Begonia ×semperflorens-cultiform Hort (Begonia semperflorens Link & Otto) is the most widely cultivated begonia (Chen and Mii, 2012) and the fourth most popular bedding plant in the United States with a total production valued at $36 million in 2009 (U.S. Department of Agriculture, 2010). Helen Kraus coined and defined the name Semperflorens-cultiform group in 1945 as a synonym (“ever flowering”) of B. cucullata var. cucullata, the first variant of the species introduced to commerce (Krauss, 1947). Semperflorens-cultiform group, marketed as wax begonias, is derived from at least five species including B. cucullata Willdenow, B. schmidtiana Regel, B. roezlii Regel, B. foliosa Kunth, and B. gracilis Kunth (Tebbitt, 2005). The wide use of the Semperflorens-cultiform group is the result of several factors including continuous bloom, compact growth habit, uniform plant growth, and disease resistance (Chen and Mii, 2012; Tian et al., 2012; Tiddleton et al., 1942). Therefore, the goal of the breeding program at USDA-ARS in Poplarville, MS, was to build on these already existing desired horticultural attributes and further improve the environmental tolerances of germplasm by introgression of useful traits from progenitor species to increase production adaption to the heat and humidity prevalent in the Gulf States region. As a result, two new wax-type begonia clones, FB08-59 and FB08-163, were recently released by the Agricultural Research Service of the U.S. Department of Agriculture. Both clones have improved environmental tolerances that increase production adaption when exposed to elevated periods of heat and humidity. Both FB08-59 and FB08-163 have survived and thrived for over 5 years under a variety of environmental stresses such as overhead summer irrigation and overwintering in #3 (25 × 23 cm) cylindrical plastic containers under ambient Plant Hardiness Zone 8 climatic conditions (U.S. Department of Agriculture, 2013). Commercial varieties commonly planted in the South such as Vodka, Whisky, Gin, Senator, Inferno Red, Badda Bing Red, and Badda Boom Scarlet used for comparison growing under the same summer conditions as FB08-59 and FB08-163 were generally killed by a combination of heat stress and Pythium before fall of each summer. The environmental tolerances of FB08-59 and FB08-163 will prove useful as parents for begonia breeders interested in developing bronze-leafed environmentally tolerant cultivars adapted to long hot, humid summers. Both clones are also adapted to overwintering in climates where the soil does not freeze in winter, which adds another dimension to environmental tolerance that may be used to develop improved clones. FB08-59 and FB08-163 regenerate after overwintering from root buds characteristic of wild-type B. cucullata (Fig. 1A) and ‘Kaylen’ (Fig. 1B). Such structures are generally absent in annual wax begonia varieties (Fig. 1C). The dominant nature of many genes associated with the environmental tolerance traits identified in FB08-59 and FB08-163 make them ideal parents for development of inbred lines with high levels of environmental stress tolerance to serve as parents for F1 hybrid seed production.
Chen, Y.-M. & Mii, M. 2012 Interspecific hybridization of Begonia semperflorens (section Begonia) with B. peaarcei (section Eupetalum) for introducing yellow flower color Plant Biotechnol. 29 77 85
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