Sicklepod Surface Wax Response to Photoperiod and S-(2,3-Dichloroallyl)diisopropylthiocarbamate (Diallate).

Sicklepod (Cassia obtusifolia L.) leaflet epicuticular fatty acid, fatty alcohol, and hydrocarbon contents were measured by gas-liquid chromatography from plants grown under 10-, 12-, 14-, or 16-hour photoperiods and treated with S-(2,3-dichloroallyl)diisopropylthiocarbamate (diallate) (0, 0.14, 0.28, 0.56, 1.12 kilograms per hectare). As diallate concentration increased, epicuticular fatty acid content decreased. Fatty alcohol content was maximal in plants treated with 0.28 kilograms per hectare diallate and was reduced from that level at herbicide concentrations above or below this rate. Hydrocarbon content patterns were similar to those of the fatty alcohols except that the hydrocarbons at 0.28 kilograms per hectare were 61% of that present in the control, whereas the concentration of fatty alcohols increased to 200% of the control in treatments of 0.28 kilograms per hectare diallate.Photoperiodic influence on the various epicuticular lipid classes showed increased fatty acid and hydrocarbon contents as the photoperiod was lengthened. Fatty alcohols were maximal under 16-hour photoperiods and minimal under 12-hour photoperiods.Photoperiod-diallate concentration interactions were demonstrated in the epicuticular fatty acid, fatty alcohol, and hydrocarbon contents of sicklepod leaflets. The amount of each lipid class present per gram leaf fresh weight was influenced by the rate of diallate applied and the photoperiod under which the plants were grown. Each lipid class responded differently to the combination of treatments.