Gaseous exchange effect on growth and tuberization of potato vitroplants

Potato microtubers incorporation offers an important alternative to the seed programs in Lara state, Venezuela. To determine factors affecting microtubers production, two uninodal micro-cuttings with an axillary bud of "Andinita" and "Kennebec" varieties were sowed under sterile conditions, with the aim of evaluating potato vitroplants submitted to three conditions of gaseous exchange: high (gauge top), medium (plastic lid) and low (plastic lid sealed with a clear plastic paper). The design was a complete randomized factorial design 2 (varieties) x 3 (gaseous exchange), 10 replications and two experimental units (vitroplants). The evaluated variables were: 30 days after sowing: vitroplants length, internodes number and fresh biomass; and 60 days after tuberization induction: number, biomass and percentage distribution of the micro-tubers size. Gaseous exchange conditions did not affect the vitroplants length. The higher inter-nodes number in both varieties was observed in low gaseous exchange conditions. When favoring exchange conditions, biomass increased, "Andinita" showed a higher fresh mass average (442.15 mg). In conditions of low gaseous exchange there was no micro-tubers formation any variety, the higher micro-tubers quantity (1.62) was observed in "Kennebec" under high exchange conditions and in this same variety, more 60% of produced microtubers were classified into 5 to 10 mm category, in gaseous exchange media. The higher micro-tubers biomass was registered in "Andinita" variety (0.683 g) in high exchange conditions. Vitroplants showed a reduced leaves growth and epinasty in low gaseous exchange conditions.