Abstract:
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.
