Growth and biochemistry of the common hyacinth (Hyacinthus orientalis L.) and the lily (Lilium longiflorum L.)

The biochemical principles underlining carbohydrate metabolism of ornamental geophytes such as hyacinth and the lily are poorly understood. The present studies were therefore undertaken to investigate the regulation and partitioning of carbohydrates, as well as growth and development of these flower bulbs. Results indicated that starch was the major storage carbohydrate in these bulbs. Starch degradation occurred through amylolysis rather than phosphorolysis. The flower accumulated the highest amount of the reserves in hyacinth, following the depletion of these substances in the bulb scales, whilst in the case of the lily; it was the stem and roots, which accumulated the highest amount of reserves. The isolation of gene fragments of starch phosphorylase and starch synthase from hyacinth as well as the sequences generated for these enzymes implies that primers which are specific to hyacinth can be designed, and full characterisation of the genes can be made in the future by making and probing genomic libraries and isolating clones from cDNA libraries. In general, peeling of bulbs prior to planting resulted in a delay in emergence and reductions in vegetative growth as well as flower quality. Hyacinth plants subjected to defoliation did not show any compensation for leaf loss because growth was always reduced whilst flowering was unaffected, however, the lily responded positively to complete shoots removal especially when herbivory occurred at the beginning of their growth. Plants produced from large bulbs, just like those from the shallow planting regimes performed better in terms of growth and flower quality as compared to those of small bulbs and deep planting. Also, the application of (NH4)2SO4 enhanced more vigorous growth and bulb yield in both species of flower bulbs than did Na2HPO4, but in hyacinth it was Na2HPO4 that produced better flower quality than the former. Varieties such as Sky Jackets and Purple Voice produced the highest vegetative growth and bulb yield, whilst Fondant and Blue Jacket recorded the highest flower quality.