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Tepary beans are heat and drought resistant relatives of common beans. This study was conducted to evaluate the role of rooting depht in drought resistance of tepary beans and common beans ; to determine the genetics of several traits in tepary-beans, especially lanceolate leaflet shape, a possible component of heat resistance ; and to attempt to transfer drought and heat resistance from tepary beans to common beans by interspecific hybridization. Field and pot trials were conducted to compare the rooting depht of common beans and tepary beans grown on stored soil moisture. Teparies always had longer roots than common bean when moisture and temperature stress was severe. This could be an important component of the greater drought resistance exhibited by teparies compared to common beans. Inheritance of leaf shape, flower color, number of seeds per pod and seed weight was investigated in crosses between one domesticated tepary (P. acutifolius A. Gray var. latifolius Freeman), P1321638, and two wild teparies (P. acutifolius var. tenuifolius A. Gray). Var. tenuifolius has lanceolate leaflets and is found in more xeric habitats than var. latifolius. Flower color was under single gene control with purple dominant to white. Leaf lenght, leaf width, and the ratio of leaf lenght to width were each controlled by no more than 3-4 genes of primarily additive effect. The mode of inheritance of the number of seeds per pod was unclear. Seed weight was controlled by a large number of genes, with both additive and dominance effects. Interspecific crosses were made between 14 lines of tepary beans and 16 lines of common beans to attempt to transfer drought esistance from teparies to common beans. Twenty-nine of the 39 mature F1 hybrid plants reared by embryo culture had either or both the common bean "Masterpiece", or tepary P1321638 as parent. Of 16 mature F1 genotypes, five produced BC1 and/or allotetraploid progeny. Field trials showed that some common bean BC1F2 and BC2F1 families outyielded common bean parental cultivars when subjected to drought and heat stress.

Kidney bean.