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Rural Industries
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Project Title
Maximising the future pay-off from rice breeding
Objective
The project addressed two RIRDC goals specific to the rice industry:
User-friendly software, namely SAMBOY-Rice (Software for Assisting Management of Breeding Options at Yanco-Rice) has been developed to facilitate the continuing use of the analyses well beyond the life of the project. This software is flexible with the ability to update and run sensitivity analysis. The economic information generated is highly valuable to breeders, research fund administrators and other scientists involved in administration of the funds in the rice breeding program.
Implications
The economic information generated will help to identify the relative costs and to decide how to reduce the total cost of the rice breeding program or increase returns from the given resources. Through more efficient breeding program the returns to the growers would increase because of better targeted varieties. The software SAMBOY-Rice will allow the future use of the analyses developed in the project.
Publications
Conference papers International 1
National 2
Farmers’ newsletters 2
Reports 2
Others 1
Total 10
RIRDC Project No: DAN-108A
Researcher: Dr. John Brennan
Organisation: Agricultural Research Institute, NSW Department of Agriculture, WAGGA WAGGA NSW 2650
Contacts: Phone: (02) 6938 1851 Fax: (02) 6938 1809 E-mail: brennaj@agric.nsw.gov.au
Project Title
A new method to facilitate rice hybridisation
Objective
Prior to this project, we had only attempted to use the approach with wheat, but suspected from theory and observation that rice would respond to the technology in the same way. The essence of the wheat system is to control the amount of boron available to the plant at a level that is adequate for growth but inadequate for fertile pollen production; boron requirements for pollen development in wheat are greater than for other processes. The manipulation is achieved via a boron-specific resin, which can be used and regenerated indefinitely.
In wheat the low-boron-sensitive stage is from 4 to 7 days long depending on temperature and begins approximately when the flag leaf is 50% emerged and ends shortly after the flag leaf ligule is visible. We suspected that the sensitive stage in rice is likely to be similar in relation to external leaf development, but this had to be established as a main aim of the project. It was proposed to control boron availability by growing plants in a hydroponics system in which the trace element could be added or removed when required.
Research & Outcomes
A hydroponics system was designed and built from readily available components to control boron availability to rice. This is described in detail in this report. The system used river pebbles as the root medium and this medium was subirrigated with a nutrient solution developed specifically for rice. It was essential to control pH of the solution close to pH 5 during the seedling stages of growth to ensure 100% survival, and rapid establishment.
Two large studies demonstrated that rice is more sensitive to boron limitation than wheat, and that, unlike wheat, the sensitive period extends before and throughout panicle development affecting all processes of development. Thus, boron limitation constrained shoot extension, reduced potentially fertile floret numbers per panicle to almost zero in extreme treatments, and fully sterilised the few florets that developed. The aim of generating high numbers of male sterile florets per panicle was not realised. It was concluded that the method can not be used in the current simple form, with plus or minus boron for a short period, to achieve the aim. On the positive side, the hydroponics system has potential for examining variation and screening for desirable root/shoot ratios and radiation use efficiency in rice breeding lines.
RIRDC Project No: CSP-3A
Researcher: Dr. Howard Rawson
Organisation: CSIRO Plant Industry, GPO Box 1600, CANBERRA CITY ACT 2601
Contacts: Phone: (02) 6246 5058 Fax: (02) 6246 5255 E-mail: hmr@pi.csiro.au
Project Title
Constraints to rice establishment and yield in the Western Murray Valley
Objectives
This project used Landsat 5 data and geographic information systems to analyse the factors suspected of causing lower yields in the WMV, complemented by field monitoring and experimentation. Muddy water occurs on sodic soils, and gypsum is commonly used to prevent muddy water during rice establishment. Gypsum has been shown to increase recharge in some situations, therefore replicated field experiments were conducted to quantify the impact of gypsum on recharge from rice for a range of soils.
Outcomes
There was no supporting evidence for the hypothesis that temperature and yield potential are higher in the EMV. Muddy water was a major cause of lower yields in the WMV, and a model for estimating turbidity from remotely sensed data was developed. Muddy water caused a reduction in daytime temperatures at the soil surface of sufficient magnitude to seriously impair seedling growth. The low rates of gypsum (1.25-2.5 t/ha) typically used to prevent muddy water doubled potential recharge. However, recharge from rice on the sodic soils of the WMV was relatively low (around 0.5 ML/ha) during the rice season, and recharge from gypsum treated sodic soils was comparable to or less than that from other soils approved for rice growing.
Implications
Climatic effects are generally far more difficult to overcome, therefore the temperature/yield potential findings eliminated a fundamental reason for accepting lower average yields in the WMV. The adverse effects of muddy water on rice establishment can be largely overcome by keeping the water shallow to increase daytime temperatures at the soil surface. Even the low rates of gypsum typically used by ricegrowers increased recharge, therefore gypsum should only be used as a last resort, and only applied on areas of the paddock predicted to have muddy water problems. Rates should not exceed 1.25- 2.5 t/ha. Gypsum should not be applied where the supply water is muddy, nor topdressed into muddy water, as the resulting layer of sediment creates a toxic environment for rice seedlings.
Publications
Barrs, H, and Humphreys, E. (1996). Using LANDSAT satellite data to assess the muddiness of rice water.
Farmers’ Newsletter Large Area No. 147, 26-9.
Humphreys, E. (1996). Rice yield trends in the Murray Valley. Farmers’ Newsletter No. 147, 41-2.
Humphreys, E. and Barrs, H. (1998). Identifying and overcoming constraints to rice establishment and yield
in the Western Murray Valley. Farmers’ Newsletter Large Area No. 150, 32-6.
Humphreys, E. and Barrs, H.D. (1998). Constraints to rice establishment and yield in the Western Murray
Valley. RIRDC Project CSI-7A Final Report. 119 pp.
Humphreys, E., Sides, R. and Fattore, A. (1996). Rice establishment: deep water and turbidity both reduce
temperature and light near the seed. Farmers’ Newsletter Large Area No. 147, 30-1.
RIRDC Project No: CSI-7A
Researchers: Dr. Liz Humphreys and Dr. Henry Barrs
Organisation: CSIRO Land and Water, PMB 3, Griffith NSW 2680,
Contacts: Phone (02) 6960 1500 Fax (02) 6960 1600 Email liz.humphreys@grf.clw.csiro.au
Towards the development of more effective nitrogen-fixing associations between rice cultivars and endophytic bacteria
Objectives
It has been recognised that nitrogen-fixing bacteria can associate with the roots and lower shoot regions of non-legumes such as rice, wheat, sugarcane, sorghum and other grasses and provide a source of biological nitrogen fixation. Recently, Rhizobium bacteria, which normally are soil saprophytes or legume symbionts, were found to form a potential beneficial association with the roots of rice plants grown in fields rotated with Egyptian berseem clovers. Similarly, in the Philippines, a group of bacteria were found to intimately reside in rice tissues and stimulate rice plant growth.
Outcomes
The bacterial inoculation of rice seedlings revealed three sources of variation to rice growth. These were differences between rice cultivars in their ability to respond to bacterial inoculation, variation in the performance of the different bacterial strains used for the inoculum and variations due to the growth medium conditions used. Some strains stimulate rice plant growth, others have little effect, while others actually inhibit seedling development. The negative plant-microbe interactions could be altered readily by changing the growth medium conditions used in the experiments.
Bacteria with specific genetic "tags" showed that the bacterial association with the root surface was not extensive and occurs in patches along the developing root. Occasionally the bacteria were located in host cells beneath the root surface. Most of these bacteria are likely to be intimate surface colonising microbes, multiplying on the plant surfaces without producing any gross disease effects but providing a source of stimulatory molecules for plant growth.
Other experiments measured the multiplication, movement and compatibility of the rice-bacteria within rice tissues. The bacteria multiply but do not move from the original leaf inoculation sites. Furthermore, the variation in bacterial strain survival suggests that many of the rice-bacterial isolates possess important "rice-adaptation" genes that may enhance their competitive ability to colonise internal sites within rice tissues.
The anatomy of both mature and young rice seedlings was investigated for possible entry sites and pathways for bacterial colonisation. Mature plants had many cell wall structures which could block bacterial movement throughout the plant. However, in young rice seedlings there are possible passageways for bacterial movement within the seedling because the vascular tissues were incompletely developed for the first few weeks.
Implications
Some bacterial strains can enhance rice plant growth and other strains can markedly inhibit rice seedling growth, unless appropriate growth medium conditions are used. Historically rice cropping in New South Wales has grown rice in rotation with legume pastures. Currently, subterranean clover pastures are rotated with rice growing about every three years. The numbers of rhizobia would increase in the solid before the new rice plantings. Both stimulatory and inhibitory rhizobia would be expected to be present, with unknown effects on the growth of the subsequent rice crops. Also unknown is the effect of various water and fertiliser regimes used in the Australian rice growing areas on the bacterial soil populations and their subsequent interactions with rice plant growth.
Publications
First manuscript in preparation.
RIRDC Project No: ANU-28A
Researcher: Professor Barry Rolfe
Organisation: Plant
Microbe Interaction Group, Research School of Biological Sciences, Australian
National University, City Campus (C069), GPO Box 475, CANBERRA
ACT 2601
Contacts: Phone: (02) 6249 4054 Fax: (02) 6249 0754 E-mail: rolfe@rsbs.anu.edu.au
Reduction of bird damage to rice crops
Objectives
The aims of this pilot project were to:
Ricegrowers in Australia suffer from sporadic disruption of newly sown and emerging rice crops by migratory birds, especially ducks. Annual losses industry-wide are estimated to be in the range of $5-10m with average damage costs around $60/ha for the industry as a whole. Losses may exceed $600-1200/ha if localised to individual crops such as those whose rice crops are in the path of migratory birds, whose farms are at the extremities of the rice area and whose need to sow early or late in the season. Currently the techniques of scaring and shooting the pest birds are either ineffective or under social threat, and in any case are relatively expensive and time consuming. No fully effective chemical bird deterrent has yet been developed for rice crops. MA is already approved for use in the food and cosmetic industries, and is regarded as being of low toxicity to mammals. Birds are reluctant to eat grain pre-treated with MA but large scale repellency in field trials is controversial. The physical chemistry of MA is not well defined and no formulation if developed for field use in aquatic crops.
Research
The research project found that the literature on the effectiveness of MA was conflicting since pen results were not reliably transferred to protection of crops in the field. Formulations for commercial use were poorly defined and some studies referred to MA concentrations in water which cannot be achieved, since MA is not readily miscible nor soluble in aqueous systems, is solid at low temperatures and sinks to the bottom of ponds. We investigated the physical chemistry of MA and developed compositions which enabled MA to be dispersed on the surface of paddies, or spread throughout the paddy water. We also evaluated the use of pure MA pre-treatment of seed. Since little was known of the potential toxicity of MA for rice crops we conducted detailed dose response studies on the effects of MA on germination and development of rice plants in mini-paddies.
Outcomes
MA was found to present significant difficulties which required complex colloid chemistry to resolve. Field formulations which dispersed in water or which floated across ponds to be highly phytotoxic to rice seedlings. Germination rates, shoot growth and root growth were all, adversely and significantly affected by treatments at MA at doses likely to be well below those required for repellency of pest birds. Exposure of rice seed to pure MA almost completely sterilised the seed within one hour.
Implications
The results are very negative for the potential application of MA as a bird repellent in aquatic crops. The reduction of crop yield is likely to exceed the damage which could be done by the birds to rice crops. Some recent published literature also suggests that MA may also be toxic for fish. The results indicate that there may be significant dangers in the use of this molecule in crops and in agricultural areas where run-off could reach rivers systems.
Publications
Methyl Anthranilate: Bird Repellent of Environmental Risk?
Staples, L., Taylor, M., Crawford, R., Harding, I., Jenkinson, S. and Sinclair, R. (1998)
Proc 11th Annual Conference on Vertebrate Pests (Bunbury, WA)
RIRDC Project No: ABT-1A
Researcher: Dr. Linton Staples
Organisation: Applied Biotechnologies Pty Ltd, Unit 1, 56-60 Export Drive, BROOKLYN VIC 3021
Contacts: Phone: (03) 9315 1424 Fax: (03) 9315 1745 E-mail: appbiotech@bigpond.com
Project Title
Preliminary studies on biology and control of the rice worm Eukerria saltensis (Beddard)
Objectives
The oligochaete worm Eukerria saltensis causes significant damage to rice crops in the Murray Valley and Coleambally Irrigation Area each year. Although ibis attracted to feed on the worms may trample establishing seedlings, there is strong evidence to support the theory that Eukerria alters the rice bay environment in a way that makes conditions unfavourable for crop establishment.
Research
Preliminary laboratory studies have shown a density-dependent relationship between Eukerria and surface water turbidity. Eukerria infestations also lead to pH, increased ammonium levels and reduced nitrate/nitrite levels in the overlying water. There is some indication of an increase in soluble phosphorus, however, further replication of the experiment is needed to clarify this point. These changes in nutrient balance may help to explain the proliferation of algae in infested rice fields.
Outcomes
Chemical trials were undertaken with carbofuran, thiodicarb and ethoprophos. Neither carbofuran nor thiodicarb provided effective control when applied to experimental enclosures in flooded fields at rates of up to 2.0kg active/hectare. Granular ethoprophos at rates up to 2.0kg active/hectare incorporated into the soil immediately prior to flooding also failed to provide a significant reduction in Eukerria numbers. In fallow rice fields carbofuran applied at 5kg active/hectare as a soil drench provided progressively improving control for 13 weeks, however, thiodicarb at up to 1.875kg active/hectare did not have any significant effect. High soil moisture and consequently poor chemical infiltration may have adversely affected the thiodicarb trial.
Implications
Chemical control of Eukerria in flooded rice fields may be difficult to achieve and emphasis needs to be placed on researching treatments that can be applied at, or immediately prior to the flooding of fields. Further research is also required on managing Eukerria infestations through crop rotations and other land management practices.
Project No: DAN-137A
Researcher: Dr Mark Stevens
Organisation: Yanco
Agricultural Institute, NSW Department of Agriculture, Private Mail
Bag, YANCO NSW 2703
Contacts: Phone: (02) 6951 2611 Fax: (02) 6955 7580 E-mail: stevenm@agric.nsw.gov.au
Enhancing
progress on developing cold resistant management strategies and rice varieties
Objective
To accelerate the development of cold resistant management strategies and rice varieties by
NSW average rice grain yields are highly correlated with temperature during the critical stages of reproductive development between panicle initiation and flowering. Low temperatures during this stage of development reduced industry yields by 25% in 1996, and can similarly affect rice yields in the future. The breeding of cold tolerant rice varieties, and the development of management options that reduce the effect of cold damage on individual crops is required. Progress in producing cold tolerant varieties and management options is limited by the ability to routinely test parent material and novel management methods.
Research
The initial experiment tested the effect of 3 night temperatures (12,15 and 18oC) on harvest index, fertility and yield of four varieties (Amaroo, Millin, Langi and Doongara). Pots of each variety were moved into the three temperature rooms for the duration of microspore development (panicle initiation to booting), flowering (booting to end of anthesis) or the whole reproductive development stage (panicle initiation to the end of anthesis).
Outcomes
Controlled temperature rooms at Yanco Agricultural Institute can now be fully utilised to test cold tolerant varieties and management practices for the NSW rice industry. Millin has been shown to have superior cold tolerance compared to Amaroo, especially at 12oC.
It is further recommended that research be conducted investigating the optimal screening techniques for cold damage. This will not only include timing, intensity and duration of treatments, but also number of pots, plants per pot, replication and number of screens required. This information in conjunction with the controlled temperature rooms will allow rapid screening of Australian and introduced rices in a regular fashion.
Implications
The testing of the YAI glasshouse facilities and the demonstration of Millin having greater cold tolerance that other
RIRDC Project No: DAN-154A
Researcher: Robert L. Williams
Organisation: NSW Agriculture, Yanco Agricultural Institute, Yanco NSW 2705
Contacts: Phone (02) 69512679 Fax (02) 69 557580
Screening rice varieties for tolerance to stem rot
Objectives
The rice growing regions of Australia are located in south-western NSW between the Murray and Murrumbidgee Rivers. Because of the area’s isolation, it is free of the more serious diseases affecting other rice-producing countries. Stem rot disease, caused by Sclerotium oryzae Cattaneo (Leptosphaeria salvinii Catt.) was first observed in NSW in the summer of 1995/96. Overseas, this is a serious disease which attacks the stem of rice plants at the water line and progresses into the inner leaf sheaths, causing major yield losses.
Research
Three experiments were conducted in a glasshouse at 25° C to rank cultivars according to susceptibility to infection by Sclerotium oryzae. Eleven cultivars (Amaroo, Bogan, Doongara, Goolarah, Illabong, Jarrah, Kyeema, Langi, Millin, Pelde and Namage and two breeding lines YRL 101 and YRL 38). In separate experiments plants were inoculated by either sclerotia placed on the soil surface of by discs of agar culture placed against the stem at water level.
Outcomes
Cultivars were not uniform in their reaction to stem inoculation. Amaroo, Kyeema, Millin and YRL 38 yielded significantly less when inoculated, with yield reductions ranging from nearly 30% in Kyeema to 9.5% in YRL 38. The length of stem colonised by S. oryzae was not reflected in yield. Lange and Pelde had the most stem tissue bearing sclerotia but their yield was not significantly affected by the disease. Amaroo had 45% less colonised stem tissue than Lange but incurred a yield reduction of 27%.
Implications
It would appear that the strain of S. oryzae present in NSW is not as virulent as strains elsewhere and therefore, under present conditions, only poses a threat to Amaroo, Kyeema, Millin and YRL 38. The yield reductions obtained reflect a possible worse-case scenario under high levels of disease pressure. Although stem rot can be classed a minor disease at present, growers should not be complacent and ignore it. Sclerotia can survive for many years and management of crop trash is important to minimise the carryover from year to year. Continual rice growing in the same field may select for more virulent variants of the pathogen, resulting in even greater potential for production losses.
Rice growers with fields known to be infected with the stem rot pathogen may consider avoiding growing Amaroo, Kyeema, Millin of YRL 38. The appearance of stem rot disease in 1995/96 serves as a warning that the industry’s relative freedom from disease is tenuous and vigilance to avoid introducing new or more virulent pathogens must be maintained.
Project No: DAN-156A
Researcher: Dr Eric Cother
Organisation: Orange
Agricultural Institute, NSW Department of Agriculture, Forest Road, ORANGE
NSW 2800
Contacts: Phone:
(02) 6391 3886 Fax: (02) 6391 3883
E-mail: cothere@agric.nsw.gov.au
