Foliar Spray of Humic Substances on Seedling Production of Watermelon cv. Crimson Sweet

The objective of this research was to study the effect of humic substances on seedling production of watermelon cv. Crimson Sweet. A completed randomized blocks design with five treatments (humic substances doses) was adopted, with five repetitions of 10 seedlings each, with a total of 250 seedlings. The following humic substances doses were studied 0 (unsprayed), 7.5, 15, 22.5 and 30 mL m-2 (0, 0.40, 0.80, 1.19 and 1.59 mL seedling-1), were sprayed at 10, 15 and 20 days after sowing. At the end of the experiment (25 days after sowing) the following variables were recorded: plant height; stem diameter; (3) dry weight of shoots and roots; root length; root volume; and leaf chlorophyll. Our studies demonstrate that: (1) foliar spray of humic substances enhances aerial part and root system of watermelon seedlings; (2) 22.5 mL m-2 dose of humic substances for foliar spray could be recommended for production of watermelon seedlings.