Factors affecting the sensitivity of chickpea ('Cicer arietinum') to isoxaflutole and its effect on nitrogen fixation

Abstract

One of the major obstacles in growing chickpea ('Cicer arietinum) successfully is its poor ability to compete with weeds. Heavy crop losses are possible in weedy situations and the lack of registered post-emergence herbicides for broadleaf weeds reduces the options for weed management. In Australia, isoxaflutole at 75 g a.i. ha⁻¹ is registered for the control of several difficult-to-control broadleaf weeds [e.g. Indian hedge mustard ('Sisymbrium orientale'), sowthistle ('Sonchus oleraceus'), capeweed ('Arctotheca calendula'), prickly lettuce ('Lactuca serriola'), wild radish ('Raphanus raphanistrum'), turnip weed ('Rapistrum rugosum'), crassula ('Crasulla' spp.), medic ('Medicago' spp.), deadnettle ('Lamium amplexicaule'), and slender celery ('Ciclospermum leptophyllum')] in chickpea. However, there have been records of chickpea crop damage due to the application of isoxaflutole at the recommended rate. The main objectives of this study were to identify genotypes tolerant or sensitive to this herbicide, to determine the soil and environmental factors affecting the herbicide sensitivity of the genotypes and to examine the effect this herbicide has on nodulation and nitrogen fixation. Variety screening trials with a range of isoxaflutole rates have found that the chickpea genotypes Howzat, Yorker, 91025-3021 (desi types), FLIP 94-92C and S 95425 (kabuli tyopes) were more susceptible to isoxaflutole damage. In comparison, the desi genotypes 97039-1275 and Kyabra recorded very minor injury and can be regarded as the most tolerant. Other genotypes - Gully, Jimbour, Amethyst, Flipper, ICLL 87322 (desi types) and Bumper, FLIP 94-90C, GCN 133-2, IG 9337, IG 96220, Kaniva, Macarena, S 95342 (kabuli types) - are intermediate in their response to isoxaflutole.