Avaliação de herbicidas pós-emergentes nas características agronômicas de linhagens e parentais de milho

Abstract

Maize (Zea mays L.) is one of the most important cereals grown in the whole world. The discovery of hybridization effects on vegetable species, as well as the yield increase given by hybrid maize, boosted the seed production system through crossings of endogamic lines and progenitors. One of the major obstacles for the success on seed production is weed competition for water and nutrients. Weed control is done with cultural practices, and one of the most important is the use of herbicies. However, little is known about the effect of the herbicides on maize genotypes used for seed production. This study evaluated the effect of the herbicides nicosulfuron and atrazine on 10 maize genotypes, 6 of them were endogamic lines and the other 4 were progenitors, in the county of Paranapanema, state of São Paulo. The trial was located in the coordinates 23°29'18.1''S and 48°45'47.8''W; treatments consisted of the aplication of nicosulfuron (dose: 60g a.i. ha-1), the mixture of nicosulfuron (dose: 30g a.i. ha-1) + atrazine (dose: 1.2 kg a.i. ha-1) or the application of atrazine alone (dose: 2.4 kg a.i. ha- 1), while the control consisted of the treatment with no herbicides, only manual hoeing. The maize genotypes analyzed presented different reactions to the herbicides tested, presenting chances in the cycle and even yield depression, reinforcing the importance of the study of the effects of each product on each genotype before using them in seed production fields.