Abstract
Humic acid application has considerable effect on crop productivity in sandy soils due to its unique biochemical characteristics. This study was conducted to optimize the mungbean production in arid conditions of Saudi Arabia by tracing out most suitable combination of levels and types of humic acid (HA) application. In this two-year study, mungbean cultivar 'NM-2006' collected from NIAB, Pakistan, was grown with HA application in liquid and solid forms at the rates of 0,20,40 and 60 kg ha(-1). Both types and levels of HA application had significant effect on growth, gas exchange traits, photosynthetic pigments, yield and quality of mungbean while the interactive effect of types and rates of HA remained non-significant for all traits in both years. Among types, solid form of HA significantly improved plant height, leaf area index, root and shoot dry weights, gas exchange traits, photosynthetic pigments, yield and related traits, and grain quality of mungbean compared with its liquid form. Likewise, higher levels of HA, 60 kg ha(-1) was the best, gradually improved all above stated traits of mungbean in both years. Similarly, SEM based evaluation revealed notable changes in the distribution of leaves mineral content; however, this change was maximum for solid HA application particularly at 60 kg ha(-1). In conclusion, HA application at 60 kg ha(-1) in solid form seemed a viable option to improve growth, gas exchange traits, photosynthetic pigments, and grain yield and quality of mungbean in sandy soils of arid climate of Saudi Arabia. (C) 2020 Friends Science Publishers