Development of Intergeneric Rootstocks for Christmas Flowering Verticordia a New Christmas Flower

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Development of Intergeneric Rootstocks for Christmas Flowering Verticordia A new Christmas flower

MARCH 2013 RIRDC Publication No. 12/110

Development of Intergeneric Rootstocks for Christmas Flowering Verticordia – a new Christmas flower

by Dr Kevin Seaton

March 2013

RIRDC Publication No. 12/110 RIRDC Project No. PRJ-000470

ISBN 978-1-74254-452-6 ISSN 1440-6845

Development of Intergeneric Rootstocks for Christmas Flowering Verticordia – A new Christmas flowe Publication No. 12/110 Project No. PRJ-000470

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Researcher Contact Details

Kevin Seaton Western Australian Department of Agriculture and Food [email protected]

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: [email protected]. Web: http://www.rirdc.gov.au

Electronically published by RIRDC in March 2013 Print-on-demand by Union Offset Printing, Canberra at www.rirdc.gov.au or phone 1300 634 313

Foreword

Traditionally, Australian flowers for export are available from autumn to late spring. There are few cultivated species that enable harvesting and export during the Christmas season, a time of high demand but low supply. Exporters have identified the need for a range of species that can be grown to meet this Christmas demand. The Australian native genus Verticordia has a good range of colours including reds and yellows to gold, with terminal flower forms. To ensure longevity and production of Verticordia as cutflower selections, grafting plants onto suitable rootstocks may be necessary.

The availability of native plants displaying a range of new colours for the Christmas market will increase exports and provide growers with an opportunity to extend their production season, providing a range of flowers that can meet this Christmas market niche.

The main benefactors will be Australian cutflower growers and nurseries who will be able to extend the season and range of colours available for sale. Growing these varieties will tend to even out the production season, enabling cutflower growers to spread their labour resources more evenly and to maintain staff in employment. Having flowers not normally available will also provide an opportunity for increased prices and profits to the flower industry. For nurseries it will provide a versatile flower that can be also used for the pot plant/amenity trade. The nursery trade is a significant industry and having new flower types will benefit sales.

The key findings of this research are:

• Verticordia species identified as suitable scions for grafting

• rootstocks identified as best suited for Verticordia scions

• flowering times and production of grafted Verticordia determined

• postharvest characteristics of grafted flowers determined

• management strategies provided for grafted flowers.

Producing grafted plants involves added cost and producers need to weigh up the potential benefits of growing these flowers in terms of the increased returns through receiving higher prices during the Christmas period. It may involve added management costs with lower yields than traditional flowers such as waxflower. However, having a mix of flowers available for an extended time should increase business and establish a producer’s market share.

This project was funded by RIRDC and the Department of Agriculture and Food, Western Australia, with in-kind contributions from the Australian flower industry.

This report is an addition to RIRDC’s diverse range of over 2000 research publications and it forms part of our Wildflowers and Native Plants R&D program, which aims to improve existing products and develop new ones.

Most of RIRDC’s publications are available for viewing, free downloading or purchasing online at www.rirdc.gov.au. Purchases can also be made by phoning 1300 634 313.

Craig Burns Managing Director Rural Industries Research and Development Corporation

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About the Author

Dr Kevin Seaton is a senior researcher in the Department of Agriculture and Food, Western Australia (DAFWA). He has worked extensively for 25 years on increasing the efficiency and profitability of the Australian wildflower industry. He has developed a number of improvements in management techniques, particularly in nutrition and irrigation of wildflower species, as well as developing practical postharvest methods.

Dr Seaton has been involved in breeding a number of new wildflowers that have helped to increase the competitiveness of the wildflower industry. He has also contributed to a number of RIRDC projects and RIRDC initiatives and reviews, such as coordinating the PMIS plan for wildflower research in Australia. He has published nationally and internationally in scientific papers and attended conferences presenting work on wildflowers. He is also an adjunct professor of the School of Agriculture and Environment at Curtin University. Acknowledgments

The support, cooperation and assistance of the Australian waxflower industry are gratefully acknowledged. The technical support from Mr Chris McMullan for conducting the grafting experiments, Mr George Morris at DAFWA’s South Perth laboratories, and Mr John Berston for managing trials at Medina Research Station is greatly appreciated. Photos were taken by Kevin Seaton of DAFWA unless otherwise indicated. Permission is required before their use. The support of a number of staff at DAFWA is gratefully acknowledged.

Contents

Foreword ...... iii About the Author...... iv Acknowledgments...... iv Executive Summary ...... vii Introduction ...... 1 Objectives ...... 3 Methodology ...... 4 Procedures ...... 4 Grafting methods ...... 4 Statistical analysis ...... 5 1. Regelia ...... 6 2. Grafted Verticordia ...... 8 2.1 Selecting Verticordia scions ...... 8 2.2 Forming grafts ...... 10 2.3 Identifying suitable rootstocks ...... 11 2.4 Grafting trials – performance of rootstocks ...... 13 2.5 Grafting trials – performance of scions ...... 13 2.6 Field performance of grafted plants ...... 14 2.7 Postharvest performance ...... 16 2.8 Grower demonstration trials ...... 17 2.9 Field management of grafted verticordias ...... 19 Implications...... 20 Recommendations ...... 21 Appendix I Field management of grafted verticordias ...... 22 Glossary ...... 26 References ...... 27

Tables

Table 1. Comparison of flowers for different selections of E. calorhabdos ...... 8 Table 2. Health rating score for scions of grafted plants ...... 12 Table 3. Health score of scions (V. albida, V. etheliana and V. chrysostachys) on a selection of rootstocks 3 to 6 months following grafting in 2007–08...... 12 Table 4. Survival of grafts of V. etheliana, V. chrysostachys and V. albida on rootstocks KPFXU, Paddy’s Pink and Laura Mae for over 100 grafts made in 2007 ...... 13 Table 5. Health rating score of scions (V. albida, V. etheliana and V. chrysostachys) on a range of rootstocks (Eclipse, Paddy’s Pink, KPFXU, Laura Mae Pearl, Sweet Georgia, Sel 768, Sel 887) 3 to 6 months following grafting ...... 13 Table 6. Vase life of V. etheliana and V. chrysostachys measured in 2009 at Medina Research Station ...... 16 Figures

Figure 1. R. velutina shows flower occurrence along the stem (left) and a close up of flowers (right) ...... 6 Figure 2. Flowering stems of R. megacephala (left) with close up of flowers (right) ...... 7 Figure 3. E. calorhabdos flowering in the bush showing flowers (left) and stem growth (right) (photos K Seaton DAFWA) ...... 7 Figure 4. E. calohabdos florets for selections 07/01, 06/116 and 06/121 (left to right) ...... 8 Figure 5. Flowers of V. albida (left) and V. grandis (right) ...... 9 Figure 6. Flowers of V. etheliana (photo K Seaton DAFWA) ...... 10 Figure 7. Flowers of V. chrysosachys (photo K Seaton DAFWA) ...... 10 Figure 8. Stages of cleft graft formation suitable for using C. uncinatum as rootstock and V. etheliana as scion (photos C McMullan DAFWA) ...... 11 Figure 9. Total stem yield (30 to 80 cm) for (a) 2009 and (b) 2010 at Medina Research Station for V. etheliana and V. chrysostachys grafted on rootstocks KPFXU, Sweet Georgia, Sel 768, Laura Mae Pearl, Eclipse, Paddy’s Pink and Sel 887 ...... 14 Figure 10. Proportion of stem size classes for V. etheliana and V. chrysostachys averaged for a range of rootstocks for (a) 2009 and (b) 2010 ...... 15 Figure 11. Grafted plants of V. chrysostachys and V. etheliana flowering in the field in December 2009 (after their 2nd flowering season) at Medina Research Station (photo K Seaton DAFWA) ...... 16 Figure 12. Flower/bud loss (%) in response to treatment with (10 ppm) ethylene of V. etheliana and V. chrysostachys measured in 2009 from flowers grown at Medina Research Station...... 17 Figure 13. Grafted plants ready for despatch to growers for demonstration trials (V. etheliana on left and V. chrysostachys on right) ...... 18 Figure 14. Demonstration trial plots on growers’ properties in Western Australia, Victoria and New South Wales at planting ...... 19

Executive Summary

What the report is about

This research report presents the results of applying grafting methods to introduce a greater diversity of flowers into the wildflower market, in particular it looks at the development of intergeneric rootstocks for Christmas flowering Verticordia. The availability of native plants displaying a range of new colours for the Christmas market will increase export opportunities and provide growers with an opportunity to extend their production season.

Although producing grafted Verticordia plants was time consuming, grafted plants proved to be sturdy under field conditions and generally easy to manage, similar to waxflower. During plant management, careful pruning was required to develop a good canopy structure. While yields were lower and stem length shorter than for waxflower, offering flowering stems with red and yellow flower colours over the November to December period may command a higher price, making the grafted plants profitable.

Who is the report targeted at?

The project has beneficial value to growers of wildflowers, particularly those who grow waxflower. It provides them with a method of producing varieties which are suited to the Christmas period by means of grafting. The techniques developed could be applied to a range of flowers that were not previously commercially available. Several varieties have been explored that could be used to tap into the Christmas cutflower market. The results of this study may also have benefit to nurseries which have skills in producing grafted plants and some of the tested plants presented in this report may have use in the pot plant/amenity trade.

Where are the relevant industries located in Australia?

The location of the strongest industry representation in Australia occurs in the south-west of Western Australia, northern Victoria and adjacent New South Wales and south-eastern Queensland. The waxflower industry comprises approximately 30 growers and has a farm gate value of approximately $8 million with approximately 25 million stems mainly exported to Japan (48 per cent), US and Canada (25 per cent) and Europe (less than 25 per cent).

Background

Traditionally, Australian flowers for export are available from autumn to late spring. There are few cultivated species that enable harvest and export during the Christmas season, a time of high demand but low supply. Exporters and RIRDC have identified the need for a range of species that can be grown to meet this Christmas demand. The Australian native genus Verticordia has a good range of colours including reds and yellows to gold, with terminal flower forms. To ensure longevity and production of Verticordia as cutflower selections, the grafting of plants onto suitable rootstocks was investigated.

Aims/objectives

The aim was to optimise grafting as a technique for producing robust Verticordia plants suited to the Christmas market. This objective involved three parts:

(i) identify waxflower varieties suitable as rootstocks for grafting Verticordia scions

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(ii) identify and test Verticordia scions that produce successful grafts and meet the requirements of the Christmas market (iii) test the production and suitability of grafted flowers over several seasons in field environments.

Methods used

The procedure used was to (i) collect, select, propagate and grow various species of Christmas flowering Verticordia; (ii) test suitability of several waxflower varieties with potential as rootstocks for grafting; and (iii) grow varieties in the field to evaluate their performance as cutflowers.

Results/key findings

A number of potential Verticordia species were evaluated in terms of suitability as scion material. Some species were found to be extremely difficult to graft and maintain in pots in the nursery and were replaced. Seven rootstocks were tested with three identified as the most suitable for grafting Verticordia.

The project showed that it was possible to produce grafted yellow (V. chrysostachys) and red (V. etheliana) scion species using suitable waxflower rootstocks.

These grafted plants were grown in the field for two years at Medina Research Station and were found to readily survive and produce flowering stems, although stem length was generally shorter and less than for waxflower.

Application of grafting techniques and use of rootstock identified in the project should enable the production of red and yellow flowers for plants that flower late in the November–December season depending on location. These plants should benefit the wildflower industry.

Implications for relevant stakeholders

The wildflower export industry relies on growing and marketing new flower varieties to remain competitive. The two issues driving new variety introduction are spreading the production season and meeting the requirements of fashion by providing new forms and colours to attract buyers’ attention on world markets. The communities involved in this process are growers and exporters as well as importers. Getting the right mix depends on how these communities work together. This project provides techniques using scions and rootstocks identified as suitable for grafting and an opportunity to expand the range of varieties available to meet the needs of the cutflower export industry.

Recommendations

Use of cleft graft to graft verticordia scions V. chrysostachys and V. etheliana onto certain waxflower rootstocks will enable the production of grafted verticordias for field cultivation for the Australian wildflower industry and the nursery industry. Of the species tested in the genuses Regelia and Eremophila, selections within the species of E. calorhabdos offer the most potential for development as Christmas flowers and warrants a new project.

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Introduction

Traditionally, Australian flowers used for export are available from autumn to late spring (Seaton and Poulish 2010). Few cultivated species enable harvesting and export during the Christmas season, a time of high demand but low supply. Exporters, researchers and RIRDC have identified the need for a range of species that can be grown to meet this Christmas demand. RIRDC funded a preliminary project that identified a number of species worth developing as Christmas flowers. Members of the genuses Regelia, Eremophila and Verticordia flower during the Christmas period and were identified as potential sources for developing Christmas cutflowers. Plants for this market will increase exports and provide growers an opportunity to extend their production season. Regelia and Eremophila genuses include red to pink flowers. The genus Verticordia also has a good range of flowers available during the Christmas season of various colours including red, white, and yellow/gold. For Regelia, terminal flowering may limit use as cutflowers while for Eremophila colour and yield can be issues. In Verticordia, yield and plant survival are the main issues for cultivation. Previous to this project, agronomic trials at Department of Agriculture and Food compared a wide range of Verticordia species and showed many perform poorly on their own roots, with short stems and low stem number (K. Seaton, pers. comm.). Grafting onto vigorous rootstocks has been proposed as one way to capture desirable forms of flowers and overcome poor performance of some native plant species; it may increase survival or provide resistance to root diseases such as phytophthora, increase pH tolerance and increase rooting ability for propagation (Wrigley and Fagg 1988; Dawson 1996). For instance, Chamelaucium species have been successfully grafted onto a phytophthora-resistant rootstock to cope with the presence of Phytophthora cinnamomi in certain situations (Young pers. comm.). Such rootstocks impart soil disease tolerance and/or vigour to the scion, allowing waxflower to be grown more successfully over a wider climatic range. Identifying particular robust, disease-tolerant wax varieties across Australia could enable these species to be commercialised as grafted plants for the summer festive-season markets. Breeding within these varieties is also a possibility, particularly to target a smaller flowering variety similar to V. grandis. V. grandis has bright red flowers in semi-terminal racemes in the summer months (DEC 2012), flowering from November through to April with a moderate vase life of 10 days; it has some tolerance of ethylene exposure but responds to silver thiosulphate (Seaton 2006). This species has been sold as a cutflower for a number of years, albeit in low volumes. Most of the stems have been harvested from the wild, particularly from new growth that occurs after fire. Very few stems have come from cultivated stands. This species is reputed to be difficult to propagate from cuttings, although advances in propagation technology and selection of better genotypes have increased strike rates. Yields reputed for one grafted plant grown in Northampton, WA, had approximately 100 stems in its fourth year after planting (Dick pers. comm.). A preliminary grafting trial on V. grandis indicated that this species may yield economically when grown on C. uncinatum rootstock (Growns pers. comm.). Other grafted plants grown in Coorow, WA, also outperformed the same genotype grown on its own roots (Ryan pers. comm.). Another potential scion for commercial development is V. albida, related to V. grandis, which has white flowers (sometimes with a pink tinge), round green leaves, and flowers in summer with an average vase life of 11 or 12 days. It has not been tried as a cultivated cutflower crop. The flowers are in semi-terminal racemes. Small numbers have been grafted onto different Chamelaucium genotypes and may be suitable for grafting. In grafting plants generally, the rootstock used is in the same family as the scion. For example, Darwinia citriodora and Chamelaucium uncinatum are used for grafting Verticordia, or eastern Australian Banksia species are used as rootstocks for grafting Western Australian Banksia species intolerant of eastern soil conditions (Dawson 1996). Several species of Verticordia have been grafted

onto rootstocks of related genera by a number of nurserymen. The grafts appear to be long-term compatible, with some species surviving at least 12 years (Vaughan, pers. comm.). The Department of Agriculture and Food, Western Australia (DAFWA) routinely graft Verticordia species onto Geraldton wax varieties or hybrids for long-term use in breeding activities. Several rootstocks have been used for Verticordia including commercially available ‘Sweet Georgia’, a small- flowered Chamelaucium. Its performance appeared to depend on the scion used and reportedly has some phytophthora resistance. The larger pink-flowered Chamelaucium uncinatum ‘Newmarracarra’ has been used in Queensland. The C. uncinatum selection ‘Eclipse’ is used for grafting other C. uncinatum because of its phytophthora resistance. DAFWA has also used a C. uncinatum x C. floriferum hybrid ‘KPFXU’ as a rootstock for grafting C. megalopetalum for use as a mother plant in its breeding program and a DAFWA-bred C. uncintum x C. megalopetalum variety ‘Laura Mae Pearl’ which is used in breeding work. These rootstocks along with others were tested in this project. An alternative to grafted plants suitable for the Christmas market is Regelia velutina which flowers from September through to February on long stems, has bright terminal or semi-terminal red flowers and silvery green leaves in spring and summer. It has had limited use as a cutflower for a number of years, particularly for its foliage. It produces long straight stems; however, flowering of the cultivated form is not terminal. Perhaps by better selection more terminal forms can be found, being more suitable as cutflowers. R. megacephala has bright terminal or semi-terminal mauve flowers and green leaves in spring and summer, flowering from September through to December on long stems. Propagation of these two species is through cuttings, and basic agronomic practices are known, although research is likely to bring improvements in yield. Another candidate for a Christmas flower is Eremophila calorhabdos. Preliminary trials showed a small number of E. calorhabdos for cutflowers in Northampton in 1996/97 which responded to irrigation and fertiliser and yielded well. The species has a commercial vase life, particularly if picked in the late bud stage. It could also be harvested for foliage. The project included a preliminary survey of the natural populations of R. velutina, R. megacephala and E. calorhabdos to select profuse, terminal-flowering forms. This forms ‘Regelia Stage 1’ of a multi-stage project for which future funding may be requested for further development. However, the main aim of this project was on developing Verticordia scions and identifying suitable rootstocks to determine those most likely to ensure flower production for the Christmas and January period. As indicated, the wildflower export industry is likely to benefit most from the introduction of a cutflower to meet the Christmas market niche. Exporters and RIRDC have commissioned work in this area in recognition of the need. Increased cultivated production will reduce the need for bush picking of some of these lines. There are no anticipated environmentally harmful effects.

Objectives

The objectives of the project were:

• to identify suitable scions for grafting which meet the requirement for production over the Christmas period, including from V. grandis and V. albida or alternatives

• to research suitable rootstocks for the grafting of these scions as cutflowers

• to determine the field performance of cutflowers produced including flowering time, yield and postharvest characteristics

• to determine the optimum rootstocks for different growing regimes across Australia

• to conduct preliminary surveys of natural populations of R. velutina, R. megacephala and E. calorhabdos as potential cutflowers over the Christmas period

• to determine the performance of two grafted Verticordia species across a range of environments.

The project included a preliminary survey of natural populations of R. velutina, R. megacephala and E. calorhabdos to select for possible Christmas flowers. This formed the ‘Regelia Stage 1’ of a multi- stage project for which future funding may be requested for further development.

Each objective is focused on producing cutflowers suitable for growing and delivery in Australia for the Christmas market. Christmas is a time of high flower demand but Australia generally has few species that can be delivered from commercial plantations during this time.

Methodology

Procedures

1. Regelia Stage 1

Survey populations of Regelia velutina, R. megacephala and Eremophila calorhabdos: populations of these flowers were located using Florabase (DEC 2012) and field surveys of natural populations were conducted to identify selections with profuse, terminal-flowering forms.

2. Grafted Verticordia

The research program objectives were:

i. Identify potential as suitable rootstocks for grafting Verticordia by conducting grafting trials. Rootstocks will include Chamelaucium uncinatum (‘Eclipse’, ‘Sweet Georgia’, ‘Sel 768’ (alkaline tolerant) and ‘Sel 887’ (acid tolerant), C. uncinatum x C. megalopetalum (‘Laura Mae’), C. uncinatum x Verticordia plumosa (‘Paddy’s Pink’), C. uncinatum x C. floriferum (‘KPFXU’) selections.

ii. Identify scion genotypes for grafting that are suitable for the Christmas market. Scions to be tested were Verticordia grandis, V. albida, V. etheliana and V. chrysostachys.

iii. Conduct grafting trials using these rootstocks and scions and evaluate in terms of survival and vigour in glasshouse.

iv. Plant surviving selections in field at Medina Research Station and evaluate in terms of field survival, production, postharvest and ethylene response over two seasons. Plantings would be in randomised plots of five plants of each combination per replicate, with three replicates, giving 15 plants per combination for a total of 210 plants per site if two species and seven rootstocks are used.

v. Finalise main scion–rootstock combinations ready for grower trials.

vi. Bulk up scion and stock material for grower plantings trials over 18 months.

vii. Identify experimental grower sites and release trial plants for planting on growers properties in Western Australia, New South Wales and Victoria. viii. Compile data and publish findings and final report.

Grafting methods

Several grafting techniques were available for use in this project including whip and tongue graft, cleft graft and side graft.

In the whip and tongue graft a sloping cut is made across the rootstock and at a point one–third of the way down, an incision is made down and back in the opposite direction to the sloping cut, creating the tongue. The scion material is prepared in a similar manner. When the rootstock and scion are joined they are locked together. This generally works best where rootstock and scion material are the same diameter.

In the cleft graft a wedge is cut to the base of the scion and a cleft is made to the top of the rootstock; the wedge of the scion is inserted into the cleft of the rootstock. Care needs to be taken not to insert the scion into the cleft past the top of the wedge.

In the side graft a sloping cut is made to the rootstock at the desired point. The scion is cut into a wedge with one side longer than the other. Once the scion has been inserted into the cut, the top of the rootstock is removed just above the union. All grafts are wrapped in film such as Parafilm® until the graft takes. It is critical to ensure that the cambium layers match in the rootstock with the scion to maintain the vascular system (McMullan 2006).

Statistical analysis Data was analysed using Genstat14 using ANOVA with Duncan Multiple range test comparing means.

Results

1. Regelia

Several surveys of Regelia velutina, R. megacephala and Eremophila calorhabdos were made of natural populations of these species and the range of flowering forms surveyed.

Regelia velutina - although some variation in colour of flowers was noted, no terminal-flowering forms were identified from surveys of populations along the south coast of Western Australia east of Albany. Flowering occurred from December to January.

R. megacephala - all plants during the flowering period showed sparse flowers on stems. Flowers were purple with yellow-tipped stamens. Flowering occurred from September to November.

Eremophila calorhabdos – variation in flower colour and density of flowering was observed ranging from pink to burgundy/red. Also, display of flowers on stems varied from very sparse to more concentrated terminally. Stems tended to be straight but were sparse in number. Flowering occurred from November to December

Of the three species, E. calorhabdos appears to be the most spectacular in flowering display, but poor yield may limit its use as a cultivated cutflower. R. velutina was considerably more vigorous in stem production but flower display was sparse and not generally terminal (Figure 1). This plant’s silvery grey foliage was quite attractive and the presence of red flower clusters gives it some appeal as a foliage plant rather than as a flowering plant. R. megacephala did not produce red flowers and flowered earlier than December, not meeting the criteria necessary to satisfy the Christmas market (Figure 2). Also, flower display was sparse on the stem and it was less attractive than R. velutina.

It may be possible to encourage more even flowering of R. velutina by conducting pruning experiments or to achieve higher stem production of E. calorhabdos by developing appropriate cultivation techniques as has been done for lifting the yield of waxflower (Seaton 2008).

Figure 1. R. velutina shows flower occurrence along the stem (left) and a close up of flowers (right)

Figure 2. Flowering stems of R. megacephala (left) with close up of flowers (right)

Figure 3. E. calorhabdos flowering in the bush showing flowers (left) and stem growth (right) (photos K Seaton DAFWA)

Variation in flower form and colour of E. calorhabdos was noted in wild populations with most florets being pink to light pink and one being deep red (Figure 3 and Table 1). Flower production in the field was low with a few flowering stems per plant and on each stem only a few florets which occurred terminally (Figure 3). Most plants were quite narrow and leaves tending to be dying; however, this may change under cultivation with the availability of irrigation water.

Table 1. Comparison of flowers for different selections of E. calorhabdos Selection Calyx length Caylx width Caylx width Plant height RHS Floret colour (mm) widest (mm) narrowest (mm) (cm)

07/01 29 11 6 140 64D pink 06/116 30 14 4 169 58B deep red 06/121 28 15 4 140 63C pink

Figure 4. E. calohabdos florets for selections 07/01, 06/116 and 06/121 (left to right)

2. Grafted Verticordia

2.1 Selecting Verticordia scions

Originally two scions, V. albida and V. grandis were nominated for the project (Figure 5). V. albida has an off-white to light pink spike of flowers, approximately 75 mm long. Observations of potted specimens indicated that this species flowers over the Christmas period in Perth but that stem production was low.

Figure 5. Flowers of V. albida (left) and V. grandis (right)

V. grandis offers spectacular crimson, large flowers in spikes. It is known to be slow growing and is unreliable on its own roots. Grafting was thought to offer an opportunity to provide more reliable plants for the cutflower industry.

Two other Verticordia species, V. etheliana var. etheliana (C. Gardner) and V. chrysostachys var. chrysostachys (Meisn) were also selected for testing as scions to suit the Christmas market.

V. etheliana (Figure 6) has large red flowers occurring in compact short spikes. It flowers from July, with peak flower production in November extending to December (George 2002).

V. chrysostachys (Figure 7) has small dense clusters of yellow flowers occurring in spikes. This species flowers mainly in the December–January summer season.

Figure 6. Flowers of V. etheliana (photo K Seaton DAFWA)

Figure 7. Flowers of V. chrysosachys (photo K Seaton DAFWA)

2.2 Forming grafts

Trial and error in working with different graft types (including whip and tongue, cleft graft and side graft) found that cleft grafts were the most practical, due to the small diameter of the grafting wood available in grafting Verticordia scions onto waxflower rootstocks (Figure 8).

Tongue Cleft Matched wood

Wrapping graft Wrapped graft Grafted Verticordia etheliana

Figure 8. Stages of cleft graft formation suitable for using C. uncinatum as rootstock and V. etheliana as scion (photos C McMullan DAFWA)

By using this technique the cambium of the rootstock and scion was able to be closely matched. As different species Chamelaucium and Verticordia were used with different bark thickness this method allowed for better matching of bark and achieving maximum cambium contact on both sides of the graft union. As part of the technique developed, scion and rootstock material was selected of different diameter material (i.e. diameter of Verticordia with rough bark being larger that Chamelaucium with smooth bark) to ensure the best match of cambium layers.

2.3 Identifying suitable rootstocks

The potential waxflower rootstocks identified for testing were: KPFXU, a C. uncinatum/C. floriferum hybrid; Sweet Georgia, a C. uncinatum/C. micranthum hybrid which has been used previously by industry as a rootstock for Verticordia grandis; Sel 768, a C. uncinatum selection selected for

alkaline resistance by DAFWA; Laura Mae Pearl, a vigorous C. uncinatum/C. megalopetalum hybrid bred by DAFWA; Eclipse, a phytophthora-resistant variant of C. uncinatum variety ‘Purple Pride’ developed in Gatton, Queensland by Ken Young; Paddy’s Pink, a V. plumose/Chamelaucium hybrid grown as a cutflower; and Sel 887, a C. uncinatum selection selected for acid resistance by DAFWA.

To narrow down suitable scions, grafted rootstocks were rated in terms of survival of the scion and scored (1 to 5) for health and vigour of scion three to six months after grafting in terms of health scores (see Table 2 and Table 3).

Table 2. Health rating score for scions of grafted plants Score Description

1 Green, healthy turgid, new buds and shoots forming, callusing at graft union, callusing observed

2 Green, healthy, no new shoots, leaves mostly turgid

3 First signs of yellowing and leaves starting to wilting with some apical tips wilting and first leaf drop observed

4 Yellowing >30% of leaves, some browning of leaves, leaf drop >30%, stems drying and shrivelling >80%, tip dying back

5 Mostly dead or severely shrivelled, with little or no green leaves, leaf drop >80%

The rootstocks Eclipse, Paddy’s Pink and KPFXU performed the best overall for all scions grafted, with scions remaining green with healthy plants. Scions grafted onto rootstocks of Laura Mae Pearl, Sweet Georgia and Sel 768 began to fail with yellowing of leaves, wilting and leaf drop. Scions on Sel 887 showed leaf browning, leaf drop, stem shrivelling and dying.

Table 3. Health score of scions (V. albida, V. etheliana and V. chrysostachys) on a selection of rootstocks 3 to 6 months following grafting in 2007–08. A low score indicates good health. Rootstock Score

Eclipse 2.04 a

Paddy’s Pink 2.29 ab

KPFXU 2.67 ab

Laura Mae Pearl 3.17 b

Sweet Georgia 3.33 b

Sel 768 3.53 bc

Sel 887 4.28 c

L.s.d. 0.95

2.4 Grafting trials – performance of rootstocks

Table 4. Survival of grafts of V. etheliana, V. chrysostachys and V. albida on rootstocks KPFXU, Paddy’s Pink and Laura Mae for over 100 grafts made in 2007 Rootstock Survival (%)

KPFXU 68.8 a

Eclipse 66.7 a

Paddy’s Pink 66.7 a

Sweet Georgia 52.2 ab

Laura Mae Pearl 43.3 abc

Sel 768 21.1 c

Sel 887 15.4 c

Analysis of variance using square root transform showed that the type of rootstock used had a significant effect (P<0.016) with rootstocks having different letters significantly different in performance (see Table 2 and Table 3). The most successful rootstocks were KPFXU, Eclipse and Paddy’s Pink. Rootstocks of acid-resistant Sel 768 and alkaline-resistant Sel 887 were least successful (Table 3). In 2009 using V. etheliana as the scion it was found that 69.6± 12.4 per cent for KPFXU, 50.8 ± 7.9 per cent for Paddy’s Pink and 23.3 ± 9.9 per cent for Laura Mae Pearl were successful. While in 2011 the success of grafting for the scion V. etheliana on VRS 2001 decreased by 12 per cent from 69.6 per cent in 2009 to 47.2 ±7.1per cent, indicating that there was some variability depending on the year the grafts were done.

2.5 Grafting trials – performance of scions

Table 5. Health rating score of scions (V. albida, V. etheliana and V. chrysostachys) on a range of rootstocks (Eclipse, Paddy’s Pink, KPFXU, Laura Mae Pearl, Sweet Georgia, Sel 768, Sel 887) 3 to 6 months following grafting

Scion Score Success (%)

V. chrysostachys 2.03 a 72.2 ±8.5

V. etheliana 2.58 a 55.0 ±8.7

V. albida 4.52 b 12.6 ±6.1

The scions V. chrysostachys and V. etheliana outperformed V. albida, producing green healthy plants, while after three months V. albida plants were yellowing, leaves were shrivelling and stems dying 4 weeks after grafting. Grafts using V. grandis as a scion were found to fail quite often with 8 per cent of grafts successfully taking and surviving. In contrast, when V. etheliana was used as a red scion the

success rate was over 50 per cent (Table 4). As V. etheliana provided a similar red flower to V. grandis research concentrated on using V. etheliana as a red scion source.

In 2011 the scions V. etheliana and V. chrysostachys were similarly successful in forming grafts when used on the rootstock KPFXU with 49.6 ± 7.1 per cent and 57.5 ± 13.1 per cent success of grafts. While for the rootstock Eclipse, the success rate of V. chrysostachys was 54.2 ± 5.3 per cent which was much more successful than when V. etheliana with 30.4 ± 7.7 per cent was used as a scion for grafting. Combining the data of both scions, it was found the for rootstock KPFXU 53.6 ± 6.5 per cent of grafts had taken, with a similar success for Eclipse with 42.3± 6.8 per cent of grafts taken.

2.6 Field performance of grafted plants

Field trials at Medina Research Station were harvested over two years.

Figure 9. Total stem yield (30 to 80 cm) for (a) 2009 and (b) 2010 at Medina Research Station for V. etheliana and V. chrysostachys grafted on rootstocks KPFXU, Sweet Georgia, Sel 768, Laura Mae Pearl, Eclipse, Paddy’s Pink and Sel 887

Average yield for V. etheliana increased from 34±6 stems per plant in 2009 to 46±7 stems per plant in 2010 and for V chrysostachys average yield was 46±5 stems per plant in 2009 and 32±5 stems per plant in 2010 (Figure 9 a, b). Overall yield for both scions averaged for 2009 and 2010 was 39 stems per plant. In 2009 yields of V. chrysostachys were 35 per cent higher than V. etheliana while in 2010 yield of V. etheliana was 44 per cent higher than V. chrysostachys.

During 2009 the best-performing rootstocks were Sel 768, Eclipse and Sel 887 (Figure 9a) while in 2010 these were KPFXU and Eclipse (Figure 9b).

Figure 10. Proportion of stem size classes for V. etheliana and V. chrysostachys averaged for a range of rootstocks for (a) 2009 and (b) 2010

Stems were predominantly 40 to 50 cm long for V. etheliana in 2009 and tended to decrease in length in 2010 to mainly 40 cm (Figure 10a, b). For V. chrysostachys stem lengths were predominantly 40 cm and increased to 60 cm in 2010 (Figure 10a, b).

Figure 11. Grafted plants of V. chrysostachys and V. etheliana flowering in the field in December 2009 (after their 2nd flowering season) at Medina Research Station (photo K Seaton DAFWA) Flowering

It was found that V. etheliana flowered at Medina from July to November with some flowering into December, while V. chrysostachys flowered from November to January with a peak in December.

2.7 Postharvest performance Vase life

Vase life of grafted plants grown at Medina Research Station was over 2 to nearly 3weeks. Vase life of flowers of V chrysostachys was 25 per cent longer than for V. etheliana. Vase life of V. etheliana leaves was significantly different (P <0.001) being 44 per cent longer than flowers and vase life of flowers and leaves of V. chrysostachys was not significantly different (P<0.05). Vase life of leaves was significantly different between scions (P <0.024) with vase life of V. etheliana leaves being 18 per cent longer compared to V. chrysostachys (Table 6).

Table 6. Vase life of V. etheliana and V. chrysostachys measured in 2009 at Medina Research Station Scion Vase life Flowers Leaves V. etheliana 16.2 23.0 V. chrysostachys 20.0 19.5 L.s.d (0.05) 1.8 3.0

Ethylene response

Figure 12. Flower/bud loss (%) in response to treatment with (10 ppm) ethylene of V. etheliana and V. chrysostachys measured in 2009 from flowers grown at Medina Research Station. Non-ethylene controls are also shown. Standard error of the mean is shown. Flower drop was low for V. chrysostachys before or after ethylene treatment (Figure 12). For V. etheliana flower drop was significantly higher (P<0.05) after ethylene treatment, but not excessive. Treatment with silver thiosulphate at 4 µM for 20 minutes was found to be effective in controlling flower drop in verticordias susceptible to ethylene (Seaton 2006). It may also be possible to use sachets of ethyl block in flower cartons to prevent the effects of ethylene on flower drop.

2.8 Grower demonstration trials

Over 100 plants were grafted (Figure 13) using V. etheliana and V. chrysostachys as scions and KPFXU and Eclipse as rootstocks. These plants were transported to growers’ properties in Victoria, New South Wales and Western Australia, planted and photographed (Figure 14). This is the last milestone of the project to complete the final report and further assessment of demonstration trials will be completed by the growers, reporting to RIRDC.

Figure 13. Grafted plants ready for despatch to growers for demonstration trials (V. etheliana on left and V. chrysostachys on right)

Figure 14. Demonstration trial plots on growers’ properties in Western Australia, Victoria and New South Wales at planting

2.9 Field management of grafted verticordias

See draft of technical note in Appendix I.

Implications

The development of waxflower rootstocks suitable for grafting Verticordia species offers opportunity to introduce new colours into the wildflower market. The use of intergeneric grafts gives a wider range of flower colours and flowering times including reds and yellows and late flowering from November to January depending on the Verticordia chosen, with a 101 species of Verticordia documented (George 2002).

Several rootstocks developed in this project were found suitable to provide robust rootstocks on which to graft Verticordia species. The advantages of producing grafted Verticordias using these waxflower rootstocks need to be weighed against the cost of grafting. Grafting verticordias is time consuming and requires a certain level of skill to be successful. Even with the best endeavours success rates can be expected to be no more than 60 per cent. This means that there are limitations to bulking up large numbers of plants. However, once plants were produced they were found to be robust and survived in the field.

Another aspect of this grafting work that became apparent was that the vigour of the waxflower rootstock was not readily transferred to the scion with yield of grafted plants much lower than would be expected from waxflower plants. Therefore, although there may be some advantage in producing these spectacular grafted plants to meet niche markets, the cost of production needs to be weighed against the expected return.

Recommendations

This project has shown that it is possible to use selected rootstocks to produce grafted verticordias that suit the Christmas market. Producing grafted Verticordia plants was time consuming but successful grafts proved to be sturdy plants under field conditions, generally easy to manage and robust, similar to waxflower. Careful pruning was required during plant management to develop a good canopy structure. Although yields were lower and stem length shorter than for waxflower, having flowering stems with flowers in red and yellow colours over the November to December period may command a much higher price making growing these grafted plants profitable. The project has shown that the cleft graft technique is suitable to graft Verticordia onto waxflower varieties and these results may be available for future work in grafting wildflowers in the Myrtaceae family.

Preliminary surveys have shown that the most promising wildflower among Regelia velutina, R. megacephala and Eremophila calorhabdos is the red to pink E. calorhabdos. Under cultivation using correct irrigation and fertiliser, this species may produce much higher yields than occur in the wild. Future projects are recommended developing selections and cultivation methods for E. calorhabdos.

Appendix I Field management of grafted verticordias

Farmnote (Draft) Grafted Verticordias for cultivation

By Kevin Seaton, Senior Research Officer, Western Australian Department of Agriculture and Food, South Perth

Red flowers grafted V. chrysostachys (foreground) and V. etheliana (in middle of picture)

Introduction Verticordia is a large genus (101 species) of Australian plants with a diverse range of colours including reds, yellows and golds, with terminal flower forms some of which flower over the Christmas period. Having red and yellow flowers available at this time should capture the festive season and fill a gap in availability of flowers at this time. Survival of productive plants in cultivation of Verticordias is problematic with many becoming woody. To ensure longevity and productivity of Verticordia as cutflowers or amenity plants, grafting plants onto suitable rootstocks may be necessary. The genus Verticordia is in the Myrtaceae family and closely related to waxflower (Chamelaucium species) and is a suitable rootstock for grafting Verticordia scions. By careful selection of rootstocks grafting may also be a way of ensuring plants survive in various soil environments. The management of several grafted Verticordia is described.

Selections Two Verticordia selections have been successfully grafted onto waxflower rootstocks. These are the bright red large flowered semi-terminal V. etheliana and the yellow small flowered V. chrysostachys. Plants of V. etheliana flowered at Medina Perth from July to November with some flowers into December and V. chrysostachys flowered from November to January with a peak in December. Both grafted species survived well in cultivation, produced moderate stem numbers with a range of short to moderate stem lengths and a vase life exceeding of 2 weeks. There form lends well to a low to medium height border amenity plant requiring minimal maintenance of a light annual prune. Soils Grafted Verticordias prefer sand over gravel at 1 meter depth, although they can be grown in deep sand provided the water supply to plants is adequately maintained. Soil pH in the range 5.5 to 6.5 (in water) is preferred. Land preparation The site should be prepared ahead of time, eliminating all weeds. Compacted sites should be deep ripped to produce a suitable seedbed. Allow sufficient time for the ground to settle before planting. Great care must be taken to select a phytophthora free site and to apply good hygiene practices to prevent the introduction of disease. Planting and establishment Use disease free plants. The best time to plant is late autumn or in early spring in warmer areas or in late spring in cooler areas. Ensure for plants tending to be root bound that their root systems are teased out during planting. The seedbed must be thoroughly wetted up at least a week before planting. Grafts can be brittle and therefore care needs to be taken when handling and planting. Use of individual wind breaks or tree guards for first 3 months after planting may be necessary on windy sites. Grafted Verticordia perform best in dense plantings to maximise yield per square metre of land and to encourage upward stem growth. This can be achieved by preparing a bed 1.2 m wide and planting in double rows with 0.6 m between rows and 1.0 m between plants in the row and planting in a staggered pattern (see figure). These can be arranged in 50 to 100 m rows with work ways between rows centred at 3 m. This gives a plant density of 6667 plants per ha. Best light interception is usually achieved if rows are aligned in north /south.

Suggested planting layout

Important Disclaimer The Chief Executive Officer of the Department of Agriculture and Food of the State of Western Australia accept no liability whatsoever by reason of negligence or otherwise arising from use or release of this information or any part thereof it. For more information visit our website www.agric.gov.au

It is also beneficial to use a mulch to reduce weed competition, moderate soil temperature and conserve soil moisture. In cooler regions the use of plastic mulch or ‘weed mat’ has been found to be suitable while in hotter climates white plastic mulch or straw mulches are more suitable. Fertilisers At planting, 10 gram of low phosphorus, slow release fertiliser, such as ‘osmocote’ or ‘nutricote’ for native plants should be spread on the soil surface (and not placed in the planting hole) adjacent to plants. Once established, plants (2-3 months) require a regular feed, preferably through the irrigation lines such that plants receive 150 kg/ha/annum of nitrogen and 115 kg/ ha/annum potassium and 7 kg/ha/annum of phosphorus and calcium together with a balance of trace elements. Fertiliser Injection (use the lower rates during first year of establishment then gradually increase the rate to the higher level in subsequent years)

Injecting fertilisers during watering (fertigation) to meet the requirements of plants can be achieved by making up a stock solution of the following fertilisers in a 200 litre drum of water.

Fertiliser Amount (g/200 litres stock tank) Rate low high Urea 2.9 - 8.70 kg Potassium nitrate 3.4 - 10.20 MAP (mono ammonium phosphate) 0.4 - 1.10 Calcium nitrate 0.3 - 0.8 Trace elements (Fertilon combi®) 0.1 - 0.20

In summer fertigate plants on a daily basis. The concentration of fertilisers injected (particularly N) should be scaled back by during autumn. In winter fertigate every third day then increase the frequency through spring. During each watering allow the irrigation system to run for10 minutes, then inject over the next 40 minutes10 litres of the stock solution per 800 plants being watered, followed by 5 to10 minutes of watering without fertiliser. Acclimatise young plants to the above fertiliser program by using the low rate and by gradually increasing the frequency of injection, i.e. first inject fertiliser one day out every three days, increasing the frequency until plants are fertigated daily

Irrigation Grafted Verticordia should be planted into moist soil and watered regularly during establishment using drippers, particularly on sandy soils. In summer, watering may need to be split into three applications per day. This usually requires an automatic watering system. Once established grafted Verticordia are low water users (i.e. 50% evaporation replacement or 4 litres per day per plant in summer in the Perth region). Pruning Plants should be lightly pruned in the first year to encourage branching. Thereafter plants should be pruned to approximately one-third of their height as this will encourage long stem production. It may be necessary to allow plants to grow for 2 years to produce sufficient stem length. Pests and diseases Plants are susceptible to botrytis and mildew which can cause leaf drop and may need regular spraying. Postharvest management Flowers can be a handled as for waxflower. They have very low ethylene response. Flowers benefit from forced air cooling.

Further Reading Farmnote No. 049/2002 Verticordia for cut flower production Acknowledgements

The support, cooperation and assistance of the Australian wildflower industry are gratefully appreciated. Funding support from Rural Industries Research and Development Corporation and Western Australian Department of Agriculture and Food is acknowledged.

Glossary

Scion – shoot or twig, especially one cut for grafting, used because of its quality floristic characteristics.

Rootstock – a root or part of a root used for stock plant propagation or grafting. Used because of its vigor or resistance to disease etc.

Cleft graft – a top-grafting method in which the scion is inserted into a cleft cut into the top of the stock.

Verticordia – large genus of native Australian plants in the Myrtaceae family mainly confined to the south-west of Western Australia, comprising 101 species, many with vibrant colours (gold, red, yellow and pink) and which tend to flower most of the year especially in late spring–summer.

References

Dawson, I 1996, ‘Grafting Australian native plants’, in Proceedings of the IV National Workshop for Australian Native Flowers, 28–30 September 1996, University of Western Australia.

DEC 2012, Department of Environment and Conservation, Perth WA, .

George, EA 2002, Verticordia, The turner of hearts, University of Western Australia Press, Australian Biological Resources Study.

McMullan, C 2006, ‘Waxflower grafting techniques and effects’, in Proceedings of Waxflower Conference 2006, Department of Agriculture and Food WA,16–17 March 2006, Technology Park, Perth, WA.

Seaton, KA 2006, ‘Comparison of vase-life and ethylene response of Verticordia cutflowers’, Journal of Horticultural Science & Biotechnology, vol. 81, pp. 721–727.

Seaton, KA 2008, Nutrient management of waxflower for quality and yield under adequate irrigation levels, RIRDC publication no. 08/016, Rural Industries Research and Development Corporation, Canberra. Seaton, KA and Poulish, N 2010, Production of premium waxflowers, Bulletin 4778, ISSN. 1833- 7236, Department of Agriculture and Food, Western Australian. Wrigley, JW and Fagg, M 1988, Australian Native Plants, 3rd ed, pp. 40–44. Harper Collins, Pymble, Australia.

Development of Intergeneric Rootstocks for Christmas Flowering Verticordia By Dr Kevin Seaton Pub. No. 12/110

Spreading the risk and having a competitive edge in marketing is critical to the survival of the Australian wildflower industry.

The availability of native plants displaying a range of new colours for the Christmas market will increase exports and provide growers with an opportunity to extend their production season.

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Cover image: Grafted plants ready for despatch to growers for demonstration trials V. etheliana (left) and V. chrysostachys (right)