Grevillea: Breeding and Development of Cut Flowers

A report for the Rural Industries Research and Development Corporation

by P.M. Martin and G.N. Brown

July 2007

RIRDC Publication No 07/101 RIRDC Project No US-105A

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© 2007 Rural Industries Research and Development Corporation. All rights reserved. ISBN 1 74151 498 3 ISSN 1440-6845 Grevillea: Breeding and Development of Cut Flowers Publication No. 07/101 Project No. US-105A The information contained in this publication is intended for general use to assist public knowledge and discussion and to help improve the development of sustainable regions. You must not rely on any information contained in this publication without taking specialist advice relevant to your particular circumstances.

While reasonable care has been taken in preparing this publication to ensure that information is true and correct, the Commonwealth of Australia gives no assurance as to the accuracy of any information in this publication.

The Commonwealth of Australia, the Rural Industries Research and Development Corporation (RIRDC), the authors or contributors expressly disclaim, to the maximum extent permitted by law, all responsibility and liability to any person, arising directly or indirectly from any act or omission, or for any consequences of any such act or omission, made in reliance on the contents of this publication, whether or not caused by any negligence on the part of the Commonwealth of Australia, RIRDC, the authors or contributors.

The Commonwealth of Australia does not necessarily endorse the views in this publication.

This publication is copyright. Apart from any use as permitted under the Copyright Act 1968, all other rights are reserved. However, wide dissemination is encouraged. Requests and inquiries concerning reproduction and rights should be addressed to the RIRDC Publications Manager on phone 02 6271 4165

Researcher Contact Details Dr. Peter Martin The University of Sydney Plant Breeding Institute PMB 11 Camden New South Wales 2570 Phone: 02 4655 0853 Fax: 02 4655 0875 Email: pmartin@camden.usyd.edu.au

In submitting this report, the researcher has agreed to RIRDC publishing this material in its edited form. RIRDC Contact Details Rural Industries Research and Development Corporation Level 2, 15 National Circuit BARTON ACT 2600 PO Box 4776 KINGSTON ACT 2604 Phone: 02 6271 4100 Fax: 02 6271 4199 Email: rirdc@rirdc.gov.au. Web : http://www.rirdc.gov.au Published in July 2007 Printed on environmentally friendly paper by Canprint

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Foreword The genus Grevillea, with more than 350 species, is one of the more prominent proteaceous components of the Australian flora. With an extensive range of growth habits and floral forms the genus has become popular for garden use throughout Australia. Some of the more upright species, with large inflorescences, have potential for cut flower use, both locally and for the export market. However, a number of problems with the currently used hybrids, including short stems, limited vase life, poor handling qualities and a limited range of flower colours resistant to premature perianth drop, have restricted their acceptance in the cut flower trade. This project is focussed on the development of improved forms for cut flower use, although plants of obvious garden merit will also be commercialised if appropriate. Improved varieties arising from the project will be entered into Plant Breeders Rights protection. It is expected that these will make a valuable contribution to the expansion of this sector of the Australian Wildflower Industry. The research has shown that it is possible to make controlled crosses between hybrids and between species with sufficient facility to make this an attractive genus for commercial plant improvement. A large number of hybrids have been successfully raised from seed and established in the field, where they are now undergoing assessment as they progressively come into flower. This project was funded from RIRDC core funds which are provided by the Australian Government. This report is an addition to RIRDC’s diverse range of over 1600 research publications. It forms part of our Wildflowers & Native Plants R&D sub-program which aims to improve existing products and develop new ones. Most of our publications are available for viewing, downloading or purchasing online through our website: • downloads at www.rirdc.gov.au/fullreports/index.html • purchases at www.rirdc.gov.au/eshop Peter O’Brien Managing Director Rural Industries Research and Development Corporation

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Acknowledgments Thanks are due to the Mount Annan Botanic Garden for access to their grevillea germplasm collection and to The Royal Botanic Gardens, Sydney for financial assistance. Thanks are also due to the Grevillea Study Group of the Australian Plants Society for financial support and advice. We acknowledge the contribution of Mr Aftab Ahmad as Technical Officer with the project in its last two years, and also the assistance of Miss Alexandra Freebairn during the conduct of the project, and in the preparation of the final report. Finally, we express appreciation to Mr Peter Abell and Professor Donald Marshall who commenced the project and were responsible for its operation during the first 15 months.

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Contents Foreword............................................................................................................................................... iii Acknowledgments................................................................................................................................. iv Contents.................................................................................................................................................. v Executive Summary ............................................................................................................................. vi

What this report is about .................................................................................................................... vi Target Readership .............................................................................................................................. vi Objectives........................................................................................................................................... vi Methods Used..................................................................................................................................... vi

Breeding Strategy........................................................................................................................... vi Breeding Technique ...................................................................................................................... vii Germination, growing-on and Assessment.................................................................................... vii

Results ............................................................................................................................................... vii Breeding ........................................................................................................................................ vii Other results .................................................................................................................................. vii

Implications for Stakeholders........................................................................................................... viii Recommendations ............................................................................................................................ viii

1. Hybrid Grevillea Production............................................................................................................ 1 Introduction ..........................................................................................................................................1 Breeding Strategy.................................................................................................................................1 Breeding Technique .............................................................................................................................2 Collection and germination of seeds and growing-on of seedlings......................................................4

Seed collection .................................................................................................................................4 Germination......................................................................................................................................7 Establishment in the Field ................................................................................................................7

Field Assessment..................................................................................................................................7 2. Results of hybridisation work and discussion................................................................................. 9

Hybridisation Results ...........................................................................................................................9 3. Training to improve the proportion of quality flowers................................................................ 14

Introduction ........................................................................................................................................14 Exploratory trials................................................................................................................................14 Conclusion..........................................................................................................................................15

4. Frost sensitivity................................................................................................................................ 16 5. Grevillea Breeding at the Plant Breeding Institute ...................................................................... 17

Appendix. Poster Paper from the 12th International Protea Conference. .....................................18

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Executive Summary What this report is about The genus Grevillea, with more than 350 species, is one of the more prominent proteaceous components of the Australian flora. With an extensive range of growth habits and floral forms the genus has become popular for garden use throughout Australia. Some of the more upright species, with large inflorescences, have been seen to have potential for cut flower use, both locally and for the export market. However, a number of problems with the currently used hybrids, including short stems, limited vase life and premature perianth drop, have restricted their acceptance in the cut flower trade. This project is focussed on the development of improved forms for cut flower use. However, given the unpredictability of the output from a hybridisation program, any forms suitable for general garden use will also be assessed and released if of sufficient merit. Target Readership The report is intended to inform current and potential growers of Grevillea as a cut flower, of progress towards the goal of providing industry with superior material and will also be of interest to commercial propagators who would need to be involved to supply the industry with the very large number of plants required whether for cut-flower use or garden use. Objectives The objectives of the project as originally laid down were as follows: • improve protocols for cut flower production of Grevillea varieties • produce advanced lines incorporating the following traits that will deliver answers to the

deficiencies in the current Grevillea cultivars as used in the cut flower industry: longer stem length, greater floral production, improved range of flower colours resistant to perianth drop, improved vase life and resistance to transport damage

• demonstrate the commercial viability of cut flower Grevilleas • breed cultivars suitable for the cut flower trade. Redefining of the objectives became necessary as the project progressed became there was insufficient funding available to undertake significant work in all four areas. A decision was made to place the main emphasis on the development of advanced lines (2nd objective) that would after appropriate assessment lead to the release of one or more PBR protected cultivars, suitable for the cut flower trade (4th objective). Methods Used Breeding Strategy Since the most promising material currently available for cut flower work has been derived primarily from crosses involving Grevillea banksii and allied species, it was considered appropriate from a commercial breeding perspective to undertake an extensive crossing program between various commercial hybrids of this parentage. The underlying concept in this method is that by making a large number of crosses and applying strict selection criteria to the progeny it is likely that variants on the existing commercial types possessing one or more of the desired improvements will be found. These new forms can then be used for further inter-crossing in an effort to combine multiple desirable features in the one plant. In contrast to the commercial approach adopted above, the project also included a more speculative element in which wide crosses were attempted. One group of crosses involved the backcrossing existing cut flower varieties to one or other of their parent species. The second group involved crossed between named cultivars and unrelated species or cultivars with desirable floral or adaptive features. The third group of crosses involved the use of two unrelated species in an attempt to create novel

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hybrids for use as parents in future work with established varieties. In this latter case, with wide crosses between apparently unrelated species, there is of course a greatly reduced expectation of success. Breeding Technique Grevilleas are generally out-breeding plants, but have varying degrees of self-fertility. In order to make controlled crosses it is necessary to emasculate selected flowers (remove pollen from florets at a suitable stage of development, typically 10-30 buds per inflorescence), remove the other buds, and a few days later transfer pollen from the chosen male parent to the stigmas of emasculated flowers. Contamination is minimised by covering flower heads with weatherproof paper bags. When closed properly, insects and birds cannot enter with foreign pollen or eat the developing seed. This also prevents pollen transfer from other inflorescences nearby that may rub against the stigmas. Germination, growing-on and Assessment The seeds often display deep dormancy and are difficult to germinate, but using tissue a tissue culture technique and growth hormones good germination rates were achieved in a short time. Seedlings were then transferred to soil in small pots and eventually planted in the field for growing-on and eventual assessment as they reached the flowering stage. Assessment focussed on the desired characters set out under Objectives, above. Results Breeding Hybrid seed was successfully produced in a majority of crosses involving varieties that have similar parentages (Table 1). This was also the case of hybrids that were effectively backcrossed to the species from which they were derived (Table 2). With the wider crosses involving either unrelated varieties or unrelated species, results were generally unsuccessful, but there were some notable exceptions, including G. decora x G. ‘Sylvia’ and G. georgeana x G. bipinnatifida (Tables 3 and 4). Material from all classes of crosses was successfully established in the field. Since it typically takes about two years for shrubby Grevilleas to reach flowering (and longer for full flowering), it will be several years before all the products of the crossing programme are assessed. However, of the approximately sixty hybrids which have so far come into flower, nine show novel characteristics of sufficient merit to warrant more detailed evaluation: three for garden use, one for filler foliage use and the remainder for cut flower work. Given these promising early indications we are confident that the project goals of producing advanced breeding lines of merit and of producing PBR protected new varieties will be adequately met. Other results In other work related to the subsidiary objectives, it was found that many existing commercial varieties are very sensitive to moderate frosts, with damage ranging from bud-burn to death of the bushes. Since many potential production areas close to major export airports are frost prone this becomes an important limitation on the development of the industry. In the assessment of the new hybrids special attention has been paid to frost susceptibility. Pruning and training experiments in an attempt to increase the number of first class bloom were generally unsuccessful, the Grevilleas proving to be essentially untrainable. However, there may be some scope for coppicing of older bushes to produce crops of vigorous young shoots with improved production potential. More work is needed on this latter point.

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Implications for Stakeholders Improved cultivars arising from this project for the cut flower industry will contribute to an expansion of the area devoted to Grevilleas and to an increased presence of this genus in the export trade. Improved garden forms will broader adaptation will increase the popularity of this already important garden shrub. In addition, the propagation industry will benefit from increased demand from both classes of user. Recommendations The new cultivars, once protected by PBR, should be promoted to the industry via field days and trade shows at cut-flower growers’ conferences. A commercial partner should be sought to undertake the bulking up and commercialisation of the new PBR-protected cultivars. Further work should be undertaken on the potential of coppicing techniques for increasing the proportion of first class blooms and/or prolonging the life of plantations.

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1. Hybrid Grevillea Production Introduction The genus Grevillea, with more than 350 species, is one of the more prominent proteaceous components of the Australian flora. With an extensive range of growth habits and floral forms the genus has become popular for garden use throughout Australia. Some of the more upright species, with large inflorescences, have been seen to have potential for cut flower use, both locally and for the export market. However, a number of problems with the currently used hybrids, including short stems, limited vase life and premature perianth drop, have restricted their acceptance in the cut flower trade. This project is focussed on the development of improved forms for cut flower use. However, given the unpredictability of the output from a hybridisation program, it is highly likely that forms suitable for general garden use will also be produced. As originally defined the objectives of the project were expressed as follows: • improve protocols for cut flower production of Grevillea varieties • produce advanced lines incorporating the following traits that will deliver answers to the

deficiencies in the current Grevillea cultivars as used in the cut flower industry: longer stem length, greater floral production, improved range of flower colours resistant to perianth drop, improved vase life and resistance to transport damage

• demonstrate the commercial viability of cut flower Grevilleas • breed PBR protectable cultivars suitable for the cut flower trade. Redefining of the objectives became necessary as the project progressed became there was insufficient funding available to undertake significant work in all four areas. A decision was made to place the main emphasis on the development of advanced lines (2nd objective) that would after appropriate assessment lead to the release of one or more PBR protected cultivars, suitable for the cut flower trade (4th objective). However, a small amount of work, reported in Chapters 3 and 4, was done on the first and third objectives. Breeding Strategy

Since the most promising material currently available for cut flower work has been derived primarily from crosses involving Grevillea banksii and allied species, it was considered appropriate from a commercial breeding perspective to undertake an extensive crossing program between various commercial hybrids of this parentage. The underlying concept in this method is that by making a large number of crosses and applying strict selection criteria to the progeny it is likely that variants on the existing commercial types possessing one or more of the desired improvements will be found. These new forms can then be used for further inter-crossing in an effort to combine multiple desirable features in the one plant. In contrast to the commercial approach adopted above, the project also included a more speculative element in which wide crosses were attempted. One group of crosses involved the backcrossing existing cut flower varieties to one or other of their parent species. The second group involved crossed between named cultivars and unrelated species or cultivars with desirable floral or adaptive features. The third group of crosses involved the use of two unrelated species in an attempt to create novel hybrids for use as parents in future work with established varieties. In this latter case, with wide crosses between apparently unrelated species, there is of course a greatly reduced expectation of success.

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Species and commercial cultivars were examined to determine the best parents to use in a crossing program. Characters were considered that are beneficial for growers and the cut flower market: • good stem length • strong flower colour • large inflorescence size and uniformity • reduced perianth drop occurrence (i.e. in vases) • long vase life • high plant vigour and floriferousness • attractive foliage colour • increased individual floret size and pleasing colour combinations. Another aspect that was considered during the parental selection process was concurrence of flowering. This means that unless pollen is stored, plants can only be crossed with other species or cultivars that are flowering at the same time. Many Grevillea species only flower during one period of the year making the challenge of parent selection even harder. Luckily, many of the G. banksii type hybrids have recurrent flushes of flowers throughout the year and can be matched up accordingly. Breeding Technique Grevilleas are generally out-breeding plants, but have varying degrees of self fertility. In order to make controlled crosses it is necessary to emasculate selected flowers (remove pollen from florets at a suitable stage of development, typically 10-30 buds per inflorescence), remove the other buds, and a few days later transfer pollen from the chosen male parent to the stigmas of the emasculated flowers. Contamination is minimised by covering flower heads with weather- proof paper bags. When closed properly, insects and birds cannot enter with foreign pollen or eat the developing seed. This also prevents pollen transfer from other inflorescences nearby that may rub against the stigmas. Despite every precaution, even when working with highly compatible parents, only about 30 per cent of the hand pollinations lead to the production of mature follicles, which normally contain two seeds each

Cross-pollination in grevilleas follows an unusual process compared with many other flowering plants. The hermaphrodite flowers are protandrous, meaning the male flower parts mature before the female stigma becomes receptive. As with other Proteaceae, grevilleas have a modified style end that forms a pollen presenter, as shown in Figure 1. At anthesis the pollen presenter is released from within the perianth limb (with anthers fused inside) to reveal pollen stuck on the pollen presenter. At this stage of development, studies have shown that the stigma surface is not yet receptive. This design enables a pollinator (bird or insect) to visit a flower to retrieve nectar, whilst having pollen dumped on its head and body. After a day or so the stigma becomes receptive; protruding out of the pollen presenter, and producing an exudate. Subsequently, when pollinators visit a new flower, the pollen is transferred and stuck to the newly receptive stigma, thus encouraging cross-pollination.

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Figure 1. The typical Grevillea floral structure. 1 floral bract, 2 pedicel, 3 nectary, 4 stipe,

5 ovary, 6 style, 7 style end, 8 pollen presenter, 9 tepals, 10 stigma, 11 perianth limb, 12 anthers.

There are several steps involved in manipulating the breeding system for artificial cross-pollination:

1. Locate inflorescences on the seed parent with a high proportion of late looping florets, i.e. styles that are looped out of the perianth, but presenter is still situated within the perianth limb.

2. Cut off any florets that have already released their style (to avoid problems with contamination).

3. Emasculate suitable florets (remove pollen). With small scissors, cut the part of the perianth below the limb upwards towards the gap created by the looped style, making sure the style and stigma are not damaged. Then carefully remove the limb from around the pollen presenter. If pollen has already dehisced onto the presenter, either discard that floret or carefully wipe off pollen and check with a hand lens that all has been removed (usually only necessary when very few flowers are available).

4. Label inflorescence, including emasculation date. Wrap a small piece of cotton wool around stem, so as to provide a barrier against ants and other potential pollinating insects. Subsequently, place a labelled paper bag over the inflorescence and secure neatly around the stem with 1 or 2 large paper clips.

5. Wait at least 2 days for the stigma to become receptive. Although naturally, the protandrous flowers may become receptive 1 day after anthesis, emasculation occurs between about 1 and 4 days before anthesis. Hence stigmas will not be receptive until they mature properly. When the stigma starts to protrude from the flat part of the pollen presenter, it is likely to be receptive and will at a minimum allow pollen to attach to the raised surface or to adhere to the exudate.

6. Collect pollen from a suitable pollen parent by finding fully looped florets that are nearly ready to release. • By lightly tapping on the loop, many species and cultivars will release the style and

hopefully present the dehisced pollen. • This floret can be carefully removed and taken whole to the bagged flowers. • Never take an already released style, unless the pattern of pollen deposited from the

anthers looks completely untouched, as this could be a source of contamination. • Some florets may not readily release pollen onto the presenter, particularly if they are not

quite mature. In this case, pollen may be scraped from the anthers themselves with more success.

7. Remove the bag from the seed parent flowers and apply the pollen onto the stigma. 8. Record that pollination took place and with what pollen parent, then label accordingly and re-

bag.

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This sequence of events is illustrated in Figures 2(a) to (n), while a bush of cv “Moonlight” with numerous bagged inflorescences is shown in Figure 3. When collecting pollen from the field, it may be necessary to store some flowers for later use. If collected during hot weather, and travelling far, it is advisable to store flowers in a cooled insulated container for transit. Pollen can also be stored in a refrigerator or freezer for at least one month. Collection and germination of seeds and growing-on of seedlings Seed collection Seeds were collected when the follicles were fully mature. They would usually break open and the two seeds inside would disperse. With the crossing bag still in place, the seeds were caught when mature, rather than having to harvest when the follicles were still closed and perhaps not yet mature. While most follicles opened naturally to release the seed, it was occasionally necessary to force them to open by drying out in an oven, or even cutting with a blade. Both of these methods were safe for the seeds, providing due care was used not to overheat or cut the seeds.

a b

c d

5

e f

g h

i j

6

k l

m n

Figure 2. (a) An inflorescence of cv “Moonlight” suitable for crossing. (b) Florets that have already opened and any that are too small or damaged are cur off. (c) An inflorescence prepared for emasculation. (d). Looped style is freed by cutting perianth before perianth cap. (e) Removal of perianth cap containing non-dehisced anthers using fingernails or tweezers. (f) Partially emasculated inflorescence. (g) Stem wrapped with cotton wool to prevent insect entry and contamination. (h) Weatherproof bag protecting emasculated inflorescence. (i) Stigma (central boss) protruding from pollen presenter (modified style end), from an emasculated flower of cv. “Moonlight”. (j) Pollen presenter from a flower of cv. “Sylvia”. Pollen which has dehisced from the fused anthers in the perianth cap is carried outwards on the pollen presenter portion of the style when it is released from the perianth cap. (k) Pollinating a flower of cv Moonlight” using pollen from cv “Sylvia”. (l) Very early fruit development with styles still attached. (m) Mature fruits, still closed and many still carrying the style. (n) Follicles opening and winged seeds dispersing through gap. (Photographs provided by Miss Alexandra Freebairn.)

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Germination The seeds often display deep dormancy or in some cases will be found to be non-viable. To maximise the chances of successful establishment the seeds were germinated in Petri dishes in darkness under semi-sterile conditions on filter paper moistened with a solution containing hormones and other growth factors at 21°C. In some cases it was necessary to nick the seed coat with a scalpel blade or partially peel the seed to achieve germination. When the seedlings had reached a height of about 2cm (usually after 14-21 days), they were transferred to small pots containing sandy potting mix and placed in the greenhouse.

Figure 3. A bush of cv “Moonlight” with numerous bagged inflorescences Establishment in the Field Seedlings grew in the glasshouse until at least 10 cm tall. They were then hardened off for a few weeks outside, and subsequently transplanted into the field. The field plantation used raised beds (made using a bed forming implement) running down hill to create row and plant spacings of 1.8 metres. A drip irrigation system was installed and open-ended plastic bags (tree guards) were used to protect young seedlings from wind and frost damage. Field Assessment The assessment plantation has been established on approximately 1 hectare of naturally sandy soil near the front entrance to the Plant Breeding Institute. The soil has a mildly acid reaction and a low content of both available and total phosphorus. An irrigation system has been installed, but it is only used in the establishment of young plants. The older plants are not normally irrigated and their performance is assessed under the relatively low natural rainfall of the Camden district. Apart from a small amount of straw mulch to help suppress weeds no fertilizer has been supplied. Occasional sprayings with “Roundup” have been made for the control of general weed growth and in the first year a programme of applications of “Sempera” was undertaken for the reduction of nut-grass infestation. Assessments have been made of early plant growth, height, leaf and bush characters and floral characteristics including date of first flowering and abundance of flowers. Because the bushes take several years to reach their mature form, the assessment process is on-going in nature. Figure 4 shows portion of the plantation with older plants on the left and recently planted seedlings in the protective bags.

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Figure 4. A portion of the plantation at the Plant Breeding Institute with older plants on

the left and recently planted seedlings in the tree guards on the right.

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2. Results of hybridisation work and discussion Hybridisation Results Hybrid seed was successfully produced in a majority of crosses involving varieties that have similar parentages (Table 1). This was also the case of hybrids that were effectively backcrossed to the species from which they were derived (Table 2). With the wider crosses involving either unrelated varieties or unrelated species, results were generally unsuccessful, but there were some notable exceptions, including G. decora x G. ‘Sylvia’ and G. georgeana x G. bipinnatifida (Tables 3 and 4). Material from all of these classes of crosses was successfully established in the field. During the growing-on of the new hybrids in the field, it was noted that a moderate number developed into small, spindly plants that showed very little vigour. Having ruled out pest and disease damage as a possible cause, it was concluded that these plants were probably displaying inbreeding depression, as a result of crosses between very closely related varieties. Consequently, when these plants flower, further complex hybrids could be created between two such plants of different parentage, with the exciting possibility that the new seedlings may exhibit strong hybrid vigour or heterosis. This would mark a new departure in Grevillea breeding.

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Table 1. Variety x related variety crosses Female Parent Pollen Parent Number of

inflorescences crossed

Seed produced

G. ‘Sylvia’ G. ‘Moonlight’ 58 yes G. ‘Sylvia’ G. ‘Golden Lyre’ 8 yes G. ‘Sylvia’ G. ‘Golden Yul-Lo’ 7 yes G. ‘Sylvia’ G. ‘Honey Gem’ 5 yes G. ‘Sylvia’ G. ‘Majestic’ 4 yes G. ‘Sylvia’ G. ‘Pink Surprise’ 1 yes G. ‘Sylvia’ G. ‘Sandra Gordon’ 1 yes G. 'Caloundra Gem' G. 'Honey Gem' 1 yes G. 'Caloundra Gem' G. 'Sylvia' 4 yes G. 'Caloundra Gem' G. 'Moonlight' 1 yes G. 'Caloundra Gem' G. 'Pink Surprise' 2 yes G. 'Coconut Ice' G. 'Sylvia' 1 yes G. 'Cream Seedling' G. 'Moonlight' 3 yes G. 'Sandra Gordon' G. 'Sylvia' 1 yes G. 'Sandra Gordon' G. 'Pink Surprise' 1 no G. 'Golden Lyre' G. 'Moonlight' 1 yes G. 'Golden Lyre' G. 'Sylvia' 1 yes G. 'Golden Yul-Lo' G. 'Golden Lyre' 1 yes G. 'Golden Yul-Lo' G. 'Moonlight' 4 no G. 'Golden Yul-Lo' G. 'Sylvia' 6 yes G. 'Honey Gem' G. 'Moonlight' 4 yes G. 'Honey Gem' G. 'Sylvia' 4 yes G. 'Majestic' G. 'Moonlight' 3 yes G. 'Majestic' G. 'Golden Lyre' 1 yes G. 'Moonlight' G. 'Cream Seedling' 4 yes G. 'Moonlight' G. 'Golden Lyre' 13 yes G. 'Moonlight' G. 'Golden Yul-Lo' 2 yes G. 'Moonlight' G. 'Honey Gem' 5 no G. 'Hot Pink Willie' G. 'Pink Surprise' 1 no G. 'Pink Surprise' G. 'Hot Lips' 1 no G. 'Red Seedling' G. 'Pink Surprise' 1 no G. 'Robyn Gordon' G. 'Sylvia' 2 no G. 'Robyn Gordon' G. 'Moonlight' 1 no G. 'Moonlight' G. 'Sylvia' 69 yes G. 'Moonlight' G. 'Majestic' 3 yes

Since it typically takes about two years for a shrubby Grevillea grown from seed to produce its first flowers and another one to two years for the plant to give a reasonable indication of its eventual form and flower producing potential, it follows that the plants currently coming into flower in our trial ground are from crosses made in 2002 and it will be several years before a final assessment of the latest crosses, made in November 2004, can be made. However, of the approximately sixty hybrids which have so far come into flower, nine show novel characteristics of sufficient merit to warrant more

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detailed evaluation: three for garden use, one for filler foliage use and the remainder for cut flower work. Given these promising early indications we are confident that the project goals of producing advanced breeding lines of merit and of producing PBR protectable new varieties will be adequately met. Figure 5 shows l while Figure 6 shows a hybrid with distinctive “pom-pom” flowers of potential interest to the garden market. In addition to the commercially significant results, the Crossing Tables provide valuable information for further work at PBI and will serve as a useful guide to anyone interested in the development of hybrid Grevilleas. Table 2. Variety x parent species – backcrosses Female Parent Pollen Parent Number of

inflorescences crossed

Seed produced

G. ‘Sylvia’ G. banksii (red) 4 yes G. ‘Sylvia’ G. bipinnatifida 9 yes G. banksii G. 'Sylvia' 1 no G. banksii (prostrate) G. 'Pink Surprise' 1 yes G. 'Moonlight' G. bipinnatifida 7 no

Figure 5. A hybrid with possible cut-flower potential.

Figure 6. A hybrid with distinctive “pom-pom” flowers of potential interest to the garden market

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Table 3. Variety x unrelated species or variety crosses Female Parent Pollen Parent Number of

inflorescences crossed

Seed produced

G. 'Sylvia’ G. georgeana 1 no G. ‘Sylvia’ G. molyneuxii 4 no G. ‘Sylvia’ G. spinosa 2 no G. 'Bon Accord' G. johnsonii 2 no G. 'Bon Accord' G. bipinnatifida 2 no G. 'Bon Accord' G. georgeana 1 no G. 'Bon Accord' G. 'Rosy Posy' 1 no G. 'Coconut Ice' G. dielsiana 1 no G. dallachiana G. 'Rosy Posy' 2 yes G. dallachiana G. 'Scarlet Sprite' 1 no G. decora G. 'Golden Lyre' 1 no G. decora G. 'Sylvia' 3 yes G. 'Evelyn's Joy' G. georgeana 2 no G. 'Evelyn's Joy' G. superba 1 no G. 'Firesprite' G. bipinnatifida 1 no G. 'Firesprite' G. georgeana 1 no G. 'Firesprite' G. superba 1 no G. 'Firesprite' G. 'Moonlight' 1 no G. 'Firesprite' G. 'Pink Surprise' 1 no G. georgeana G. 'Moonlight' 1 yes G. 'Gold Rush' G. georgeana 2 no G. 'Hot Pink Willie' G. georgeana 1 no G. 'Kay Williams' G. bipinnatifida 1 no G. 'Moonlight' G. juncifolia 1 yes G. 'Moonlight' G. juncifolia x eriostachya 1 yes G. 'Moonlight' G. leucopteris 1 no G. 'Moonlight' G. plurijuga 1 no G. 'Moonlight' G. spinosa 1 no G. 'Moonlight' G. dielsiana 1 yes G. 'Moonlight' G. georgeana 2 no G. 'Pink Surprise' G. georgeana 1 no G. 'Robyn Gordon' G. decora 1 no G. 'Scarlet Sprite' G. bipinnatifida 1 no G. 'Scarlet Sprite' G. 'Amethyst' 2 no G. sericea G. 'Rosy Posy' 1 no G. superba G. 'Sylvia' 3 yes G. wickhamii ssp aprica G. 'Rosy Posy' 1 no

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Table 4. Species x species crosses Female Parent Pollen Parent Number of

inflorescences crossed

Seed produced

G. aurea G. bipinnatifida 1 no G. banksii (alba) G. juncifolia x eriostachya 1 no G. bipinnatifida G. georgeana 1 no G. bipinnatifida G. spinosa 1 no G. bipinnatifida G. erectiloba 1 yes G. bipinnatifida G. plurijuga 1 yes G. sericea G. dallachiana 1 no G. sericea (white) G. sericea (pink) 2 no G. superba G. bipinnatifida 3 no G. superba G. erectiloba 1 no G. superba G. georgeana 1 yes G. wickhamii ssp aprica G. georgeana 2 no G. dryandri G. bipinnatifida 2 no G. georgeana G. bipinnatifida 2 yes G. georgeana G. johnsonii 1 no G. georgeana G. superba 1 no G. johnsonii G. georgeana 3 no G. johnsonii G. bipinnatifida 2 no G. johnsonii G. superba 1 no G. juncifolia G. bipinnatifida 2 no

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3. Training to improve the proportion of quality flowers

Introduction In relation to the subsidiary goals of the project some useful progress was also achieved. The work on flower production protocols was focussed on pruning and training methods in an effort to improve the number of long stemmed, first class flowers. Exploratory trials Exploratory trials with young bushes of G. cv. “Moonlight” suggested that partial inclination of the main axis of the branches increased length and straightness of the stems of some lateral flowers. However, in subsequent trials with more mature bushes, it was found that although young branches of G. cv “Moonlight” and of the natural hybrid G. eriostachya x juncifolia could be trained along horizontal wires, the lateral flower bearing stems grew out at random angles (some almost straight down). Subsequently, when flower buds were formed a small region at the base of the inflorescence proved to be gravity-sensitive and brought the flower cluster into a vertical position (Figure 7), the final result for most inflorescences being totally unacceptable for cut flower production.

Figure 7. Right angle bending of inflorescence stems. Anatomical studies showed that the lateral stems of these vigorous bushes were very strongly lignified at an early stage of growth and lacked the flexibility required to bend upwards (Figure 8). It is clear that the woody Grevilleas of interest for cut-flower work are not amenable to training in the way that grape vines are.

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Figure 8. Inflorescence stem section showing heavy lignification (pink stain). Given that the best flowers are usually produced as terminal inflorescences on vigorous young branches, it is suggested that future work involving the periodic coppicing of established bushes might lead to a simple and cheap way of producing quality flowers at easily accessible heights for picking. Conclusion Pruning and training experiments in an attempt to increase the number of first class bloom were generally unsuccessful, the Grevilleas proving to be essentially untrainable. However, there may be some scope for coppicing of older bushes to produce crops of vigorous young shoots with improved production potential. More work is needed on this latter point.

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4. Frost sensitivity In other work related to the subsidiary objectives, it was found that many existing commercial varieties are very sensitive to moderate frosts, with damage ranging from bud-burn to death of the bushes. Since many potential production areas close to major export airports are frost prone this becomes an important limitation on the development of the industry. In the assessment of the new hybrids special attention has been paid to frost susceptibility. In the winter of 2002 a series of heavy frosts (to minus 6 degrees screen temperature) inflicted severe damage on our original Grevillea plantation. Damage ranged from loss of buds on developing inflorescences (Figure 9) and shedding of florets from mature inflorescences to leaf and shoot burn and even total collapse and death of plants. It is clear that in outer western Sydney and similar cut-flower growing areas, commercially viable out-door production of Grevillea flowers for the winter market will require close attention to frost sensitivity, and that screening of new varieties intended for release must include rigorous frost sensitivity testing. Developmental analysis of the inflorescences of cv. “Moonlight” and similar varieties with buds sensitive to frost showed that the maximum flower bud number is reached by the time the inflorescence primordium is about 15mm long, so frost damage inflicted on these small and scarcely noticeable primordia cannot be repaired by subsequent growth and may not become apparent until weeks later when the buds are approaching opening and long sections of inflorescence axis are seen to be bare. In response to these observations, reaction to frost is now an important selection factor in the assessment of new hybrids from our breeding programme.

Figure 9. Young Grevillea inflorescence showing frost damage ranging from browning and shrivelling of buds to shedding of complete buds (e.g. in the central and basal regions).

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5. Grevillea Breeding at the Plant Breeding Institute As a result of previous interest in Grevilleas at the PBI and using a small portion of the funds from the current project, a germplasm collection of about 80 important Grevillea hybrids and species was established in open ground at the Plant Breeding Institute. This collection is supplemented by access as needed to the collection of about 150 species of Grevillea maintained in large pots at the nearby Mt Annan Botanic Garden. The Institute is therefore well placed in terms of access to a large and diverse germplasm collection of Grevilleas. In addition approximately thirty species grow wild in the Camden/Burragorang district, facilitating population studies of some of the smaller species such as G. rosmarinifolius and G. buxifolia. In addition to the work funded by this project, other work by staff and students supported by University funds (e.g. the PhD project of Alexandra Freebairn) have led to the development of specialised techniques such as cotyledon culture which have streamlined the process of hybrid production (see Appendix). The Institute is currently seeking a commercial partner to undertake the bulking up and marketing of new PBR-protected cultivars arising from the RIRDC Project and intends to use the accumulated resources and knowledge to continue to breed Grevilleas in the future.

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Appendix. Poster Paper from the 12th International Protea Conference.