Selectivity of Herbicide Associations with Chemical Protector in the Treatment of Sweet Sorghum Hybrid Seeds

Abstract

ABSTRACT Sweet sorghum culture is an alternative to sugar and ethanol production. With the aim of evaluating herbicide tank-mix selectivity associated or not to sweet sorghum seed treatment with naphthalic anhydride, two experiments with ESX5200 and EJX7C5110 hybrids were performed in red oxisol (clayey) field conditions, in the municipality of Campo Mourão, Paraná state. A randomized block design was used, with 4 x 2 factorial scheme, with four replications. The first factor represented three herbicide associations and a control sample without herbicide, and the second factor was constituted by the absence or presence of seed treatment with naphthalic anhydride (5.0 g kg-1). Herbicide treatments were tank-mixes of atrazine + S-metolachor (2,640 + 480 g ha 1) (pre-emergence); atrazine + S-metolachlor + isoxaflutole (2,640 + 480 + 11.25 g ha-1) (pre-emergence) and atrazine + S-metolachlor (1,500 + 384 g ha-1) (post-emergence). The following characteristics were evaluated: intoxication, plant height, stalk diameter, number of internodes per stalk and plant density, performed 60 days after emergence (DAE); stalk yield and Brix, were evaluated on day 85 DAE. Atrazine + S-metolachlor tank-mix applied in pre or post-emergence did not affect growth, development, yield and stalk quality of the ESX5200 and EJX7C5110 sweet sorghum hybrids. Sweet sorghum seed treatment with naphthalic anhydride provided partial protection against the action of atrazine + s-metolachlor + isoxaflutole tank-mixes, being more evident for the ESX5200 hybrid.