Effect of different treatments on the conversion of 'Hayward' kiwifruit synthetic seeds to whole plants following encapsulation of in vitro-derived buds

Abstract

Encapsulated buds excised from in vitro proliferated shoots of the 'Hayward' kiwifruit (Actinidia deliciosa (A. Chev.) C. F. Liang et A. R. Ferguson) can be used for non-embryogenic synthetic seed production. Three experiments were carried out to evaluate the aptitude of apical and axillary buds (microcuttings) towards encapsulation and synthetic seed production, and to find the treatments able to induce conversion of the synthetic seeds to whole plantlets. 'Hayward' proliferating shoots are useful sources of microcuttings for encapsulation and synseed production, since a proliferation protocol is already available. Encapsulation, although considered necessary, depressed microcuttings' vigour and vegetative activity. Cold treatments provided to the in vitro proliferating mother shoots boosted bud vigour and subsequent conversion. Increase of concentration of sucrose in some steps of the protocol also enhanced conversion, which in some conditions reached a rate of 57.5%. Potential applications of encapsulation and the synthetic seed technology in kiwifruit germplasm exchange and commerce are also discussed.