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R. S. Bringhurst

Abstract

For the most part, I direct my remarks to the role of public agency fruit breeders, since that is what most of us are. I feel justified in this role because first, I am convinced that we can provide the best possible varieties at the lowest cost and second, at times, we may be the only protection the grower has against the unscupulous.

Open access

Facundo Barrientos and R. S. Bringhurst

Abstract

A haploid (2n = 28) derived from Fragaria × ananassa Duch. cv. Tioga (2n = 56) was obtained after pollination with Potentilla anserina L. The sublethality of the true hybrids is an excellent screen for exposing the polyhaploids that might be difficult to detect in normal octoploid populations.

Open access

Victor Voth and R. S. Bringhurst

Abstract

Eight non-everbearing California strawberry cultivars were evaluated under the standard winter planting system (October-November) in comparisons involving differentials in plant harvest and transplanting dates and comparing approximately 30, 15 and 0 days of cold storage conditioning at Santa Ana, a relatively warm-winter south coastal California site. The varieties differed greatly in performance and the results were consistent with that which is known of their varying performance under commercial conditions. ‘Sequoia’ was almost an ideal performer but the fruit lacks firmness. Photoperiod is important in governing the reproductive response under this planting system since the duration of the fruiting period for a given variety was directly associated with how long the plant had grown under short days. However, chilling appeared to be the dominant factor governing acceptable performance in all varieties except ‘Sequoia’. ‘Sequoia’ performed satisfactorily over the entire range of treatments and although it responded to chilling, apparently it has a short rest period. Of the other varieties that are of great economic importance in California, ‘Fresno’ and ‘Shasta’ evidently have relatively long rest periods and cannot be manipulated satisfactorily under the winter planting system whereas ‘Tioga’ is intermediate and responds favorably to manipulation.

Open access

S. Arulsekar, R. S. Bringhurst, and Victor Voth

Abstract

Genetic analysis of phosphoglucoisomerase and leucine amino peptidase allozymes clearly indicated that the octoploid cultivated strawberries Fragaria × ananassa Duch. are highly diploidized. A 4-locus genetic model is proposed for the PGI allozymes in the octoploid strawberries commensurate with the genomic structure. The LAP system needs further investigation in order to establish the number of loci and alleles present. The possible adaptive value of the biochemical diversity found in the Fragaria species is discussed.

Open access

Bruce H. Barritt, R. S. Bringhurst, and V. Voth

Abstract

Strawberry (Fragaria × ananassa Duch.) seedlings from 54 crosses between day-neutral and short-day parents were evaluated in western Washington for the proportion which flowered by September and for the earliness of such flowering when it occurred. The day-neutral progeny of ‘Aptos’, ‘Brighton’, ‘Hecker’, CN5, CN11, CN20, WSU 1714E and SHRI 7020/131, all day-neutral parents, flowered early. The day-neutral progeny of ‘Aiko’,’Linn’, ‘Olympus’ and ‘Tioga’, all short-day parents, flowered late. Crosses producing the highest percentage of day-neutral seedlings also had the highest percentage of day-neutral seedlings which flowered early. Reciprocal crosses produced similar results relative to the proportion of day-neutral seedlings and for the proportion of such seedlings which flowered early. For date of first flowering, general combining ability was found to be more important in these crosses than specific combining ability.

Open access

D. V. Shaw, R. S. Bringhurst, and V. Voth

Abstract

Strawberry (Fragaria × ananassa) seedlings were evaluated for yield, fruit weight, and commercial appearance in two field trials established in 1985 and 1986. Genetic analyses for unbalanced diallels were performed to quantify genetic, environmental, and interaction variance for each trial separately, and for crosses common to two locations in a single year. When data from crosses common to two test locations were analyzed simultaneously, narrow-sense heritabilities (h2) averaged 0.35 (±0.11), 0.21 (±0.07), and 0.08 (±0.06) for yield, fruit weight, and appearance score. Broad-sense heritabilities (H2) were 0.35 (±0.11), 0.27 (±0.12), and 0.21 (±0.11) for the same traits, respectively. These estimates do not differ significantly from heritabilities estimated from the ancestral breeding population 20 years ago. Estimates of H2 for single-location analyses were biased upwards by dominance × location interactions for all traits. Additive × location interactions were detected for appearance score and contributed a small bias to single-location estimates of h2. Use of biased estimates in predicting genetic gain could lead to errors in choice of appropriate selection strategy.

Open access

R. S. Bringhurst, S. Arulsekar, J. F. Hancock Jr., and Victor Voth

Abstract

Starch gel electrophoresis was employed to distinguish the University of California-released strawberry cultivars. Isozyme patterns of 3 enzyme systems (PGI, LAP, and PGM) were studied. Fourteen of the 22 cultivars studied were classified uniquely by using the 3 enzyme systems. The use of electrophoresis as a tool in breeding clonally propagated crops is discussed.