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Eight strawberry cultivars or advanced selections from the Univ. of California, Davis, breeding program were screened for polymorphisms using the polymerase chain reaction (PCR) and 43 random 10-base DNA primers. Over 60% of the primers screened resulted in replicable polymorphic banding patterns (amplification profiles), and a subset of ten primers that exhibited high levels of amplification profile polymorphism was used to identify each of the eight genotypes uniquely. There was also a significant product-moment correlation (r = 0.64, P < 0.01) between number of shared amplification profile phenotypes and pairwise coefficient of coancestry. This technology shows high promise as a means of verifying the identity of cultivars and developing a genetic map of the octoploid cultivated strawberry.
Twenty-one western and 13 eastern strawberry [Fragaria × ananassa (Duch.)] cultivars were grown in a polyethylene-covered greenhouse (polyhouse) in deep beds at either 10 × 10 or 25 × 25 cm spacing. Runners were removed weekly from the closest-spaced plants (hills), and the more open-spaced plants were allowed to set four runners on each side of the mother plant before the runners were removed (matted rows). Temperatures were allowed to fluctuate normally in the polyhouse, except that winter temperatures were maintained above 0C. The average yield of eastern and western cultivars did not differ significantly in most comparisons, but the average fruit weight of the Californian cultivars was significantly higher than the eastern ones, and Californian cultivars allocated a higher proportion of their biomass to reproduction. Nonbearing plants of eastern and western cultivars produced similar numbers of runners per plant and daughters per runner. There was no significant relationship between CO2 assimilation rate and yield. Interbreeding eastern cultivars with the most productive western genotypes might result in increased yields, but only if the higher reproductive efforts of the western types can be captured and transferred.
An elite group of 38 strawberry accessions representing all subspecies of the beach strawberry [Fragaria chiloensis (L.) Miller] and the scarlet strawberry (F. virginiana Miller) was planted in a replicated design at five locations across the United States, and evaluated for plant vigor, flowering date, runner density, fruit set, fruit appearance, and foliar disease resistance. Considerable genotyp× location interaction was observed for many of these traits. However, a few genotypes were impressive at all locations including PI 551735 (FRA 368) with its unusually large, early fruit, and PIs 612486 (NC 95-19-1), 612493 (Frederick 9), and 612499 (RH 30), which were very vigorous and had unusually good fruit color. Genotypes that were superior at individual locations included PIs 551527 (FRA 110) and 551728 (Pigeon Pt.) in Maryland for their large fruit, and PI 612490 (Scotts Creek) in Oregon which had extremely large fruit, superior color, firmness, and flavor. The PIs 612495 (LH 50-4), 612498 (RH 23), and 612499 (RH 30) performed well as day neutrals at multiple sites.