Although strawberry species have existed for an estimated 50 million years (17), and their use by man has been dated to the bronze age (19), only after the 14th century A.D. were strawberry plants gathered from the wild and grown in gardens. These first cultivated strawberry plants were grown for both ornamental and medicinal purposes (11). The strawberries of the past were different from those of today. The fruit was small, plants were not productive, and in many respects were far inferior to the large fruited cultivars that are now grown in many parts of the world.
Selfed progenies were generated using 10 day-neutral genotypes from the University of California (UC) strawberry breeding program as parents and their offspring were classified for late-summer flowering response. The grandparents of each selfed progeny included one of four day-neutral genotypes and one of eight short-day genotypes. Under the null hypothesis of genetic control by a single locus with the allele for day-neutrality dominant to the allele for short-day flowering response, all of these day-neutral parent genotypes must be heterozygous and their selfed offspring were expected to fit a 3:1 ratio of day-neutral: short-day phenotypes. The percentage of day-neutral offspring observed over all progenies was 70.9%, and was significantly smaller than the expected value of 75% (χ2 1 = 5.08, P < 0.02). The percentage of day-neutral offspring for individual progenies ranged from 41.4% to 84.8%, and highly significant heterogeneity was detected among progenies (χ2 9 = 40.3, P < 0.01). Selfed progeny means for the cumulative late-summer flowering score calculated using the day-neutral fraction of offspring varied from 1.31 to 2.35 and progeny means for the number of inflorescences per plant ranged from 3.5 to 9.9; these differences among progenies were highly significant (P < 0.01). These observations can be used to conclusively reject the hypothesis that day-neutrality in this domestic strawberry population is controlled by a single locus.
The genetic opportunity for selection of early fruiting strawberry cultivars was evaluated using seedling populations from the Univ. of California (UC) breeding program in three years. Narrow-sense heritabilities for early season yield and for the proportion of an individual's total yield expressed early were moderate (h2 = 0.24-0.53) and broad-sense heritabilities were slightly larger (H2 = 0.31-0.70), suggesting the presence of some nonadditive genetic variance for these traits. These two traits were genetically correlated with each other (rg = 0.78-0.98), but only early yield was consistently genetically correlated with seasonal yield (rg = 0.52-0.82). Selection was performed for each trait using an index on full-sib family means and individual phenotypic values in two of the three years, and predicted response was compared with that obtained using vegetatively propagated runner plants from selected genotypes in the subsequent fruiting season. Statistically significant (P < 0.05) selection response was obtained in one of two years for each trait, and combined analysis demonstrated highly significant (P < 0.01) response for both traits. However, realized response over all traits and years was just 27.3% of that predicted based on the estimated heritabilities and applied selection intensities. These results suggest that selection for early yield should be based at least in part on runner plant evaluations rather than exclusively on seedling performance.
Eighteen strawberry genotypes from the University of California's breeding population were evaluated over two years for yield and fruit size with complete, partial, and no control of natural infestation by Tetranychus urticae Koch. The numbers of mites per leaf accumulated for the entire season or counted at peak infestation, and the number of mite-days accumulated for the season for partial control treatments were 31.7% to 44.0% of corresponding values realized for uncontrolled infestation, and values differed significantly between treatments for all three variables. Yields for the no-control and partial-control treatments averaged 81.6% and 85.0% of the yields obtained with complete spidermite suppression for the 2 trial years; fruit sizes were 95.1% and 92.0% for corresponding comparisons. Yield and fruit size differed significantly between the complete-control treatment and any level of infestation, but statistically significant differences between partial and complete mite control treatments were detected only for fruit size in a single year. Analysis of variance demonstrated significant or highly significant variation due to control level, genotype, and their interactions for both yield and fruit size, but resolution of variance components demonstrated that genetic × treatment interactions explained just 0% to 8% of the phenotypic variance for yield and fruit size in a 2-year evaluation. Genotypic variances, those reflecting genetic effects that were stable across treatments, were at least 9.3 times as large as interaction variances for these traits. There appears to be no evidence for partial resistance that might be expressed at intermediate levels of spidermite infestation.
Field experiment on production systems of `Selva' day-neutral and `Totem' June-bearing strawberry was established in 1995 on the spring-killed cover crop mulched plots using randomized complete-block design. Seven soil cover treatments consisted of `Wheeler' rye (Secale cereale) and `Micah' and `Steptoe' barley (Hordium vulgare), `Micah' residue applied on soil surface, a wedge of perlite (artificial medium) placed next to strawberry row, perlite with `Wheeler' rye, and no treatment were used. During the early summer, cover crops were replanted between strawberry rows and mowed down after 6 weeks. In both cultivars, plant growth doubled during mid-summer, and `Micah'on surface produced better growth than the growth in other treatments. No significant difference was found on CO2 assimilation rate (mmol·m–2·s–1), leaflet length, and number of leaves and runners among treatments (P ≥ 0.1). Yield of `Totem' was ignored during the establishment year. In `Selva', `Micah' residue on surface produced 36% more crowns per plant and the greatest total yield than that of any other treatment. `Micah' on surface produced 50% more shoot biomass and 45% greater yield compared to `Micah' barley planted in the plot. Total `Selva' yield was 61% greater in perlite treatment than the yield in perlite with `Wheeler' rye and 31% greater than the control treatment. Comparison of `Selva' strawberry total yield and average fruit production between cover crops vs. control treatment using non-orthogonal contrast indicated no significant difference might suggests no detrimental interaction between cover crops and strawberry.
The present research was undertaken to examine carbohydrate composition and distribution patterns and induction of flowering and runner formation in attached and detached strawberry plants grown under varying temperature conditions. There was an interaction between attached mother and daughter plants. Daughter plants affected flowering in mother plants, and mother plants influenced vegetative growth in daughter plants. Attachment and high temperature decreased root soluble carbohydrate concentration and promoted runner formation in both mother and daughter attached plants, suggesting that changes in carbohydrate concentration in the roots may be correlated with changes in vegetative growth. According to the results of this research, high temperatures are likely to enhance vegetative growth, whereas lower temperatures are likely to enhance the floral response. Differential temperature regimes applied to the mother/daughter plant experimental system could be an alternative to photoperiod treatments as a tool to study the correlation between environmental conditions and changes in vegetative and reproductive growth in strawberry.
Relatively few herbicides are registered in Alabama or in the southeastern United States for use in annual hill plasticulture production of strawberries. Acquisition of 24(c) special local needs status for certain herbicides could make more of these chemistries available to the strawberry industry. These herbicides, especially when applied as tank mixes pose potential risks to strawberry plant growth and fruit yield. Special local needs status for these herbicides has been granted for other states, but more evaluation of these products in Alabama soils under plastic mulch is needed. The objective of this study was to assess tank mix applications of preemergence herbicides with different modes of action on plant growth, crop yield, and fruit size of ‘Camarosa’ strawberry. A study was conducted at the Chilton Research and Extension Center in Clanton, AL, in 2018 and 2019. Pendimethalin (3.5 L·ha–1) and S-metolachlor (1.6 L·ha–1) were evaluated for potential phytotoxicity in ‘Camarosa’ strawberry when applied alone or in tank mixes with napropamide (8.6 kg·ha–1), sulfentrazone (0.3 L·ha–1), or terbacil (0.42 L·ha–1) by comparing them to a nontreated control. At 18 weeks after planting, pendimethalin tank mixed with napropamide reduced plant dry weight by 33% compared with the control, but this reduction was not significant. Additionally, tank mixes of pendimethalin with sulfentrazone, napropamide, and terbacil reduced shoot dry weight by 43%, 52%, and 43%, respectively, compared with pendimethalin alone. Pendimethalin + napropamide tank mix reduced relative growth rate by 95% compared with the control between 6 and 18 weeks after planting. All treatments were similar to the control in marketable yield. Differences in plant growth parameters did not appear to affect yield by the end of the experiment. All single applied treatments along with S-metolachlor tank mixed with napropamide and sulfentrazone; pendimethalin tank mixed with sulfentrazone and terbacil appeared to be safe for direct application to strawberry planting beds covered in polyethylene mulch.
The development of new strawberry ( Fragaria × ananassa ) cultivars with improved flowering, fruit quality, and disease resistance is an ultimate goal for fruit breeders worldwide. Selective breeding has resulted in tremendous crop improvement, but
The octoploid cultivated strawberry, Fragaria × ananassa Duch. (2 n = 8 x = 56), was derived from accidental hybridization between two American octoploid species, F . virginiana and F . chiloensis , during the early to mid-1700s ( Darrow
There is a need in Queensland winter strawberry ( Fragaria × ananassa Duch.) production areas for a highly flavored, early-ripening cultivar to replace or be an alternative to ‘Kabarla’ ( Herrington, 1995 ). ‘Kabarla’ has benefited the