Effect of Plant Growth Stimulants on Alfalfa Response to Salt Stress

Abstract

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 . 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.

Can Humic Substances Improve Soil Fertility under Salt Stress and Drought Conditions?

“…Our results contrast with those of Pettit (2004), who stated that humic substances neutralize pH. In soils affected by salts, there might be a reduction in pH and not a neutralization, accompanied by a reduction of fertility in the presence of humic substances (especially those with more humic acid concentration), a fact also recently observed by another research (El‐Sharkawy et al, 2017).…”

Effects of seaweed ( Ulva lactuca ) and freshwater ( Spirogyra sp.) algae extracts on the salt tolerance of the bean ( Vicia faba L.)

“…The work of El-Sharkawy et al (2017) on seaweed extracts highlighted the improvement of the alfalfa response to salinity stress, this improvement resulted in a decrease in electrolyte leakage; these same authors showed that high saline concentrations significantly increase electrolyte leakage compared to the control (non-saline).…”

Strain-Specific Biostimulant Effects of Chlorella and Chlamydomonas Green Microalgae on Medicago truncatula

“…These studies especially focus on the mechanisms of these microorganisms in root development and nodulation but pay little attention to the plant architecture and leaf morphology. A few studies exist on plant growth stimulating seaweed extracts applied under normal [36] and salt stressed [35] conditions. However, no study has used living green microalgae cells for growth stimulation of legumes.…”

“…In addition, they sequester carbon, which makes them promising candidates for fuelwood. Although most studies on legumes focus on their interaction with plant-growth-promoting rhizobacteria (PGPR), a few studies evaluate the effect of seaweed and MA biostimulants on these plants including Phaseolus vulgaris [7,30], Vigna radiata [6,31,32], Glycine max [33,34] and Medicago sativa [35][36][37]. In plant biostimulant studies, MA were administered to plants in the form of extracts [32,[38][39][40], dry biomass [41][42][43][44][45], spent medium/supernatant [46,47], whole cultures [46] as well as cell suspensions [47,48], and desirable results were achieved.…”