Desarrollo y mejoramiento de germoplasma de maíz con tolerancia a sequía para las zonas tropicales de América Central - México, DF (México) CIMMYT : 1997 - Printed
Drought is an adverse abiotic factor that further limits the productivity of maize cultivation in marginal environments of Central America and the Caribbean. Drought problems are aggravated when maize is sown on hillside soils with limited water retention capacity or in environments with scarce or erratic rainfall. In these areas, average yield ranges between 0.3 and 0.5 t/ha. Based on this appraisal, the Regional Maize Program (Programa Regional de Maiz, PRM)for Central America and the Caribbean, in conjunction with CIMMYT, is developing a collaborative project for maize genetic improvement. The purpose of this project is to generate and release improved synthetic varieties adapted to limited rainfall conditions and with agronomic performance superior to that of cultivars sown by farmers in marginal areas. The genetic improvement approach used consists of recurrent selection of S2 lines of the population Tuxpeño Sequia C6 (TS6) x BS19TS6. Through recurrent selection, we are attempting to accumulate the frequency of favorable genes that determine the cultivars' adaptation to low rainfall conditions and in turn contribute to yield stability in marginal environments. The S2 lines are generated in Honduras. The superior fraction is recombined and experimental synthetics are formed for evaluation in regional trials in multiple environments. Lines are evaluated in Guatemala, El Salvador and Honduras with varying levels of drought. The superior fraction is selected on the basis of an index which includes yield, prolificacy, and anthesis-silking interval. In 1995, the fourth selection cycle was completed, in which the average yield of the experimental variety surpassed the population average by 2.3 t/ha. The outcome of this collaborative project has been the release of synthetic varieties in various countries in the region. Among them is the synthetic B-107, which has up to a 20% greater grain yield than other improved varieties.
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