Irrigation effects on pinitol content of jojoba leaf blades and floral buds

Abstract

One of the factors limiting jojoba ( Simmondsia chinensis (Link) Schneid.) production in the USA has been frost damage to flower buds. Research indicates that drought can be used to increase the frost tolerance of jojoba. In certain other plants, frost-hardiness is related to an increase in soluble carbohydrates including pinitol. D-Pinitol is also present in jojoba and is a major soluble sugar constituent of its leaves and buds in the fall and winter. In this study we evaluated the influence of irrigation water management, season and clone on pinitol content of jojoba over a 2 year period. The plants studied were from two clones in two irrigation regimes: a wet treatment (WT) that received water biweekly throughout the growing season, and a dry treatment (DT) that received no irrigation water after June to provide fall and winter water stress. Leaf water potential and relative water content were lower 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 flower buds. Pinitol content of leaves was highest in the spring and lowest in the summer. There were no consistent differences between clones in pinitol content of tissue.