ESTABLISHMENT AND IN VITRO CLONAL PROPAGATION OF THE SPANISH AUTOCHTHONOUS TABLE GRAPEVINE CULTIVAR NAPOLEON: AN IMPROVED SYSTEM WHERE PROLIFERATING CULTURES ALTERNATE WITH ROOTING ONES

Abstract

MS-1 and C₂D media both contained 2 mg/l of 6-benzyladenine (BA) led to the best results of six culture media assayed for in vitro establishment of shoot tips from the table grapevine cultivar Napoleon. The parameters considered were survival, viability, number of axillary buds and shoots developing per explant, main shoot length and percentage of explants with secondary shoots. The viability and production of axillary buds and shoots were seriously affected by the time of the year when the buds were collected. The developmental stage of the axillary buds and the position of the nodal segments on the growing shoots taken from the mother plant signifi cantly infl uenced the in vitro response. The production of axillary buds and shoots, and the length of the main developed stem, significantly increased with distance from the shoot tips. A combined and sequential micropropagation protocol where proliferating cultures of axillary-bud microcuttings from in vitro-grown plants alternate with rooting cultures of the resulting shoots is described, and its commercial exploitation by the nursery industry is discussed.