Drought stress damages an estimated 3 to 22% of the planted maize area in Thailand every year, resulting in yield losses estimated to be from 129,000 to 858,000 metric tons, worth 10 to 80 million US dollars. The maize breeding program for drought tolerance was established in Thailand in 1982. The maize population KK-DR was developed from six source materials and has been improved for tolerance to drought using an S1 recurrent selection scheme. After three cycles of population improvement, three synthetic varieties were developed. These three synthetics, together with seven other open-pollinated varieties and six hybrid varieties, were evaluated in 1991 and 1992 to compare yield potential and other agronomic characters under artificial water stress and non-stress conditions in the summer season. The experiments were also conducted in both years under rainfed conditions in the rainy season to compare seasonal effects. In general, hybrids outyielded the open-pollinated varieties under drought, and by an even greater margin under well-watered conditions. The results demonstrated, however, that not all hybrids performed better than the open-pollinated varieties under drought; one of the synthetic varieties showed higher yield potential and more drought tolerance than some hybrids. Maize grown in the summer season under plentiful water showed higher yield potential than in the rainy season.

English

9802|AGRIS 9702

Jose Juan Caballero

CIMMYT Publications Collection