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United States Department of Agriculture

Agricultural Research Service

Related Topics

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

Location: Floral and Nursery Plants Research Unit

Project Number: 8020-21000-062-00
Project Type: Appropriated

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

Objective:
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, Cornus, Clethra, and Styrax, and utilize genetic markers to accelerate the breeding process. Sub-objective 1.A. Evaluate germplasm for nursery production and landscape potential. 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.

Approach:
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 and determined by nondestructive measurements. Destructive measurements will include root and shoot biomass and a quality rating to determine kinked, circling, or girdling roots. 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. The primary role of ARS in this cooperative project will involve root pruning treatments on bare root trees, assessing root regrowth, and determining the optimal chemical application timing for maximum root uptake. Root quality will be assessed by the number of main lateral roots generating from the shoot transition zone, the branching structure of the main lateral roots and secondary root formation, and the amount of fibrous roots present. 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. The interaction of irrigation management with the nutrient release from low nutrient formulations of controlled release fertilizers will be tested in large nursery containers (7 to 25 gal). 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.

Last Modified: 10/23/2014
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