Abstract
The aim of this study was to determine how different phosphite and phosphate rates applied together affect the growth and morphology parameters in cucumber plants as well as to characterize the nutritional and physiological state of phosphorus (P). Different foliar application rates of phosphite were applied to analyze subsequent biomass production, the relative growth rate, morphological parameters, P bioindicators, P forms, and P-use efficiency. The data suggest that the application of phosphite as a P fertilizer at a rate of ≥0.5 mM would be an appropriate and effective strategy under suboptimal conditions of phosphate in the growth medium, represented by 0.5 mM in our work, as it improved the growth parameters, number of flowers, leaf area, nutritional state of P, incorporation of P in structural organs, and P-use efficiency by the plant. The results indicate that the validity of the foliar use of phosphite as a P fertilizer in cucumber plants was subject to phosphate availability in the culture medium.