Comparative Studies on Vegetative and in vitro Propagation of Elite Selected Jojoba Strains

Abstract

Aims: Evaluate the responses of five jojoba genotypes to in vitro nodal segments and shoot tip culture under different growth regulators combinations. Study Design: Comparative evaluation between vegetative and in vitro propagation of jojoba genotype. Place and Duration: The study was carried out in tissue culture lab of fruit breeding department during 2015. Methodology: Five selected elite genotypes of jojoba symbolled by ‘C10, C16, C18, C19 and C21’, and cultivated in the Cairo-Alexandria desert road were propagated asexually via cutting and in vitro culture technique. Two types of explants were tested; shoot tips of two months age with 0.5 to 1 cm length and semi- hard nodal segment of six months age was divided into parts with 1 to 4 cm containing from 1-2 buds after removing whole leaves except small portion to determine cutting side cultivation.   Results: Explants taking time has a great effect on jojoba plant proliferation, it was noticed that the best time for taking explants begin from the mid of March to mid of April; moreover, type of tested explants revealed different response towards proliferation. Concentrations of different growth regulators played an important role on growth and proliferation of jojoba genotypes. It was clear that combination of BA+NAA (3 mgL-1 and 0.5 mg L-1 respectively) showed highest rate of multiplication in respect to shoot number, shoot length and leaves number. Regarding rooting, proliferated plants failed to initiate roots when different types of hormones (BAP, TDZ and NAA) with different concentration (0.5, 1 and 2 mg/L) were tested. However, the tested genotypes failed to initiate any roots. On the other hand, propagation via stem cutting treated with IBA at 1500, 2500 and 3000 ppm; from these concentrations, only 3000 ppm success to initiate roots. It was clear that by increase the rooting percentage the survival percentage increase. Conclusion: Propagation via stem cutting treated with IBA at 1500, 2500 and 3000 ppm proved that 3000 ppm concentration was the best method for obtaining the highest percentage of rooting in semi-hard wood cuttings of jojoba plants using medium comprising of peat moss, perlite and vermiculite with ratio (1:1:1); however, it is difficult to initiate roots via in vitro culture technique.