Effects of timing of nitrogen side-dressing application in sunflower with and without weed control.

• Autor(a) principal: Fleck, Nilson Gilberto
• Data de Publicação: 2014
• Outros Autores: Silva, Paulo Régis F. da
• Tipo de documento: Artigo
• Idioma: por
• Título da fonte: Pesquisa Agropecuária Brasileira (Online)
• Texto Completo: https://seer.sct.embrapa.br/index.php/pab/article/view/15864
• topic: Helianthus annuus; agronomic traits; yield componenis; cultural control; Helianthus annuus; características agronômicas; componentes do rendimento; controle cultural.

With the objective of determining the effects of timing of nitrogen (N) side-dressing application on grain yield and other agronomic traits of sunflower (Hlianthus annuus L.) 'cv. Contisol 711' and to evaluate the possible interaction that it could exert on weeds as a cultural method of control, this research was carried out at Guaíba, RS, Brazil, in the growing seasons of 1985/86 and 1986/87. Treatments were composed by presence and abscence of weeds, application of 80 kg/ha of N, at V4, V10_11 , R1 and R3 growth stages, according to the scale of Schneiter and Miller (1981), and by a check without N application. Weed presence during all plant cycle decreased grain yield by 12%. The response of sunflower to the timing of N application occurred only in the 1986/87 growing season, when grain yield decreased linearly as the timing of N application was delayed from V4 to R3 stage. Only in the second growing season N application reduced grain oil content in relation to the check treatment. Timing of N application did not affect this characteristic. Manipulation of timing of N application could not be considered an efficient auxiliary method in sunflower weed control.