Effect of temperature on seed development in jojoba (Simmondsia chinensis (Link) Schneider). II. Wax content and composition

Jojoba plants were grown in large pots in temperature-controlled phytotron glasshouses. The flowers were hand-pollinated and the seeds were grown under a range of eight temperature regimens from 15/10 to 36/31µC (8/16 h; photoperiod 16 h). The concentration of wax in the seed was determined by nuclear magnetic resonance and the wax composition and the composition of the ethanolysis products of the wax were determined by gas chromatography. At 21/16µC the wax concentration increased with seed growth until the seed reached 75% of its mature weight and then stabilized at about 45%. The wax concentration in mature seeds was only slightly affected by temperature, except for the extreme treatments of 15/10 and 36/31µC where the concentration was reduced. The main effect of temperature on wax composition was the depression of the percentage of waxes with carbon chain lengths greater than 40 at temperatures over 30/25µC. This depression was associated with a reduction in the percentage of C₂₂ and C₂₄ fatty acids and alcohols. The effects of temperature will have to be taken into account by plant breeders selecting for high wax content or for a particular wax composition.