Jojoba (Simmondsia chinesis (Link) Schneider): A Potential Shrub in the Arabian Desert: II. Effect of Drought Stress on Vegetative Growth and Nutritive Value*

2, 4, 8, 12, 24 and 48 week intervals) were assessed in a randomized complete block design field ex-periment in Western Saudi Arabia. Results of eight seasons (2 years) revealed no significant differences among the irrigations regimes on each of nine mor-phological traits studied, with the exception of plant height (summer) and spe-cific leaf area (summer and winter), in the first year. In the second year, all traits, except for total dry weight and leaf weight in the autumn and number of leaves, in all seasons, were adversely affected by drought stress. On the aver-age, estimates recorded at the 1, 2, 4 and 8 weeks intervals were highest while those recorded at the 48 weeks interval were the lowest; and those recorded at the 12 and 24 weeks were intermediate in magnitude. Thus, depending on the season and the character under study, there were no clear boundaries among the irrigation regimes. Drought stress had also significantly affected accumulation of P, K, Cu, Fe and Mn contents in leaves, whereas that of N and Zn were not affected. On the average, lowest levels of N, P, K, Cu, and Fe, and highest of Mn were recorded in the driest regime. Soil moisture contents generally increased with soil depth and decreased with drought stress whereas total amount of water applied in a period of 33 months ranged from 1719 to 4581 m3 ha–1