Vavilov's Law of Homologous Series and de nove crop plant domestication

The law of homologous series, if valid, should provide us with useful guidelines in the domestication of new crop plants. The value of domesticants is likely to be in the production of materials which are in demand but otherwise unavailable in adequate amount or in the exploitation of agriculturally marginal environments where established crop plants are unreliable in performance. A model for such a system of new domestication can be developed in the Leguminosae and the tribe Phaseoleae in particular. The distribution of grain legumes in the family is not random. There are concentrations in the tribes Vicieae and Phaseoleae, with the greater number in the latter. Within the Phaseoleae the greatest concentration of domesticates is to be found in the sub-tribe Phaseolinae within the genera Vigna and Phaseolus . The sub-genus Ceralotropis of Vigna is remarkable in that the majority of species have been domesticated. This suggests that the two genera and perhaps Vigna in particular have a concentrated potential for domestication. It would certainly be sensible, if the need arose for new pulse crops in marginal agricultural environments, to consider candidate species with appropriate ecological adaptation from these genera. In product-led attempts at domestication it would be useful to consider the biosystematic background of candidate species and if there is a choice to concentrate efforts on those species with domesticated relatives. The application of the Law of Homologous Series could in these circumstances serve to direct and concentrate effort where it is likely to be most effective.