Effect of Humic Acid on Some Morphological and Biochemical Properties and Nutrients Concentration of Aloe vera under Salinity Stress

The objective of this study was to investigate the effects of humic acid and salinity on the growth and chemical composition, and some biochemical properties of Aloe vera. The experiment was conducted as a factorial arranged in a completely randomized design with three replications under greenhouse conditions. Treatments consisted of three salinity levels (0, 60, and 120 mM) and three humic acid levels (0, 150, and 300 mgL-1). Some plant properties such as height, root length, leaf and root dry weights, total chlorophyll content, the ability of reactive oxygen species scavenging (DPPH: Diphenylpicrylhydrazyl), and some nutrients concentration were measured. The results showed that application of 120 mM salinity significantly decreased plant height (7%), root length (47%), leaf and root dry weight (26, 50%), total chlorophyll content (45%), leaf P (15%) and K (23%) concentrations, and significantly increased ability of reactive oxygen species scavenging (DPPH) (20%) and Na concentration (113%). Application of 300 mgL-1 humic acid significantly increased plant height, root length, root dry weight, total chlorophyll content, and DPPH in Aloe vera. Interaction of salinity and humic acid did not have any significant effect on the studied properties.