Irradiation of seeds of Pineapple orange resulted in the generation of a mutant,

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1 SEEDLESS PINEAPPLE ORANGES Irradiation of seeds of Pineapple orange resulted in the generation of a mutant, initially identified as USDA -0-0, with reduced seed count. Horticultural characteristics of this mutant was evaluated in replicated field trials consisting of trees on four rootstocks (Swingle, Carrizo, Cleopatra mandarin, and sour orange) at two locations in Florida (Lake and Osceola Counties). Data have been collected over five harvest seasons (994, 995, 99, 00, 00) on fruit yield and juice quality (color, soluble solids, and total acidity). Fruit of the mutant ripen during the typical midseason of other Pineapple oranges. Fruit produced by the irradiated mutant contain very few seeds and many fruit have no seeds. The low seed count could make this selection much more valuable for the midseason fresh fruit market than the seedy Pineapple oranges that are presently available Fruit from irradiated Pineapple orange selection USDA 0 0 are essentially seedless (Table ). Fruit size of USDA 0 0 averages between 7. and 7.4 cm in diameter. Fruit shape and peel characteristics of the USDA 0 0 were rated as good and stem end peel disruption (plugging) was not a problem. Fruit yields (expressed as 90 lb. boxes per tree) of USDA 0 0 are presented in Table ; these results are comparable with reported yields for eight clones of Pineapple oranges on twelve rootstocks over eight years (average. boxes per tree) (Bureau of Citrus Budwood Registration, 005). Yields of USDA 0 0 were similar at two locations. Pineapple oranges are known to be susceptible to preharvest fruit drop (Tucker et al, 99) and a major limitation of Pineapple is it s poor ability to store fruit on the tree (Young, 98). Some observations

2 suggest that the seedless mutants are less prone to fruit drop than the wild type Pineapple orange. Total soluble solids for fruit of USDA 0 0 are presented in Table. Harding et al. (940) reported that Pineapple oranges harvested in January or February from trees grown on rough lemon rootstock in central Florida averaged between 0. and. total soluble solids. In each case, total solids, total acid and ratio of solids to acid fell within the maturity standards as defined in the Florida Citrus Code (Florida Statutes, 005). Effects of rootstock on total soluble solids, total acidity and solids acid ratio did not differ significantly due to rootstock (data not shown). Yield of juice and pounds solids per box for USDA 0 0 is presented in Table 4. Juice color scores for USDA 0 0 are presented in Table 5. Although no statistical analysis of the data was possible, all juice color numbers were high enough (color number 5) to be classified as reasonably good (not as good as USDA OJ, but not yellow). Juice color scores (color number 40) would be classified as good (equal to or better than USDA OJ) according to US Standards for grades of orange juice (USDA, AMS, 98). The overall average for juice color, based on one year of data from Lake Co. and two years of data from Osceola Co. exceeded CN which would be classified as good. In summary, USDA 0 0, a seedless mutant of Pineapple orange resulting from seed irradiation produced fruit with acceptable quality. Yields of USDA 0 0 averaged. to.8 90 lb. boxes per tree which is comparable for reported yields for Pineapple oranges (Bureau of Citrus Budwood Registration. 005). Total soluble solids (0.4.8%) were similar to previously published results (Harding et al., 940) and color numbers (ave..) indicate the juice was acceptable. Seedlessness should make these selections more

3 attractive as a fresh market fruit than is standard Pineapple. In addition, should the seedless selections prove to be less prone to preharvest fruit drop than the standard Pineapple, this would be another positive effect of modifications from irradiation. 4 Literature Cited 5 Bureau of Citrus Budwood Registration Florida Statutes, 005. Ch. 0, Florida Citrus Code, USDA -0-0 fruit

4 4 Table. Number of seeds per fruit and fruit diameter for USDA 0 0 irradiated Pineapple orange. Mean seed numbers were calculated from four fruit from each of four rootstocks at the Lake County location. Fruit diameter was measured on fruit grown on Carrizo citrange. Seeds/fruit Selection Range Means ± se Diameter (cm) ± Table. Yields of USDA 0 0 irradiated Pineapple orange at the Lake and Osceola County locations. Boxes/tree Selection Lake Osceola

5 5 Table. Average total soluble solids (TSS), total acid (TA), and solids-acids ratio (S/A) for USDA -0-0 irradiated Pineapple orange from trees on four rootstocks averaged over 5 seasons at the Lake and Osceola County locations. TSS (%) TA (%) S/A Lake Osceola Lake Osceola Lake Osceola 0.4 c.4 ab 0.8 c Table 4. Yields of juice and lbs. solids for USDA -0-0 irradiated Pineapple oranges grown at the Lake and Osceola County locations on Carrizo and Swingle rootstocks. Percent juice Pound solids/box Lake Osceola Lake Osceola (Carrizo) (Swingle) (Carrizo) (Swingle) Table 5. Juice color number (CN) values for USDA 0 0 irradiated Pineapple oranges at the Lake and Osceola County locations averaged over years. Osceola Lake (99) (994) (995) Average CN

LA Early : A New Early Market Satsuma

May 2001 Circular Number 140 LA Early : A New Early Market Satsuma W. J. Bourgeois, R. J. Constantin, and M. J. Falcon Visit our website: www.lsuagcenter.com Louisiana State University Agricultural Center