Effects of folic acid concentration and spraying frequency on the growth of Atlantic potato plantlets during acclimatization

Abstract

Acclimatization is a stage in potato micropropagation because in vitro-derived plantlets must adapt to ex vitro conditions. This study evaluated the effects of folic acid concentration and spraying frequency on Atlantic potato (Solanum tuberosum L.) plantlet growth during acclimatization. A split-plot design with three replications included spraying frequency (once, twice, or three times per week) as the main-plot factor and folic acid concentration (0, 0.05, or 0.1 ppm) as the subplot factor. Each experimental unit contained three plantlets. Spraying frequency significantly affected height increment at 3–6 weeks after planting (WAP), with three-times-weekly spraying producing lower growth than once- or twice-weekly spraying. Folic acid concentration and its interaction with spraying frequency significantly affected height increment at 3–5 WAP. Leaf number was affected by folic acid concentration at 3, 5, and 6 WAP, by spraying frequency at 3 and 6 WAP, and by their interaction at 5 WAP. At 6 WAP, untreated plantlets produced more leaves than folic-acid-treated plantlets. Root number was affected by both factors; 0.1 ppm folic acid reduced root number, whereas twice-weekly spraying produced the highest mean. Survival remained high across treatments. No treatment combination consistently optimized all growth responses. These findings provide a basis for refining folic acid application during potato acclimatization and highlight the need to separate spraying frequency from cumulative liquid volume and folic acid dose in future experiments.