Tolerância do arroz irrigado a herbicidas em função do tratamento de sementes com dietholate

Abstract

Weed control is one of the most important factors on rice yield potential expression. In this context, the use of herbicides is highlighted to be more profitable method of weed control. Clearfield™ technology, as well as seed treatment with dietholate aiming to increase the selectivity of the herbicide clomazone rice are viable and efficient tools for the control of many weeds. However, the association of dietholate-clomazone can cause a decrease on post-emergence herbicide selectivity. Dietholate is a known Cytochrome P450 inhibitor, that playsrole on herbicide metabolism in plants that might cause great injury to rice seedlings and consequently reduce crop productivity. The objective of this study was evaluate the toxicity of postapplied herbicides on rice cultivars with and without dietholate combined with clomazone in pre-aplication. The hybrids Avaxi and Arize CL showed similar tolerance and physiological characteristics to imazapic + imazapyr: Net photosynthesis rate, stomatal conductance and transpiration of hybrid Avaxi CL are influenced by higher rates of (imazapic + imazapyr). Early sowing date done in September can adversely affect the selectivity of bispyribac-sodium, and penoxsulam profoxydim on rice cultivar IRGA 424.