Browsing by Author "Parfitt, RC"

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Does rotating cultivars with intermediate resistance influence pachymetra root rot of sugarcane : ASSCT peer-reviewed paper
(ASSCT, 2019) Jensen, AS; Croft, BJ; Parfitt, RC; Brown, PH
Concerns have been raised by industry members over lower than expected cane yields associated with high oospore levels in sugarcane cultivars rated to have intermediate resistance to pachymetra root rot. This is a significant issue, as intermediate cultivars represent more than 70% of the sugarcane grown in Australia. It is possible that planting the same intermediate cultivar in successive crop cycles could lead to increased yield losses due to pachymetra root rot. This paper examines the residual soil-borne effect of the current major sugarcane cultivars on the following sugarcane crop in three field trials, located in the Herbert, Central and Southern growing regions. Levels of oospores of Pachymetra chaunorhiza and cane yields were assessed in ratoon crops of replicated cultivar-assessment trials and in subsequent crops of intermediate resistant Q208A (planted on the sites of previous cultivar trials). The relationships between Pachymetra oospore levels and cane yield in Q208A crops and pre-plant oospore levels were examined. High oospore levels occurred in plots planted to some intermediate cultivars, as well as susceptible cultivars. In the following crop of Q208A, which was planted into plots of the previous cultivar trial, Pachymetra oospore levels at harvest were related to oospore levels prior to re-planting at all trial sites. Cane yield (t/ha) of Q208A was significantly related to pre-plant oospore levels at a site near Bundaberg (P=0.0049). Yield losses of 21% were incurred at 120 oospores/g soil in Q208A. Cultivation of Q208A following a crop of Q208A did not result in higher Pachymetra oospore populations or yield losses compared with planting Q208A after other cultivars of similar resistance rating. In the Herbert and Central field trials, Pachymetra oospore levels were lower and there were no significant relationships between oospore levels and yield in Q208A planted at these sites. We demonstrate that significant yield losses in Q208A are associated with high Pachymetra oospore levels that occur under intermediate and susceptible cultivars in the previous crop. There was no evidence to support the hypothesis that repeatedly planting the same intermediate cultivar could lead to host-cultivar-specific virulence in P. chaunorhiza. Greater emphasis should be placed on breeding and selecting highly resistant cultivars that are suited to soil types conducive to Pachymetra
Exploiting introgression for the development of productive and regionally adapted varieties for NSW : final report 2013/022
(Sugar Research Australia Limited, 2020) Parfitt, RC; Beattie, RN
This project aimed to explore sugar cane variety improvement opportunities available through introgression in relation to 2-year cropping, temperate cane growing conditions of NSW and frosting. It provided an opportunity to review the NSW selection program that has been operating since early 2000.
Reviewing and extending knowledge of fibre quality assessment within the SRA breeding program to develop optimally adapted varieties for the Australian sugar industry
(Sugar Research Australia Limited, 2018) Kent, GA; Parfitt, RC
This project aimed to improve knowledge of the significance of fibre quality measurement data to improve its value for variety selection and to provide guidance on further research work to utilise fibre quality requirements to guide variety development. It provided an opportunity to review the fibre quality assessment program that has been operating since 1992 and the way fibre quality is utilised in the breeding program. The three existing fibre quality measurements, shear strength, impact resistance and short fibre content have proven to be useful indicators of fibre quality. Shear strength appears to be the most robust measurement while short fibre content appears to correlate best with factory effects. No promising alternative fibre quality measurement methods have been identified after consulting cotton, forestry and timber products and pulp and paper industries and overseas sugar industries. Fibre quality is currently measured two years before the release of a variety. Fibre quality assessment could be done by SpectraCaneTM as early as eight years before release at low cost or by laboratory methods as early as seven years before release at considerable cost. Assessment by laboratory methods one year earlier could be done at modest cost. Correlations were found between fibre content, short fibre content, and several key factory operation and performance parameters. An economic analysis on a per hectare basis, considering sugar, molasses and electricity production benefits and harvest, transport, season length and auxiliary fuel costs is considered a suitable way of accounting for the net benefit of a variety.