Strawberry variety named `Mira`

An ananassa type strawberry plant characterized by its high productivity and high disease resistance. The cultivar is suited for propagation in the field and produces slightly tart fruit which is acceptable for the fresh market.

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Description
BACKGROUND OF THE INVENTION

The present invention includes a new and distinct cultivar of Fragaria ananassa known by the varietal name `Mira`, originally designated as "K84-5". The new variety resulted from a cross performed in 1982 between the unpatented cultivars `Scott` and `Honeoye`. The new variety first fruited at the Robinsons Corner research field of the Atlantic Food and Horticultural Research Centre, Agriculture and Agri-Food Canada in Chester Basin, Nova Scotia, Canada in 1984. The new variety was first asexually reproduced by runners in 1985 at the Atlantic Food and Horticultural Research station in Kentville, Nova Scotia, Canada. Since 1992, propagules of the new variety have been tested at the Agriculture and Agri-Food Canada research centers in Charlottetown, Prince Edward Island, Buctouche, New Brunswick and Fredericton, New Brunswick, all of Canada and at the Newfoundland Department of Agriculture field site at Pynn's Brook, Newfoundland, Canada and has been found to retain its distinctive characteristics through successive propagation.

The new variety is typical of short-day varieties and produces fruit over a four week period in northern temperate climates. `Mira` ripens in the mid-late season, and the pattern of production is similar to the standard variety `Kent` but three to five days later. `Mira` has a yield substantially greater than the varieties `Annapolis` (unpatented), `Cavendish` (the subject of U.S. Application Ser. No. 08/535,610, filed Sep. 8, 1995), `Blomidon` (unpatented), and `Bounty` (unpatented) and a yield equal to `Kent` (unpatented). The appearance of `Mira` is superior to `Kent` because of improvements in the uniformity of `Mira's` fruit shape and, unlike `Kent`, the fruit color of `Mira` does not darken excessively when over-ripe or after storage.

DESCRIPTION OF THE DRAWINGS

The accompanying photographic drawing illustrates the characteristic fruit and foliage of the new variety `Mira`, with the color being as nearly true as possible with color illustrations of this type.

DESCRIPTION OF THE PLANT

The following detailed description sets forth the characteristics of the new cultivar. Color references are made to The R.H.S. Colour Chart of The Royal Horticultural Society of London and were also determined using a Minolta Colorimeter.

Classification: The new variety is botanically classified as Fragaria ananassa and commercially classified as a short-day strawberry.

Plant and foliage: When propagated in the nursery, `Mira` has similar runner production to the unpatented variety `Honeoye` but produces more runners than `Kent`. The leaf color of `Mira` and `Kent` are medium green while `Honeoye` leaves are darker green. Comparative statistics for foliar characteristics, including leaflet measurements, serration description, and petiole pubescence are given in Table 1. Individual central (terminal) leaflets of `Mira` are slightly longer and more narrow than those of `Kent` and `Honeoye`. Hence, the leaflet shape of `Mira` is more ovate and less rounded than those of `Kent` and `Honeoye`. The leaflet serrations of `Mira` and `Kent` are semi-pointed whereas they are more rounded for `Honeoye`. The serration at the tip of the central leaflet is small for `Honeoye` but medium in size for `Mira` and `Kent`. The leaf and petiole pubescence for `Mira`, `Kent`, and `Honeoye` are similar with the exception that `Honeoye` has more hairs on the leaflets.

                TABLE 1                                                     

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     Foliar characteristics for                                                

     `Mira`, `Kent`, and `Honeoye`                                             

              Cultivar                                                         

     Foliar Character                                                          

                `Mira`      `Kent`     `Honeoye`                               

     ______________________________________                                    

     Central leaflet                                                           

     Length (mm)                                                               

     mean       84.2        82.5       83.8                                    

     range      68-100      72-100     65-97                                   

     Width (mm)                                                                

     mean       68.4        72.3       70.3                                    

     range      56-85       60-87      55-87                                   

     Length/width ratio                                                        

                1.23        1.14       1.19                                    

     Truss length (cm)                                                         

                28.9        30.6                                               

     No. leaflets/leaf                                                         

                3           3          3                                       

     Leaf convexity                                                            

                flat        flat       flat                                    

     Serrations                                                                

     Number     moderate    moderate   many                                    

     Shape      semi-pointed                                                   

                            semi-pointed                                       

                                       semi-round                              

     Tip serration size                                                        

                medium      medium     small                                   

     Leaf pubescence                                                           

                sparse      sparse     medium                                  

     Petiole pubescence                                                        

     Density    sparse      sparse     sparse                                  

     Direction  perpendicular                                                  

                            perpendicular                                      

                                       perpendicular                           

     Leaf Color                                                                

     Upper surface                                                             

                Green Group Green Group                                        

                137A-137B   137A                                               

     Lower surface                                                             

                Green Group Green Group                                        

                138B        138B                                               

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Blooming characteristics: The length of bloom for `Mira` and `Kent` is about three weeks when grown in Kentville, Nova Scotia, Canada in a matted row cultural system. Flowering for both `Mira` and `Kent` typically begins on June 1 and ends on June 21 of each year.

Disease resistance: `Mira` has a much higher level of resistance to red stele root rot (Phytophthora fragariae) than `Kent` and `Honeoye` and these varieties' reaction to distinct races of the pathogen are given in Table 2. `Mira` is resistant to race A-1, A-2, and A-3 while `Kent` and `Honeoye` are susceptible to these races. `Mira` and `Kent` are moderately resistant to powdery mildew (Sphaerotheca macularis) but `Honeoye` is susceptible. `Mira` and `Honeoye` are moderately resistant to leaf scorch (Diplocarpon earliana) and common leaf spot (Mycosphaerella fragariae) but `Kent` is susceptible to both. `Kent` and `Honeoye` are resistant to green petal phytoplasma and `Mira` is moderately resistant. `Mira` and `Honeoye` are less affected by fruit rot (Botrytis cinerea) than `Kent`.

                TABLE 2                                                     

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     Resistance of `Mira`, `Kent`, and `Honeoye`                               

     to races of Phytophthora fragariae (red stele root rot).                  

     Cultivar                                                                  

     Race    `Mira`        `Kent`  `Honeoye`                                   

     ______________________________________                                    

     A-1     R             S       S                                           

     A-2     R             S       S                                           

     A-3     R             S       S                                           

     A-4     R             S or I  S                                           

     A-5     S             S       S                                           

     A-6     MR            S or I  S                                           

     A-7     S             S       S                                           

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      S = susceptible; I = intermediate; MR = moderately resistant; R =        

      resistant                                                                

Genetic fingerprinting of leaf extracts: Random Amplified Polymorphic DNA banding patterns with primers UBC59, UBC76, UBC85, UBC100 and UBC287 (all available from the University of British Columbia, Nucleic Acid-Protein Service Unit) distinguished `Mira` from seven other strawberry varieties including `Scott` and `Honeoye`, the parents of `Mira` as shown in Table 3. The banding pattern of `Mira` with primers UBC59, UBC85, and UBC100 was distinct from the other varieties. The primer UBC100 produced a distinct pattern for all eight varieties. This testing was done in the Biotechnology Laboratory of the Atlantic Food and Horticultural Research Centre following the techniques of Levi et al., Identification of Strawberry Genotypes and Evaluation of their Genetic Relationships Using Randomly Amplified Polymorphic DNA (RAPD) Analysis, Adv. In Strawberry Research, 13:36-39 (1994).

                TABLE 3                                                     

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     Genetic fingerprinting of `Mira` and seven other                          

     strawberry varieties by Random Amplified Polymorphic                      

     DNA. Bands from reliable polymorphic RAPD fragments                       

     from three replications are represented as 0 = absent or 1 = present.     

     Primer                                                                    

     UBC59        UBC76    UBC85    UBC100 UBC287                              

     Band Number for each primer and DNA pattern                               

     Variety 12345    123      123    12345  123                               

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     Mira    00111 a  100 a    111 a  00111 a                                  

                                             010 a                             

     Scott   10010 b  100 a    100 b  00010 b                                  

                                             010 a                             

     Honeoye 10011 c  000 b    010 c  10100 c                                  

                                             011 b                             

     Totem   10001 d  100 a    000 d  11110 d                                  

                                             101 c                             

     Annapolis                                                                 

             01111 e  101 c    010 c  11101 e                                  

                                             011 b                             

     Cavendish                                                                 

             11011 f  101 c    000 d  11100 f                                  

                                             111 d                             

     Blomidon                                                                  

             11111 g  101 c    010 c  11010 g                                  

                                             011 b                             

     Kent    11111 g  100 a    011 e  10110 h                                  

                                             011 b                             

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Flower and fruit production characteristics: Comparative statistics for flower and fruit characteristics near mid-season, including fruit color, are given for the three cultivars in Table 4. Flowers of `Mira` and `Honeoye` are positioned even with the foliar canopy but flowers of `Kent` are above the canopy. Flowers of `Mira` and `Kent` are medium in size and smaller than for `Honeoye`. Calyx size, as measured with a leaf area meter, is smaller for `Mira` and `Kent` than for `Honeoye`. The calyx coloration of `Mira` is medium green. The position of the calyx on a raised neck for `Mira` is in contrast to the other two varieties which have a position even with the top of the berry. `Mira` berries pick with a much longer stem than for `Kent` and `Honeoye`. The fruit shape of `Mira` is conic comparted to short-conic for `Honeoye` and ovoid for `Kent`, as confirmed by the length/width ratios. The seeds of `Mira` are more deeply indented than those of the other two varieties. Berries of all three varieties are moderately firm but `Mira` has tougher skin. The exterior fruit color of `Mira` and `Kent` is more toward orange while `Honeoye` is more toward purple as reflected in hue angle. `Mira` has a lighter interior than the other two varieties. The flesh coloration of `Mira` is about RHS 41 A, becoming progressively lighter in coloration towards the core. After a 7 day period of storage, the exterior hue angle changed -6% for `Mira`, -28% for `Kent`, and -17% for `Honeoye` indicating that `Mira` holds its color well in storage while the other varieties darken.

                TABLE 4                                                     

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     Flower and fruit charcateristics for                                      

     `Mira`, `Kent`, and `Honeoye`                                             

                  Cultivar                                                     

     Character      `Mira`    `Kent`     `Honeoye`                             

     ______________________________________                                    

     Flower position                                                           

                    even      above      even                                  

     (relative to leaf canopy)                                                 

     Flower truss length                                                       

                    medium-long                                                

                              medium-long                                      

                                         short-                                

                                         medium                                

     Number of flowers per truss                                               

                    11.1      11.2                                             

     (average)                                                                 

     Flower size (diameter)                                                    

                    medium    medium     medium-                               

                    (32.7 mm) (32.4 mm)  large                                 

     Flower color   white     white                                            

     Petal spacing  touching  overlapping                                      

                                         touching                              

     Calyx area (cm.sup.2)                                                     

                    3.8       3.9        6.3                                   

     Calyx position raised neck                                                

                              even       even                                  

     Fruit stem length                                                         

                    very long medium     medium                                

     Fruit shape                                                               

     length/width ratio                                                        

                    1.00      0.76       0.97                                  

     subjective     conic     ovoid      short-                                

                                         conic                                 

     Seed position  indent    even       slight                                

                                         indent                                

     Fruit firmness (N)                                                        

                    4.6       4.8        5.2                                   

     Skin toughness (g)                                                        

                    15.3      6.2        9.2                                   

     Color (R.H.S. Colour CHart)                                               

     Fruit exterior Red Group Red Group                                        

                    42A       46A                                              

     Fruit interior Red Group Red Group 44B                                    

                    41A                                                        

     Color (Minolta Colorimeter)                                               

     Fruit exterior                                                            

     hue angle      27.9      29.1       24.8                                  

     chroma         45.9      38.9       37.8                                  

     lightness      36.2      37.1       32.3                                  

     Fruit interior                                                            

     hue angle      50.2      47.3       44.2                                  

     chroma         23.8      28.1       34.6                                  

     lightness      63.0      55.0       56.1                                  

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Production characteristics: `Mira` has been widely tested for several years. As shown in Table 5, `Mira` typically yields equal to `Kent` (the high yield standard variety in the trials). The percent of fruit classified as unmarketable is typically lower for `Mira` than `Kent` due to the greater resistance of `Mira` to Botrytis fruit rot. The fruit of `Mira` are slightly smaller (by weight) than `Kent` and the season of harvest is consistently later than `Kent`. Subjectively, `Mira` has a flavor similar to `Kent`, but more tart. `Mira` fruit will be acceptable for the fresh market and attractive to growers because of high productivity and disease resistance. `Mira` produces abundant runners in the nursery and is readily propagated by conventional field techniques.

                TABLE 5                                                     

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     Performance of `Mira` and `Kent` for 1993, 1994, 1995, and 1996           

     averaged over four sites: Kentville, NS; Charlottetown, PEI;              

     Boctouche, NB; and Pynn's Brook Nfld. Plants were grown in matted         

     rows and three blocks of 3 m long rows were harvested at each site.       

     Total Yield % yield SIze      Mean harvest                                

     (t/ha)       unmarketable                                                 

                             (g/fruit) (day of year)                           

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     1993                                                                      

     `Mira`  19.3      6.2       13.7    208.1                                 

     `Kent`  21.1      9.0       14.5    205.7                                 

     1994                                                                      

     `Mira`  24.7     14.2       12.0    199.9                                 

     `Kent`  25.0     18.8       12.3    198.8                                 

     1995                                                                      

     `Mira`  23.8      8.0       13.4    199.0                                 

     `Kent`  21.5     10.2       13.9    197.0                                 

     1996                                                                      

     `Mira`  16.1     11.8        9.8    198.3                                 

     `Kent`  19.3     11.4       10.4    197.3                                 

     ______________________________________                                    

Claims

1. A new and distinct variety of strawberry plant substantially as shown and described.

Referenced Cited
U.S. Patent Documents
PP8623 March 1, 1994 Lopez
PP10460 June 23, 1998 Khanizadeh et al.
Other references
  • UPOV-ROM GTITM Computer Database, 1998/04, GTIJOUVE Retrieval Software, Citation for `Mira`.
Patent History
Patent number: PP11438
Type: Grant
Filed: May 26, 1998
Date of Patent: Jul 11, 2000
Assignees: Atlantic Food and Horticulture Research Centre (Kentiville), Agriculture and Agri-Food Canada (Kentiville)
Inventors: Andrew R. Jamieson (Kentville), Nancy L. Nickerson (Port Williams), Donald L. Craig (Nova Scotia)
Primary Examiner: Howard J. Locker
Assistant Examiner: Wendy A Baker
Law Firm: Webb Ziesenheim Logsdon Orkin & Hanson, P.C.
Application Number: 9/84,137
Classifications
Current U.S. Class: Strawberry (Plt/208)
International Classification: A01H 500;