Nursery trees of new, promising apple selections [NY-75334-35 (A), NY-75414-1 (B), and NY-75413-30 (C)] from the Geneva breeding program exhibit a distinct apical dominant growth pattern characterized by poor lateral-shoot formation (feathering). To induce feathering, the trees were foliar-treated singly or sequentially with various concentrations of Promalin (1.8%w/w GA4+7 + 1.8%w/w 6BAP) and Accel (0.18% w/w GA4+7 + 1.8% w/w 6BAP), by themselves and in combination. Regardless of branching agent, concentration, and type of application, treated trees, as compared to the control, on average, induced 11.3 vs. 2.2, 6.6 vs. 0.4, and 6.6 vs. 2.0 feathers/tree for selections A, B, and C, respectively. In most instances, higher concentrations of both chemicals induced more feathers than lower concentrations. Tree height and caliper were less affected than lateral-shoot production.
Virginia Miller-Roether, Paul E. Read, and Erika Szendrak
The American Chestnut Foundation (ACF) has conducted a breeding program aimed at developing blight-resistant chestnut trees exhibiting the phenotype of American Chestnut (Castanea dentata). We developed a protocol for in vitro micropropagation and multiplication of candidate blight-resistant plants from the ACF breeding program. The protocol included forcing dormant shoots to budbreak, culture establishment, shoot multiplication, inducing a functional root system on the microcuttings produced by this system and establishment of autotrophic plants. Because Castanea spp. is recalcitrant to rooting, a unique bilayer method of rooting was developed. The unique bilayer consisted of a clear basal medium of 50% DKW and 50% WPM (Long and Preece), with a continuous level of 0.01 mg IBA/L and 0.2 mg BA/L. The clear basal medium was over-laid with an opaque layer. Rooting response occurred for 27 of the 31 genotypes at various frequencies. Rooted plantlets were planted in 50% peat: 50% perlite in order to become autotrophic and acclimated. Acclimated trees were planted in 10″ × 2″ Deepots® and placed in the greenhouse. These trees exhibited a very vigorous functional root system. Acclimated trees were hardened off, placed in cold storage (≈4-5 °C) for 5 months. All trees placed in cold storage broke dormancy for spring growth and ≈100 trees were sent to ACF for planting into field trials.
Dale E. Kester and Thomas M. Gradziel
16 ORAL SESSION 5 (Abstr. 033-439) Fruits/Nuts: Breeding and Genetics
Thomas M. Gradziel and Dale E. Kester
33 POSTER SESSION 6 (Abstr. 513-529) Fruits/Nuts/Berries: Breeding and Genetics
Dan E. Parfitt, Chih-Cheng T. Chao, Craig Kallsen, Joe Maranto, and Louise Ferguson
33 ORAL SESSION 2 (Abstr. 392–396) Breeding & Genetics–Fruits/Nuts
Twenty variables were recorded on 15 apricot (Prunus armeniaca L.) genotypes differing in growth habit and blossom time to detect possible associations among morphological and phonological traits. The widest range of variability observed among phenotypes was for fruit size and factors associated with adaptation to local conditions, such as blossom season and yield potential as expressed by number of buds, flowers, and fruits per length of fruiting spurs. The most important morphological traits correlated with fruit weight were tree growth habit, apical and basal diameter of fruiting spurs, and bud and leaf size. Multivariate analysis allowed tree and variable grouping, which might encompass the basic criteria for apricot breeding programs in central México.
R. Neal Peterson
The pawpaw (Asimina triloba) is a new crop in the early stages of domestication. Recently commercialization has become feasible with the availability of high quality varieties. The history of pawpaw varieties is divided into three periods: 1900-50, 1950-85, and 1985 to the present. The history before 1985 was concerned primarily with the discovery of superior selections from the wild but experienced a serious break in continuity around 1950. The third period has been characterized by greater developmental activity. Larger breeding programs have been pursued, regional variety trials initiated, a germplasm repository established, and a formal research program at Kentucky State University (KSU) instituted. Future breeding will likely rely on dedicated amateurs with the education and means to conduct a 20-year project involving the evaluation of hundreds of trees. For the foreseeable future, governments and universities will not engage in long-term pawpaw breeding.
Jenny Knoth, John Frampton, and Ray Moody
The authors gratefully acknowledge Christmas tree growers Dale Taylor and Tom Wright for their maintenance and culture of the field trials. The Nursery and Tree Improvement Program of the South Carolina Forestry Commission and the
Kim D. Bowman
`Cipo' sweet orange [Citrus sinensis (L.) Osbeck] is distinctive among citrus selections because of reduced tree height and procumbent growth habit. Open-pollinated seeds were collected from `Cipo' orange and `Pineapple' sweet orange (C. sinensis) at Riverside, California, and grown under cool greenhouse conditions. Seedlings of `Cipo' were relatively uniform in morphology (including drooping shoot habit) and were presumed to be apomicts derived from nucellar embryos. `Cipo' seedlings were distinctly different from `Pineapple' in several characteristics, including smaller shoot altitude/extension ratios (a measure of uprightness) and broader stem-petiole angles (`Cipo' 1.33 radians; `Pineapple' 0.84 radians). The procumbent habit of `Cipo' appeared to be related to a preference for horizontal shoot orientation rather than a weakness of stem structure. Some increased sensitivity to ethylene was observed in the `Cipo' seedlings. `Cipo' is proposed as a resource for hormone research and a potential parent in breeding for unique tree morphology and reduced tree size.
José Luis León and Enrique Troyo-Diéguez
The high cost of inputs and water deficit in arid lands demand the use of more drought tolerant species into the agricultue. The flora of the deserts offer a variety of fruits and vegetables that may diversify horticulture. `Cimarrón' wild plum tree or “ciruelo cimarrón” (Cyrtocarpa edulis Brand.:Anacardiaceae) is one of the species with potential importance in arid lands. C. edulis is an endemic tree of the meridional portion of the Baja California peninsula, occurring along arroyos and on gentle slopes in sandy soils. The flesh of the fruits is edible, with a slight acid tang, and is used locally. Actual exploitation is based on the fruit harvest in natural dry forest and xerophilous shrubs, where average density is near 100 trees/Ha. There is a growing interest in marketing the dried fruits, especially for the snack industry, hence, the need to develop a breeding program in order to establish it as a reliable fruit crop.