Diurnal pattern of plant water relations and canopy photosynthesis of maize, sorghum and pearl millet under field conditions

Leaf water potential decreased from morning to noon hours and thereafter recovered in the evening in all the crops. Leaf diffusive resistance was negatively related to irradiance, except at mid day when it increased slightly at highest photon flux density in response to low teaf water potential. Canopy photo synthesis increased linearly with the irradiance in three crops. Sorghum maintained higher rates of net photo synthesis either for a given value of PAR or leaf diffusive resistance than pearl millet and maize.