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ARS Home » Northeast Area » Washington, D.C. » National Arboretum » Floral and Nursery Plants Research » Research » Research Project #425049

Research Project: Genetics, Genetic Improvement, and Improved Production Efficiency of Nursery Crops

Location: Floral and Nursery Plants Research

Project Number: 8020-21000-062-000-D
Project Type: In-House Appropriated

Start Date: Apr 14, 2013
End Date: Apr 13, 2018

The long term objectives of this project are to develop superior germplasm of selected nursery crops, increase the knowledge base related to the genetics and breeding of these species, identify physiological constraints related to nursery crop production, and develop environmentally sound, cost-efficient production systems for the nursery and landscape industry. Over the next 5 years the focus will be on the following objectives: Objective 1: Develop, evaluate, and release improved germplasm of selected nursery crop species, including, but not limited to, Hydrangea, Osmanthus, and Callicarpa, and utilize genetic markers to accelerate the breeding process. Sub-objective 1.A. Evaluate germplasm including, but not limited to, Hydrangea, Osmanthus, and Callicarpa for nursery production and landscape potential. Sub-objective 1.B. Develop and apply molecular markers for Hydrangea mapping and marker assisted selection. Sub-objective 1.C. Accelerate the development of superior Hydrangea germplasm using ploidy manipulations and wide hybridization. Objective 2. Investigate physiological complexities associated with transplanting nursery crops and root system architecture for better adaptation and application to diverse production systems. Sub-objective 2.A. Determine root growth, root quality, and plant performance in traditional and novel nursery containers during production and post production landscape settings. Sub-objective 2.B. Evaluate transplantability and survivability of container and bare root trees during nursery production and in postharvest landscape settings. Objective 3. Develop improved nursery production systems with an integrated approach toward water and nutrient use and cultural management strategies.

During the next three years, Hydrangea selections from previous breeding cycles will be propagated and distributed to evaluators, and crosses will be made for developing new breeding populations. Germplasm evaluation of new species and cultivars will ensure a broad base for future cultivar development. Osmanthus genetic resources will be tested for cold-tolerance and disease-resistance. Previously developed molecular markers for O. fragrans and Chionanthus will be tested across accessions to determine relationships between cultivars, inform subsequent breeding strategy, and expand the molecular toolkit for this genus. The Callicarpa breeding program will focus on development of superior floral, fruit, and foliage characteristics. At least ten accessions of Callicarpa representing five species will be evaluated over multiple years in randomized complete block designs in field plots at McMinnville, TN. This evaluation will focus primarily on fruit color and abundance with a secondary emphasis on compact form. New plants or underutilized native plants in a range of environments will be evaluated to identify superior landscape qualities, environmental sustainability, and production potential. Traits to be evaluated include flowering characteristic and duration, growth rate and habit, fruit development, foliage characteristics, cold and heat tolerance, drought tolerance, susceptibility to insect and disease pressure, possible invasiveness, and nutrient and irrigation management. Traditional cylinder-style containers will be compared to novel containers that are modular and low profile with air root pruning capabilities that allow a more natural spreading root growth. Plant responses, including photosynthesis, trunk diameter increase, and shoot growth, will be documented for a two-year period. Transplant success of bare root harvested ornamental trees will be examined as compared to the quality and mass of the root system as affected by root uptake of neonicotinoid insecticides for control of flatheaded appletree borer. Phloem and leaf tissue will be collected over time to determine insecticide uptake. The effect of fertilizer coating and fertilizers with lower ratios of nitrogen and phosphorus will be studied in conjunction with micro-cyclic irrigation in large container production systems. Container substrate moisture levels will be monitored using a gravimetric technique. Weekly container leachate analysis will be conducted during the growing season to determine the effect of irrigation treatments on nutrient release.