THE RATE OF OUTCROSSING IN GRAIN AMARANTHS

Studies of intraspecific and interspecific outcrossing rates were carried out for grain amaranths using two populations of A. hypochondriacus (populations 1008 and 1024) and two populations of A. cruentus (populations 1034 and 434). The studies were conducted at Kabete Campus, University of Nairobi and National Horticultural Research Station, Thika, during the months April to August 1988 and October 1988 to February 1989. The mean intraspecific outcrossing rate estimates for A. hypochondriacus and A. cruentus were 10.4 % and 10.9 % respectively. The mean interspecific outcrossing rate involving population 1024 as the dominant marker parent and 1034 as the recessive marker was 1.2 percent. The study involving population 434 as the dominant marker parent gave the mean interspecific outcrossing rate as 6.5 percent. The intraspecific and interspecific outcrossing rate estimates showed substantial variation. Significant differences in outcrossing rate estimates were noted due to locational and seasonal variations. The factors probably contributing to the variations were believed to be locational and seasonal differences in pollinator density and differences among the populations.