Abstract

Salt impedes plant growth and yield. This study was conducted to explore the effect of plant growth stimulants (seaweed extract, humic acid) and potassium sulfate in alleviating salt stress in barley (Hordeum vulgare L.). Initially, 10 barley genotypes were germinated in a growth chamber at five salt levels (0, 0.5, 1.0, 1.5, and 2.0%). Increasing salt concentration reduced germination percent, the speed of germination, and seedling weight. One salt-tolerant genotype (Sharqiya Estate) and one salt-sensitive genotype (Red Sea) were selected and planted in greenhouse pots containing 2 kg of sand, then subjected to 10 and 15 dS m^-1 salt levels using CaCl₂.2H₂O: NaCl (2:1) mixed with Hoagland solution. Four treatments consisting of (1) control (Hoagland solution), (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 were applied to each genotype under both salt levels. Seaweed extract resulted in higher shoot dry weight in the salt-sensitive genotype under both salt levels and maintained a low Na⁺/K⁺ ratio compared with humic acid and potassium sulfate. It also resulted in higher relative yield, relative water content, higher proline, and lower electrolyte leakage in the susceptible genotype at 10 dS m^-1, but the result was not different from humic acid and potassium sulfate treatments at 15 dS m^-1. Seaweed extract resulted in the highest catalase activity at 15 dS m^-1 in both genotypes, with higher magnitude in the salt-tolerant genotype. These results suggest that seaweed extract has potential in improving barley growth under salt stress.

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