Increasing growing points and oil yields in lavender by growth regulator sprays

Abstract

Immature plants ofLavandula angustifolia x L. latifolia (cv. Twickle Purple) were sprayed with Atrinal and P293 when the growing shoots bore four to six expanded leaves. Atrinal increased the number of inflorescences per plant by stimulating otherwise dormant axillary buds on the shoots of the current season. The number of nonflowering shoots arising on older wood was also increased. The number of florets and the fresh weight per inflorescence were reduced, but the number of florets per plant was increased overall. Oil content per plant was doubled without altering oil composition or floret structure. Flower stalks were shortened below and between the floral nodes. Atrinal sprays achieved a machine-harvestable canopy in 3-year-old plants. Untreated plants required a full year longer to develop similar canopies. P293 and manual disbudding were not as effective as Atrinal. It is suggested that such spray treatments have a useful potential in reducing the time required for the development of the mature canopy form, and so obtaining earlier financial returns on establishment costs.