Ground Cover Supplement : GC Supplement - Pulse breeding advances
8 GROUNDCOVER Issue 125 | Nov -- Dec 2016 | PULSE BREEDING ADVANCES HERBICIDE TOLERANCE HERBICIDE TOLERANCE DELIVERS OPTIONS The development of herbicide-tolerance traits in pulse crops has become a breeding priority to further strengthen the role of pulses in broadacre farming systems By Dili Mao, Jeff Paull, Chris Preston, Shi Ying Yang, Tim Sutton, Simon Michelmore and Larn McMurray South Australian Research and Development Institute and University of Adelaide n The rapid adoption of the first herbicide-tolerant lentil XT varieties by Australian growers demonstrates the likely demand for these traits in other pulses, particularly faba beans, for which no crop broadleaf weed- control options are available. The development of multiple herbicide tolerances, particularly for different modes of action, is important to ensure sustainable weed-control options. Pulse crops have a narrow safety margin to many of the registered herbicides, such as metribuzin (Group C). Field trials were conducted to evaluate varietal differences for metribuzin tolerance in faba bean, field pea and lentil lines using a range of rates applied post- emergent at the five-node growth stage. Results showed that while faba bean lines AF03019 and NuraA showed no significant yield loss at any rates, FarahA and 1952/1 suffered significant yield loss at all rates when compared with untreated controls. Similarly, in field pea lines, results showed that PBA OuraA and Yarrum performed significantly better than KaspaA and Sturt at all rates. The same trends were also seen in lentils. More than 1000 accessions of lentils and faba beans, and 200 of field peas, were screened for improved levels of metribuzin tolerance. From this, intermediate levels of improved tolerance were confirmed in two lentil and four faba bean lines. While this is unlikely to be sufficient for new or novel herbicide applications, it will increase the safety margin to registered uses and is being incorporated into Pulse Breeding Australia (PBA) breeding programs. Mutagenised populations of lentils, faba beans and chickpeas were screened for tolerance to a range of herbicides. Selections with high levels of apparent tolerance were identified in each crop. FABA BEANS Studies showed high levels of improved tolerance to imazapyr (Group B) in all four faba bean lines. The field tolerances of the two best agronomically performing lines, IMI-1 and IMI-3, were compared using four different imidazolinone herbicides applied post-emergent at the five-node growth stage. IMI-3 incurred no yield loss for any herbicides tested, while IMI-1 only suffered significant yield loss at high rates of imazapic. Cross tolerance to other Group B chemistries were compared in faba bean and XT lentil varieties. IMI-3 had a similar level of cross tolerance to the XT lentil varieties with improved tolerance to imidazolinone herbicides and flumetsulam, as well as a low level of improved tolerance to soil residues of some sulfonylurea herbicides. IMI-1 also showed improved tolerance to imidazolinone herbicides, but remained sensitive to flumetsulam and sulfonylurea herbicides. PBA incorporated these traits into its elite faba bean breeding lines and the most advanced of this material progressed to National Variety Trials (NVT) in 2016 with the potential for commercialisation in the next few years. The intermediate levels of metribuzin Response of an elite line incorporating the IMI-3 trait (left) compared with NuraA (right) to a high rate of imazapyr applied post-emergent at the five-node growth stage at Hart Field Site, SA, 2016. PHOTO: DILI MAO tolerance are also being incorporated into these elite lines. The aim is to combine tolerance to several herbicides for greater flexibility in choice of herbicides. LENTILS Two lentil selections were shown to have a high level of metribuzin tolerance. Field validation in an associated PhD study confirmed high levels of tolerance in the mutated selections. This trait is being incorporated by PBA into elite lentil breeding material, including into the Group B XT tolerant lentil varieties, with the aim of developing dual tolerant varieties. CHICKPEAS Dose response studies have confirmed several chickpea selections with a high level of Group I tolerance. PBA has started incorporating lines with this trait into the chickpea breeding program, however evaluation is still ongoing. Promising results from last season have shown a similar tolerance in other crops and identified Group B tolerance in chickpeas. FUTURE WORK The development of lines with intermediate levels of herbicide tolerance from existing germplasm, combined with high levels of improved tolerance from novel germplasm, will help improve grower confidence, expand weed-control options and reduce the rotational limitations of pulse crops. o GRDC Research Codes DAS00131, UA00163, UA00158, DAS00113 More information: Dili Mao, email@example.com; www.grdc.com.au/PBA GROWER MESSAGE Herbicide-tolerance traits have been incorporated into Pulse Breeding Australia's elite faba bean breeding lines. The most advanced material progressed to National Variety Trials in 2016, with the potential for commercialisation in the next few years.
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