Three brazilian Manihot species with tolerance to stress conditions By

A study of natural habitats of three wild Manihot species, M. caerulescens Pohl, M. stipularis Pax, and M. procumbens Mueller has revealed certain genetic potentialities in the material. It has been possible to detect, among other characteristics, resistance to drought and excessive soil toxicity and adaptation to cool temperature. Wild Manihot species represent a potential source of many genetic characters, but, for the most part, the value of these characters in improving cassava has not been determined (Martin 1976). Economic characters of wild cassava such as a tuber formation, nutritive value of tuber and resistance to severe conditions have received little attention from botanists working on flora. For this season, our aim was to collect and screen these species to detect useful characteristics for use in breeding programs. A survey of some species in their natural habitats was reported by the author earlier (Nassar 1978a,b). The present report describes three other species. The program for conservation and evaluation of wild Manihot species at the Instituto de Ciências Biológicas, Goiânia permited extend trips to be made to severa