Optimizing Watermelon Grafting Techniques...Grafting –A propagation technique Grafting is a...
Transcript of Optimizing Watermelon Grafting Techniques...Grafting –A propagation technique Grafting is a...
Optimizing Watermelon Grafting Techniques
Abigail Attavar, MS StudentPinki Devi, PhD Student
Dr. Carol Miles, ProfessorDepartment of Horticulture
Problem: Verticillium Wilt
• Caused by Verticillium dahliae (Vd)
• Symptoms are chlorosis, necrosis and wilting
• Management is difficult because:• Persistent in soil for up to 14 years (in the
form of microsclerotia)
• Wide host range of about 400 plant species
• Soil fumigation with methyl bromide in the past but new fumigants are less efficient
• Soil solarization has moderate efficiency
Verticillium wilt disease progress
Grafted watermelon Non-grafted watermelon
WSU NWREC Mount Vernon, September, 2017
Grafting as a biological disease management strategy
Grafting – A propagation technique
Grafting is a technique that joins together two plants through their stem vascular tissues in order to take advantage of their combined characteristics.
Graft union
Scion
Rootstock
Splice grafting
1 2 3 4
Step 1. Cut the rootstock at 45° angle, under the cotyledon leavesStep 2. Cut the scion at 45° angle, ensuring the diameter is the same as the rootstockStep 3. Place a grafting clip onto the rootstock, rootstocks should occupy half the length of the clipStep 4. Place the scion into the grafting clip
One cotyledon grafting method
1 2 3 4
Step 1. Cut the rootstock at a 60° angle with one cotyledon remaining on the plantStep 2. Cut the scion at a 60° angle below the cotyledons, where its diameter matches that of the rootstockStep 3. Join the two cut stems togetherStep 4. Secure with a grafting clip.
Graft the plants
Place grafted plants in healing chamber
Monitor the healing process daily
Gradually reintroduce grafted plants to greenhouse environment conditions
Acclimate plants to natural environmental conditions
Seed scion and rootstock
Transplanting to Field
Plant the graft union well above the soil line
Efficiency of grafting as a disease management strategy
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Non-graftedSelf-graftedStrong TosaEmphasis
Watermelon 2010 & 2011
Buller, S., Inglis, D. and Miles, C., 2013. Plant growth, fruit yield and quality, and tolerance to verticillium wilt of grafted watermelon and tomato in field production in the Pacific Northwest. HortScience, 48(8), pp.1003-1009.
Soil infestation of Verticillium dahliae: 18.0 cfu·g–1 at Mount Vernon, WA
Verticillium Wilt Progress
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42 60 70 83
Eltopia
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42 60 70 83
Eltopia
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42 60 70 83
Othello
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42 60 70 83
Othello
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45 52 59 72 89
Mount Vernon
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45 52 59 72 89
Mount Vernon
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Black plastic mulch Clear plastic mulch
Days after transplanting
Dabirian, S., Inglis, D. and Miles, C.A., 2017. Grafting watermelon and using plastic mulch to control verticillium wilt caused by Verticillium dahliae in Washington. HortScience, 52(3), pp.349-356.
Fruit Yield
Yield per plant (kg)
Treatment Eltopia Othello Mount Vernon
TriX Palomar (non-grafted) 14.7 30.4 7.4 b
TriX (Super Shintosa) 12.2 28.1 14.6 a
TriX (Tetsukabuto) 11.0 28.7 11.8 a
TriX (Just) 11.1 23.4 12.7 a
P-value 0.37 0.17 0.009
Soil infestation with Verticillium dahliae: <1 cfu g-1 at Eltopia, 2.6 cfu g-1 at Othello, and 27 cfu g-1 at Mount Vernon
Fruit Quality
Firmness (N)
Lycopene
(𝜇g.g-1) TSS %
Treatment
Eltopia 2.20 b 38.58 a 10.28
Othello 2.44 b 36.54 a 10.51
Mount Vernon 3.00 a 27.85 b 10.54
P-value < 0.0001 < 0.0001 0.22
Current research on watermelon grafting at WSU
Problem: Availability of Rootstocks
• Grafting onto a resistant rootstock can help manage the disease for watermelon• BUT resistant rootstocks are not
easily available
Solution: Screening germplasm for resistance
• Germplasm in USDA National Germplasm System is collected from all over the world• Potential sources of resistant rootstock
• Screened 56 germplasm accessions from 4 different rootstock species for resistance to Verticillium wilt
• 16 resistant accessions were used as rootstock for watermelon grafting and we assessed:• Yield• Fruit number• Fruit quality
Study conducted in 2017 at Mount Vernon, WA
Problem: Rootstock Regrowth
The meristem tissue below the axillary bud
Squash leaves
• Scouting plants in the greenhouse• Removing rootstock regrowth in the field
• Time consuming• Labor intensive
• Competition with scion for light, space, and water and nutrient uptake
• Decreases graft success• Death of scion
Possible solution
Splice grafting can be more efficient and cost effective grafting method
➢ Eliminate rootstock regrowth➢ 2-3 times faster than other
available techniques➢ Less labor cost
Limitation:• Low carbohydrate level• Dessication of the grafted seedling
during healing• Low survival rate
Past research
Gra
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0% Sucrose 1% Sucrose 2% Sucrose 3% Sucrose
Days after grafting
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Repeat 1
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Repeat 2
Dabirian, S. and Miles, C.A., 2017. Antitranspirant Application Increases Grafting Success of Watermelon. HortTechnology, 27(4), pp.494-501.
Ongoing research
Greenhouse studies: To increase survival of splice-grafted watermelonStudy 1. Effect of antitranspirant applied prior to graftingStudy 2. Effect of sucrose in combination with antitranspirant
applied prior to grafting
Field Study: Effect of grafting method on fruit maturity and quality as compared to non-grafted watermelon
• Emergence of female flower• Harvest date• Hollow heart and hard seed formation • Quality: fruit firmness, total soluble solids, lycopene content
Rootstock Species Cultivar Company Website
Interspecific
squash hybrid
Cucurbita maxima x
C. moschata
Carnivor, Super Shintosa,
Strong Tosa
Syngenta http://www.syngenta-us.com/crops/vegetables
Shintosa camelforce,
Ercole
Nunhems http://www.nunhemsusa.com/www/NunhemsInternet.nsf/
id/US_EN_WatermelonCobalt, Ferro Rijkzwaan https://www.rijkzwaanusa.com/crop/rootstockJust, Tetsukabuto, Titan,
Keystone
Takii seeds http://www.takiiseed.com/
Flexifort Enza Zaden http://www.enzazaden.us/Rootpower Sakata http://sakata.co.za/product/rootpower/RS 841 Seminis https://www.ahernseeds.com/products/rs841/?lang=en
Samura Genome seeds http://www.genomeseeds.com/prodect/rootstock/cucurbit-
rootstock/502Bass BS-1, AQ Origene seeds http://www.origeneseeds.comKardosa Aruba seed https://www.arubaseed.com/rootstocks
Calabash gourd Lagenaria siceraria Pelop Rijkzwaan https://www.rijkzwaanusa.com/crop/rootstock
Bingo, Valett F1, Savor Takii seeds http://www.takiiseed.com/Emphasis Syngenta http://www.syngenta-us.com/crops/vegetablesMacis Nunhems http://www.nunhemsusa.com/www/NunhemsInternet.nsf/id/US_EN_
HomeRS 3532 Aruba seed https://www.arubaseed.com/rootstocks/
Wax gourd Benincasa hispida Round, Oblong Kitazawa seeds https://www.kitazawaseed.com/seeds_winter_melon.htmlCitroides Citrullus lanatus Carolina Strongback Syngenta http://www.syngenta-us.com/crops/vegetables
Watermelon Citrullus lanatus Yokozuna F1 Takii http://www.takiiseed.com/goods_list/goods_list_2.php?called=catego
ry&vctg_no=29
Commercially Available Rootstocks
www.vegetablegrafting.org
Acknowledgements
• WSU Mount Vernon NWREC Vegetable Horticulture Staff• WSU Mount Vernon NWREC Plant Pathology Department• Funding provided by:
• Washington State Department of Agriculture• United State Department of Agriculture
SCRI No. 2011- 51181- 30963 and 2016-51181-25404• Northwestern Agricultural Research Foundation
• Seed companies:
Thank you.
Questions?
For more information on vegetable grafting, visit www.vegetablegrafting.org