THERMAL NEEDS FOR THE FLOWERING OF SORGHUM IN THE CIENEGA DE CHAPALA

Abstract

Th base temperature (Tb) and thermal requirements (RT) were determined for the period sowing-anthesis of nine grain sorghum (Sorghum bicolor L. Moench) lines adapted to the Chapala region, Jalisco, México. The procedure was based on a linear regression analysis between the mean temperature (T) and the days to anthesis (t), expressed as development rate (1/t), using data collected in 11 planting-dates field experiments carried out between 1984 and 1987. The results showed a Tb and RT of 12.7°C and 672 growing degree days (GDD) for the line R 5A; 13.7°C and 598 GDD for ATX-378; 14.7°C and 515 GDD for E 15A; 15.7°C and 395 GDD for ATX-623; 11.7°C and 674 GDD for B 106A; 13.1 oc and 650 GDD for R 27 A; 15.2°C and 482 GDD for B 198A; 14.6°C and 529 GDD for RTX-430, and 12.9°C and 639 GDD for 3-252. These data are pretended to be used to improve the prediction of days to flower of these lines in hybrid seed production programs.