Effect of inoculum density and immersion time on the production of potato microtubers in temporary immersion systems and field studies

Abstract

Microtubers can be easily induced in vitro, however so far their small size and low yield have restricted their use as propagules. Temporary immersion systems were used to produce potato microtubers and the effect of culture parameters as inoculum density and time of immersion on microtuberization were studied. When the inoculum density was increased from 60 to 90 explants per TIS no differences were observed regarding the number of microtubers per plant. However, fresh weight of the microtubers was superior with 60 explants (164.70g) compared with 47g obtained with 90 explants per TIS and the diameter of microtubers was affected adversely too. Immersion times of 2 minutes increased the number of microtubers per plant, as well as their size and quality, compared to immersion times of 30 minutes. In field studies plants derived from microtubers produced minitubers with higher diameter and fresh weight than plantlets from in vitro culture, with minituber numbers per plant similar in both treatments. The feasibility of developing a protocol for microtuber production in TIS and their direct planting into open field for the commercial production of potato minituber seed was demonstrated. Key words: explant density, liquid culture, microtuberization, semi-automation, Solanum tuberosum L.