Effect of Humic Acid Application on Growth and Chlorophyll Contents of Common Bean Plants (Phaseolus vulgarisL.)Under Salinity Stress Conditions
Pot experiment was carried out at the research greenhouseof the King Abdul-Aziz University, Jeddah, Saudi Arabia to study the effect of humic acid (HA)on biological aspects (plant height, number of leaves and root length and plant growth biomass as well as chlorophyll contents) of common bean plants (Phaseolus vulgaris L.) under salinity stress conditions at 15, 30 and 45 days after planting (DAP).Four different salinity levels (0, 25, 50 and 100 mMNaCl) combined with and without HA supply at 3g L–1) in split plot design with three replicates were assigned. Results indicated that HAsupply significantly increased plant height, number of leaves, root length, shoot and root fresh and dry weights as well as chlorophyll contents of common bean than control plants at 15, 30 and 45 DAP, respectively. While, no significant responding was found for shoot fresh weigh at 15 DAP and root fresh weight at 30 DAP.Salt stress significantly declined the plant morphological and fresh and dry biomass as well as chlorophyllcontents and leaf area in shoot leaves. Application of HA markedly mitigated the adverse effects of a biotic stress on all studied biological aspects. Lastly, humic acid supply significantly increased the relative growth rates of shoot and root under saline conditions and humic is considered as a promising soil amendment to overcome adverse effects of salinity stress.