Selectivity of 2,4-D salts applied at different phenological stages of wheat cultivars

Abstract

The selectivity of the herbicide 2,4-D depends on the plant species, the formulations produced and/or the developmental stages of the plants to which it is applied. The objective of this study was to assess the best stage of development of wheat cultivars for the application of 2,4-D salt formulations. The experimental design consisted of randomized blocks arranged in a factorial scheme (2 × 2 × 4 + 1) with four replicates. The treatments evaluated were wheat cultivars (OR 1403 and TBio Toruk), 2,4-D formulations (amine and choline salts) and crop development stages (before tillering start, at full tillering, first node and booting), another control without herbicides. 2,4-D choline and amine cause greater phytotoxicity when applied at the phenological stage of the first node of the cultivar OR 1403 and less at TBio Toruk. The highest number and length of ears, number of full grains, thousand grain weight, hectoliter weight, grain productivity and lowest number of sterile grains generally occurred when 2,4-D-choline was applied at the first node of the cultivar OR 1403 and when 2,4-D-amine was applied at the rubberization of TBio Toruk. The highest grain yields occurred when 2,4-D-choline and amine were applied to varieties in wheat booting.