Tolerância do sorgo granífero ao herbicida tembotrione

Abstract

RESUMO -O sorgo granífero é uma espécie de destaque perante as culturas utilizadas em sucessão na região dos cerrados. No entanto, não há nenhum herbicida seletivo a essa cultura registrado para o controle de gramíneas infestantes. Dessa forma, o presente trabalho teve por objetivo avaliar a seletividade do herbicida tembotrione aplicado em pós-emergência da cultura do sorgo granífero cultivar AG-1040. O ensaio foi disposto no delineamento de blocos ao acaso em esquema fatorial 5 x 3, com quatro repetições. Os tratamentos corresponderam a cinco doses do herbicida tembotrione (0, 42, 88, 126 e 168 g de i.a. ha -1 ), aplicados em três estádios fenológicos da cultura: três, cinco e oito folhas completamente expandidas. Foram avaliados os níveis de intoxicação, a altura das plantas, a biomassa seca da parte aérea e o rendimento de grãos da cultura. O herbicida tembotrione apresentou maior intoxicação quando aplicado nos estádios mais precoces da cultura do sorgo. Mesmo com os diferentes níveis de seletividade, que podem variar em função da dose e da época de aplicação, o cultivar de sorgo estudado apresentou tolerância satisfatória ao tembotrione, sugerindo potencial de utilização desse herbicida nessa cultura. Palavras-chave: Sorghum bicolor, seletividade, inibidores de HPPD.ABSTRACT -Grain sorghum is a prominent species among the crops used in succession in the Brazilian savanna region. However, no herbicide with selectivity to sorghum is currently registered for grass weed control. Thus, this study aimed to evaluate the selectivity of tembotrione applied in post-emergence on grain sorghum crop (cultivar AG-1040). The experiment was laid out in a randomized block design in a 5 x 3 factorial with four replicates. The treatments were five tembotrione doses, 0, 42, 88, 126 and 168 g a.i. ha -1 , applied at three phenological stages of the crop: three, five, and eight expanded leaves. The variables evaluated were phytotoxicity level, plant height, shoot dry biomass and crop grain yield. Tembotrione showed higher phytotoxicity potential when applied at the early stages of sorghum growth. In spite of the different selectivity levels, which may vary depending on the dose and time of application, the sorghum cultivar studied showed a satisfactory tolerance to tembotrione. The results obtained indicate that this herbicide has the potential to be used in grain sorghum crop.

Potential Use of Tembotrione (HPPD-Inhibitor Herbicides) in Grain Sorghum

“…More evident reductions of sorghum growth were observed when the herbicide application was carried out at earlier growth stages (3 leaves stage) (Dan et al, 2010a). Injury reduction was twice as much more pronounced when compared to applications at 5-and 8-leaf stage.…”

“…Studies carried out with doses ranging from 0 to 168 g ha -1 , demonstrated grain yield reductions of 25, 16 and 15% for applications performed at 3, 5 and 8 expanded leaves stages, respectively ( Figure 5) (Dan et al, 2010a). (Dan et al, 2010a).…”

“…Based on the effect of crop dose-response in relation to stages when the herbicide application was performed, results so far indicate that earlier applications are more harmful to grain sorghum development (Dan et al, 2010a). In this study, they evaluated the effect of tembotrione (0,42,88,126, and 168 g ha -1 ) applied to three phenological stages of sorghum (S1: 3-leaf stage, 15 days after emergence; S2: 5-leaf stage, 23 days after emergence; S3: 8-leaf stage, 31 days after emergence).…”

Weed Phytosociological and Floristic Survey in Agricultural Areas of Southwestern Goiás Region

“…Soil cover by the species in question, along with sorghum stover on the surface, may cause allelopathy (Vidal & Trezzi, 2004) and has influenced the smaller number of species in the study area. Additionally, sorghum presents limitation of grass herbicides for use in postemergence (Archangelo et al, 2002;Dan et al, 2010), which favors the simultaneous development of the C. echinatus species with the culture, and its spread in the growing area.…”

Residual activity of herbicides used in soybean agriculture on grain sorghum crop succession

“…In Brazil, sorghum has been highlighted mainly as second crop, being indicated as a viable alternative in corn replacement as succession crop, both for straw formation to the direct planting system and for grains and fodders production (Dan et al, 2010).…”