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  • Author or Editor: V. Voth x
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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

Abstract

Strawberry (Fragaria × ananassa Duch.) seedlings from biparental crosses were planted in two trials at Watsonville, Calif. Sept. 1985 and 1986. The 1985 trial was scored on three dates and the 1986 trial on four dates for leaf spot (Ramularia tulasnei) infection. Individual seedlings were assigned a value of 0 to 5 on each date, with 0 indicating no infection and 5 indicating very severe infection. Average infection scores were lowest for the earliest scoring dates in both years (0.93 and 0.38) and maximum at late scoring dates (2.83 and 1.49). Narrow-sense heritabilities for infection scores estimated using partial diallel analyses were 0.07 and 0.03 for the earliest scoring dates in the two trials and were 0.24 and 0.28 for the latest dates. Early season estimates of broad-sense heritabilities were calculated as 0.13 and 0.03, whereas estimates based on later scorings ranged from 0.32 to 0.52. The low heritabilities for early scoring dates result from incomplete and uneven infection, indicating that selection under field conditions will be most effective under conditions of very high infection. The moderate heritabilities and predicted gains estimated for high-infection conditions suggest considerable opportunity for improvement of leaf spot resistance by recurrent breeding and selection using available quantitative genetic variation.

Open Access

Abstract

Genetic variation for percent soluble solids, percent titratable acidity, and fruit firmness was analyzed for representative progenies from the California strawberry breeding population. Fruit samples were harvested from individual seedlings from 28 biparental crosses, organized in two factorial mating sets. Individual narrow-sense heritabilities were estimated as 0.07, 0.48, and 0.38 for solids, acids, and firmness, respectively. Broad-sense heritabilities were estimated as 0.35, 0.78, and 0.38 for the same traits, suggesting the presence of dominance variance for soluble solids and acidity, but not for firmness. Opportunities for genetic manipulation of traits with different additive-dominance genetic variation profiles are discussed.

Open Access

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