Biological Nitrogen Fixation in White Lupin.

We are conducting research with white lupin (Lupinus albus L.) to develop it as a food/feed grain crop in addition to its use a green manure crop. There is limited information regarding nodulation as related to seed composition traits in lupin. In our experiments with ten lupin lines and seven bradyrhizobial strains, ANOVA indicated that lupin lines and bradyrhizobial strains had significant effects on root nodulation. The interaction between lupin lines and bradyrhizobial strains was non-significant. The root nodulation score for ten lupin lines ranged from 0.25 (VSL-585) to 1.43 (VSL-184). The root nodulation score for seven bradyrhizobial strains varied from 0.03 (S96-A5) to 1.57 (S96-A19). This experiment identified the S96-A19 bradyrhizobial strain to the most efficient nodulation. Alkaloid categories and bradyrhizobial strains had significant effects on root nodulation. The interaction between alkaloid categories and bradyrhizobial strains was non-significant. The highest root nodulation was observed in bitter lupin lines in the category 4 (high alkaloid content) whereas the lowest root nodulation was observed in the relatively sweet lines in categories 1 and 2 (low alkaloid content). The root nodulation scores in lupin lines in categories 0, 3, and 4 were similar, thus, indicating that the same bradyrhizobial strain could be used to effectively inoculate white lupin lines. Other experiments indicated that root nodulation score was positively correlated with seed contents of aluminum, manganese, and dragondorff score (total alkaloid content) and negatively correlated with seed contents of potassium, sodium, and zinc. Details of these experiments will be presented and discussed.