IRRIGATION EFFECTS ON PINITOL CONTENT OF JOJOBA LEAF BLADES AND FLORAL BUDS

One of the factors limiting jojoba (Simmondsia chinensis (Link) Schnei d.) production in the USA has been frost damage to flower buds. Resear ch indicates that drought can be used to increase the frost tolerance of jojoba. In certain other plants, frost-hardiness is related to an i ncrease in soluble carbohydrates including pinitol. D-Pinitol is also present in jojoba and is a major soluble sugar constituent of its leav es and buds in the fall and winter. In this study we evaluated the inf luence of irrigation water management, season and clone on pinitol con tent of jojoba over a 2 year period. The plants studied were from two clones in two irrigation regimes: a wet treatment (WT) that received w ater biweekly throughout the growing season, and a dry treatment (DT) that received no irrigation water after June to provide fall and winte r water stress. Leaf water potential and relative water content were l ower in the fall and winter in the DT than in the WT. Water stress did not appear to stimulate pinitol accumulation in jojoba leaves or flow er buds. Pinitol content of leaves was highest in the spring and lowes t in the summer. There were no consistent differences between clones i n pinitol content of tissue. (C) 1998 Elsevier Science B.V. All rights reserved.