Pre-Harvest Desiccation of Bean with Diquat: Comparison Between Aerial and Ground Applications and Spray Volumes

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发表日期：

2025年5月20日

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Valter Vaz,
Vicente Bezerra Pontes Junior,
Maria Carolina Gomes Paiva,
Elisa Maria Gomes da Silva,
Guilherme Augusto de Paiva Ferreira,
Marcos André Barbosa de Carvalho,
Vinícius Pereira Cunha,
Ricardo Alcántara-de la Cruz,
Francisco Cláudio Lopes de Freitas

摘要

Desiccation is an important practice for uniformizing grain moisture and anticipating harvest. This practice is commonly used in crops like corn and soybeans; however, its adoption in bean cultivation is still low and relatively recent. This study aimed to evaluate the spray quality and defoliation efficiency of diquat applied at different spray volumes using drones and a CO₂ pressurized backpack sprayer, as well as its impact on the anticipation of mechanized bean harvest across two crop seasons (dry beans and winter beans). In all treatments, the applied dose of diquat corresponded to 400 g a.i. ha⁻¹. Spray droplet density increased 6.8-fold from 5 L ha^-1 (19.6 droplets cm^-2) to 20 L ha^-1 (134.3 droplets cm^-2), with a smaller increase (1.65 times) from 20 L ha^-1 to 200 L ha^-1 (222.4 droplets cm^-2). Coverage increased 6.6 times from 5 L ha^-1 (0.8%) to 20 L ha^-1 (4.96%), and 7 times from 20 L ha^-1 to 200 L ha^-1 (35%). At 4 and 7 days after application (DAA), defoliation was 10% lower with spray volumes of 5 and 10 L ha^-1 compared to the 15, 20, and 200 L ha^-1 volumes for dry bean, while for winter beans, defoliation ranged from 70 to 87%. Defoliation reached 100% at 11 DAA across all treatments in both dry and winter beans. In dry beans, the grain moisture content remained above 30% in all treatments at 6 DAA, while in winter beans, this percentage was only observed in the untreated control up to 12 DAA. In contrast, herbicide treatments reached harvestable moisture levels (18 − 17%) at 12 DAA, whereas the controls achieved harvestable moisture only at 26 DAA for dry beans and 24 DAA for winter beans. Pre-harvest desiccation allowed for an earlier harvest by 15 days for dry beans and 12 days for winter beans, regardless of the application method or spray volume. Herbicide treatments for desiccation, whether applied aerially or terrestrially, did not affect bean productivity. Diquat application via remotely piloted aircraft was effective for spray volumes ranging from 5 to 20 L ha^-1.