Interactive Impacts of Soil Salinity and Jasmonic Acid and Humic Acid on Growth Parameters, Forage Yield and Photosynthesis Parameters of Sorghum Plants

Abstract Soil salinity, whether natural or induced, is one of the most serious environmental stresses limiting crop production in the world. In this study, the impacts of foliar application of jasmonic acid and soil amendment with humic acid on growth parameters, forage yield, chlorophyll content, and physiological characteristics of forage sorghum were studied to mitigate salinity in combination with different concentrations under greenhouse conditions. The plants were subjected to salinity at 0.26 (S0), 2.3 (S1), and 4.7 dS m−1 (S2), different rates of humic acid at 0, 373.21, and 746.42 kg HA ha−1, were designed as HA0, HA1, and HA3 respectively, and jasmonic acid at 0 (JA0), 5 (JA1) and 10 mM (JA2) as a foliar application. Salinity stress had detrimental effects on all the parameters and they were gradually reduced with increased salinity. Applications of humic acid and jasmonic acid mitigated the inhibitory effects of salt stress on these variables at all salinity levels. The rate of HA1 increased fresh weight, chlorophyll a and b, transpiration rate, relative humidity, stomatal conductance to CO2 and stomatal conductance by 14.2%, 45.6%, 41.8%, 50.2%, 11.2%, 32.1% and 18.5% respectively, under S2. In addition, jasmonic acid at JA1 treatment increased plant height, elongation percentage, fresh and dry weight, chlorophyll a and b, relative humidity, and stomatal conductance to CO2 under S2. Interaction between JA2 and HA1 improved all the traits except plant height, elongation percentage, and leaf area, suggesting that JA and HA can reduce the negative effects of salinity on the sorghum. In conclusion, jasmonic acid and humic acid treatments improved the forage sorghum performance under salinity conditions through anthesis stages, better photosynthetic and growth parameters, which reduced the impacts of salinity, and resulted in better plant growth and biomass production, and help the plant to improved salt tolerance.