Morphogenic Responses to Propagule Trimming, Spectral Irradiance, and Photoperiod of Grapevine Shoots Recultured in Vitro

Abstract

Abstract In an effort to improve grapevine micropropagation, shoot proliferation and rooting in response to explant preparation and incubation conditions were investigated. The explants were three- to four-node shoots (15 mm) of the Vitis hybrid ‘Remaily Seedless’ cultured in vitro. The factors considered were white light of diverse spectral irradiance distributions, blue light, red light, 10-hr light/14-hr dark and 16-hr light/8-hr dark photoperiods, and leaf and/or apex removal from the explant. In white light and short days, leaf and/or apex removal did not affect shoot production; however, more shoots of at least three nodes, the desired size for micropropagation, were produced when leaves were retained. Shoot production was significantly greater in blue than in red light. Differences in shoot production in white lights of various spectral irradiance distributions were attributed to differences in blue : red irradiance ratios. Shoot production was greater with ratios of 0.6 to 0.9 than with lower and higher ratios. A greater percentage of subcultured shoots rooted in long days and red light than in blue or white light. The number of roots produced per shoot, and total root length, were also greater in red light.