Varieties, plant breeding and release

Permanent URI for this collectionhttp://elibrary2.sugarresearch.com.au/handle/11079/13841

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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The transfer of high CCS traits from wild relatives to sugarcane using biochemical markers
(2003) Grof, C; Manners, J
Over the last 40 years of sugarcane breeding in Australia there have been significant improvements in cane yield but little to no improvement in commercial cane sugar (CCS). It has been hypothesised that this lack of gain is due to the narrow genetic base of current breeding programs and has provided the impetus to examine new sources of germplasm that may provide desirable traits. Broadening the genetic base through the introgression of new Saccharum germplasm could allow the incorporation of 'new' genes for CCS into commercial sugarcane and result in increased CCS. However carefully targeted approaches are required to identify favourable genetic components of value from available new germplasm for introgression.
Environmental stimuli for sugarcane suckering in the wet tropics : SRDC final report BSS221
(2003) Berding, N; Hurney, AP; Bonnett, GD; Joseph, F
The northern section of the industry has been in crisis for most of the years in the decade up to 2002 because of declining CCS. This decline has been due to increased extraneous matter levels due largely to increased sucker culm content of the crop. These have developed because of marked wet episodes during the harvest period in the majority of years in this period. This resulted in open canopy situations, because of sprawling and lodging, increased light penetration, and initiation and development of sucker culm populations.A hypothesis was proposed that excessive mature-crop moisture, combined with continued excessive nitrogen use, particularly early in the decade were initiating variables for the problem. Observations suggested that light, via an open canopy situation, also was a driver.The project tackled the problem with a preliminary series of experiments that allowed optimisation of management and data collection techniques for use in a main experiment proposed. The main experiment sought to establish the importance of levels of three environmental variables, light, nitrogen and moisture, on sucker initiation, and their interaction with each other and with two cultivars of known suckering propensity under commercial conditions.The preliminary experiments allowed us to make the following recommendations for the design and methods for the main experiment:1. The late nitrogen application of 70 kg N will be in late April early May if the weather is suitable and as soon as possible thereafter if the weather is too wet to allow the application at the desired time.2. That spectroradiometry measurements will be made in the core plots at a height of 10 cm and 1 m to determine the effect of plant spacing on the spectral composition received. Photosynthetically active radiation measurements will also be made.3. A similar soil sampling and nitrate measurement regime will be made in the main experiment as that in the preliminary experiment with the exception that more frequent smaller diameter cores will be taken to speed up sampling.4. Sucker counting and other trial management will continue as originally proposed.5. Applications of late N will be made in separate experiments on different cultivars and if possible to soils with low basal nitrate levels.
Knowledge of sugarcane physiology and climate-crop-soil interactions : SRDC final report
(2003) Inman-Bamber, NG
Compared to other crops, knowledge of growth mechanisms in sugarcane is inadequate. The question arises as to how much longer can we continue to prosper from sugarcane if knowledge of the growth processes on which our industry depends, remains outdated? Sucrose accumulation and efficient use of resources are primary concerns for this industry. To date we have only limited understanding of climate and management links to sucrose content or CCS and this undermines our ability to manage water, nutrients, varieties and the harvest schedule for maximum CCS and optimum cane yield. Cane and sucrose yields are often below potential for reasons about which we can only speculate (Leslie and Byth, 2000). In the past, research funds have been directed at opportunities for raising limitations to yield and efficiency of resource use at the gene and enzyme level as well as at the crop and paddock level. There has been no attempt to integrate research or information across these disciplines or to assess where progress toward sustainable production is most likely to be achieved. SRDC recognized that it was now time for each discipline interested in the same processes to get together to find out how their different approaches could be complementary. SRDC also recognised the need to review past data relating to crop growth in the later stages of crop development to see if something could be done about under performing crops during this stage.
Pathways to exploiting enhanced photosynthetic efficiency for higher sucrose and biomass yield
(2011) Inman-Bamber, NG
Australia has one of the highest commercial cane sugar (CCS) levels in the world but unfortunately CCS appears to have plateaud at about 14% of fresh cane weight over the past 20 years. Up to now in breeding programs, increased fibre has been considered to have negative economic impacts because of adverse effects on sugar extraction and milling rate. It is possible that high fibre genotypes can produce higher biomass yields than high sucrose types because high sucrose content in the stalk may feedback negatively on photosynthesis either through end-product suppression or through sugar signalling compounds. This is now an assumption which is gaining acceptance through recent publications. Prior to this project this assumption had not been tested using high fibre and high sucrose clones. Feedback inhibition is also suspected to be the cause of the ‘reduced growth phenomenon’, a term applied to lower than expected biomass accumulation after a certain stage in crop development. This project aimed to establish the role of cane stalk sucrose in feedback inhibition of photosynthesis in order to reveal existing limitations to increasing sucrose content and biomass yield.
SRDC Research Project final report Increased CCS, cane yield and water use efficiency by exploiting interactions between genetics and management
(2009) Inman-Bamber, NG
In October 2003 delegates at an international workshop on sugarcane physiology funded by SRDC concluded that priority should be directed at a better understanding of traits responsible for high yield and high sucrose content, in order to better design future genotypes. While pathways of sucrose accumulation were and are being investigated at the molecular and cellular levels, there was no concurrent work at the crop level. Consequently it is difficult to answer the questions- To what extent will genetic improvements be modified by management and the environment? and conversely, To what extent does management and environment influence the selection of varieties? These and other questions about the genotype x environment (GxE) interaction on sucrose accumulation and lodging were the major concerns of this project with sucrose accumulation as the predominant issue. This project forms part of a large effort now underway worldwide to find alternative methods to develop cultivars with improved sugar content. The main objective was to better understand the interactions between sugarcane genetics and the environment (including management) with respect to sugar accumulation. After four years of intensive work the project has delivered extensive new knowledge on the physiology of interactions between sugarcane genetics and the environment with respect to sugar accumulation and lodging and as such has met the main objective of the research.
Building strategic research capacity for the sugar industry aimed at overcoming physiological, biochemical and environmental constraints to cane growth, breeding and sucrose yield
(1999) Grof, C; Campbell, J
Using the CSIRO Controlled Environment Facility, the discrete effects on the rate and extent of sucrose accumulation in sugarcane of four significant environmental parameters (daily light integral, radiation levels, temperature and humidity) have been investigated. These experiments have attempted to address some existing industry problems and have provided some basic understanding of sugarcane physiology, a platform from which to launch a more detailed investigation of the metabolic processes that control the rate and final level of sucrose accumUlation.
The role of root growth and activity in determining sugarcane productivity : SRDC final report CLW002 (previously CSS02 & CSS2S)
(1999) Magarey, R; Nable, R; Reghenzani, J; Smith, J; Berthelsen, S; Grace, D; Robertson, M
Research conducted in this project aimed to better understand the relationship between root and shoot growth, in areas such as how the size of the root system affects shoot growth, do particular root parameters have a controlling influence on shoot growth, how do soil characteristics affect root penetration rates, and how the root system develops through the life of a sugarcane crop. This was achieved through the application of a wide range of experimental techniques in both the glasshouse and field situation. The study of root systems in sugarcane is difficult - due to the size of the crop and the length of the cropping period. As a result there have been few previous studies on sugarcane root systems in Australia, and indeed around the world. A number of techniques were either developed, or adapted, in this project research. A soilless aeroponic culture technique was installed and refined at Tully Sugar Experiment Station. This allowed sugarcane roots to be examined on a daily basis and root measurements made, or root pruning to occur. This overcame the difficulty of dealing with the bulky, opaque soil medium. A tall pot system was adapted for sugarcane where sugarcane could be grown for an extended period in controlled conditions. This enabled plant water relations to be studied in association with modification to root growing conditions. Root image analysis techniques were further refined for sugarcane, allowing measurement of both whole glasshouse-grown root systems, or the quantification of root lengths in material from soil cores obtained in the field. A technique for growing sugarcane with a split root system was also adapted enabling the direct and indirect effects of water stress and root pruning in a soil culture to be examined, and the likely presence of root signals as a mechanism for control of shoot growth. Studies using these techniques facilitated an examination of the relationship between roots and shoots under various experimental conditions - ranging from controlled conditions with no soil in the glasshouse, through other soil-based glasshouse trials, to the field situation. This gave depth to project results and a broader understanding of root-shoot relationships using a range of experimental observations.
Efficient use of water resources in sugar production: a physiological basis for crop response to water supply
(1999) Inman-Bamber, NG; Robertson, MJ; Muchow, RC; Wood, AW
Although sugar is produced in the some of the most humid regions of Australia, water remains a major limitation to production. Experience in other rainfed and irrigated production systems in Australia has shown that use of both surface and ground water resources can easily have long term impacts on future productivity of the system. There is no reason why the sugar industry should be exempt from the consequences of ignorance or mismanagement in regard to the hydrological cycle. At the outset of this project, it was clear that efficient use of water (both rainfall and irrigation) was central to profitable and sustainable sugarcane production. Maximum profitability in fully-irrigated systems required the application of water to match crop water requirements for cane and sucrose production, as moderated by climate and management inputs. Under supplementary-irrigation, the timing of water application in relation to growth stage and climatic conditions was thought to be critical for maximising the economic benefit from a limited water resource. In rainfed systems, profitability could be maximised, by matching management inputs to the production potential and production risk as determined by rainfall variability in different climates. During the life of this project, there has been increased public awareness of water as a production factor and more importantly as a national resource and major component of a fragile environment. The National Agenda for Water Reform has moved in the direction of full recovery of water supply cost, separate water and property rights, specific water allocation to the environment and increased water use efficiency in agriculture. A new initiative on water use efficiency has been launched by DNR who have asked the sugar industry to make 60,000 MI available for irrigation from existing water resources. The products ofCTA016 are therefore highly pertinent for the current focus on water use in the Australian sugar industry. Radiation and temperature as key sugarcane production factors were the subject of SDRC Projects CTA004 and CTA012. These projects have led to a better understanding of the processes of yield and CCS accumulation under conditions of high water and nutrient inputs. Limits to yield in terms of these climatic factors have been identified. Crop growth mechanisms driven by radiation and temperature have been established and captured in mathematical expressions which were necessary for the development of the Sugarcane module now in use within the APSIM modelling environment. In CTA016, the strategic research approach of the earlier projects was extended to water as production factor. Water has of course been extensively researched in the sugar industry largely from the perspective of irrigation requirements. CTA016 was designed to build on past research by going into more detail in order to improve our knowledge of the soil-plant-atmosphere continuum of water. Knowledge of the mechanisms identified as important have been formalised mathematically and incorporated into the APSIM-Sugarcane modelling environment. This project has thus augmented the output from the earlier projects by adding the water balance and crop response to water stress to modelling capability. This capability was then used extensively in developing practical guidelines for saving water during drying off and during early stages of development. This modelling capability was also tested and used in a later more applied project (CTAOI8) to facilitate more efficient use of limited water supplies under supplementary irrigation.
Biomass accumulation in sugarcane : final report 79/9028
(1984) Kingston, G; Ham, GJ; Ridge, DR; Leverington, KC
Growth analysis experiments were conducted at Ayr and Bundaberg from 1979 to 1982 to study biomass accumulation in plant and ratoon crops of sugarcane. Crops were planted and ratooned in March, June, September and December, and harvested at 6, 9, 12 and 15 months of age. Data were acquired for yields of total fresh and dry matter, in addition to yields of the following vegetative components: dry leaf, green leaf, tops and stalks. Fibre analyses were determined on all components, while glucose, fructose and sucrose % were also determined in the latter three components. It was shown that yield of total dry matter increased with age at harvest for all months of crop initiation. Potential for dry matter accumulation was closely associated with intercepted solar radiation. Growth for three months was ranked December-March > March-June > September-December > June-September. These rankings represented the interaction of crop growth stage with solar radition. The proportion of total dry matter allocated to soluble and structural carbohydrate was shown to be dependent on variety as well as an interaction between age at harvest and month of harvest. Canes older than nine months of age, harvested between June and December, had established a plateau type equilibrium between the proportion of total dry matter in soluble and structural carbohydrate. Good prospects existed for forward extension of the crushing season to March for ethanol production based on 15 month old cane. Models were developed to describe the growth of yield components of the biomass in relation to intercepted solar radition, month of crop initiation, age at harvest and crop class.

Varieties, plant breeding and release

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