MICRO-CLIMATIC IMPACTS ON THE RELATIVE GROWTH OF CENCHRUS-CILIARIS AND CENCHRUS-SETIGERUS

Cenchrus ciliaris and Cenchrus setigerus created favourable micro-clim ate within the canopies by maintaining lower temperatures (by 2 to 9-d egrees-C) and vapour pressure gradients and high humidity (by 3 to 11 %). Energy balance studies showed that the net radiation, soil heat fl ux and latent heat of vaporization over the grass cover were higher du ring wet years compared to the values during low rainfall years. Accum ulated stress degree days showed that C. ciliaris developes an early s tress than C. setigerus. The transpiration rates of these grasses at v egetative phase were 16 to 18 mug cm-2 s-1 and diffusive resistances w ere 0.60 to 0.73 s cm-1. During low rainfall years, C ciliaris produce d higher dry matter yield, water and energy use efficiency than C seti gerus whereas under high rainfall conditions C setigerus performed bet ter than C ciliaris.