Résumé
Sorghum [Sorghum bicolor (L.) Moench] plays a pivotal role in the economy of the Sudano-Sahelien zone, particularly Mali where production depends mainly on traditional cultivars (mostly the guinea race) that are hardy, have good grain quality, are photoperiod sensitive and have long stalks, but yields are generally very low due to low harvest index. Increasing population, soil fertility decline and changed climate will require the use of more productive ideotypes of sorghum to avoid jeopardy of livelihoods. The search for such ideotypes prompted several studies involving the use of sowing date to determine the effects of simulated climate change scenarios on phenology, height and yield of short-day sorghum cultivars (mostly guinea race). These studies reveal that delayed sowing reduces the height, the number of leaves produced as well as cycle duration of the plants, with significantly variable genotypic patterns (Abdulai et al 2009; Bunting and Curtis, 1968; Kouressy et al., 1997). However information on the other races of sorghum as well as the physiological basis of these observations is scanty. A study was therefore designed to elucidate the physiological basis for the genotypic differences observed in response to date of sowing by the use of functional growth analysis (Hunt R. 1982) which provides a useful framework with which to assess physiological components in cropping systems.