| Abstrakt: |
Preharvest desiccation of rice (Oryza salivaL.) would improve timeliness of harvest and allow more efficient and faster combining of the grain. Field studies to determine the suitability of diquat (6,7‐dihydrodipyrido [1,2‐α:2′,1′‐c]pyrazinediium ion), glyphosate [N‐(phosphonomethyl)glycine], paraquat (1,1′‐dimethyl‐4,4′‐bipyridinium ion), and sodium chlorate as preharvest desicants for rice were conducted for 2 years. Diquat at 0.28 kg/ha and paraquat at 0.14 kg/ha resulted in good leaf desiccation in 2 days under the hot cloudy conditions of the studies. Three days were required for desiccation when diquat at 0.14 kg/ha was applied, while 4 days were required when sodium chlorate at 5.04 kg/ha was applied. Glyphosate at rates up to 1.12 kg/ha did not adequately desiccate rice leaves in 7 days under the conditions of this study. When applied to rice with grain moisture of 22%, diquat at 0.56 kg/ha, paraquat at 0.14 kg/ha, and sodium chlorate at 5.04 kg/ha significantly reduced grain moisture 3 days after application. Diquat at 0.14 kg/ha and glyphosate at 1.12 kg/ha required 7 days to reduce grain moisture. Only paraquat at 0.14 kg/ha 7 days after application to 16.5% moisture rice reduced grain moisture. Whole kernels after milling were slightly reduced by diquat at 0.28 and 0.56 kg/ha, paraquat at 0.14 kg/ha and sodium chlorate at 5.04 kg/ha, all applied to 25% grain moisture rice 7 days before harvest. None of the desiccants evaluated reduced grain yield, seed germination, or 1,000 grain weight. These results indicate that diquat, paraquat and sodium chlorate may have potential as preharvest desiccants for rice. |
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