Synthetic Seed Preparation, Germination and Plantlet Regeneration of Litchi (<i>Litchi chinensis</i> Sonn.)

Abstract

Litchi chinensis sonn.) ranks second after mango amongst the most important fruit crops cultivated worldwide. Litchi is a very valuable crop throughout the world because it is a table fruit and wines are also produced from it. The existing cultivars are highly polyploidy and heterozygous in nature. It is propagated through air layering and marcottage methods and storability is very low. Synthetic seeds can be stored for a long time and its genetic constitution could remain the same. For germplasm maintenance and clonal propagation, synthetic seeds can be used. Somatic embryogenesis has been reported from anther or embryogenic suspension culture in various species of litchi. Regeneration via organogenesis and somatic embryogenesis from zygotic embryos has also been reported in certain species. Developing a methodology for getting somatic embryogenesis with a high frequency from zygotic embryos which is available once in a year, would be particularly useful for genetic improvement of litchi. Cotyledonary stage somatic embryos developed from zygotic embryos were encapsulated in 2% alginate gel. The encapsulated somatic embryos (ESEs) germinated successfully on 0.7% agar medium containing 3% sucrose concentration in NN basal medium (half strength of major and minor salts) with 1 mg &middot; l -1 of gibbrellic acid. Percentage germination and plantlet development for ESEs was higher than that of non encapsulated embryos (NSEs). In comparison to different hormones, gibberellic acid has a significant influence on the germination rate of ESEs after one week of dehydration was seen maximum at 9% sucrose and abscisic acid (1 mg &middot; l -1 ) in half strength of major and minor salts in Nitsch and Nitsch medium resulting in extended storage up to 90 days without loss in germination potential and capability to regenerate into plantlets. Normally developed plantlets regenerated from ESEs were successfully adapted to soil to obtain a full grown plant.