Effect of Humic Acid and Amino Acid Foliar Applications on the Growth Characteristics, Yield, and Fruit Quality of Tomato (Solanum lycopersicom L.)

The foliar application of organic compounds and biofertilizers is a suitable method for optimal nutrition of plants. This study aimed to investigate the effect of the foliar application of humic acid and amino acids on the quantitative and qualitative characteristics of tomato fruits under field conditions in 2019-2020. The treatments included the control, three concentrations of humic acid (1, 2, and 3 g L-1), three concentrations of amino acids (2, 4, and 6 g L-1), and combined treatment of humic acid (3 g L-1) + amino acid (3 g L-1). The results showed that the effect of the treatments on plant fresh and dry weight, leaf chlorophyll content, fruit number, total yield and marketability, and fruit quality except the fruit length was significant. The highest leaf pigment content, fruit number (30.3 per plant), yield (50.3 tons ha-1), and marketable yield (43.1 tons ha-1) were related to the combined treatment of humic acid + amino acids. Furthermore, the highest fruit quality characteristics such as firmness, TSS, vitamin C, anthocyanin, and potassium were observed for the humic acid at 3 g L-1, which showed no significant difference with the combined treatment of humic acid + amino acid. In general, it was found that the foliar application of organic compounds improved the yield, yield components, and fruit quality of tomato plants, so that the combined application of humic acid (3 g L-1) + amino acids (3 g L-1) had the highest effect on improving the quantitative and qualitative characteristics of tomato plants.