The Horticultural and Breeding Unit conducts applied and basic research in citrus genetics and breeding, water quality and plant nutrition, and post-harvest physiology.

Citrus genetics and breeding: to develop scions and rootstocks having enhanced tolerance of environmental stress. resistance to diseases and pests, and improved fruit quality and yield. Specifically, desirable genetic traits are identified within species of citrus and among closely related genera and species, and are combined by conventional breeding and/or cellular and molecular engineering techniques. Results of this research are new and superior citrus varieties and rootstocks. New breeding lines with unique combinations of desirable traits are also produced that are used by citrus breeders and other researchers. The breeding program is one of the oldest in the world and evaluates over 50,000 trees each year at the two USDA research farms in Leesburg and Ft. Pierce, Florida. Over 80 percent of the citrus trees planted in the U. S. contain a variety developed by this laboratory, making the USDA breeding program the most successful breeding program in the world.

Water Quality and Plant Nutrition: To develop the quality and management of water usage by ornamental, vegetable, and citrus producers through the development of methods to reduce the chemical and nutrient content of runoff and ground water, improving the efficiency of irrigation systems, identifying ornamental species tolerant of saline water, and defining the optimum requirements of ornamental plant growth to minimize grower costs.

Post-Harvest Physiology: To identify and characterize the abiotic and biotic factors that lead to post-harvest losses of fresh horticultural products. The overall objective of this research is to develop a better understanding of the physiological and biochemical basis of post-harvest losses. Results of the research contribute to the development of new technologies for maintaining quality and reducing losses that occur during distribution of fresh fruits and vegetables from the farm to the consumer.

Questions and/or comments: mlawrence@ushrl.ars.usda.gov