Varieties, plant breeding and release

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Research outcomes: Comprehensive and efficient variety breeding, selection and release programs responding to yield expectations, environmental constraints, resource scarcity and regional preferences. Faster varietal adoption using advanced methods for bulking, distribution and planting.

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Optimisation of the initial stages of the New South Wales selection program : SRDC final project report BS96S
(2002) Piperidis, G
The main aim of this project was to obtain the basic information required to implement an efficient and effective breeding and selection program in NSW. However, the project suffered major difficulties that affected the delivery of the proposed objectives. In spite of this, useful information that will have impact on the NSW selection program was obtained from the available data. In areas where two-year crops predominate, selection from Stage 1 and Stage 2 trials should be applied based on the data from two-year old crops. In addition, there was a strong correlation between the estimated net merit grade (NMGVol) and calculated net merit grade (NMG) in both the one-year and two-year Stage 2 crops at Broadwater. The correlation between the one-year NMGVol and the two-year NMG, however, was not significant. The results also show that family selection combined with visual selection in Stage 2 was generally more effective to identify elite clones in Stage 3 than family selection alone. Additionally, when the Brix of clones was taken into account the efficiency of identifying elite clones was increased even further.
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.
Duplication of photoperiodic initiation facility at BSES : SRDC Final report BSS218
(2000) Berding, N
Partnership-funded research by SRDC and BSES has resulted in excellent flowering being obtainable in populations of parental sugarcanes that flowered reluctantly, or never, under natural conditions at BSES Meringa. This improved flowering was obtained using plant management and initiation techniques developed in this research, using the BSES photoperiod facility (PF) commissioned in 1986. The objective of this project, an infrastructure proposal, was simple in that duplication of the existing PF was proposed. A project manager was engaged to facilitate the project. Essentially, the existing PF was duplicated. Changes to the design were made to minimise costs, and improve functionality. The concrete slab was simplified and the front portal frame design modified to allow installation of three normally-rolled roller doors. A new generation control system, based on direct digital controllers was installed. A prolonged and intense monsoonal season, coupled with delays in the delivery of key components and unforeseen time required for commissioning of the control system, resulted in a delayed start to the initiation regime on 9 October 1999. Once in-house expertise had been acquired to allow complete checking of the controller functions, and misinterpreted operational specifications corrected, the PF operated fully as expected. As a consequence of these factors the implementation of the first initiation regime was less than satisfactory. The level of initiation achieved fell well below that possible. Ten clones produced 97 panicles, with the number per clone ranging from 1 to 68, the latter being produced by the clone Mandalay, a S. spontaneum clone originating from Myanmar. The duplicated PF is a state-of-the-art facility that is now fully operational after debugging during the first, delayed operational run. The facility is committed to the CP2002 funded project BSS219 for five years.
High day temperature inhibition of sugarcane flowering : SRDC final report BSS158
(2000) Berding, N; King, RW
The objectives of this project was to determine the sensitivity of the floral initiation process in sugarcane to day temperatures exceeding 32?C.The objective was not achieved because no meristems were initiated in the five experiments conducted, and therefore the hypothesis remains untested. This was despite precise temperature control being effected in the CSIRO phytotron.
GxE interactions on ratooning of genotypes under trash blankets under cool/wet conditions : SRDC final report BS169S
(2000) Bull, TA
This project was established to investigate the magnitude of the genotype by environment interaction effect for ratooning under a trash blanketing under cool/wet conditions. A population of 50 genotypes was deemed necessary for this study but was not manageable in a fully replicated agronomic trial. Hence, it was necessary to assess a population of 50 genotypes and select a representative sub-population of 25. Accordingly fifty genotypes (40 unselected genotypes and 10 cultivars) were planted in the field at Bundaberg BSES station at fortnightly intervals from February to August 1997. Measurements of shoot emergence, stalk elongation and leaf appearance from each planting date were used to calculate base temperatures and thermal times for each parameter for each genotype. Plots of base temperature against thermal time were used to display the range of variation present in the population and to select a sub-population of 25 genotypes (21 genotypes and 4 cultivars) that represented this range. Population means and standard deviations for the selected 25 genotypes were not significantly different from those for the original 50 genotypes.
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.

Varieties, plant breeding and release

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