Responses of jojoba explants to different salinity levels during the proliferation stage in vitro

Jojoba (Simmondsia chinensis Link Schneider) explants were cultured under four levels of sodium chloride salinity (0, 56.4, 112.8 and 169.2 mM) during the proliferation stage. The fresh and dry weight of explants, as well as their mean shoot length increased up to the medium salt concentration, while the mean shoot number decreased. Salinity enhanced the length and thickness of leaves as well as the thickness of shoots. Sodium and chloride ions accumulated significantly under saline conditions while the opposite stood for nitrate ions as well as for potassium, which concentration decreased significantly in the high salt treatment. Ethylene evolution was highest under the high salt concentration and low at the low and medium salt treatment, even lower than that of the control and therefore it exhibited a significant strong negative relationship with the changes of both fresh and dry weight during the third month under saline conditions. Explants were transferred separately from each salt treatment to the rooting stage at the end of the third month. There were not any significant differences among explants deriving from different salt treatments in the rooting percentage, the root number and length, 6 weeks after the incubation of explants into the rooting medium.