LEAF PROTEIN CONTENTS AND NITROGEN-TO-PROTEIN CONVERSION FACTORS FOR 90 PLANT-SPECIES

The leaf protein contents of 90 plants covering taxonomically diverse groups ranged from 0.2 to 7.5 g% fr. wt. The nitrogen-to-protein conve rsion factors (k(A)') based on nitrogen recovered from amino acid anal yses ranged from 5.15 to 5.93, reaffirming that the traditional factor of 6.25 is not valid for plant proteins. A more practical conversion factor (k(p)) based on the ratio of protein from amino acid data to Kj eldahl nitrogen Varied from 3.28 to 5.16. Variations in both leaf prot ein contents and the conversion factors to some extent correlated with the taxonomic groupings of the plants. For a good estimate of the lea f protein content from Kjeldahl nitrogen, factor k(p), established usi ng plants sampled from the same taxonomic group, should be used. Howev er, for plants in general, a k(p) of 4.43 should provide a reasonably good estimate of the protein content.