Effect of combined inoculation strains on growth of lupin on newly reclaimed land in Egypt

Inoculation studies with Bradyrhizobium isolates were investigated in a gla sshouse and field experiment to compare the effects of single and multiple rhizobium inoculations on growth and symbiotic performance in lupin cultiva tion. A clear difference in host-strain compatibility was observed 120 days after sowing (greater number and dry weight of nodules, higher shoot dry w eight and total N accumulation). To confirm the results from the glasshouse , combined inoculations with a different level of N fertilizer and six lupi n cultivars were tested on newly reclaimed land at Tahreer Governorate, Egy pt. N fertilizer application significantly decreased nodulation status of w hite lupin, but increased seed and straw yields compared with the non-ferti lized control. Two combined inoculations were superior to the other strains in terms of infection and development of nodules in four accessions (1, 20 , 30 and 32) and the cultivar Giza 1. All combinations of rhizobium strains tested enhanced the growth and total N accumulation of the lupin cultivars . Rhizobium inoculation increased seed and straw yield compared with the no n-inoculated control. Reactions of the tested strain inoculations and inter action between Rhizobium strains and host plant in the glasshouse were almo st identical to their reaction in the field. The results from this study su ggest that the improvement through development of combined inoculation stra ins could be possible and would offer security for nodulation. High yields were accomplished with seed inoculation, particularly when lupin was cultiv ated for the first time and indigenous populations of rhizobia in the soil were low.