Location: Floral and Nursery Plants Research2008 Annual Report
1a. Objectives (from AD-416)
Accelerate development of superior Hydrangea germplasm using wide hybridization, molecular markers, and ploidy manipulations. Develop, evaluate, and release improved germplasm of selected nursery crops species, including Hydrangea, Cornus, Clethra, and Styrax. Investigate physiological constraints with transplanting nursery crops and root system changes for better adaptation into production systems. Develop improved nursery production systems with an integrated approach of bio-plastic containers, plant water and nutrient use, and cultural management.
1b. Approach (from AD-416)
Use wide hybridization to improve H. macrophylla. Use molecular markers for studying genetic relationships and creating genetic linkage maps in Hydrangea. Develop a polyploid series in H. macrophylla. Develop, evaluate, and release improved germplasm of Hydrangea, Cornus, Clethra, and Styrax. Evaluate germplasm for nursery production and landscape potential. Determine root growth, root quality and plant performance in non-traditional nursery containers. Determine transplantability and survivability of bare root trees during nursery production and in post harvest landscape settings. Determine the relationship of cyclic irrigation and low nutrient inputs with container-grown ornamental trees. Determine the influence of irrigation and nutrient inputs on bio-based materials for container nursery production.
3. Progress Report
Second-generation progeny derived from hybrids between H. macrophylla and the GUIZ 48 selection of D. febrifuga were evaluated. Several plants that had been backcrossed to H. macrophylla exhibited the lacecap type inflorescence found in some H. macrophylla cultivars; however, sterile flowers were lime green rather than the blue or pink color typically observed in H. macrophylla. These plants were backcrossed again to H. macrophylla. Crosses between H. macrophylla and additional D. febrifuga selections were made. Flowering occurred for the first time among putative hybrids between Clethra alnifolia and C. cavaleriei; floral characteristics were intermediate between parents and indicate that the plants are of hybrid origin. Flatheaded appletree borer attacks adversely impact nursery crops but can be controlled with post plant applications of imidacloprid insecticide. Pre-transplanting treatments of imidacloprid were made to container grown tree liners to evaluate insecticidal efficacy. Pre-treating tree liners was identified as a more efficient method of application compared to a post transplanted field application as well as considered a value-added component to container grown tree liners. This research is under National Program 301, Component 3, Problem Statement 3B: Capitalizing on Untapped Genetic Diversity; and Component 3, Problem Statement 3C: Germplasm Enhancement/Release of Improved Genetic Resources and Varieties. This project also contributes to the NP 305 Action Plan, Component 1, Problem Statement 1C: Greenhouse, High Tunnel, and Nursery Production Systems.
1. Analysis of Genetic Relationships among Hydrangea paniculata Cultivars This research was done in cooperation with the Vegetable and Ornamental Research in the Gulf South Project (6404-21220-003-00D) at the Southern Horticultural Laboratory. Although several panicle hydrangea (Hydrangea paniculata) cultivars are well-known in the trade, little is known about their parentage or relationships to each other. Simple sequence repeat (SSR) markers were used to analyze relationships within H. paniculata. This study identified potentially unexploited sources of germplasm within H. paniculata and relationships between existing cultivars of this popular shrub. This information will be of value when selecting parents for breeding programs. This research is under National Program 301, Component 3, Problem Statement 3B: Capitalizing on Untapped Genetic Diversity.