Genetic Studies of Perennial Habit in Some Species of the Genus Oryza
Perennial habit was observed in various accessions of three species of Oryza (Oryza sativa, Oryza glaberrima and Oryza punctata) and their intervarietal and interspecific hybrids. In the specific case of TOS PURPLE and TOS 15223, the F1 was advanced to the F2 to monitor the mode of segregation for the perennial habit exhibited by TOS PURPLE. Two kinds of perennial habit were noticed in the three species studied – continuous production of new tillers by the rootstock leading to a massive accumulation of above and below-ground biomass as in all O. punctata accessions and AWGU DWARF-W; production of new tillers from the rootstock after a period of quiescence at the end of a life cycle with the old tillers completely dead as in TOS PURPLE. All O. barthii and O. glaberrima accessions are annuals. This paper reports the behavior of the first type and full details of the second type of perennial habit. The interspecific crosses showed that perennial habit while the second type is conditioned by a single recessive gene i.e. it is recessive to the annual habit. The significance of this finding for peasant agriculture is discussed.