Variation in alkaloid content of Russell lupins and L. arboreus : a dissertation submitted in partial fulfilment of the requirements for the degree of Bachelor of Horticultural Science (Hons.) in the University of Canterbury [Lincoln College]

Abstract

The total alkaloid content of the leaves of eighteen lines of Russell lupin and one line of Lupinus arboreus was measured by acid titration. The alkaloid content of material harvested in spring was generally lower than its content in autumn-collected leaves. All lines of Russell lupin contained statistically equivalent percentages of alkaloids in autumn – the average content was 2.4%. In spring, one line contained more (3.1%) and one line less (1.5%) alkaloid than the other lines tested. L. arboreus contained significantly more alkaloid than the Russell lupins in both autumn and spring (7.9 and 5.2%). The alkaloids were measured by a method which accounts for chlorophyll from leaf material. This method differs from methods used for analysing seed meal in that an additional extraction with HC1 is used to separate the alkaloids from the leaf chlorophyll. This modification means that the method would be too time-consuming to be of use in mass screening of bitter lupin leaf material from breeding programmes. The results are discussed in relation to palatability and toxicity of the alkaloids to grazing animals. The high variability within lines is discussed as is the absence of any particularly low-alkaloid lines.