Two field experiments were carried out at Experimental Farm, Fac. Agric., Zagazig University, Egypt to
study the influence of potassium fertilization rates (0.0, 25 and 50 kg K2O/faddan), humic acid rates (0.0, 1.0, 2.0
and 3.0 ml/l) and their combination treatments on growth parameters, yield components, chemical constituents and
glactomanan production of cluster bean plant. These trials were conducted during the 2017 and 2018 summer
seasons. Plant height, number of branches and leaves/plant and total dry weight /plant increased significantly by
using 50 kg K2O /faddan. Also, the highest values of pods number/plant, seed yield /plant and /faddan as well as
glactomanan yield/plant and /faddan were achieved with the same rate of potassium. Total chlorophyll content and
nitrogen, phosphorus and potassium percentages increased by the highest rate of potassium under study. Moreover,
the highest rate of humic acid (3 ml/l) recorded the maximum values of abovementioned parameters compared to the
other rates (1.0 and 2.0 ml/l) and control. The present study recommends that using potassium at 50 kg K2O /fad.
combined with 3 ml/l of humic acid for increasing seeds and glactomanan yields per faddan of cluster bean plants
grown under similar field conditions.