Genotypic variation of metribuzin and carfentrazone-ethyl tolerance among yellow lupin (Lupinus luteus L.) germplasm

Abstract

Yellow lupin (Lupinus luteus L.) is a high-protein grain legume growing well in a range of acid soil types. However, the lack of herbicide tolerance for effective weed control has limited its adoption in broad acre farming systems. In order to breed herbicide-tolerant cultivars, a source of resistance needs to be identified. This paper reports the identification of a number of highly tolerant yellow lupin genotypes to metribuzin and carfentrazone-ethyl herbicides. Suitable dosages (LD50) of the two herbicides were identified as 150 g ai ha−1 (ai = active ingredient) for metribuzin and 200 g ai ha−1 for carfentrazone-ethyl. These dosages were used to screen diverse yellow lupin landraces and wild types to quantify the diversity of the germplasm. Considerable variation in response to the two herbicides was observed among the genotypes screened, ranging from complete plant death to no symptoms. Yellow lupin cv. Pootallong was susceptible to metribuzin, but three accessions (P20873, P23291 and P28800) were identified as tolerant with no plant damage. Four accessions (P20873, P20879, P23298 and P28832) showed higher tolerance to carfentrazone-ethyl than the standard cultivar Pootallong. A breeding line P20873 had the highest tolerance to both herbicides, indicating the possibility for developing yellow lupin cultivars with tolerance to both herbicides.