Enhancing mechanized harvesting of mungbean (<em>Vigna radiata</em> L.) with defoliation and desiccation using chemical agents in Sri lanka

In Sri Lanka, mungbean production faces labour shortages and high costs, especially during harvesting. Desiccants and defoliants are essential for drying and preparing crops for mechanical harvesting. The study aimed to identify the most effective chemical agent (defoliant or desiccant) and its optimal concentration for mechanical harvesting, by testing NaCl, Urea (both at 0.25 M, 0.5 M, 0.75 M, and 1 M), and Ethrel at 10⁻⁴ M as separate treatments. It also aimed to evaluate the best timing for applying 0.5 M (40 g/L) NaCl, identified as the most effective in the previous experiment, to maximize harvested yield and assess its long-term effects on soil pH and electrical conductivity (EC). Although the treatments significantly (p < 0.05) impacted seed lightness and germination percentages of seeds immediately after harvesting, with no significant difference (p > 0.05) in the germination one month after harvesting. The study found that 0.5 M NaCl was the most efficient treatment for defoliating and desiccating the mungbean MI 6 variety, achieving significantly highest desiccation and defoliation percentages, maintaining significantly highest germination percentage of seeds and having minimal impact on soil pH and EC. The significantly highest yield was obtained by applying 0.5 M NaCl three days after the due date for the first pick. 0.5 M NaCl application showed minimal impact on soil chemical properties, with no significant changes in pH and EC levels observed over long-term monitoring. Thus, 0.5 M NaCl can be effectively utilized to desiccate and defoliate mungbean plants for easy mechanical harvesting.