Progeny testing, both formal and informal, has been a component of the University of Florida strawberry breeding program. Informally, the potential of numerous parental combinations has been assessed by growing small populations of each combination, and then ranking these populations according to visual impression. Formal progeny testing, where variables are measured on seedlings in a replicated measurement block, was used during the 1987-88 season. Several families were identified as promising, based on an analysis of yield, fruit size, firmness, and appearance data.
C. K. Chandler, C. M. Howard, and E. E. Albregts
Joseph A. Fiola, Gojko Jelenkovic, and Gene Galletta
The major objective of the NJUS Strawberry Breeding Program is the development of early ripening cultivars with excellent fruit flavor and size for production under conventional matted-row, and high density annual production systems. In the 1993 replicated Step 3 trials (1991; 1992 planted), sixteen selections had higher yield than `Earliglow' (8127, 11312 kg/Ha), ranging from 8433 kg/Ha to 13334 kg/Ha. Thirty-one had higher weighted average fruit weight (WAFW) over the season than `Earliglow' (8.8 g; 8.4 g), ranging from 9.0 g to 12.3 g.
Selection for phenotype best suited for annual stem includes: low runnering, strong vigor, earliness, and large fruit size. In 1993 harvested Step III, four selections had comparable or higher yield (range: 12,866 to 27,128 kg/Ha) than `Chandler' (12,950 kg/Ha), as well as larger primary and WAFW (range: 13.5 to 16.4 g). All selections were significantly earlier than `Chandler'. In summary, the NJUS Strawberry Breeding Program has selections for the matted-row and annual production systems which are early, with excellent fruit flavor, size, and firmness for fresh market production.
Douglas V. Shaw, John Hansen, and Greg T. Browne
One hundred-eighty six strawberry genotypes from the Univ. of California strawberry (Fragaria ×ananassa Duch.) breeding program were evaluated for resistance to Phytophthora cactorum Schroet. in trials conducted over 6 years; 60 of these genotypes were tested in 2 years or more. Mother plants of each genotype were grown in a propagation nursery beginning in June, and runner plants were set into soil infested with inoculum from a mix of four P. cactorum isolates in August or September of the same year. Runner plants of each genotype were harvested from the inoculated nursery, transferred to a fruiting field location, and evaluated for disease symptoms during the winter and spring following inoculation using a disease severity score. Significant variation for the disease severity score was detected due to years, genotypes, and their interaction. Differences among genotypes were responsible for 60.6% of the phenotypic variance, whereas years and year × genotype interactions contributed relatively little to this variance, 8.2% and 9.3%, respectively. A separate analysis conducted using a balanced subset of six cultivars that were present in all trial years detected variance components due to years and year × genotype interaction slightly smaller than those estimated for the complete trial, 5.0% and 3.9%, respectively. These results highlight the utility of the screening system and suggest that stable resistance to P. cactorum is obtainable in California strawberry breeding populations and production systems.
Seth D. Wannemuehler, Chengyan Yue, Wendy K. Hoashi-Erhardt, R. Karina Gallardo, and Vicki McCracken
perennial plant breeding into a decision support tool to provide an overview of a day-neutral strawberry breeding program. Breeding programs differ in procedures, costs, or both, which results in every program having unique cost structures. This makes the
Hugh A. Daubeny
Vance M. Whitaker, Luis F. Osorio, Tomas Hasing, and Salvador Gezan
systems for winter and spring markets. In 1968 the University of Florida (UF) started a strawberry breeding program ( Whitaker et al., 2011 ), although some open-pollinated seedling selection was performed before that time. Since that time, the breeding
Royce S. Bringhurst, Victor Voth, and Douglas Shaw
Gene J. Galletta
This review briefly summarizes the status of the Southern strawberry industries during the 20th century. Objectives, contributions, and personnel of the Southern state and federal improvement programs are presented. The future of the southern strawberry industries and their reduced number of breeding programs are predicted, with emphasis on the objectives which may have to be altered to accommodate new and continuing problems.
F.J. Lawrence, G.J. Galletta, and D.H. Scott
Douglas B. Walsh, Frank G. Zalom, Douglas V. Shaw, and Kirk D. Larson
Forty-eight strawberry (Fragaria ×ananassa Duchesne) or (Fragaria L. sp.) genotypes from the University of California advanced-cycle breeding population were evaluated over 7 years for susceptibility to and tolerance of infestation by two-spotted spider mite (Tetranychus urticae Koch). In pairwise tests, 23 photoperiodically short-day genotypes were compared with the short-day cultivar Chandler, and 23 day-neutral genotypes to the day-neutral cultivar Selva. Feeding by T. urticae resulted in substantial yield reductions regardless of genotype. Yield reduction from feeding by T. urticae averaged 29.9% for short-day and 23% for day-neutral genotypes. Calculation of variance components for day-neutral genotypes determined that none of the variation in yield was explained by the interaction of genotype and T. urticae infestation, whereas 24.4% of the variation in yield for short-day genotypes was explained by the interaction of genotype and T. urticae infestation. Under current strawberry production practices in California there appears to be little potential for breeding direct resistance to T. urticae for day-neutral genotypes. However, some gains in breeding direct T. urticae resistance may be achieved within short-day genotypes. Phenotypic path-coefficient analysis for direct and indirect effects, and simple correlation coefficients of T. urticae feeding determined there were substantial differences between short-day and day-neutral genotypes in their yield responses to T. urticae feeding. For short-day genotypes, the greatest direct effect on yield resulted from T. urticae feeding in June. For day-neutral genotypes, the greatest direct effects resulted from T. urticae feeding in April and May and were probably due to the day-neutral genotype's more complex flowering responses. Several high-yielding cultivars have been developed and released over the 7 years of this study. It appears the new cultivars that were bred for current cultural practices exhibited a consistent plant response for greater yield both in the presence and absence of T. urticae feeding.