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- Author or Editor: Adam Dale x
Genetic variation in the architecture of berry crops will be reviewed. Examples will be given where changes in plant architecture have given increased yields, stabilized yields and improved fruit quality in strawberry, raspberry, highbush blueberry and currants.
Red raspberry will be emphasised as recent research on the architecture of the fruiting cane has enabled breeding strategies, based on plant architecture, to be developed.
Black currant (Ribes nigrum L.) plants of eight varieties were grown either through black plastic mulch or in bare soil and with the area between the rows cultivated or sodded with red fescue (Festuca rubra L.). Over 6 years, black plastic mulch increased yields by 26% over no mulch and cultivation between the rows increased yield by 32% compared to sod. The effect of both treatments was additive, cultivation and black plastic increased yield by 68% over grass and no black plastic. Growers are recommended to plant black currants through black plastic and avoid using sod between the rows.
Fruit from black, red and white currants, and gooseberries (Ribes L.) were grown commercially in North America at the beginning of the 20th Century. However, when white pine blister rust (WPBR) (Cronartium ribicola J. C. Fisch.) was introduced into the new world, their cultivation was discontinued. About 825,000 t (908,000 tons) of Ribes fruit are produced worldwide, almost entirely in Europe. The fruit is high in vitamin C, and is used to produce juice, and many other products. Now a wide range of imported Ribes products is available particularly in Canada, and the pick-your-own (PYO) market is increasing. Two diseases, powdery mildew [Spaerotheca mors-uvae (Schwein.) Berk. & Curt.] and WPBR, are the major problems encountered by growers. Fortunately, many new cultivars are resistant to these two diseases. Commercial acreage of Ribes in North America is located where the growing day degrees above 5 °C (41 °F), and the annual chilling hours are at least 1200. Initially, the Ribes industry will develop as PYO and for farm markets. But for a large industry to develop, juice products will needed. Our costs of production figures indicate that about 850 Canadian dollars ($CDN) per 1.0 t (1.1 tons) of fruit will be required to break even.
Certified red raspberry stock is produced in vegetative propagation beds. Typically, all over-wintering canes in these propagation beds are removed after the first year and a crop of vegetative canes is grown and harvested the second year.
Terminal stem cuttings of seven woody nursery species [boxwood (Buxus sempervirens L. `Green Mountain'), coralberry (Symphoricarpus × chenaultii Rehd. `Hancock'), lilac (Syringa velutina Kom.), Peegee hydrangea (Hydrangea paniculata Siebold. `Grandiflora'), purple-leaf sandcherry (Prunus × cistena N.E. Hansen), Rose-of-Sharon (Hibiscus syriacus L. `Lucy'), and winged spindle-tree (Euonymus alata Thunb.) Siebold. `Compacta')] were rooted under outdoor lath (50% shade) and mist in leached rooting media consisting of 0, 20, 40, 60 and 80% by volume of 2-year-old grape pomace amended in binary mixtures with sphagnum peat, perlite or composted bark. Rooting performance, expressed in terms of percent rooting, mean root number per rooted cutting, and length of the longest root per cutting, was regressed on level of pomace. When there were differences due to amendments, most species rooted better with perlite than with bark and peat, to a lesser degree, due in part to more favourable air-filled porosities with perlite (33% to 42%) than with bark (29% to 37%) or peat (24% to 35%). With boxwood, increasing level of pomace up to ≈60%, especially when mixed with perlite or peat, resulted in substantial increases in rooting percentage, root number and length. All three rooting parameters of winged spindle-tree decreased linearly with increasing level of pomace with perlite or bark. The effect of pomace level on other species varied between these extremes with little or no negative effect on rooting.
Growth and fruiting of 8 red raspberry (Rubus idaeus L.) cultivars, 4 of Pacific Northwest origin and 4 of British origin, were studied over a 4-year period at 2 sites, Abbotsford, British Columbia, and Invergowrie, Scotland. The sites are in the world’s 2 main production regions for the crop, and the cultivars include those important in the respective regions. The cultivars in the same origin group generally outyielded those of the other group at their place of origin. The cultivars yielding well at Invergowrie were those that had thick canes and produced fruit with high drupelet set. Those that yielded well at Abbotsford produced, in comparison, more fruiting laterals per cane. These characteristics would be useful in selecting for high yield in seedling populations grown at the respective sites.
Intraspecific crossing of `Guardian' and `Midway' cultivated strawberry (Fragaria ×ananassa Duch.) produced a family of genotypes, some of which suppressed root-lesion nematode [Pratylenchus penetrans (Cobb)] population counts and produced large berries and high yield. Unlike `Midway', `Guardian' also suppressed P. penetrans. Among several beach strawberry [Fragaria chiloensis (L.) Duch.] and woodland strawberry (Fragaria virginiana Duch.) genotypes, variation was found in resistance and tolerance to root-lesion nematodes. Three F. chiloensis genotypes showed tolerance, and at least two genotypes may be somewhat resistant. Three F. virginiana genotypes also were tolerant, and three were resistant. Also, one (`Little Cataraqui 4') combined root growth vigor with nematode resistance. We concluded that exploitable genetic diversity in vigor and reaction to root-lesion nematodes exists in wild Fragaria and in F. ×ananassa.
Pedigrees of 134 North American strawberry (Fragaria × ananassa Duch.) cultivars introduced since 1960 were used to calculate 1) the genetic contribution of founding clones to these cultivars; 2) genetic relatedness among these cultivars; and 3) inbreeding coefficients of these cultivars. Fifty-three founding clones accounted for the pedigrees of these cultivars, with a mean genetic contribution ranging from <0.1% to 11%. Cultivars were clustered according to the genetic contribution into groups strongly related to geographic region of origin. Cultivars developed in California plus those derived in large part from California germplasm were a distinct cluster. The remaining cultivars divided strongly into two geographical divisions, with cultivars of a western or northern origin primarily in the first division, and cultivars of a southern or eastern origin primarily in the 2nd division. Cluster groups within each division also were related to the region of origin of cultivars. Cultivars also were clustered on the basis of Wright’s coefficient of relationship, a measure of genetic relatedness. Cluster groups from this analysis were strongly related to region of origin of cultivars, and were similar in content to groups based on genetic contributions. Inbreeding coefficients ranged from 0.0 to 0.875, but were <0.5 for all cultivars developed from cross-fertilization. Inbreeding coefficients were related partly to region of origin of the cultivars, but this relationship was probably an indirect result of unequal numbers of generations of controlled hybridization from common ancestors. For example, cultivars developed in California, which resulted from more generations of hybridization, generally had higher inbreeding coefficients. Strategies are suggested for maintaining and increasing genetic diversity of North American breeding populations.
Four winter-hardy strawberry selections and three cultivars where planted in northern Ontario in 2003 in a split-split plot trial where half the rows were mulched and half were left uncovered for the winter. Within each split plot, half the rows were sprayed for tarnished plant bugs and half were not. Yield and tarnish plant bug damage data was collected for two picking years. Two selections maintained their yields in the unmulched plots compared to the mulched plots. Yield for one of these selections was higher in the unmulched plots the first picking year and equal to the mulched plots in the second year. The remaining cultivars and selections produced less when not mulched for the winter. Except for the two selections that maintained their yields in the unmulched plots, plots where straw was applied for the winter had less tarnish plant bug damage. When the plots were sprayed for tarnish plant bugs, damage was reduced for most but not all selections and cultivars.