Browsing by Author "Cox, MC"

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Breeding clones with high early sugar content : SRDC final report BSS93
(2002) Cox, MC
The project BSS25 ?Breeding of clones with high early sugar content? concluded that the potential for increasing CCS through breeding and selection was greatest early in the season. BSS25 commenced a recurrent selection program with short generation interval aimed mainly at population improvement. The aim of BSS93 was to continue a recurrent selection program for early CCS and to assess the realised genetic gain made in the previous project.At the start of BSS93, BSES had changed its selection program from family assessment in clonal 4-sett plots to family assessment as original seedlings. The recurrent selection program for high early CCS reflected this change. Twenty families with high early CCS parents were selected for planting in New South Wales, southern, central, Burdekin, Herbert and northern regions from 1993 to 1996. At each location, the best 600 out of 1 200 seedlings (based on visual appearance) were sampled in May and June in the following year for CCS. The best 10 clones, based on mean CCS, were selected as parents and sent to Meringa for further crossing. Two hundred clones in total were selected as parents. The 10 parent clones and up to 10 additional clones were selected for testing in Clonal Assessment Trials. A total of 377 clones were selected over the duration of this project. Of these 377 clones, 107 clones were derived from families with at least one recurrent parent from the previous project. Good performing clones from this stage were promoted to advanced selection stages. A number of clones from both the current and previous projects have performed well in advanced trials. To date, two varieties have been released, Q185A (central region) and Q205A (southern region).Replicated trials were planted in the southern, central and northern regions to assess the genetic gain realised in the selected clones from the previous project (BSS25). Parents and elite (selected) clones from the families tested were included along with a base population (a group of 29 randomly selected clones from the breeding population) and a core population (a group of 30 clones from core selection programs with known high early CCS). Trials were sampled for CCS in May and June in plant and first-ratoon crops. Mean CCS was calculated and the various populations were compared.At all locations, the parent population had significantly higher CCS than the base population, and the core and elite populations had significantly higher CCS than the parent population. At Bundaberg, the elite population had significantly higher CCS than the core population, but there were no differences in mean CCS between these two populations at Mackay or Meringa.In terms of realised genetic gain, at Bundaberg both southern parent and elite populations showed steady gains from 1987 to 1991, averaging about 0.26 unit of CCS per year. There were no indications of a decrease in variability in these populations and it was concluded that it was likely further genetic gains would be sustained in the future.At Mackay, the central parent populations showed a modest but somewhat inconsistent improvement over the period and this was repeated for these populations tested at Bundaberg and Meringa. The central elite populations showed good improvement for the first 3 years, but this was not sustained over the subsequent 2 years. Extremely difficult selection environments (flooding and extreme moisture stress) impacted on the clonesselected in the final two elite populations and may explain this decline. It was difficult to come to a firm conclusion on continued genetic gain for the central region.At Meringa, the northern parent populations showed a small, but significant improvement over the 4 years of about 0.13 units of CCS per year. However, the northern elite populations showed no improvement over this period. This was not expected, as the parent populations showed a fairly steady improvement. Interestingly, good improvement was shown by the northern elite populations (first 3 years only) when grown at Bundaberg (0.39 unit CCS per year) and Mackay (0.21 unit of CCS per year). It is difficult to explain these results, but it may indicate that the wet tropics pose some unique difficulties in breeding and selection for high early CCS.
Effects of pachymetra root rot and nematodes on some elite sugarcane clones in Australia
(ASSCT, 2016) Bhuiyan, SA; Croft, BJ; Wong, E; Ogden-Brown, J; Turner, M; Parfitt, R; Magarey, RC; Bull, J; Cox, MC
PACHYMETRA ROOT ROT and nematodes are the two most important soil-borne pathogens of sugarcane in Australia. An experiment was established in Yandaran, Queensland in grey forest soil with high Pachymetra spore counts (>100 000 spores/kg). Fifteen elite varieties and one advanced clone, from pachymetra root rot susceptible, intermediate and resistant categories, were planted in the experiment. The experiment was maintained until the second ratoon crop and Pachymetra and nematode populations were assessed in each crop. In addition, the incidence of smut was recorded before harvesting. Cane yield (TCH), commercial cane sugar (CCS) and sugar yield (TSH) were also measured in each crop. Pachymetra spore counts remained significantly lower in resistant varieties compared to susceptible and intermediate varieties until the second ratoon. In intermediate and susceptible varieties Pachymetra spore counts increased substantially, in particular, in second ratoon. In intermediate varieties such as Q232A and Q208A Pachymetra spore counts increased more than three times from plant crop to second ratoon. Numbers of nematodes, in particular root-lesion nematode, more than doubled in the second ratoon crop compared to the plant and first ratoon crops. Only Q248A had significant levels of smut, with 25% and 30% infected plants in the first and second ratoon crops, respectively. Yield reduction was substantial in the second ratoon compared to the plant and first-ratoon crop. Sugar yield decreased by 45% in the second ratoon compared to the first ratoon. Mostly, poor or negative correlations were observed between both Pachymetra spore counts and nematode numbers and yield.
Field performance of transgenic sugarcane plants carrying genes for resistance to SCMV : final report BSS154
(2000) Smith, GR; Taylor, GO; Harding, RM; Stringer, JK; Cox, MC; Yoyce, PA
The field resistance of transgenic sugarcane plants to sugarcane mosaic potyvirus was successfully demonstrated, and a number of transgenic lines are available for consideration for agronomic evaluation. Some of the transgenic lines yielded significantly more tonnes sugar per hectare in this trial, but a firm conclusion about the overall performance of the transgenic lines compared to the parental clone can not be concluded due to the limitations of this trial. These plants contain the coat protein gene of sugarcane mosaic virus and prove that pathogen-derived resistance can be engineered into a genetically complex monocot. The precise molecular basis of the resistance appears to be RNA mediated. More research is necessary to prove this as a number of the resistant lines do not exhibit the usual RNA profiles of transgenic plants from other species which are virus resistant. A second pathogen-derived resistance gene, based on the virus replicase gene, is also capable of conferring virus resistance in sugarcane.Analysis of sugar and syrup produced from transgenic cane has revealed that no genes, native or transgenic, survive the laboratory production process. There is every confidence that this result would also be found with mill produced sugar, when the opportunity to mill transgenic sugarcane eventuates. There is now good scientific evidence to contribute to the debate that sugar manufactured from transgenic sugarcane plants is indistinguishable or substantially equivalent to sugar produced from non-transgenic plants.
How do current ratings of sugarcane varieties for resistance to smut relate to natural infection
(ASSCT, 2018) Bhuiyan, SA; Cox, MC; Croft, BJ
SUGARCANE SMUT, CAUSED by a fungus Sporisorium scitamineum, is an important disease of sugarcane in Australia. Sugarcane smut can be managed effectively through the propagation of resistant varieties. In Sugar Research Australia’s (SRA) smut screening experiments, stalks of varieties from various stages of breeding programs are cut into one-eye setts and then dipped into a smut spore suspension (5 × 106 spores/mL water) for 10 min at 31 °C. After germination, the plants are transplanted to the field and disease incidence is measured in the plant crop and first and second ratoon crops. This method is effective for screening of a large number of varieties in a relatively short period (10–12 months) and is used in other countries. Although this method is widely accepted, it has some drawbacks: i) test plants are subject to very high disease pressure; and ii) it does not replicate natural infection. Three experiments were established in 2007, 2008 and 2009, to determine if the ratings obtained by artificial inoculation technique predict field resistance of varieties. All experiments were planted with 10 or 5 replicates of the test varieties planted between rows of infected Q205A, and maintained until second ratoon. Highly susceptible varieties Q205A and Q157 had >40% infected plants in plant crops whereas little smut was observed in intermediate and resistant varieties. Average % of smut infected plants increased in all experiments from the plant crop (5–12%) to first ratoon (21–46%) and second ratoon (26–59%) crops. The correlation coefficient values between smut incidence in the natural infection experiments and the historical ratings obtained using dip-inoculation methods ranged from r = 0.82 to 0.72, indicating a good agreement between natural infection trials and dip inoculation ratings.
Manual of procedures for the control of BSES Limited varieties: variety audit, DNA fingerprinting and plant breeder's rights
(2004) Cox, MC
Plant Breeders' Rights (PBR) is designed to protect industry investment in Plant breeding. Currently it protects the equity of growers and millers continuing to support plant improvement through the 'Service Fee'. However, different funding arrangements in the future may increase the importance of PBR to BSES Limited. Thus, it is imperative that the procedures described in this manual are rigorously followed to ensure that PBR is not compromised and can, if necessary, be defended in court.
Maximising whole-of-industry benefits from the Australian sugarcane improvement program through an optimal genetic evaluation system
(2007) Wei, X; Stringer, J; Jackson, P; Cox, MC
An optimal genetic evaluation system (GES) is the backbone of any breeding program because maximising genetic gains is primarily a matter of efficient selection. A GES provides information to breeders about which individuals should be selected as parents for crossing and which ones should be selected for commercial production.At the commencement of this project, selection of both parents and clones for commercial production was principally based on the index knows as net merit grade (NMG). NMG is based on the performance of a test clone (or a cross) relative to the average of a number of commercial varieties (or corsses) for the traits of commercial cane sugar (CCS), tonnes of cane per hectare (TCH), appearance grade and fibre content. NMG was used to generate a breeding code for selecting parental clones for crossing. Cross ratio, a measure of each cross's performance relative to the whole population at each selection stage, was used to determine priority of crosses. For selecting elite clones to be retained for further testing, NMG was used in all three selection stages to determine which clones would be advanced to next stage.
Optimum family felection for net merit grade : stage 2 trials BS45S
(1996) Cox, MC
Mass selection of individuals in seedling or early clonal stage trials is routinely used in most sugarcane improvement programs throughout the world. It is, however, inefficient as the Heritability of cane yield on a single plant basis is low. In Australia, the introduction of mobile truck-mounted weighing equipment offered the opportunity to implement family selection utilising weighed family data. Family selection has been used in some Bureau of Sugar Experiment Stations' (BSES) selection programs since 1986 and is now routinely used in all regional selection programs. This research has demonstrated that a combination of family and mass selection in stage 2 of selection will result in larger genetic gains and a higher frequency of superior clones in later stages than mass or family selection alone. This combination allows improved efficiency since fewer resources are required to select only within superior families in the first ratoon crop than to mass select individuals across the entire population. A liberal family selection rate (about 40%) balances genetic gain and the need to maintain a broad genetic base. While mass selection rates did not vary in this work, it is believed that differential seelction rates within families sould be used so that more clones are selected out of the best families. The availability of objective family data also allows more accurate estimation of the breeding value of parents utilising best linear unbiased predictors (BLUP). This results in better genetic combinations through crossing and provides more objective information on new parents.
Optimum time of harvest for high early sugar varieties : SRDC Final report BS705
(1997) Ridge, DR; Cox, MC
To assess the optimum time of harvest for high early ccs varieties, two experiments were conducted on the BSES Experiment Station at Bundaberg between 1993 and 1996. The first experiment included eight varieties selected to represent early, mid-season and late maturing varieties, planted in both spring and autumn. the varieties were harvested in May, June, July, August and September in plant, first and second ratoon crops. Ratoon crops were 12 months old at harvest. Data on cane yields and ccs for each harvest date allowed assessment of the benefits of high early ccs varieties for extending the harvest season and for increasing productivity during the normal harvest season. The objectives for this report was to determine yield and ccs of cane varieties, particularly high early ccs types at various times during the season; evaluate ratooning of varieties harvested at different times; assess the effect of harvesting system on ratoon performance; examine the economic implications of strategic timing in the harvest of varieties.
Plant resistance to canegrubs : SRDC final report BSS132
(BSES, 2002) Allsopp, PG; Cox, MC; Nutt, KA
The project sought to determine the range and types of resistances to feeding by canegrubs in sugarcane clones and their wild relatives. Resistance was tested in both pot trials and field trials and the importance of several biochemical factors in this resistance was investigated.Field and pot trials showed that a range of tolerance and antibiosis resistance mechanisms to canegrub feeding exists within the current sugarcane genome and close relatives. Tolerance effects were apparent in the growth of tops, roots and stubble. Antibiosis effects were apparent on grub survival and grub growth. Some of these tolerance effects are partially correlated with the general vigour of clones, but there are a number of clones that depart from the general relationships for tolerance and antibiosis. These clones would be especially important in any future program to increase the levels of resistance within the breeding gene pool.There was reasonable repeatability of pot-based tolerance levels between pot trials and with results derived from field trials. However, the type of canegrub and its underlying biology influenced the usefulness of field trials.Biochemical investigations showed no clear relationships between any factor and antibiosis phenotypes. However, there were indications that the type of cell-wall sugars may influence resistance to canegrubs. In addition, the data clearly indicated that the quantity and type of phenolic compounds in the roots change following feeding by canegrubs.
Procedures for the establishment and operation of approved seed plots: fourth edition 2013
(Sugar Research Australia Limited, 2013) Croft, BJ; Cox, MC
Hot-water treatment of sugarcane cuttings (stalks or stalk pieces) to control the spread of diseases and pests was pioneered in Australia. Hot-water treatment can reduce the risk of cuttings being infected with ratoon stunting disease, leaf scald, chlorotic streak, sugarcane smut and downy mildew and can free cuttings of insect pests. It does not usually control virus diseases such as sugarcane mosaic and Fiji leaf gall. Hot-water treatment is only a part of an integrated pest management program and must be used in combination with disease inspection, crop management and hygiene to reduce the risks of reinfection (see attached ‘Procedures for the establishment and operation of approved-seed plots’).
Seasonal distribution of growth and sugar accumulation in sugarcane : SRDC project BS5S Final report
(1995) Cox, MC
At existing levels of cane yield, an extra unit of sugar content during May, June and July represented 47 6000 tonnes of sugar worth $13.3m at 1987 prices when this project was initiated. The situation now, with annual crops of greater than 30m tonnes and higher sugar prices, would provide greater returns. The potential for increasing early sugar through breeding and selectio has been demonstrated (see BS25S Final Report). Selection for high early sugar content may change the seasonal pattern of yield accumulation and affect regional adaptation.
SmutBuster: accelerated breeding of smut-resistant sugarcane varieties : SRDC final report BSS325
(BSES, 2011) Cox, MC; Croft, BJ; Bonnett, G
Sugarcane smut is caused by the fungus, Ustilago scitaminea Syd., and is one of the most serious diseases of sugarcane. At the end of 1983, only the sugar industries of Australia and Fiji remained free from smut. Sugarcane smut was reported for the first time in Australia in July 1998 in the Ord River Irrigation Area. Eight years later, smut was identified on the east coast of Australia at Childers. By December 2007 sugarcane smut was widespread and established in the Bundaberg?Isis, Central Queensland and Herbert River districts, and by 2010 the Mulgrave, Tully and Burdekin districts were also infested. The average yield loss reported in papers at the time of the east coast smut incursion was 6% yield loss for each 10% increase in per cent-infected plants. To minimise losses susceptible varieties will need to be completely replaced with equivalent/higher yielding smut-resistant varieties, as fast as possible. This would necessitate changing ~80% of the2006 sugarcane crop. Replacement of susceptible varieties will be achieved, not only by rapid scale-up of smut-resistant varieties, but also accelerated development of high yielding,smut-resistant varieties. The parental pool of high breeding value, smut-resistant germplasm was however severely limited, adversely impacting the core crossing program. Without a significant plant breeding response, the rate of genetic gain for productivity would decrease and fewer productive, smut-resistant varieties would be released from the BSES-CSIRO Sugarcane Variety Improvement Program. The SmutBuster project was a key component of the RD&E response to sugarcane smut with the specific objective of developing high yielding smut-resistant varieties through the utilisation of high breeding value parental germplasm with susceptible reaction to smut.
Whole-farm planning for management of varieties to maximise productivity and reduce losses from diseases : SRDC final report BSS294
(2009) Croft, BJ; Cox, MC; Millard, D; Burrows, A
The appropriate selection of sugarcane varieties is critical for maximising profitability and sustainability for both growers and millers in the Australian sugarcane industry. Growers are faced with many complex decisions when selecting varieties such as yield potential, suitability to soil type, optimum mix of varieties to maximize sugar content throughout the season, resistance to diseases and pests, ratooning ability and tolerance to stresses such as drought, frost and flooding. This project has developed a web-based variety decision support tool and information resource for the Australian sugarcane industry named QCANESelect to help growers make the best variety choices.