Although the bulk of maize seed sales by Kenya Seed Company are for intermediate and late maturity maize hybrids, these are grown on only 20 to 30% of the land area. The rest of the area receives scant and irregular rainfall in seasons as short as 60 days. In 1985, the seed company initiated a breeding program to develop maize hybrids for the vast arid and semi-arid regions of Kenya, areas which support 50% of the population. This target environment receives 250 to 500 mm of rain per season. Since use of fertilizer was known to be low, selection and evaluation was done at fairly low fertility levels. Initial work involved screening of early maize varieties in dry areas, and later, evaluation of crosses among selected varieties. Selected S1 lines from these varieties were used to form heterotic drought-tolerant populations KSDA and KSDB. The populations are being improved using S1 reciprocal-recurrent selection. This selection system was ideal in terms of flexibility. It can be used to generate open-pollinated varieties, topcrosses, and assorted hybrid types. Selection emphasized grain yield, but other observable traits thought to reflect tolerance to moisture stress and low soil fertility were considered. Dryland hybrids DH01 and DH02 were recommended for release in 1995. The mean performance of DH01 was 4.8 t/ha, about 48% above Katumani Composite B (KCB), based on testing over six years in 36 sites. This hybrid took 56.8 days to flower, while KCB took 53.3 days. DH02 gave a mean grain yield of 4.5 t/ha at 57.0 days to flower. Results to date indicate good opportunity to develop even better varieties using this comprehensive breeding system. Water management of irrigated trials, though expensive, would offer more precise information.

English

9801|AGRIS 9702

Jose Juan Caballero

CIMMYT Publications Collection