干旱区生态环境知识资源中心

A protocol via axillary bud multiplication and another via somatic embryogenesis was developed for in vitro propagation of Ziziphus spinachristi using young axillary shoot buds and immature cotyledon explants obtained from a desert field grown tree. The shoot buds produced multiple shoots when cultured on MS solid medium supplemented with BA at low concentration and callus at higher concentrations. The cotyledon explants produced somatic embryogenic callus or somatic pro-embryos when cultured on MS solid medium supplemented with 2,4-D and BA depending on the 2,4-D concentration in the culture media. MS media without any growth hormones was found to be highly suitable for the embryo multiplication, germination and growth of plantlets produced both by axillary shoots and somatic embryogenic methods. Rooted plantlets were produced and acclimatized through axillary bud and somatic embryogenesis pathways. Plant production was faster through the axillary bud method than the somatic embryo method in the initial periods. Plantlet survival during acclimatization was higher on the group of plantlets subjected to photoautotrophic culture conditions prior to greenhouse acclimatization. Micro-propagated plantlets passed through photoautotrophic culture showed 100% survival and plantlets directly hardened showed 50% during the greenhouse and field acclimatization. Among the plantlets produced via somatic embryogenesis and axillary shoot multiplication pathways, plants produced by axillary shoot method produced flowers and fruits faster than the plants produced by somatic embryogenesis method. Plants produced by axillary buds showed horizontal growth and embryogenesis method showed vertical growth. Among the two pathways, embryogenesis method is better for the desert rehabilitation purpose and axillary bud method for the fruit production. The results showed that the plantlets micropropagated from axillary buds of mature trees bypass the juvenile phase during the field growth and establishment while plants produced by embryogenesis method is similar to the seedling plants having an initial juvenile phase.