Effect of humic acid on the growth of seedling tomato (Solanum lycopersicum) and melon Cucumis melo)

Abstract

This study evaluated the effect of HS extracted from mineral coal on the growth of tomato (Solanum lycopersicum) and melon (Cucumis melo) plants to determine the role that humic substances (HS) play as promoters of plant growth. Three concentrations of HS were evaluated in 200 grams of soil. The fertilizer (urea 0.3%) and humic acid in concentrations of 0.05%, 0.1%, and 0.2% were added directly and at the same time to the amount of soil, using a control sample without the addition of humic acid. Increase measurements were made at three-day intervals up to 45 days. Plants treated with high concentrations of HS demonstrated a significant increase in roots (p>0.05). In both plants, the concentration of 0.2% in HS showed the greatest increase in growth, with the melon plant showing the greatest variation as time passed, with its highest peak in 36 days (13.1 ± 0.05cm) of the experiment, while in the tomato plant the maximum growth occurred in 30 days (9.2 ± 0.01 cm). The Dunnett test showed that there was no statistically significant difference between the control and the concentrations of 0.05% and 0.1% (p>0.05), while among the control and the soil sample with a concentration of 0.2% there was a statistically significant difference (p<0.05). The results show a notable influence of humic acid on the growth of the studied plants, especially at high concentrations.
 Keywords: fertilizer, horticulture, humic acid, soils.

Influence of the application of humic substances on the growth of watermelon and melon seedlings

“…The use of humic substances in tropical Cerrado soil improves growth and development, biomass and quality of watermelon and melon seedlings. Reports have demonstrated that HS are able to regulate plant growth due to their biostimulation effects similar to auxins (Zandonadi et al, 2007;Canellas & Olivares, 2014;Olaetxea et al, 2015;Olivares et al, 2017;Qin & Leskovar, 2020b), with structural and physiological changes in roots and shoots (Tarón Dunoyer et al, 2022). This fact corroborates the results of increased plant height and stem diameter reported herein, in which the magnitude of the effects on seedling growth and development are induced by the contribution of HS.…”

“…Seedlings assimilate the absorbed nutrients and use them for their metabolism and biomass production. Some changes induced by HS in the nutritional status of plants include the up-regulation of the gene expression of some of the nutrient transporters located in the plasma membrane, which promote the absorption of secondary ions and nutrients (Olaetxea et al, 2019;Pizzeghello et al, 2020), thereby increasing nutrient use efficiency (Tarón Dunoyer et al, 2022). Jing et al (2020) have also reported improved growth of maize seedlings with the use of HS.…”