Foliar Spray of Humic Substances on Seedling Production of Papaya (Pawpaw)

The objective of this research was to study the effect of humic substances on seedling production of papaya cv. Formosa. A completed randomized blocks design with five treatments (humic acid doses) was adopted, with five repetitions of 10 seedlings each, with a total of 250 seedlings. The following humic substances doses studied were 0 (unsprayed), 7.5, 15, 22.5 and 30 mL m2 (0, 0.40, 0.80, 1.19 and 1.59 mL seedling-1), were sprayed at 15, 25 and 35 days after sowing. At the end of the experiment (45 days after sowing) the following variables were recorded: (1) plant height; (2) stem diameter; (3) dry weight of shoots and roots; (4) root length; (5) root volume and (6) Leaf Chlorophyll. Thus, our studies demonstrate that: (1) humic substances sprayed positively affect aerial part and root system of papaya seedlings and (2) seedling quality of papaya are improved by humic acids foliar spray although further studies are need to obtain a dose recommendation.