Browsing by Author "Lakshmanan, P"

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A review of nitrogen use efficiency in sugarcane
(2015) Bell, MJ; Biggs, J; McKellar, LB; Connellan, J; Di Bella, L; Dwyer, R; Empson, M; Garside, AJ; Harvey, T; Kraak, J; Lakshmanan, P; Lamb, DW; Meier, E; Moody, P; Muster, T; Palmer, J; Robinson, N; Robson, A; Salter, B; Schroeder, B; Silburn, M; Schmidt, S; Skocaj, DM; Stacey, S; Stanley, J; Thorburn, P; Verburg, K; Walker, C; Wang, W; Wood, A
The Great Barrier Reef (GBR) is the world's largest coral reef ecosystem, providing both substantial economic benefit to Australia and significant international ecological value. The health of the GBR is under pressure from sediments, pesticides and nutrients (especially nitrogen) discharged from nearby catchments. Discharge of nitrogen is of particular concern as it stimulates outbreaks of the Crown of Thorns Starfish, a major predator of GBR corals. Recent research has shown that the amount of nitrogen fertiliser applied in excess of crop uptake is an important determinant of nitrogen discharge from catchments, so increasing the efficiency of nitrogen use in cropping systems is an important step in protecting the economic and ecological benefits provided by the GBR. Importantly, an increase in nitrogen use efficiency (NUE) also offers opportunities to improve productivity and profitability of agricultural industries, with such benefits a major incentive for industry adoption and practice change. The Australian sugarcane industry is a significant contributor to the anthropogenic loads of nitrogen entering the Great Barrier Reef lagoon, with recent estimates in the Reef Water Quality Protection Plan (2013) suggesting it contributes 18% and 56% of particulate and inorganic nitrogen loads, respectively. A focus on improving NUE in the Australian sugar industry to reduce these loads wherever possible is a logical outcome from these statistics. While the relative impact of dissolved inorganic nitrogen (DIN) and particulate nitrogen (PN) is still uncertain, recent NUE forums in the sugar industry in 2014 identified clear target reductions in DIN that would be needed in order to significantly improve water quality in line with Reef Plan (2013-18) targets. The forum also identified a clear need for a joint industry-government funded research program to improve NUE in sugarcane cropping systems. The review conducted for this report was commissioned and funded by the Australian Government Reef Programme to provide a foundation for this joint NUE research program. The review was tasked with providing an improved understanding of past and current research effort and available field trial information (both published and unpublished) relating to nitrogen management in the sugar industry. From this perspective the review was then tasked with identifying research gaps and opportunities for future research projects and field trials that would collectively contribute to improving NUE from both agronomic and production perspectives as well as delivering significant reductions in nitrogen lost to waterways and the Great Barrier Reef lagoon. It is widely recognized that in any crop, the demand for N is determined by the size of the crop and the fundamental efficiency with which that crop produces a unit of biomass or harvested product from a kg of acquired N (N use efficiency - NUE). Therefore a good understanding of yield potential at the spatial scale of the productivity unit (i.e., farm, several blocks of similar productivity, individual blocks or within-block) about which N fertilizer management decisions (rate, form, placement, timing) are made is required, along with an understanding of how that yield potential varies with seasonal conditions. Collectively, this could be called seasonal 'block' (or productivity zone) yield potential, and it will produce a crop N demand that may vary from year to year. The sugar industry is currently operating at the district level (generally comprising several thousand cropped hectares across variable soil types and landscapes), and basing N demand for all growers in the district on the best farm yield ever achieved over a 20 year time frame. It is apparent that overall NUE could be improved by basing N fertiliser inputs on the seasonal yield potential of the productivity unit.
A sugarcane tissue culture system for mass propagation and transformation : SRDC final report BSS242
(2004) Lakshmanan, P; Grof, C; Geijskes, R
The core research strategy we conceived was to develop the initial observation of direct shoot regeneration in sugarcane leaf tissues to a generic and efficient plant production technology for sugarcane and probably for other major monocot crops, and then use that system to develop a novel method for sugarcane transformation. The main objectives of this project were: 1. Protect identified IP by patent; 2. Develop an efficient direct plant regeneration system for sugarcane and determine clonal stability of plants produced by this method (now referred to as the SmartSett® system); 3. Develop microprojectile and/or Agrobacterium-mediated transformation systems based on SmartSett®; 4. Establish the utility of SmartSett® to other monocot crops; 5. Technology transfer to other groups. These objectives were met.
Field assessment and further development of high-sucrose sugarcane: final report 2014/069
(Sugar Research Australia Limited, 2017) Wu, L; Lakshmanan, P; Zhao, L
Sucrose accumulation is critically important in determining sugarcane productivity. Yet, improvement in sucrose content in sugarcane has been almost stagnant for decades in many sugarcane growing countries, including Australia. This project has made significant improvement in sucrose content in sugarcane varieties by manipulating the activity of a specific gene involved in sucrose metabolism. In a previous study, we created transgenic sugarcane clones with Q117 background, which showed 15-25% improvement in sucrose content under glasshouse conditions. This high-sucrose phenotype was reproduced in the field in this project. The same transgenic technology was successfully applied to Q208A and Q240A and improvement of one to two units in CCS were recorded for seven lines, out of 365 tested, under field conditions. The high-sucrose phenotype was stable across plant and first ratoon crop during the two-year field study. Despite of the increase in sugar content, three lines showed comparable cane yield and fibre content to that of untransformed controls. Molecular analyses of high-sucrose lines confirmed that the phenotype was caused by RNAi-mediated down-regulation of target gene expression. The study demonstrates the potential of targeted gene manipulation for sucrose improvement in already established sugarcane varieties. Considering the growing resistance to genetically modified food crops, use of alternative emerging technologies such as gene editing may be the way forward for realising the same or better results.
Meristem transformation for sugarcane genetic engineering : SRDC final report BSS209
(1999) Smith, GR; Lakshmanan, P; Elliott, AR; Grof, CPL
More crop per drop : SRDC final report BSS305
(2011) Basnayake, J; Jackson, P; Inman-Bamber, G; Lakshmanan, P
Water stress is the major constraint to productivity in the Australian sugar industry, with an estimated cost of $260 million/annum (CSE014 Milestone Report 3.5). In 2003 and 2004, the losses exceeded $140 million in Mackay alone. This impact may increase with climate change. About 40% of the Australian sugarcane production is rain-fed with or without supplementary irrigation. With the erratic rainfall and the increasing cost and restrictions on water use, efficient use of available water is an increasingly important priority in irrigated production systems as well.Varieties that adapt well to drought and use water efficiently are becoming increasingly important for sustainable sugarcane production. Australian sugarcane breeding programs, however, do not explicitly address selection for response to dry conditions. To effectively address this issue there is a need to understand the main physiological mechanisms underlying genetic variation in response to different types of water stress environments in sugarcane. Hence, this project was initiated to determine the potential of Australian sugarcane germplasm for developing water use-efficient and drought tolerant commercial cultivars.In this project the phenotypic and genetic variations of traits that confer or linked to drought tolerance and water use efficiency (WUE) and their contribution towards productivity were studied in a genetically diverse sugarcane population. Field experiments were conducted for 3 years under rainfed, fully irrigated and managed drought conditions at three locations in the Northern Queensland. The experiment sites were in Home Hill in the Burdekin shire, Crystal Creek in the Herbert Shire and Dalbeg in the upper Burdekin. All trials were conducted in commercial sugarcane farms and followed the best crop management practices. A genetically diverse population (131 genotypes) comprising S. officinarum crosses with wild relatives, commercial cultivars including foreign clones, advanced lines in the selection program and some parental clones in the BSES breeding program was used as test clones. Clone performance was evaluated under rainfed, irrigated and managed drought conditions adopting most appropriate statistical field designs for the respective sites. The agronomic and cane yield characteristics, fibre, sugar and sugar quality characteristics and physiological traits related to drought tolerance were collected during the crop growth period and at harvest. Appropriate statistical methodologies were used to analyse and interpret the results at the end of the project.
SaveN Cane : developing selection tools for N-efficient sugarcane
(2015) Schmidt, S; Lakshmanan, P; Cox, M; Robinson, N
This project supports the sugar industry’s intensifying efforts to reduce its nitrogen (N) footprint that is caused by inefficient use of N fertiliser by the crop. The industry aims to minimise N pollution of coastal waters and emission of potent greenhouse gas nitrous oxide from soil without negatively impacting the economic sustainability of sugar production. International research addressing this pervasive problem in grain and other crops indicates that effective approaches combine agronomic innovation of N supply and nitrogen-use efficient (NUE) crop varieties. This UQ-SRA collaborative project, aimed to advance knowledge of N use efficiency of crop varieties through systematic testing of a considerable number of sugarcane clones with diverse genetic background (commercial varieties from Australia and overseas, identified water-use-efficient clones, crosses with ancestral canes). Additional value was derived from a collaboration with QLD DAFF (Andrew Robson) to advance remote sensing of crop N, and investigations of the effects of N fertiliser on soil biology (Graham Stirling-nematodes, UQ consortium-bacterial and fungal communities). Brazilian researchers (Sao Paulo State) have since established sister experiments based on this project. Clones were cultivated with low or recommended N rates (20-40 or 160-200 kg N-fertiliser per year) in two field trials (Mackay, Burdekin). The contrasting N rates were based on concepts that (i) NUE traits are only obvious in low-N environments, and (ii) ideal crop varieties will be strongly responsive to N supply and efficiently acquire N from fertiliser and indigenous soil reserves. NUE traits of 64 clones were characterised over three years (plant crop-1st ratoon crop-2ndratoon crop) by quantifying the effects of contrasting N supply on growth in early, mid and late season. Clone vigour and ratooning ability were evaluated, as was canopy development and photosynthetic performance, the ability to acquire and store nitrate, N allocation to stalks and leaves, and sugar and biomass yields. Project deliverables focused on generating knowledge on the genetic variation in N response and NUE traits and ranking of clones across environments with different soils to study the magnitude and the robustness of NUE traits. The overall deliverables and key findings include: (i) Establishment of field experimental conditions with limited N availability suitable for screeningsugarcane populations for NUE and N-related crop attributes. The field trial set-up was demonstrably effective in evaluating a considerable number of clones over a 3-year crop cycle; (ii) Knowledge of genetic variation for NUE in Australian sugarcane germplasm; (iii) NUE screening for photosynthetic performance, N uptake and accumulation attributes and yield parameters (CCS, sugar and biomass yields) identified benefits/drawback of experimental approaches; (iv) Generated data on trait variation across clones, crop stages and environments, demonstrating that environmental conditions markedly affected crop performance as evidenced by moderate (22%, Mackay) and strong (45%, Burdekin) reduction in yields with low N supply. Soil characteristics are a likely cause as clones at Mackay acquired on average 3- and 2-fold more N than at the Burdekin site over the plant-1st ratoon cycles at low and recommended N supplies; (v) Plant vigour appears to be a major determinant of NUE in sugarcane; (vii) Clones with contrasting NUE and N response have been identified for use in next-step NUE trait research; (viii) Remote sensing showed potential for screening sugarcane germplasm, but its application at early stages of crop growth requires further investigation. Taken together, the project has achieved the stated objective and fulfilled a role in SRA’s focus area of (1) optimally-adapted varieties, Plant breeding and release. The project outcomes have been communicated to the industry nationally and internationally, have been evaluated in the context of global efforts in advancing NUE in crop and cropping systems, and are in preparation for peer review and publication in highly ranked international scientific journals. The project is strongly aligned with industry interests as evidenced by interest of growers, national and international collaborators. Logical next steps towards developing N use-efficient sugarcane in the Australian breeding program include advancing understanding the basis of clone sensitivity to N and tools for rapid selection of N-responsive clones.
SRDC Research Project Harnessing soil biology to improve the productivity of the new sugarcane farming system
(2010) Schmidt, S; Schenk, P; Lakshmanan, P
This project addresses the knowledge gap of how management affects soil biological processes. This is important because management has to maximise soil health and nutrient relations. Knowledge of soil biology in context of management strategies will allow optimising economic and environmental outcomes for the sugar industry. The project assessed how management options of the ‘new sugarcane farming system’ (reduced tillage, legume break crop, trash blanketing, and reduced nitrogen (N) fertiliser application), impact soil biology. We examined the functional groups and activity of soil microbes in context of soil N availability and gaseous emissions. Sugarcane soils in North and Southern Queensland, including the Yield Decline Joint Venture site in Ingham and two commercial farms with contrasting management practices in Bundaberg, were used for this research. A suite of well established and new methods were applied to analyse soil biological processes. A focus on soil microbiological processes is justified because microbes are the main drivers of N turnover in soil. Microbes supply N to crops by breaking down complex organic matter and soil-bound N, but also compete with plants for more easily-accessible N. Microbes convert N into easily leachable nitrate and gaseous N forms and are drivers of carbon (C) turnover in the soil. These microbial processes have not been comprehensively studied in sugarcane soils with different management. A special focus of this study was the development and application of novel molecular techniques to monitor soil microbial gene expression. This approach allows microbial functional analysis by treating soil as a “super organism” rather than deducing function from the presence of particular microbial taxa which is biased towards known microbial taxa.
Sugarcane for future climates : final report 2013/029
(Sugar Research Australia Limited, 2017) Stokes, C; Jackson, P; Basnayake, J; Inman-Bamber, G; Lakshmanan, P; Natarajan, S
Increasing costs of irrigation in irrigated production regions, and seasonal periods of water deficits in rain-fed production regions are impacting greatly on profitability, sustainability, and expansion of the Australian sugarcane industry. Improving crop transpiration efficiency (TE, defined as growth per unit of water used) is one strategy to help address these issues.