Studies were made to assess the physiological maturity for harvesting the seed of Prosopis juliflora with high germination and vigour. Sufficient number of flowers were tagged at the time of anthesis. The developing pods were collected at weekly intervals, and pod and seed development were studied at each collection. Pod and seed weight increased with the increase of age and reached the maximum at 91 days after anthesis (DAA). In this stage pod colour turned from green to straw yellow. The seed extracted at this stage resulted in maximum seed weight,germination and vigour potential. Since the germination potential andvigour of this species started declining after this stage (91 DAA), the physiological
maturity stage for honey mesquite (P. juliflora) could be fixed at about 91 daysafter anthesis.