Shoot regeneration from Rubus leaves was obtained on a medium containing MS salts, vitamins and sugars, Staba vitamins, casein hydrolysate (100 mgl-~) and 10 #M thidiazuron. Shoot regeneration from Malus leaves was obtained on N 6 rice anther medium with 5 #M thidiazuron. In vitro pretreatment of source shoots with either colchicine or thidiazuron enhanced the organogenic potential of detached leaves of two Rubus hybrids. The response to colchicine was quadratic and occurred at non-mutagenic concentrations (75-250 #M). The response to thidiazuron was exponential between 0 and 5 #M. When applied as a pretreatment, the effectiveness of several different cytokinins (benzyladenine, thidiazuron, zeatin) at enhancing Malus and Rubus organogenesis was related to the shoot proliferation activity of the cytokinin and to treatment-induced variation in leaf and petiole size.

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Data from a four-parent diallel, involving one highbush (Vaccinium corymbosum L.) clone and three interspecific hybrids grown on mineral soil unamended with organic matter, were analyzed to determine combining ability effects for six traits: plant size, berry size, the number of days between flowering and fruiting (# DBF&F), the ratio of total fruit weight to canopy volume (TFW: CYV), days to fruit ripe, and yield. General combining ability effects were significant for all characters tested, except yield and berry size in 1984. Specific combining ability effects were significant for plant size in 1983, #DBF&F in 1984, TFW: CYV in 1984, and berry size in 1985. Vigorous and productive highbush cultivars can be developed for mineral soils by using the interspecific clones from this study and their selected recombinant to combine the genes for plant vigor with the high-quality fruit traits of highbush cultivars.

Vigor, petiole length, stand, runner production, yield per square meter of matted row, and numbers of trusses per crown were greater in tissue culture-produced plants when compared to runner plants of strawberry (Fragaria × ananassa Duch). Leaf area and shape, number of serrations per leaflet, petiole pubescence density, flowers per truss, yield per crown, harvest time, small fruit weight, and percent imperfect fruits did not vary appreciably between propagation methods. Size of large fruit and mean fruit weight were less in tissue culture-produced plants. All changes in performance were caused, at least in part, by the increased vigor and axillary bud activity of tissue culture-produced plants. Tissue culture propagation of strawberry is particularly adapted to production of planting stock for nurseries because 60% more runner plants are produced from tissue culture plants. Production of variant plants from tissue culture was largely limited to 1 meristem-tip line. For certain cultivars, some adjustment of nursery inspection procedures for off-type plants will be required.