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UF/IFAS Plant Breeding

UF/IFAS Plant Breeding


In Florida, lettuce is primarily planted as a rotational crop with sugarcane and other local commodities on 10,000 acres of rich organic muck soils in the Everglades Agricultural Area (EAA). Florida lettuce is harvested for whole head consumption, packed, and baby leaf production. The crop is planted in protected structures on a small scale with the potential to increase production in these structures. Lettuce represents an 80-million-dollar business to Florida growers and situates the state as the third-largest lettuce producer. Initially, lettuce was introduced as a crop by UF/IFAS researchers in the state of Florida. 

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From the Beginning

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The UF/IFAS Lettuce breeding program started with Dr. Victor Guzman who introduced the crop to the state. However, first attempts to grow lettuce failed early in the 1950s. The crop was finally established in the 1960s thanks to the development of adapted local cultivars by the UF/IFAS lettuce breeding team. 

The UF/IFAS lettuce breeding program has historically worked with growers in the EAA to understand the challenges the growers faced and establish breeding priorities. Some historical cultivars were released by this program including the romaines ‘Tall Guzmaine’ and ‘Short Guzmaine’. Many of these cultivars are used as parents in lettuce breeding programs worldwide. In the United States alone, there is a 25% chance that a modern romaine cultivar has Tall Guzmaine in its pedigree. The cultivar has several good characteristics for the industry, including noticeable disease resistance such as Corky Root Rot caused by a soil-borne bacterium. 

Today and Tomorrow 

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In a subtropical environment such as the one in Florida, disease resistance has been and will remain a priority for the lettuce industry. Sporadic diseases such as Bacterial Leaf Spot will continue to be important in the UF/IFAS lettuce breeding program. Currently, this program has advanced breeding lines that will become cultivars resistant to the strains of Xanthomonas hortorum pv. vitians found in Florida. Research and breeding efforts in diseases such as Fusarium Wilt of Lettuce and Downy Mildew are critical to the industry as well. 

The UF/IFAS lettuce breeding program also focuses on improving issues that will dimmish yield in lettuce in a non-predictive environment including heat tolerant cultivars and the improvement of associated disorders to this stress (bolting, tipburn, etc.). Disorders in postharvest such as pinking in lettuce and other leafy vegetables are concerns to growers in the state and this program initiated the work on this issue for Florida Lettuce. 

As more sustainable practices will be in demand in the future, the current UF/IFAS lettuce breeding program is identifying lettuce cultivars that efficiently uptake nutrients focusing on Phosphorus. Eventually, improving lettuce that efficiently uptakes nutrients can translate into savings for lettuce growers. The program is also seeking to improve tolerance to herbicides, as weeds are an enormous issue to lettuce growers, and they are limited by herbicide labels because of the rotational nature of the crop. Additionally, consumers in niche markets like the ones produced in protected structures can benefit from the nutritional content of lettuce. The UF/IFAS lettuce breeding program is working towards growing a more nutritious crop. 

High Impact Releases

Manatee' (YEAR): 'Manatee' is historically important in Florida's lettuce production and was the major cultivar before 2011. However, it did not have good yield overall in variety trials, particularly in 2011, because it had low yield in the mid-season trials. 'Manatee' has resistance to early bolting and grows better in the early growing season (from late September to early October) and late growing season (from middle of April to early May) when temperatures are high. This cultivar can be used in lettuce production in both the early and late growing seasons when other cultivars are not suitable for production due to hot weather. 'Manatee' also has medium resistance to aphids. 

'Terrapin' (YEAR): This romaine cultivar had the highest yield and the highest percent of marketable heads in variety trials. It can be planted from November to January and harvested from January through March to maximize profits. 

'Okeechobee' (YEAR): This cultivar yielded well in variety trials, and its yield was stable across the years. It is suitable for production in the months of November through April. 

'Gator' (YEAR): This iceberg cultivar has been used for lettuce production for many years. In the variety trials, it had the highest yield among the iceberg cultivars in 2010 but the lowest yield in 2011. However, the yields of all three iceberg cultivars were not significantly different in 2011. 'Gator' can continue to be used as a major cultivar in lettuce production in south Florida. 

Many other cultivars including iceberg cultivar Floricrisp 1265 were released and this cultivar is now used as a breeding parent in other lettuce breeding programs. A more extended list of cultivars formerly released by the UF/IFAS lettuce breeding program, and their characteristics can be found at HS1225/HS1225: Evaluation of Lettuce Cultivars for Production on Muck Soils in Southern Florida ( 

Research Contacts

Germán S. Miranda

Germán Sandoya

Breeding & Genetics
Horticultural Sciences | Everglades REC


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