Interspecific and Intergeneric Hybridization in Baptisia and Thermopsis

Interspecific and intergeneric crosses were performed between species in the genera Baptisia and Thermopsis with the goal to create hybrids with the best qualities of both parents. Baptisia australis (L.) R. Br. was used as both male and female parent in intergeneric crosses. Thermopsis chinensis Benth. ex S. Moore, T. lupinoides (L.) Link, and T. villosa Fernald & B.G. Schub. were used as male and female parents in both interspecific and intergeneric crosses. Pollen was collected from B. alba (L.) Vent., B. bracteata Muhl. ex Elliott, and B. lanceolata (Walt.) Ell. and used to make interspecific and intergeneric crosses. Putative hybrids were obtained from both interspecific and intergeneric crosses. Interspecific crosses produced a higher percentage of fertile crosses and number of seeds per fertile cross than intergeneric crosses. Germination rate was not different between interspecific and intergeneric crosses. B. australis consistently produced less seed per cross when used as either male or female parent than Thermopsis species in both interspecific and intergeneric crosses.  When comparing species in both interspecific and intergeneric crosses to determine the best female parents, we found no difference among female parents for percentage of fertile crosses or germination rate. When comparing species to determine the best male parents, no difference was found for percentage of fertile crosses or germination rate in either interspecific or intergeneric crosses. Since seedlings could be obtained from both interspecific and intergeneric crosses, production of a Baptisia-Thermopsis hybrid is feasible and the breeding program should be continued. Progeny is being evaluated to confirm hybrid status and select the best plants for the next generation of crosses. Other steps to be taken in this breeding program are the addition of new Baptisia species as parents, use of bridge parents, and selection of the species producing the most fertile crosses for male and female parents.