Selectivity of nicosulfuron and atrazine on different corn hybrids | Selectivity of nicosulfuron and atrazine on different corn hybrids

English. Nicosulfuron and atrazine are herbicides widely used for weed control on corn crops. However, itsselectivity is often fairly questionable due to genotypic variability of hybrids in the market. In thiscontext, this study aims to assess both nicosulfuron selectivity and atrazine mixture in 34 corn hybrids.Treatment was arranged in a completely randomized block design, in a split-plot scheme (34x5)with four replicates, in which corn hybrids constituted the plots and herbicides the subplots. 34 cornhybrids were submitted to four herbicide treatments: nicosulfuron (rates of 50 and 60 g ha-1) andnicosulfuron + atrazine (20 + 1500 and 40 + 3000 g ha-1) as well as a non treated check for each hybrid.Application was performed at 19 days (V4/V5) after corn emergence. Phytointoxication symptomswere assessed at 7; 14 and 21 days after treatment application. One thousand grain weight andhybrid yield were also determined. Based on the results, it was observed that the phytotoxic effectsof nicosulfuron+atrazine (40+3000 g ha-1) were enough to reduce the weight of 1000 seeds in hybridsBMX61, BMX750, and NB7405. Nevertheless, herbicide treatments, either alone or associated withatrazine, were selective to the 34 genotypes studied.

Portuguese. Nicosulfuron and atrazine are herbicides widely used for weed control on corn crops. However, itsselectivity is often fairly questionable due to genotypic variability of hybrids in the market. In thiscontext, this study aims to assess both nicosulfuron selectivity and atrazine mixture in 34 corn hybrids.Treatment was arranged in a completely randomized block design, in a split-plot scheme (34x5)with four replicates, in which corn hybrids constituted the plots and herbicides the subplots. 34 cornhybrids were submitted to four herbicide treatments: nicosulfuron (rates of 50 and 60 g ha-1) andnicosulfuron + atrazine (20 + 1500 and 40 + 3000 g ha-1) as well as a non treated check for each hybrid.Application was performed at 19 days (V4/V5) after corn emergence. Phytointoxication symptomswere assessed at 7; 14 and 21 days after treatment application. One thousand grain weight andhybrid yield were also determined. Based on the results, it was observed that the phytotoxic effectsof nicosulfuron+atrazine (40+3000 g ha-1) were enough to reduce the weight of 1000 seeds in hybridsBMX61, BMX750, and NB7405. Nevertheless, herbicide treatments, either alone or associated withatrazine, were selective to the 34 genotypes studied. Seletividade de nicosulfuron e atrazine em diferenteshíbridos de milhoNicosulfuron e atrazine são herbicidas de dupla aptidão mais utilizados no manejo de plantasdaninhas na cultura do milho. No entanto, sua seletividade é bastante questionada em função davariabilidade genotípica dos híbridos presentes no mercado. Neste contexto, objetivou-se com estetrabalho avaliar a seletividade do herbicida nicosulfuron e da mistura com atrazine em 34 híbridos demilho. O ensaio foi implantado em delineamento de blocos casualizados em esquema de parcelassubdivididas 34 x 5, com quatros repetições, adotando-se os híbridos na parcela e herbicidas nasubparcelas. Os 34 híbridos de milho foram submetidos a quatro tratamentos herbicidas, sendoeles: nicosulfuron nas doses de 50 e 60 g ha-1 e nicosulfuron + atrazine nas doses 20 + 1500 e 40 +3000 g ha-1, além de uma testemunha sem herbicida para cada híbrido. A aplicação foi realizada19 dias (V4/V5) após a emergência do milho. Foram avaliados os sintomas de fitointoxicação aos7, 14 e 21 dias após a aplicação dos tratamentos. Determinou-se, ainda, a massa de mil grãose a produtividade dos híbridos. Com base nos resultados, constatou-se que os efeitos fitotóxicosda mistura nicosulfuron+atrazine (40+3000 g ha-1) foi suficiente para reduzir a massa de mil grãosnos híbridos BMX61, BMX750 e NB7405. Entretanto, os tratamentos herbicidas, sejam eles na formaisolada ou associada ao atrazine foram seletivos aos 34 genótipos estudados.