EFFECTS OF BIOREGULATORS ON THE TERPENOID ALDEHYDES IN ROOT-KNOT NEMATODE INFECTED COTTON PLANTS

Four naturally occurring and two synthetic plant growth bioregulators were surveyed for their effects on terpenoid aldehydes (TAs) that have been associated with defense mechanisms against the root-knot nematode Meloidogyne incognita (Kofoid and White) Chitwood (RKN) in cotton (Gossypium hirsutum L.). Salicylic acid (2-hydroxybenzoic acid), Pix (BAS 083 = mepiquat chloride = 1,1-dimethylpiperidinium chloride), and Burst (a mixture of cytokinins) increased the terpenoid aldehyde content of cotton roots, whereas kinetin [6-(furfurylamino)purine], indole-3-acetic acid, and gibberellic acid (2,4a,7-trihydroxyl-methyl-8-methylene-4b-gibb-3-ene- 1,10-dicarboxylic acid 1,4a-lactone) had either no significant effect on the TAs or decreased them. If the plants were inoculated with RKN, additional amounts of root gossypol and hemigossypolone were induced by the treatments with salicylic acid, Pix, and Burst.