Environmental conditions affect herbicide selectivity on paddy rice in Southern Brazil

Abstract

Rice yield in Southern Brazil has increased linearly over the years. Early season sowing is the primary contributor to rice yield increase in Southern Brazil. However, that practice might expose rice seedlings to the risk of low-temperature stress, which can enhance herbicide injury and reduce rice yield. This research evaluated the effect of sowing dates on herbicide selectivity and agronomical rice traits. We conducted field experiments during the 2010/11 and 2011/12 growing seasons in Capão do Leão, RS, Brazil. The experimental design was a complete randomized block with a factorial arrangement. Factor A was early-sowed (in September) and late-sowed (in November); factor B was herbicide treatment (bispyribac-sodium, cyhalofop-butyl penoxsulam, metsulfuron-methyl, and nontreated check). Rice response to herbicide treatments differed between years. In 2010/11, bispyribac-sodium, penoxsulam, and metsulfuron-methyl injured rice only on early-sowed. In both years, early sowing rice promoted higher yield potential despite herbicide injury. The injury caused by the herbicides bispyribac-sodium, penoxsulam and metsulfurom-methyl was transient did not lead to yield losses. Cold temperature close the application increases the injury of ALS herbicides.

Resposta do arroz irrigado a herbicidas em função do sombreamento e da inundação do solo

“…Resultado similar foi verificado por GALVIN et al 2022 em plantas de arroz 7 DAA, onde houve atraso no crescimento e nanismo de plantas com a utilização do inibidor de Protox oxifluorfen, para controle de plantas espontâneas de Oriza sativa na Califórnia. A intensidade da injúria foi reduzindo com o tempo e aos 28 DAA atingiu níveis inferiores a 10%, o que corrobora com o descrito por outros trabalhos que apresentaram essa recuperação natural das plantas a fitotoxicidade por herbicidas (MARTINI et al 2023, GALVIN et al 2022. A aplicação de apenas IM resultou na menor fitotoxicidade durante as avaliações (Tabela 1).…”