Temperate zone (deciduous) fruit crops are cultivated largely in areas far removed from their center of origin. Selection and breeding have improved climatic adaptation in these perennial crops. Current breeding programs are attempting to broaden this adaptation by developing cultivars with high mid-winter cold tolerance, late blooming to avoid spring freezes, and increased disease resistance. The attainment of these and other breeding objectives will recessitate the use of noncommercial exotic germplasm. The range of these fruits also is being extended to the subtropics and tropical highlands through selection and breeding. It is only through genetic manipulation that more productive and adapted plant materials are likely to be developed. Germplasm centers are needed to maintain and provide the array of genetic variability necessary for continued scion and rootstock improvement.
Scion cultivars have been the basis of fruit industries and the main concern of most fruit research. Stock cultivars have often been taken for granted and rootstock breeding neglected because it has not been immediately rewarding to the breeder. Rootstock breeding, like many long term research programs, has not been strongly supported by various granting agencies, which often seek quick solutions to industry problems.
V. myrsinites Lam. is most susceptible to canker among the blueberry species native to Florida and survives by resprouting from underground rhizomes. V. darrowi Camp suffers less canker damage than V. myrsinites, some mature colonies showing little or no damage but others being nearly destroyed by the disease. Most mature V. darrowi colonies in the State have some stems cracked and swollen by canker. Old native plants of V. ashei Reade and V. fuscatum Ait. show light to moderate canker damage in many parts of the State but both species are more resistant than the previous two. V. elliottii Chapm. shows no canker over much of its range in Florida, but localized populations have moderate to high infection. Only one cankered plant of V. arborewn Marsh, has been found, and no canker has been found on V. stamineum L.
Florida's early season, fresh market rabbiteye blueberry (Vaccinium ashei Reade) industry has been based mainly on the cultivars Beckyblue, Climax, Aliceblue, and Premier. Both ‘Aliceblue’ and ‘Premier’ have given problems with poor fruit set after mild winters, particularly in areas south and east of Gainesville (1); thus, there is a need for additional early ripening cultivars to interplant with ‘Beckyblue’ and ‘Climax’. ‘Bonita’ is being released for this purpose by the Institute of Food and Agricultural Science from the Univ. of Florida blueberry breeding program.
‘Flordablue’ (Fig. 1) has been released by the University of Florida, Institute of Food and Agriculture Sciences Fruit Crops Department to fill the need for a blueberry with fruit quality and earliness of northern highbush cultivars and adaptation to the climate of central Florida.
Recently observed hybrid populations of peach [Prunus persica (L.) Batsch] provide evidence for the presence of a single gene controlling full red skin color. The fruit of seedling populations of `UFQueen' × `Springbaby', `UFQueen' × `Springprince, FL93-12C × `Springprince, FL92-22C × BY79P1945, and AP98-18 o.p. were rated for percent red skin color at full maturity. At this stage of development, “full red” phenotypes display red color over the entire surface of the fruit, including the stem cavity and portions of the fruit shaded by leaves or stems. Both crosses with `UFQueen yielded populations displaying a 1:1 segregation ration for partial red: full red. All other crosses produced populations that did not deviate significantly from a 3:1 segregation ratio. These data are consistent with the hypothesis that the “full red” phenotype is a single gene recessive trait. We propose the gene symbols of fr and Fr for the recessive full red and dominant partial red (wild-type) alleles, respectively.
Breeding low-chilling peach and nectarine cultivars began in Florida in 1953. Objectives were to produce low-chilling, early-ripening peach cultivars with fruit qualities equal to temperate-zone cultivars. Low chilling was essential for local adaptation (4). Early ripening was essential to allow production of the earliest-season peaches on the domestic market with little competition from other states and to allow harvest of the crop during the relatively dry period of late April and May. Feral selections descended from Spanish seed introductions through St. Augustine, Fla., seed importations from Okinawa, and ‘Hawaiian’, a South China clone, served as the main sources of low chilling (18). These sources were hybridized with high-chilling U.S. clones having commercial fruit qualities. Resultant seedlings were selected for best adaptation and improvement in fruit qualities above that of the low-chilling parents. Chilling requirements of progeny were near midparent values; chilling requirements of the F2 seedlings ranged from equal to the low parent to equal to the high parent (14), indicating that many genes are involved in chilling. Selections were intermated, and low-chilling progeny were hybridized with other high-chilling U.S. clones, resulting in more progenies for further selection. Commercial fruit size and satisfactory horticultural qualities were obtained after six generations of crosses and backcrosses. Clonal selections made during these six generations and in subsequent generations serve as the basis for most low-chilling cultivars currently grown in Florida, southern Texas, and southern California. Selections from this program are either grown commercially or being evaluated in many tropical and tropical highland areas of the world (11, 16, 19, 24).
‘Flordacres’ peach [Prunus persica (L.) Batsch] is released for grower trial by the Florida Agricultural Experiment Station (Fig. 1). It bears attractive fruit with yellow flesh and ripens after ‘Flordaking’ and before ‘June Gold’ in northern Florida.
‘Flordastar’ peach [Prunus persica (L.) Batsch] is released for grower trial by the Florida Agricultural Experiment Station (Fig. 1). This cultivar bears attractive, yellow-fleshed fruit that ripen before ‘Flordaprince’ in central Florida.