Issue No 8, July 1997.

NOTICE: Hard copies of the Australian New Crops Newsletter are available from the publisher, Dr Rob Fletcher. Details of availability are included in the Advice on Publications Available.

13. New Crops research projects

The University of Melbourne
The Plant Molecular Genetics and Germplasm Development Group

Postgraduate research projects currently being conducted in this group in new crops in Australia are as follows:

Rebecca Ford , PhD student

A low level of genetic diversity was found to exist between cultivars/accessions of Lens culinaris indicating that a narrow genetic base exists within the germplasm in the lentil breeding program. Lens species have been separated based on unique molecular marker patterns generated from PCR with the primers for the 5S rRNA gene spacer regions. Species-specific markers were developed for introgression studies in Lens interspecific crosses. Markers specific to Ascochyta blight resistance are being sought by screening a range of RAPD markers on DNA bulks of F3 plants segregating for resistance and susceptibility. A marker, RP04, was linked within 15 cM of the resistance gene and will be developed further for use in identifying disease resistant germplasm in the breeding of resistant lentil cultivars.

Ford, R, Pang, E C K and Taylor, PWJ (1997). Diversity analysis and species identification in Lens using PCR generated markers. Euphytica (In press).

Ford, R, Pang, E and Taylor, P (1995). Development of molecular markers for the genetic improvement of lentils. Proceedings of the 35th Australian Society of Plant Physiologists Conference, Sydney.

Taylor, P, Croft, A, Ford, R, Hayes, J and Pang, E (1996). Development of molecular markers for grain legume (Pisum, Lathyrus and Lens) crop improvement in Australia. Proceedings of the 4th Plant Genome Conference, San Diego, USA, p42.

Development of molecular markers for Ascochyta blight resistance in Lathyrus sativus
Allison Croft , PhD student

The genetic variation between L. sativus accessions and between L. sativus, Pisum sativum and other Lathyrus species has been examined using RAPD analysis. The results indicate a low level of genetic variation between L. sativus accessions, indicating that new sources of variation may be required for improving this species as a crop. These results have also been used to determine the genetic relationships between the Lathyrus spp., and between these species and P. sativum. L. sativus accessions exhibiting varying reactions to Ascochyta pinodes have been identified and crosses have been made between resistant and susceptible plants to study the genetic control of resistance and to develop molecular markers linked to resistance genes.

Croft, A, Pang, E and Taylor, P (1995). Intraspecific and interspecific genetic variations in the genus Lathyrus. Proceedings of the 35th Australian Society of Plant Physiologists Conference, Sydney.

Transferring Ascochyta blight resistance from Lathyrus sp. to field pea (Pisum sativum) via protoplast fusion
Jennifer McCutchan, PhD student

Field pea (Pisum sativum) and grass pea (Lathyrus sativus) plants were established in vitro and the meristematic shoot-tip tissue was digested in enzymes to produce protoplasts. Field pea protoplasts were cultured, regenerated cell walls, divided and developed into minicallus. Embryo-like structures developed on this callus after transfer to solid medium. Protoplasts of Pisum and Lathyrus will be fused and somatic hybrid plants screened for Ascochyta blight resistance.

McCutchan, J S, Pang, E C K and Taylor, P W J (1996). Somatic embryo regeneration from protoplasts of field pea (Pisum sativum). International Association for Plant Tissue Culture (Australian Branch) Vth Meeting, Gatton, p 18.

McCutchan, J S, Pang, E C K and Taylor, P W J (1996). Plant regeneration from protoplasts of field pea (Pisum sativum). Proceedings of the 36th Australian Society of Plant Physiologists Conference, Canberra, No. 104-02.

Kabuli chickpea (Cicer arietinum) cultivar improvement through biotechnology
Janine Croser , MAgrSc student

Chickpea improvement has been slow, due to limited genetic resources in the cultivars and a lack of adapted biotechnology techniques. Double-haploid plants contain a single set of chromosomes which are useful for selection of desirable traits. Anther/microspore cultures of chickpea were established, callus regenerated and embryoids developed on the callus. A micropropagation system for clonal multiplication of chickpea has been established. This tissue culture system will be used to regenerate hybrids by embryo rescue after interspecific hybridisation. Using RAPD analysis, the genetic similarity among cultivars of chickpea and accessions of C. reticulatum and C. echinospernum were estimated and dendograms constructed. The cultivars of chickpea and accessions of C. reticulatum and C. echinospernum clustered into separate groups. However, the genetic diversity within and between the three species was very low. Species-specific stable probes will be identified using RAPD (random amplified polymorphic DNA) and repeat sequence analysis and used to monitor the introgression of the wild species genome into the cultivar genome. These techniques will offer the breeder some tools to speed the development of higher yielding, disease resistant cultivars that are tailored to meet market demands.

Croser, J S, Brouwer, JB and Pang, EC (1996). Cultivar improvement in kabuli chickpea (Cicer arietinum) through tissue culture techniques. Proceedings of the 14th International Congress of Sexual Plant Reproduction, Lorne.

Croser, J S, Brouwer, JB and Pang, EC (1996). Speeding development of kabuli chickpea (Cicer arietinum) cultivars through tissue culture techniques. Proceedings of the 14th International Congress of Sexual Plant Reproduction, Lorne.

Epidemiology and physiologic specialisation of mint rust (Puccinia menthae Pers.) on peppermint
Jacky Edwards, PhD student

Edwards, J, Parbery, DG, Halloran, GM, Pang, ECK (1995). A comparison of the field disease cycle of Puccinia menthae on Todd Mitcham peppermint and Scotch spearmint. 10th Biennial Australasian Plant Pathology Society Conference, Lincoln University, Christchurch, New Zealand, 28 - 31 August 1995, Scientific Programme and Abstracts p74.

A study of the field disease cycle of mint rust (Puccinia menthae) on peppermint and Scotch spearmint was carried out at the Ovens Research Station, Myrtleford, north-eastern Victoria, from February 1994 to July 1995. All stages of the mint rust life cycle were observed on Scotch spearmint, but only uredinia and telia were observed on peppermint. Urediniospore viability studies suggested that the urediniospores remained viable throughout the winter months on peppermint and were the source of inoculum for the new season's growth. This has implications for the effective control of mint rust by growers in this region.

Edwards, J, Halloran, GM, Parbery, DG, Taylor, P and Pang, ECK (1996) Mint Rust And The Peppermint Oil Industry Of North-Eastern Victoria. 1st Australian New Crops Conference, The University of Queensland Gatton College, 8-11 July 1996.

Peppermint oil production is an emerging industry in north-eastern Victoria. The potential yields for the region have not been reliably achieved due to the disease mint rust. Mint rust is caused by the fungus, Puccinia menthae Pers., and yield losses from infection are due to defoliation of the crop and a reduced menthol component of the essential oil. The disease cycle in north-eastern Victoria is compared with that reported elsewhere. Control measures are discussed.

The University of Queensland, Department of Agriculture

Postharvest effects of high temperature on mango fruit
Dr Suzan E. Hetherington

The sustained development of the Queensland mango industry is linked with the development of export markets. For high quality fruit to be accepted in the international market place, it has to be free of both tetriphid fruit flies and chemical residues. Non-chemical treatments used to eradicate fruit flies in fresh horticultural produce require that the harvested produce be heated for a short period of time. At present, the out-turn of fruit from these high temperature treatments is variable. Fruit may be unmarketable due to heat inactivation of ripening processes and also to the development of skin scald. This project aims to determine the physiological factors that pre-dispose mango fruit to high temperature damage and to establish the extent to which this fruit can be heat hardened to resist high temperature damage.

Collaborators:

Ms K. Jacobi, Queensland Department of Primary Industries and Department of Agriculture, The University of Queensland

Dr E. Macrae, Horticulture and Food Research Institute of New Zealand, Auckland

Funding Agency: ACIAR

Effects of fruit calcium status on the post-harvest storage of mango
Dr Suzan E. Hetherington

The postharvest storage life of subtropical mango fruit is short, compared with that of fruit native to temperate regions. This restricts crop export potential. When placed under low temperature storage, mangoes can become chill injured within weeks and lose the ability to ripen. For temperate fruits however, elevated levels of cell calcium have been reported to ameliorate chilling injury and extend fruit storage life. This project aims to investigate the relationship between the calcium status of mango fruit and the ability of the fruit to withstand low temperature storage. Total fruit Ca levels will be manipulated in the field by imposing soil water deficits on developing fruit of different phenological age. After harvest, fruit from the different treatments will be assessed for total Ca content and the postharvest storage life of the fruit assessed. Field work is being carried out at Ayr, and postharvest storage trials are being conducted at the QDPI, Hamilton in Brisbane.

Collaborators:

Dr P.J. Hofman, Queensland Department of Primary Industries, Horticulture Postharvest Group, Hamilton

Ms S.L. Simmons, Department of Agriculture, The University of Queensland

Funding Agency: Department of Agriculture, The University of Queensland

Fruit splitting in litchi
Dr Suzan E. Hetherington

Fruit splitting may occur during the final stages of litchi fruit development. The reason for the fleshy aril rupturing the fruit skin is not yet known. However, there is some suggestion that water stress during the early stages of fruit development may limit skin growth, thereby reducing the volume available for the aril. This project aims to document the cellular development of litchi fruit and to determine the effect of transitory periods of water stress on fruit development. Experiments on field grown trees are being conducted at Caboolture and pot experiments are being carried out in the Department of Agriculture.

Collaborators:

Dr C.A. McConchie, CSIRO,
Division of Horticulture

Mr U. Kumcha, Department of
Agriculture, UQ

Funding Agencies: CSIRO/UQ Collaborative Research Grant, Department of Agriculture, UQ

Fungal diseases of waxflowers in Queensland
Dr H.J. Ogle

Waxflowers (Chamelaucium spp.) are becoming increasingly important in commercial horticulture. They are produced throughout Australia and are marketed predominantly in Japan, North America and Europe. In 1992, the National Waxflower Priority Setting Workshop identified pathogen control as a high priority and recognised that, in the short term, there is a need for pathogen identification. This project is designed to answer this need by providing a publication that describes and illustrates the major fungal pathogens of waxflowers.

Funding Agency: Department of Agriculture, UQ

Nipat Sukvihbul

Micropropagation and physiolog-ical studies on the ferns Sticherus flabellatus R.Br. and Platycerium superbum G.J.J. et E.T.
Ms Edna Vida

The University of Queensland, Department of Botany

Seed infection of mungbean by Macrophomina phaseolina
Michael J. Fuhlbohm

CRC for Tropical Plant Pathology and Department of Botany, UQ

Charcoal rot, caused by the anamorphic fungus Macrophomina phaseolina [Tassi (Goid.)], is an economically important disease of mungbean [Vigna radiata (L.) Wilczek]. The pathogen is seed-borne and seed transmitted. When infected seed is germinated, a wet, fast spreading, black rot develops on sprouts. This rot is unacceptable to sprouting companies and lucrative overseas markets. If M. phaseolina is detected during standards testing, a downgrading of the sample to a lower price can be expected.

In 1996, 41% of the samples we tested were positive for M. phaseolina. External contamination of the seed coat can be caused at harvest from infested soil adhering to the seed.

There are several possible modes of seed infection. In glasshouse studies, we have found that by inoculating developing pods with microsclerotial inoculum of M. phaseolina, seed infection rates approaching 100% can be obtained. High humidity was necessary for infection. The size of the green pods at inoculation had no effect on the subsequent high levels of seed infection in those pods. Pods that developed from inoculated flowers contained up to 20% infected seed. The fungus was not detected in seeds from pods that developed after inoculation, even on the same peduncle.

The low seed infection rates that are associated with Australian growing conditions could not be reduced further by foliar applications of the fungicide carbendazim at flowering and early pod fill. M. phaseolina can infect at least 500 species and we have found that most weed species in Australian mungbean fields are also hosts. Since the pathogen is able to survive in soil for many years in the absence of a host, conventional rotations are not a viable method of reducing soil-borne inoculum.

Current research initiatives include studies of pathology and histopathology of other possible modes of seed infection and the evaluation of post-harvest treatments of mungbean seed to eliminate M. phaseolina.

Collaborators:

E.A.B. Aitken, CRC for Tropical Plant Pathology and Department of Botany, UQ

N.J. Ryley, CRC for Tropical Plant Pathology and Queensland Department of Primary Industries, P. O. Box 102 Toowoomba, Australia 4350.

Marketing analysis of new crops
Chai McConnell

Economic analysis of new crops
Greg Ferguson

The ecological sustainability of harvesting native foliage in south-east Queensland
Leif Peterson

The genetic variability of moth bean Vigna aconitifolia
Glen Beech, MAgrSci 1996

Identification of superior cashew trees for northern Australian conditions
Felipe dela Cruz, PhD 1997

Cashew is a highly cross-pollinated crop and trees derived from seedlings do not breed true-to-type. The most effective and quickest approach to improving this highly heterogeneous crop will be to identify superior trees, combining high yields with good quality kernels. This study was conducted to identify superior trees from amongst the trees originally derived from seedlings at Cashews Australia, Dimbulah, in Far North Queensland. Morphological characterisation and preliminary evaluation were carried out to determine the extent of variability present in the cashew population. Morphological characteristics associated with high productivity were identified.

The nut yield characters were the most variable characters studied, with the number of nuts per tree showing the highest variation. Total nut weight per tree was positively correlated with the nut number per tree whilst nut number per tree was negatively correlated with the mean nut weight per tree. The lack of significant correlation between the total nut weight and the mean nut weight indicated the possibility of selecting high yielding trees with good quality nuts.

From the original 135 well-buffered trees evaluated, nineteen trees combined levels of total nut weight per tree, number of nuts per tree and mean nut weight per tree higher than the mean of the cashew population studied. Four trees were considered superior since they produced total nut weights of more than 6.0 kg per tree and more than 6.0 g mean nut weight. These trees were recommended as mother trees to be used for asexual propagation.

A wide range of variation was observed in the nut, apple, tree, leaf and panicle characters. Testa weight, shell weight, nut weight, kernel weight, apple weight and the number of panicles per tree showed wide variation.

Highly positive correlations were observed amongst the nut, shell and kernel characters, except for shelling recovery which showed negative correlations with the nut and shell characters. Apple weight was highly correlated with apple length and diameter whilst it was not significantly correlated with the total soluble solids (TSS). Apple weight, length and diameter also showed positive correlations with the nut characters, except shelling recovery, with which they were negatively correlated. Highly significant correlations were observed amongst the tree and leaf characters. The leaf characters were positively correlated with the nut, shell and kernel weights. Panicle length was highly correlated with panicle width but it was not significantly correlated with the number of panicles per tree.

The total nut weight per tree was highly correlated with the tree characters (height, girth and canopy spread). Nut number per tree was negatively correlated with the nut characters (except shelling recovery) and with apple characters (except TSS) and positively correlated with tree canopy spread. Mean nut weight per tree was negatively correlated with shelling recovery and positively correlated with the apple characters (except TSS) and leaf characters.

Multiple correlation analysis showed that kernel weight, nut width and tree canopy spread were the most important characters influencing the total nut weight per tree. The tree canopy spread highly influenced the number of nuts per tree whilst apple TSS and the number of panicles per tree influenced mean nut weight per tree.

A wide range of variation was also observed in the qualitative characters studied. High total nut weight was highly associated with trees bearing apples with shallow cavity at the apex and early flowering season. High nut number per tree was highly associated with trees bearing apples with a level apex and early flowering season. High mean nut weight was highly associated with large nut stylar scar, deep cotyledonary grooves and an oblique apple apex.

The northern and western quadrants of the cashew tree canopy produced higher total nut weight, nut number, total number of shoots and number of shoots with panicles than the eastern and southern quadrants. In addition, well-buffered trees produced significantly less total nut yield than trees located in the border and poorly-buffered trees.

The identification of superior trees will be useful in increasing nut production and improving the quality of nuts produced at Cashews Australia. The morphological characters associated with the nut yield components will be useful in selection work.

Extraction of essential oils from potential new crops
Luigino Doimo, PhD student

Studies of osmoregulation in foxtail and proso millets
Mr Karyudi, PhD student

Yield-related characters in foxtail and proso millets
Stephen Mitchell, PhD student

Light interception as a determinant of seed and gum yield in guar (Cyamopsis tetragonoloba)
Helen Murphy, PhD student

Investigation of techniques of sex determination for papaya breeding
Songpol Somsri, PhD student

Investigations into ginseng as a potential new crop
Tony Sadler, PhD student

New crops for the eastern Darling Downs and Burnett regions
Gerry Kregor

Development of the DOOR-Marketing program using action research
Peter Blessing

Environmental and physiological basis of adaptation in black gram (Vigna mungo)
Adrien Mourges

This study is assessing the influence of environment on phenology and yield in black gram. Seven lines have been selected from an initial group of 87 for further investigations. A multi-environment study comprising various combinations of photoperiod and temperature was commenced in July 1996 and has been completed recently.

Control of flowering, breeding systems and population biology of Banksia species
Mary Rieger, PhD abstract

The aims of this research were to improve understanding of the control of flowering in relation to photoperiod and temperature to increase knowledge of the floral initiation trigger for Banksia. An exploration of population biology in relation to genetic variation present in commercial and natural populations of Banksia will provide more information on the pool of variation available for breeding programs. Using molecular biology techniques to explore areas such as pollen competition and gene flow may improve our understanding of these important processes.

The floral initiation of Banksia coccinea and Banksia hookeriana were examined in controlled environment conditions. Both species were subjected to four different treatments: long (16h) and short (8h) daylengths at high (25/20°C) and low (15/10°C) temperatures.

During these treatments vegetative flushing, vegetative extension growth and flowering were measured. Banksia coccinea showed a significant response to photoperiod while Banksia hookeriana responded to temperature. The flushing pattern for the two species was similar with most flushing occurring in late spring.

The most significant vegetative extension growth for both species occurred during the flush period of late spring/summer. Banksia coccinea under 16 hours and 25/20°C produced maximum average vegetative growth of 6 cm. This treatment also resulted in maximum flowering for Banksia coccinea.

Contrastingly, maximum vegetative growth for Banksia hookeriana was observed at both daylengths and 25/20°C. The two high temperature treatments resulted in flowering at both 16h and 8h, but no flowering was observed for low temperature treatments.

A survey of genetic variation of Banksia coccinea and Banksia menziesii in eleven South Australian commercial and fourteen Western Australian natural populations was conducted. DNA was extracted from leaf material and the random amplified polymorphic DNA (RAPD) technique was utilised. Individuals and populations were compared using the simple matching similarity index. Dendrograrns were developed to establish relationships between natural and cultivated populations.

Within cultivated populations, similarity comparisons between individuals of Banksia coccinea ranged from 70 - 93%, while within natural populations values ranged from 63 - 93%. The highest similarity value between populations in South Australia was 96% while the highest similarity value between populations in Western Australia was 74%.

The dendrogram constructed from between population similarity values indicated that the South Australian populations were closely linked but also indicated some links to Western Australian populations. Within cultivated population comparisons of Banksia menziesii ranged from 54 - 81%, while within natural populations values ranged from 53 -98%. The similarity value between populations in South Australia ranged from 66 - 92%, while the highest between natural population value was 94%, with all other values above 80%.

The dendrogram constructed from the between population similarity values indicated that the Western Australian populations were closely related. There were links between the South Australian cultivated and some natural Western Australian populations.

Pollen competition experiments were carried out on Banksia menziesii. On a total of six plants, six inflorescences per plant were hand pollinated. One inflorescence was selfed, one was crossed, two inflorescences had self pollen followed by cross pollen applied and in the last two the latter process was reversed. Mature seeds were collected after twelve months and the DNA extracted. The RAPD technique was applied to determine the status of the double pollinated seeds and confirm the status of the self and crossed seed.

Gene flow in a small population was examined for two species, Banksia praemorsa and Banksia prionotes. Open pollinated seed was collected from a number of inflorescences and the DNA extracted. The RAPD technique was used to identify the father of each seed and hence the frequency and direction of pollen and therefore gene flow. A survey of potential pollinators was also conducted to establish which pollinators were transferring pollen. Honeybees and honeyeaters were the most common agents of the pollen transfer.

Growth control of Australian Acacias
Mary Parletta, PhD abstract

The Australian genus Acacia includes species with attractively-shaped and coloured phyllodes or bipinnate leaves, producing many bright yellow flowers in spherical or cylindrical inflorescences. Some species naturally attain a mature height of less than one metre.

This research aimed to produce a small flowering pot plant of Acacia, less than 35 cm high and capable of producing more than 50 inflorescences within twenty four months, or a potted foliage plant achieving less than 35 cm height within twelve months, or a flowering tub plant less than 1 m high with more than 50 inflorescences within thirty six months.

The species tested were A. acinacea, A. baileyana, A. baileyana purpurea, A. buxifolia, A. cometes, A. crassuloides, A. craspedocarpa, A. decors, A. drummondii elegans, A. glaucoptera, A. imbricata, A. meisneri, A. myrtifolia, A. notabilis, A. podalyrifolia, A. polybotrya, A. retinodes, A. semilunata, A. vestita and A. verniciflua. All experimental plants were grown from seed.

Reduction of plant height was achieved in other genera using techniques such as high night temperature and chemical application of growth retardants. Flower development in A. pycnantha is known to be responsive to low temperature. Thus experimentation included both controlled environment and chemical treatments.

Low temperature (15°C day/10°C night) reduced shoot length and node number in mature plants of A. notabilis. Paclobutrazol (2 mg active ingredient) reduced vegetative growth at both 15/10 and 20/8 temperatures.

High night temperature (20/25) had no effect on height or flowering of A. imbricata or A. glaucoptera, or on height of A. craspedocarpa.

After several weeks at low temperature (15/10), strong flowering occurred in plants of A. acinacea, A. buxifolia, A. drummondii elegans, A. glaucoptera, and A. myrtifolia, but at high temperature (25/20) weak flowering occurred after a few days and was not sustained. Examination by environmental scanning electron microscopy of A. drummondii elegans inflorescences showed inhibition of stamen development and anthesis at high temperature.

Seedlings of A. acinacea and A. imbricata treated with paclobutrazol (2 mgai) or A. glaucoptera treated with 4 mgai, either alone or in combination with pruning or 6, benzyl-amino purine, produced flowering plants of less than 35 cm height within twenty four months. However paclobutrazol reduced the number of inflorescences in A. acinacea. Pruning did not control plant height. The cytokinin 6, benzyl-amino purine did not increase branching and flowering at the rates tested.

A. vestita treated with 2 mgai paclobutrazol and A. baileyana and A. podalyrifolia treated with 4 mgai paclobutrazol produced foliage pot plants less than 35 cm high either alone (A. podalyrifolia, A. vestita), or in combination with pruning, within twelve months. A. cometes and A. crassuloides produced small sized foliage plants without treatment within twelve months.

A. buxifolia, A. decora and A. drummondii elegans produced tub plants less than one metre tall with more than 50 inflorescences within twenty eight months with no chemical treatment.

The period of juvenility before flowering for A. drummondii elegans was nine months, for A. glaucoptera sixteen months, A. cometes twenty three months and A. meisneri seventeen months. The holding period to flowering could be minimised for A. drummondii elegans and A. glaucoptera by selection of sowing time.

This study has produced a protocol for production of flowering pot plants of A. acinacea using a combination of pruning and paclobutrazol. A protocol for tub plants of A. drummondii elegans. A. buxifolia and A. myrtifolia produced satisfactory results for a flowering tub plant with pruning only, thus avoiding the need for chemical treatment.

Variability in plant size and maturity presented problems in the research. This should be addressed by investigation of clonal propagation of early flowering selections. Future work is required to finalise a protocol which combines low temperature flowering control with time of sowing and chemical size control to produce a potted flowering Acacia plant in the minimum time possible.

Genetic diversity and interspecific relationships in Banksia L.f. (Proteaceae)
Tina Maguire, PhD abstract

Banksias are amongst the best known Australian wild flowers. They are used in ornamental horticulture and last well as fresh cut flowers, or indefinitely as dried arrangements. Breeding and selection of new cultivars for the cut flower industry is currently underway. This thesis aimed to increase the knowledge essential for conservation biology and for focused and efficient breeding of banksias.

Pollen storage and viability testing are important adjuncts to a plant breeding program. Banksia menziesii pollen was stored at 20°C, 4°C, -20°C, -80°C and -196°C and assessed using a semi-solid medium of 1% agar, 15% sucrose, 0.01% boric acid, 0.03% calcium nitrate, 0.02% magnesium sulphate, 0.01 % potassium nitrate, and an incubation temperature of 25°C. Germination remained constant at around 70% in all treatments except at room temperature 20°C, which had only 25% germination after six months.

Pollen viability was assessed using fluorescein diacetate (PDA), but the results did not reflect the loss of germinability at 20°C. There was no effect of floret position on the inflorescence on germination; but pollen viability varied over the flowering period with maximum germination mid- season.

Interspecific hybridisation was assessed as a potential breeding tool, and for the assessment of species relationships within the genus. Pollen tube growth was investigated using controlled hand pollination of the commercially significant species Banksia coccinea, to species of Banksia, and the related genus, Dryandra.

Currently, the relationship between B. coccinea and the other species groups within Banksia is unclear. It has been found previously that success of pollen tube growth in the pistil following interspecific pollination was largely related to taxonomic distance between the species. Thus, interspecific hybri-disation is a suitable technique to determine the compatibility relationships of the problematic species B. coccinea.

Some species supported no germination of B. coccinea pollen. Others produced pollen tube abnormalities including thickened walls, bulbous swellings, non-directional growth, burst tubes and branched tubes. Control of pollen tube growth in the pistil was imposed in the pollen presenter, a specialised region of the style for pollen presentation to foraging fauna, and in the upper style.

There was no significant reciprocal effect on pollination success in the lower style. The results of pollen tube compatibility in the lower style indicated that B. coccinea had a closer affinity to the section Oncostylis, than to section Banksia, where it is currently placed.

Given the distinct morphology and close pollen-pistil relationship to section Oncostylis, it was proposed to move B. coccinea out of section Banksia to a new section Coccinea, the sister section to Oncostylis. Intergeneric crosses of B. coccinea with Dryandra species resulted in some compatibility, with one cross having low numbers of pollen tubes in the pollen presenter and upper style region. These results indicated a close relationship between Banksia and Dryandra, which are sister genera in the tribe Banksiae, family Proteaceae.

Species relationships within Banksia were also assessed using molecular techniques. Random amplified polymorphic DNA (RAPD) markers were assessed for their usefulness at various taxonomic levels within the genus. It was found that RAPDs are informative at the close species level, but not at more distant levels, such as between distantly related series, sections, and subgenera.

In addition, species relationships at higher levels were investigated using direct polymerase chain reaction (PCR) sequencing of chloroplast DNA (cpDNA) spacer regions between the trnL and trnF exons. These regions were thought to be universal for plant species and informative at the intra and interspecific level of plants. Using the region between trnL and tniF, relationships within Banksia, and between Banksia and Dryandra were investigated. It was found that this region was conservative, with little variation between species.

Section Banksia formed a group, section Oncostylis another group, and B. coccinea, along with two Dryandra species, was placed between the two sections. Resolution at this node however, was not complete. Subgenus Isostylis formed two groups away from the two sections in subgenus Banksia, with B. illicifolia and D. formosa together. B. cuneata was more distantly related. Based on DNA sequence and RAPD data, it appeared that Banksia and Dryandra may be artificial genera, and that in the presence of each other, they cannot be separated using RAPD or trnL DNA sequence data.

Genetic variability within species of Banksia was investigated using RAPDs. Levels of genetic diversity were generally high, ranging from 0.59 - 0.90. This agreed with previous work using isozymes, pollen tube and fruit set data, showing that Banksia species are predominantly outcrossing.

In particular, a detailed study was conducted on a geographically restricted, rare and endangered species, B. cuneata. Using RAPDs on all known populations, it was found that levels of genetic diversity were high, ranging from 0.65 - 0.74, and that there was no significant genetic differentiation between populations.

In conclusion, this study contributed to knowledge essential for further improvement and conservation of Banksia species, and raised questions regarding the currently accepted taxonomic relationships within Banksia and between Banksia and Dryandra.

Eucalyptus and ornamental horticulture
Delaporte Kate

Post-harvest physiology of bean sprouts
Ramatollah Golru

Oriental hot chilli development in Australia
Mayuree Krajayklang

Plant reproductive biology of Banksia
Merran Matthews

Horticulture and marketing of Banksia
Raelene Mibus

Breeding biology of Acacia baileyana
Anne Morgan

Horticulture of foliage eucalypts
Michelle Wirthensohn

Aspects of Chinese water chestnut (Eleocharis dulcis) diversity, physiology and production in Australia.
Ms Mei Li, MAppSci student

Some aspects of germination, early growth and development in high value rainforest species in Central Queensland.
Nick Smith, MAppSci student

Autecology of Cassia brewsteri with respect to gum production.
David Cunningham, MAppSci student

Assessment of active constituents in Echinacea purpurea during production and processing
D. Stuart, PhD student

Processing of Asian radish (daikon)
R. Coogan, PhD student

Assessment and development of the germplasm of Trigonella foenum-greacum within the temperate cropping zone.
Dr Rob Norton and Ms Kate McCormick

The basis of the project is to assess various accessions of this species as a grain or green-manure crop in the south-eastern grain growing regions. We have accessed approximately 210 lines from various genetic resource centres and are starting the evaluations this year.

Factors affecting yield and composition of floral extract from Boronia megastigma (Nees).
Hazel S., MacTavish, PhD thesis, 1995

MacTavish, H.S. and Menary, R.C. (1997a). Optimising solvent extraction of Boronia megastigma (Nees) flowers. Journal of Essential Oil Research (in press).

MacTavish, H.S. and Menary, R.C. (1997b). The effect of flower maturity and harvest timing on floral extract from Boronia megastigma (Nees). Annals of Botany (in press).

MacTavish, H.S. and Menary, R.C. (1997c). Volatiles in different floral organs, and effect of floral characteristics on yield of extract from Boronia megastigma (Nees). Annals of Botany (in press).

Yield and quality of concrete from Boronia megastigma (Nees).
RIRDC research grant,
Professor RC Menary, Dr HS MacTavish

The flowering physiology of Nerine bowdenii.
Martin Blake

The genus Nerine contains a number of species of autumn flowering bulbs which have recently been introduced into Tasmania as potential floriculture crops. There is significant potential for Nerine to be grown as a cut-flower crop in Tasmania and south-eastern Australia. However, low flowering percentages in field planting due to flower bud abortion limits the commercial viability of the crop. The project is examining the physiological basis of flowering and flower bud abortion in order to develop appropriate commercial practices for cut flower production. The project is an ARC-funded APA (Industry) project with Channel Bulbs as the industry partner. Dr Phil Brown and Dr Ron Crowden from the University of Tasmania are co-supervisors.

Leaf and Extract Production from Tasmannia lanceolata
Chris Read, PhD abstract 1996

This study examined several aspects of the preparation, extraction and analysis of solvent soluble compounds from leaf material of Tasmannia lanceolata and reported a preliminary survey of extracts of some members of the natural population of the species in Tasmania.

A major constituent of these extracts, polygodial, was shown to be stored within specialised idioblastic structures scattered throughout the mesophyll and characterised by a distinctive size and shape and a thickened wall. The contents of these cells were sampled directly, analysed and compared with the composition of extracts derived from ground, dry whole leaf. This result was supported by spectroscopic analysis of undiluted oil cells in whole leaf tissue.

In a two year field trial, the progressive accumulation of a number of leaf extract constituents (linalool, cubebene, caryophyllene, germacrene D, bicyclogermacrene, cadina-1,4-diene, aristolone and polygodial) during the growth flush was followed by a slow decline during the subsequent dormant season. These results were interpreted in relation to leaf dry matter accumulation, in order to propose a harvest period within which leaf material will produce consistent composition of extract.

Under four levels of irradiance in a growth cabinet experiment the plant exhibited many characteristics of a 'shade' species, in particular, a limited ability to acclimate to high light levels. Assimilation rates were highest at 150mmol m-2s-1. The optimum new assimilation rate was obtained from 18-25°C. The effect of level of irradiance on the proportion of extractable compounds in the leaf was reported and discussed in relation to a probable production system in which the new canopy is largely removed at the end of each growth cycle.

The ontogenetic patterns determining canopy architecture were observed in the field and used, with support from the results of a trial pruning of mature trees, to discuss the likely outcome of various harvest methods. These results were combined to suggest a production strategy for maximum yield of leaf extract of consistent composition. The strategy proposed harvesting in late summer, after new leaf has achieved full maturity and may enable full canopy recovery in the subsequent growing season.

Pollination and Fruit Set in Fennel
Linda M. Reynolds, PhD, 1995

Foeniculum vulgare Mill. (fennel) is grown commercially in Tasmania as an essential oil crop. Although oil is produced throughout the plant, approximately 95% is located in the fruits. Fruit set directly influences oil yield. In Tasmania, commercially grown fennel frequently has a percentage fruit set less than 50%. Research was undertaken into factors influencing fruit set, with the objective of improving fruit set, oil yield and economic returns to growers.

Fennel is protandrous and therefore self-incompatible through the timing of pollen production and stigma receptivity. A field trial demonstrated that at high planting densities, fennel produced fewer higher order umbels. This reduced the time span of pollen production and reduced the quantity of pollen available for pollination of the flowers developing later in the season. Although pollen viability of glasshouse plants was often poor, this problem was not observed in the field.

A field trial involving the application of exogenous hormone gave rise to the hypothesis that competition within the fennel canopy causes poor fruit set. This competition could be a result of factors including nutrients or carbon dioxide. The two factors studied in more detail were light intensity and water stress.

Trial results suggested fennel was an obligate heliophyte. It has an open canopy as an adaptation to avoid the absorption of light in excess of that which can be utilised in photosynthesis. In the Tasmanian environment, this feature is beneficial in allowing penetration of light through the canopy and prevents shading of the lower umbels. Fennel is inefficient with respect to light absorption. Light may be a limiting factor.

Initial experiments on the effect of water stress in fennel showed that stomata reacted slowly to decreasing water availability, remaining open despite the plant wilting.

Fennel has a root system capable of tapping water at depth and was thought to be a phreatophyte.

Fennel plants were able to adjust to cycles of decreasing water potential. After a few cycles of water stress, they no longer wilted.

Attempts were made to test the theory that fennel adapts to water stress by increasing its osmotic potential. Results were inconclusive.

Contact: Dr Rob Fletcher, School of Land and Food, The University of Queensland Gatton College, 4345; Telephone: 07 5460 1311 or 07 5460 1301; Facsimile: 07 5460 1112; International facsimile: 61 7 5460 1112; Email: r.fletcher@mailbox.uq.edu.au

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originally created by: GK; latest update 6 June 1999 by: RF