Patent Grant
PP16124
Genus and species: Pyrus communis L.
The present invention relates to a variety of a pear tree and more specifically to a pear tree variety that yields a high-quality, early season pear for the fresh market.
The variety ‘HW616’ was developed by Agriculture and Agri-Food Canada at Harrow, Ontario. The variety has been described by Hunter et al, HortScience, Vol. 37 (1):224-226, February 2002. To applicants' knowledge, the variety has not been made publicly available. It will be marketed under the brand name AC HARROW GOLD.
The new and distinct pear variety, which has been given the designation of ‘HW616’, produces a high quality early season pear primarily for the fresh market. ‘HW616’ is picked about ten days before ‘Bartlett’ (unpatented), the reference cultivar it most closely resembles. ‘HW616’ has an attractive golden yellow (RHS color designations fruit with no blush, smooth skin, very good flavor with a good balance between sweetness and acidity, and exceptionally juicy. Fruit size of ‘HW616’ is equivalent to that of ‘Bartlett’. The tree of ‘HW616’ is medium in size, upright to spreading. ‘HW616’ has excellent resistance to natural fire blight (Erwina amylovora) infections (9.6 rating), whereas ‘Bartlett’ is susceptible to natural infections (4.2 rating). The response to infection following inoculation with the causative organism is more severe in ‘Bartlett’ (mean lesion length 63% of shoot length, with some lesions extending into subtending woody tissues) than in ‘HW616’ (mean lesion length 25% of shoot length, maximum lesion length of 52% of shoot length).
‘HW616’ resulted from a controlled cross between ‘Harvest Queen’ (unpatented) and ‘Harrow Delight’ (unpatented) made in 1975 by Dr. H. A. Quamme at the Agriculture and Agri-Food Canada Research Centre at Harrow, Ontario. It was selected as a hybrid seedling (H7535-100) in 1983 by F. Kappel, and propagated by budding onto pear seedling rootstocks. In 1985, it was advanced and testing began in 1987 at the Harrow Research Centre. Propagation for regional trials in cooperation with the Western Ontario Fruit Testing Association began in 1985, and test trees were placed in regional trials beginning in 1987. Evaluations of second test orchards have been conducted by F. Kappel and D. M. Hunter, and W. G. Bonn has evaluated disease resistance.
Asexual propagation maintains uniformity and stability of ‘HW616’. No variants, off-types or mutants have been observed. The variety will be maintained at the Agriculture and Agri-Food Canada Harrow Research Centre in a virus tested budwood orchard, and in the holdings of the Canadian Clonal Gene bank.
The color terminology is in accordance with The Royal Horticultural Society (R.H.S.) Colour Chart.
zShoots harvested in Feb., 1996, from mature trees (>10 years old) grown on ‘Bartlett’ seedling rootstock at Harrow, Ont., Canada.
zLeaves (1 leaf/shoot, 10 shoots/tree, 4 trees/cultivar, n = 40) were harvested Jul. 27, 1995 from trees (>8 years old) grown on ‘Bartlett’ seedling rootstock at Harrow, Ontario, Canada.
The adaxial surface of leaves of HW616 obtained from the mid-section of current season's extension growth from trees (˜10 years old) grown on ‘Bartlett’ seedling rootstock at the AAFC Jordan Farm, Jordan Station, Ontario, Canada, was described using The Royal Horticultural Society Colour Chart as 137A, while the abaxial surface was described as 147B. Both adaxial and abaxial leaf surfaces were described as smooth. Flowers: At Harrow, Ontario, Canada, the date of first bloom of HW616 is about May 7 (depending on season), later than ‘Harrow Delight’ (˜May 4) and ‘Harvest Queen’ and ‘Bartlett’ (˜May 6). The date of full bloom is ˜May 11, similar to ‘Harrow Delight’ and ‘Harvest Queen’ (˜May 11) and earlier then ‘Bartlett’ (May 13). Flower descriptive data obtained at ˜ full bloom are presented in Table 3.
In controlled pollination tests, fruit set was used to determine pollen compatibility when pollen from a known source was applied to stigmatic surfaces immediately after emasculation of the flower. Because emasculated pear flowers are even less attractive to bees and other pollinating insects than non-emasculated flowers, bagging was not considered necessary. ‘HW616’ appears to be reciprocally pollen compatible with ‘Bartlett’, ‘Seckel’ (unpatented), ‘Old Home’ (unpatented), and ‘Harvest Queen’. While ‘HW616’ will pollinate ‘Harrow Delight’, ‘Harrow Delight’ will not pollinate ‘HW616’. Results of reciprocal pollinations between ‘HW616’ and ‘Bosc’ (patented) have been variable and inconclusive.
‘HW616’ was tested at the Canadian Centre for Plant Health, Saanichton, B.C., using woody-host and herbaceous-host biological indicators, and by serological and molecular methods, and found to be free of all known viruses, virus-like agents, viroids and phytoplasmas. Virus-tested trees have been planted in the Canadian Clonal Gene Bank at Harrow.
zNatural fire blight infections, rated on a scale of 1 (tree dead) to 10 (no blight), are means ± SE of 10 to 20 years at Harrow, Ont., Canada. The rating system was modified from van der Zwet et al. (1970) by assigning values of 10 = no visible blight and 9 = <3% infection. For ‘HW616’, ‘Harrow Delight’, and ‘Harvest Queen’, ratings were made on the own-rooted seedling tree. For ‘Bartlett’ and ‘Kieffer’, ratings were made on trees grown on Bartlett
yInduced infections were measured in late July, ≈5 weeks after inoculating 10-20 actively growing shoots with 20 μL of a cocktail of six virulent strains of Erwinia amylovora (108 cfu/mL). Values indicate lesion length expressed as a percentage of total shoot length. Data are means ± SE of 10 to 22 years.
zMeans separation within rows by Duncan's new multiple range test, P = 0.05. Means within rows followed by the same letter are not significantly different.
yRatings reported are based on evaluations of fruits ripened immediately after harvest.
xAppearance, flavor and texture ratings [on a scale of 1 (least desirable) to 9 (most desirable)] were determined each year by two to four trained panelists.
wWeighted score = (3 × appearance) + (5 × flavor) + (2 × texture).
vGrit rating is on a scale of 1 (undesirable, i.e. large and/or many grit cells) to 5 (desirable, i.e., very small and/or few or not grit cells).
uJuiciness rating is on a scale of 1 (dry) to 5 (very juicy).
tCore size rating is on a scale of 1 (small) to 5 (large).
zDetermined with masked identity taste panels involving four trained panelists. Fruits were processed in syrup containing 15% (w/v) sugar. Processing rating for pear halves is the average of ratings for flavor, texture and appearance on a scale of 1 (least desirable) to 5 (most desirable). Samples, including a masked identity ‘Bartlett’ sample, were compared to a known ‘Bartlett’ sample. Data presented are means of 5 years.
yDetermined with masked identity taste panels involving four trained panelists. Fruits were processed with no additional sugar. Processing rating for purée is the average of ratings for viscosity, color, and flavor on a scale of 1 (least desirable) to 5 (most desirable). Samples, including a masked identity ‘Bartlett’ sample, were compared to a known ‘Bartlett’ sample. Data presented are means of 5 years.
xMeans separation within rows by Duncan's new multiple range test, P = 0.05. Means within rows followed by the same letter are not significantly different.
In the 5th leaf, trees of HW616 grown on ‘Bartlett’ seedling rootstock had a trunk cross sectional area (TCSA) of 22.4∀5.9 cm2 (n=4), while ‘Bartlett’ on ‘Bartlett’ seedling rootstock in the same planting had a TCSA of 16.8∀2.7 cm2 (n=3). By the 8th leaf, TCSAs were 59.2∀13.5 cm2 for HW616 and 41.5∀2.7 cm2 for ‘Bartlett’.
| Number | Date | Country | |
|---|---|---|---|
| 20040006799 P1 | Jan 2004 | US |
