Selectivity of 2,4-D formulations and doses for peanut genotypes

Abstract

Weed interference in peanut is one of the main limiting factors of plant growth, development and productivity. Based on this assumption, to develop alternative weed control is necessary to weed management. The objective of this study was to evaluate the phytotoxic effects of different formulations and doses of 2,4-D on runner peanut genotypes. The genotypes evaluated were: IAC OL3, IAC 870, IAC 505 and IAC OL4. The experiment was carried out in a completely randomized design, with four replicates, arranged in a 2 x 8 factorial scheme (herbicide formulation x doses). The single doses of 2,4-D applied were: 0, 228, 456, 910 and 1370 g a.i. ha^-1 at 25 days after emergence (DAE), and the sequential doses were: 114 + 228, 228 + 228, 228 + 456 g a.e. ha^-1 applied at 25 and 40 DAE.  The phytotoxic effects were evaluated at 7, 14, 21, 28 and 35 days after the treatment application (DAT). At 35 DAT were determined the main stem length, the number of primary branches, the length of the most developed primary branch and the dry mass of shoot and root. It was verified that the plants submitted to the highest doses presented high initial intoxication. In addition, was observed differential morphological behavior among the genotypes. Regardless of the type of 2,4-D formulation (choline salt and amine salt), the application of 2,4-D at 228, 456, 114 + 128, 228 + 228 g a. e. ha^-1 were not phytotoxic. The doses at 1370; 910 and 228 + 456 g a. e. ha^-1 were phytotoxic to the genotypes.