The average yield of maize (Zea mays L.) in Kenyan highlands is approximately 3.5 t/ha while mean yield in the National Performance Trials (NPT) range from 6.0 to 8.0 t/ha. A study was made on the NPT environments used from 1985 to 1990. Using common entries from a three year testing cycle starting in 1985, environments were classified based on yield as low ( < 4.0 t/ha); intermediate (4.0 to 9.0 t/ha) and high (>9.0 t/ha). Of the 18 to 26 environments used in the four cycles only two to four environments fell in the low category. One to five environments were classified as high potential and the rest were in the intermediate group. No significant differences in yield were observed among entries in the low and high potential environments, except in the 1986 - 88 cycle of the latter. On the other hand, significant differences among entries were observed in the intermediate group in all the four cycles. The CV's of the low group were 1.5 to 2.0 times that of the intermediate and high groups. The observed location means, ranging from 1.1 to 11.6 t/ha shows the variability of the mandate areas of the Highland Breeding Program and the effect of stress. The observed stress was due to drought, late planting and improper application of inputs. Results of this study suggest that the Highland Breeding Program should modify its testing scheme to include more locations and have better control of errors in the low potential areas.

English

9712|AGRIS 9702

Jose Juan Caballero

CIMMYT Publications Collection