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A Maize Breeding Methods Study in Kenya¹

Four years of reciprocal recurrent selection has produced rapid improvement in one of the parental varieties (‘Ecuador 573’), in the variety cross, and in a commercial topcross maize (Zea mays L.) hybrid. The improved strain of Ecuador 573 is now used as the male parent of the current commercial hybrids, ‘H611C’ and ‘H613C,’ and they yield approximately 25% more than the original versions.

Estimates obtained from seven years of the selection trials showed no changes in genetic variances for yield. Hence, this rate of improvement is not expected to change in the near future. Progress from modified ear-to-row selection was greater in the introduced Ecuador 573 variety and in KCA, (‘Kitale II’ x Ecuador 573)syn-4, than in the local Kitale II variety. No improvement was detected in KCA from mass selection. An increased number of ears per plant was associated with yield improvement by reciprocal recurrent selection and modified ear-to-row selection. Selection for lodging resistance and blight resistance in the breeding nurseries resulted in slight improvements in the varieties under reciprocal recurrent selection and in the variety cross. Greater attention to ear height and lodging resistance is required to reduce harvesting losses in the commercial maize crop in Kenya.

Key Words: Zea mays L. • Recurrent selection • Genetic variance • Yield improvement • Corn

² Research Geneticist, USDA-USAID-EAAFRO, Kitale, Kenya; Research Geneticist, Plant Science Research Division, Agricultural Research Service, Iowa State University, Ames, Iowa 50010; and Research Geneticist, Plant Science Research Division, Agricultural Research Service, Northern Grain Insects Research Laboratory, Brookings South Dakota 57006.

Received for publication February 25, 1972.