Browsing by Author "Harrison, M.N."
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Item Genotype by Environment Interactions in Maize in Eastern Africa(1973) Penny, L.H.; Eberhart, S.A.; Harrison, M.N.37 environments in 1968-69. A large proportion of the genotype by environment interactions could be explained. by differential responses among varieties to altitude and to environments. Because temperature is highly oorrelated with altitude in East Africa, the altitude response may be primarily a temperature response. Days to tassel increased an average of 21.8 days per km. of increased altitude with a range of 17.7 to 23.7 days per km. The average increase in yield was 17 q / ha. per km. with arrange of 3.5 to 27.9 q/ha. per km. Varieties that involved high-altitude source material and those that had been selected at high altitudes yielded relatively better at higher altitudes than varieties that involved low-altitude source material and yielded nearly as well as low altitude varieties at low and medium altitudes. Predicted yields for an Eastern African location obtained with the parameters mean yield, response to altitude (bA), and response to the environmental index WI) estimated from extensive regional trials should be more reliable than observed results from a limited number of trials at that location. The current commercial varieties and recently developed experimental material seem to be adapted throughout Eastern Africa within the appropriate altitudinal zone with the permission of the Director, East African Agriculture and Forestry Research Organization.Item Progress from Half-Sib Selection in Kitale Station Maize(1973) Eberhart, S.A.; Harrison, M.N.; A.R.S. U.S.D.A., Iowa State University, Ames, Iowa, U.S.A. International Institute of Tropical Agriculture, P.M.B. 3520, Ibadan, Nigeria.A strain of Kenya flat-white maize (Zea mays L.) had been maintained on the Agricultural Research Station at Kitale, Kenya for several years by visual selection of the ears at harvest (mass selection) to provide seed the following year. Since the Kenya flat-white complex apparently traces back to varieties from South Africa that originally came from the southern U.S.A such as "Hickory King", "White Horse tooth", "White Pearl", and others [6], the late maturity and disease resistance of the Kenya strain suggests that mass selection has been effective in developing adapted varieties for Kenya conditions.
