The wide diversity in the genus Salvia represents an untapped genetic resource to improve and diversify Salvia grown as floriculture crops. Interspecific hybrids have formed naturally or by chance hybridization of cultivated plants, but the degree to which species are cross-compatible is largely unknown. The crossability of nine Salvia species selected to cover a wide range of the diversity in European and American species was evaluated in a full diallel mating scheme. Overall, crossability of the selected species was low with only five of 72 interspecific cross combinations producing viable seed, whereas all nine species were self-fertile. Successful crosses were mostly within close phylogenetic groupings. The majority of successful crosses were between species with different chromosome numbers, suggesting that chromosome number differences alone are not a major barrier to hybridization in this genus. A Salvia nemorosa × Salvia transslyvanica F2 population exhibited transgressive segregation for several horticulturally important traits, including flower size, plant height, and time to flower. Plant height was correlated positively with flower length, inflorescence branch number, and time to flower. Time to flower was correlated positively with flower length. Individuals with desirable trait combinations were identified within the population.
Joseph Tychonievich and Ryan M. Warner
David Tay, Joseph Tychonievich, and Stephanie Burns
The Association of Official Seed Analysts adopted X-ray technology for testing agricultural and forest tree seeds in 1979. It has not been applied on flower seeds. To date, its use is still lacking, despite the relatively simple and nondestructive nature of the test. One of the reasons for the slow adoption is the lack of a simple X-ray unit that gives instant high resolution digital images. The Faxitron MX-20, a cabinet X-ray unit designed for high detail radiographic imaging of medical specimens, fulfills this need. The high magnification capacity of 1×, 1.5×, 2×, 3×, 4×, and 5×, and the low kilovoltage (kV) provide enhanced image performance with good quality contrast. The exposure time and X-ray tube kV can be selected to produce the best images. Its laser locator eases the positioning of a sample under examination accurately and the 2-× 4-inch field of view digital camera with 10 lp/mm resolution provides the instant high quality on-screen viewing of seed sample images. The most useful application at the Ornamental Plant Germplasm Center is not in seed testing as recommended for agricultural and tree seeds, but as a tool during seed cleaning to see in a matter of seconds whether empty, immature, insect-damaged, and broken seed have been removed. It has proven useful in Achillea, Alstroemeria, Aquilegia, Aruncus, Aster, Baptisia, Begonia, Campanula, Chrysanthemum, Coreopsis, Dianthus, Euphorbia, Geranium, Hemerocallis, Impatiens, Iris, Lilium, Lupin, Lysimachia, Narcissus, Pelargonium, Penstemon, Petunia, Phlox, Platycodon, Ranunculus, Rudbeckia, Salvia, Silene, Stokesia, Tagetes, Talinum, Verbena, Veronica, and Viola.