A Good Start

There are two citrus breeding programs in the Sunshine State: The University of Florida Citrus Plant Improvement Program and the USDA-Agricultural Research Service Citrus Improvement Program. Collectively, these dedicated breeding programs have the capability of generating thousands of unique citrus hybrid plants each year. While the creation of unique citrus hybrids is essential, early evaluation of this material is a limiting factor. Finite capacity and resource limitations necessitate a more rapid and effective means of evaluating this material.

UF/IFAS and USDA researchers are employing their skills and experience to breed for desirable fruit and tree characteristics. Plants that do not possess the target characteristics must be culled out and eliminated early in the process, so that only the most promising selections move into more comprehensive evaluation.

Juvenile Detention

Several countries have tried methods for reducing the natural juvenility period for new crosses, with the goal of inducing earlier bloom and fruit production. New Varieties Development & Management Corp.'s (NVDMC) exploration trips, organized with the assistance of Dr. Fred Gmitter of UF/IFAS, have provided exposure to systems in Japan and South Africa. While both systems are effective in reducing citrus juvenility, they function quite differently. Common to all of these systems is the training of one vertical stem on a trellised support system, speeding vertical growth and causing the plants to flower and produce fruit as quickly as possible. NVDMC has since funded (through its contract with the FDOC) the construction and management of two Florida juvenility reduction systems. One is located at the A.H. Whitmore Farm near Leesburg. The structure at Whitmore was built for the benefit of the USDA breeding program. This large structure is outdoors and is simultaneously evaluating several unique techniques to help determine which horticultural practices (girdling, thorn removal, etc.) contribute the most to juvenility reduction. The second structure is located at the Citrus Research and Education Center in Lake Alfred. The IFAS structure is smaller, but is covered for freeze protection and more rapid plant growth through the winter months.

Raising Results

Plants were entered into the IFAS structure in May 2009. All of the IFAS plants were started in a greenhouse with some pre-trained to a single stem, others not. By April 1, 2010, 30 plants in the IFAS structure had flowered. Results from USDA are forthcoming. These models offer greater hope to Florida nurseries and growers. While they may not reveal whether varieties will be commercially successful, they will eliminate poor performers and accelerate the evaluation of plants most likely to meet industry needs. Rapid evaluation of new crosses is but one way that the Florida breeding programs are working to improve the competitive position of the citrus nursery operator and grower.