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- Author or Editor: Adam Dale x
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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.
Abstract
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.
The objectives of the study were to determine whether raspberries responded to decreased red to far-red ratio and whether it was more effective at the beginning or end of the dark period. Increased proportions of far-red light increased the internode length when at the beginning of the dark period on the three raspberry cultivars `Lauren',`Reveille', and `Titan'. Cultivars varied in that internode length also increased in ambient daylength compared to short days in `Lauren' and `Reveille', but not in `Titan'. They also responded differently to photoperiod: `Titan' and `Lauren' grew under short days, whereas `Reveille' ceased growth.
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.
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.
Experiments were conducted to determine the chilling temperature and length of time required to break dormancy in red raspberry (Rubus idaeus L.). Five weeks of 7 °C with no light was sufficient to break dormancy in `Autumn Britten', `Nova', `Polana', and `Tulameen', while at least 8 weeks were needed for `Titan'. Comparisons with various chilling unit models allowed a model to be developed that could account for the observed chilling variation. In this model, each chilling hour was weighted as follows: below 5.6 °C = 1; 5.7 to 8.0 °C = 0.5; 8.1 to 11 °C = 0; 11.1 to 13 °C = -0.5; and >13 °C = -1. Plants of `Nova' and `Tulameen' chilled before flower initiation occurred, broke dormancy, and the resulting lateral branches remained vegetative. When the plants were fruited in the greenhouse, we were able to produce a second crop on the fruiting canes when the lateral branches that had fruited were removed. These experiments show that raspberries can be manipulated so that plants chilled in mid-September in the Northern Hemisphere can be induced to fruit by the beginning of January.
Abstract
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.
Micropropagation of strawberries is an extremely effective tool to rid strawberry plants of Colletotrichum infections. The continued health of these plants depends on a vigorous sanitation program throughout the nursery system in North America. Propagating healthy strawberry plants requires a series of steps: plants are micropropagated, virus-tested, screened for fungal and bacterial pathogens, and finally grown under strict guidelines for two growing seasons in propagator's fields. In the propagator's fields, the plants are inspected for visual symptoms of diseases and checked for trueness-to-type. This paper reviews the protocols used to develop specific pathogen-tested strawberry plants in Ontario and, where appropriate, discusses alternate techniques.