to have a positive effect in alleviating salt stress in alfalfa.

Biological Growth Stimulants, Humic Acid, Salt Stress, Seaweed Extract, Potassium Nanoparticles

El-Sharkawy, M. , El-Beshsbeshy, T. , Al-Shal, R. and Missaoui, A. (2017) Effect of Plant Growth Stimulants on Alfalfa Response to Salt Stress. Agricultural Sciences, 8, 267-291. doi: 10.4236/as.2017.84020.