Selection for an effective rhizobial inoculant strain for pongamia

Abstract

Pongamia ('Millettia pinnata') is a leguminous tree grown for seed oil in sub-tropical and tropical Australia. It has no known diseases, is tolerant of salt and drought conditions and produces large seeds containing 27-34% oil. Oil yields of 2 t/ha/yr are possible (Williams and Gresshoff2006). Pongamia is reported to establish symbiosis with several species of rhizobia and bradyrhizobia (Biswas et al. 2013). This study involved screening of root-nodule bacteria for symbiotic effectiveness with pongamia. There is currently no commercial rhizobial inoculant for pongamia in Australia, although recent literature states that soybean strain CB1809 is suitable (Scott et a1. 2008). A highly effective inoculant for pongamia would offset the need for application of nitrogen fertiliser and reduce the cost of establishment and ongoing plantation nutrient management.