Effects of 1--Naphthylphthalamic Acid on Root and Leaf Development of and the Related Metabolic and Physiological Features.

The effects of 1--naphthylphthalamic acid (NPA) applied as an aqueous solution on uncooled grape hyacinth () bulbs were investigated, focusing on histological measurements and the determination of various metabolites in developing roots. bulbs were kept for a defined number of days in distilled water (control) or aqueous NPA solutions, and then 2 cm sections of root tips were taken for histological measurements. Longitudinal and cross sections were taken in these root pieces, followed by measurements of their basic parts and microscopic images. Determinations of polar compounds by GC/MS and phenolic metabolites by HPLC/MS/MS were carried out in freeze-dried root samples. NPA inhibited the growth of the roots and caused swelling of their elongation parts, as well as changes in the dimensions of other parts of the roots and disruption of the gravitropic direction of their growth. However, NPA did not affect leaf growth and the amino acid, organic acid, and major carbohydrate content in the roots, but increased the level of unknown saccharides, probably oligofructans. The decrease in the contents of many phenolic compounds observed in our study under the influence of NPA may indicate that this could be one of the symptoms/causes of root growth disorders. In turn, the reduction in polyphenol levels may have been related to an increase in the number and length of root hairs.