Phytotoxic response and yield of chickpea ('Cicer arietinum') genotypes with pre-emergence application of isoxaflutole

Abstract

Balance® (75% a.i. isoxaflutole) at 100 g/ha is registered in Australia for the control of several broadleaf weeds in chickpea. Polyhouse and field experiments were carried out to examine the tolerance of chickpea genotypes to isoxaflutole. Seven rates of isoxaflutole [0, 18.75, 37.5, 75 (recommended rate), 150, 300 and 600 g a.i./ha] were applied to 20 genotypes in the first polyhouse experiment while in the second experiment, 16 genotypes were tested. In the field, six genotypes were treated with five herbicide rates (0, 37.5, 75, 150 and 300 g a.i./ha). There was a strong dose response in the polyhouse experiments in visual injury ratings, plant height, and shoot and root dry weight. In general, there was less herbicide injury to the kabuli genotypes than in the desi chickpea genotypes. Chickpea genotypes Yorker, Howzat, Amethyst, Gully, 91025-3021, Jimbour, S 95425 and FLIP 94-92C exhibited higher overall mean injury rating in experiment 1. Among these genotypes, shoot dry matter was reduced significantly in Amethyst, Jimbour, 91025-3021 and S 95425. Root dry matter in Amethyst, Jimbour, Yorker, 91025-3021 and S 95425 was also reduced significantly. Height was reduced significantly in all of the above eight genotypes. Although there was less overall injury level in the second polyhouse experiment, which was at lower temperatures, Howzat, Yorker, 91025-3021, FLIP 94-92C and S 95425 again recorded high overall mean injury ratings and should be regarded as more susceptible to isoxaflutole than the other strains. In comparison, 97039-1275 and Kyabra recorded very minor injury symptoms in all the experiments and can be regarded as the most tolerant. The herbicide injury to the genotypes in the field was less than in the polyhouse although Yorker and 91025-3021 showed injury symptoms at early stages of growth. The injury symptoms were temporary and did not produce significant effects on the overall crop growth and yield. It is suggested that plant breeding programs take into account the relative susceptibility of new chickpea genotypes to isoxaflutole.