Pea is one of the most important crops in the world. Among the many ways of utilization of this crop are that related for forage production. Forage pea may be cultivated alone as a pure crop, or in mixture with other crops, usually cereals. In recent time, several attempts have been made to cultivate forage pea with other legumes, where pea would play the role of cover crop. The results reported here are obtained in a greenhouse experiment aimed to assess the pea as a companion crop for establishment of lucerne (Medicago sativa L.), red clover (Trifolium pratense L.) and sainfoin (Onobrychis sativa L.) as undersown crops. The semi-leafless pea cultivar Jezero with three population densities (30, 60 and 90 plants per m2) were used in this experiment. Two control treatments also included in the experiment – the perennial legumes grown as a pure stand, and the perennial legumes with oat as a cover crop. The effect of pea on forage yield, chlorophyll content, leaf surface and LER is determined. According to obtained results, the best combination for lucerne is 30 pea plants per m2, 90 for red clover and 60 pea plants per m2 for sainfoin
