The effect of Jarum Mas (Striga asiatica), a parasite, on the gas exchange capacity and leaf chlorophyll content of two local grasses was studied. Infection by S. asiatica reduced the host photosynthetic capacity by reducing the apparenl quantum yield used for CO, fixation. In Ischaemum indicum, lower photosynthesis rates were also due to the reduction of RuBP-carboxylase capacity and the RuBP-carboxylase regeneration capacity of the host
