Scientia Horticulturae 139 (2012) 53–57 Contents lists available at SciVerse ScienceDirect Scientia Horticulturae journa l h o me page: www.elsevier.com/locate/scihorti Longevity of crapemyrtle pollen stored at different temperatures A.S.M.G. Masum Akond a , Cecil T. Pounders b,∗ , Eugene K. Blythe c , Xinwang Wang a,∗∗ a Texas AgriLife Research and Extension Center, Texas A&M System, 17360 Coit Road, Dallas, TX 75252, USA b USDA-ARS Thad Cochran Southern Horticultural Laboratory, Box 287, 810 Highway 26 West, Poplarville, MS 39470, USA c Coastal Research and Extension Center, Mississippi State University, South Mississippi Branch Experiment Station, Poplarville, MS 39470, USA a r t i c l e i n f o Article history: Received 9 December 2011 Received in revised form 14 February 2012 Accepted 16 February 2012 Keywords: Lagerstroemia spp. Pollen germination Pollen transportation Interspecific cross Breeding a b s t r a c t Temperatures for storage of crapemyrtle (Lagerstroemia spp.) pollen over time were studied using clones of two interspecific hybrids (L. ‘Cheyenne’ and L. ‘Wichita’) and five species (L. indica ‘Catawba’, L. sub- costata (NA 40181), L. limii (SHL2004-1), L. speciosa (MIA 36606), and L. fauriei ‘Kiowa’). Pollen samples were stored at room temperature (23 ± 1 ◦ C), 4 ◦ C, -20 ◦ C and -80 ◦ C. Germination of pollen samples was examined at 0, 7, 15, 45, 75, or 105 days of storage (DOS) and data were analyzed using linear models. Fresh (0 DOS) pollen of L. ‘Cheyenne’ showed the highest germination (80%). For all other clones, pollen germination at 0 DOS ranged from 44% (L. speciosa) to 77% (L. fauriei ‘Kiowa’). Pollen of all clones lost their viability within 7 DOS at room temperature. Overall, this study indicated that Lagerstroemia pollen is best maintained over time when pollen is stored under refrigeration, with a storage temperature of -20 ◦ C often being preferable to 4 ◦ C. Lowering the storage temperature to -80 ◦ C is generally unnecessary, but not deleterious to pollen germination. Storage of viable crapemyrtle pollen for no longer than 75–105 days is adequate for allowing breeders to efficiently execute hybridization of germplasm flowering at different times or in widely separated locations. Published by Elsevier B.V. 1. Introduction Crapemyrtles (Lagerstroemia spp.) are valued ornamentals due to their wide assortment of inflorescence colors, diversity of growth habits, and long summer-flowering period (up to ∼120 days). Mem- bers of the genus Lagerstroemia are native to Southeast Asia and Indo-Malaysia and have been cultivated for centuries for timber and ornamental use in landscapes. Confusion exists on the exact number of species, with reports ranging from 56 (Furtado and Srisuko, 1969) to 80 (Cabrera, 2004). Generally, most species of Lagerstroemia have small, inconspicuous, pale white to lavender flowers. A few species, such as L. speciosa and L. indica, have larger and more colorful flowers. Most cultivars selected before the latter part of the 20th century were chance seedlings chosen for unique color or growth habit, and were asexually propagated by dormant cuttings (Egolf and Andrick, 1978). In recent years, much progress has been made in breed- ing improved crapemyrtle cultivars. A study by Pounders et al. (2006) indicated a late-acting self-incompatibility system or inbreeding depression for L. indica and interspecific crosses with ∗ Corresponding author. Tel.: +1 601 403 8769; fax: +1 601 795 4965. ∗∗ Corresponding author. Tel.: +1 972 952 9619. E-mail addresses: Cecil.Pounders@ARS.USDA.GOV (C.T. Pounders), xw-wang@tamu.edu (X. Wang). L. fauriei, which resulted in decreased pod set and much lower seed germination for self-pollinations. Such results indicate self- ing of crapemyrtle to produce homozygous lines for traits would be unproductive. Research in the United States has focused on developing hybrids between parents with disease or pest resis- tance and those with more desirable horticultural traits for asexual production (Pounders et al., 2007a). Understanding the diversity and stability of traits associated with commercial crape- myrtle germplasm available for breeding programs expedites ongoing breeding programs and projected landscape performance (Pounders et al., 2010). Interspecific hybridization to introduce new traits and improve genetic diversity in germplasm has also made valuable contributions to the development of improved clones for commercial production (Pounders et al., 2007b). The ability to store pollen is critical to plant improvement programs when individuals to be hybridized do not flower concur- rently or when individuals are geographically separated (Sedgley and Harbard, 1993). Pollen storage has the potential to improve plant breeding through germplasm exchange and preservation to increase genetic diversity (Hanna and Towill, 1995). Success of hybridization programs often depends on the availability of clean, viable pollen from elite paternal trees. Conditions of storage which result in retention of viability vary, with freeze drying and liquid nitrogen the most successful methods for long-term pollen storage of a range of plant species (Sedgley and Griffin, 1989). Pollen viabil- ity in many genera may decrease quickly depending upon storage 0304-4238/$ – see front matter. Published by Elsevier B.V. doi:10.1016/j.scienta.2012.02.021