VARIATION IN FLORAL NECTAR AMINO ACIDS WITH AGING OF FLOWERS, POLLEN CONTAMINATION, AND FLOWER DAMAGE

ABSTRACT

The nectar of Hibiscus rosa-sinensis L. shows an increase in amino acid concentration with the aging of the flowers, correlated with an increase in the number of detectable amino acids. The amino acid concentration of the nectar increased drastically after pollen addition both in Hibiscus and in the two other species investigated. The main amino acid responsible for this increase was proline. After puncturing or otherwise injuring a flower, the amino acid composition of the nectar is altered. In this case, the increase is due mainly to asparagine. Although contamination of nectar by pollen may be a common and natural event in many flowers, especially in those pollinated by butterflies, such an alteration in nectar constituents should be carefully discussed when considering amino acid concentration or composition in relation to pollinator—plant coevolutionary lines.