In Vitro Microtuberization in 30 Potato Varieties

Potatoes, Solanum tuberosum, when grown in the Caribbean, are planted in October. Freshly harvested potatoes require 2-3 months of cool storage, vernalization, to break dormancy to sprout and grow. Obtaining seed potatoes, normally harvested in the fall in the continental USA, don’t have the vernalization for October planting in the Caribbean. The objective was to study the influence of MS medium with 10% sucrose on induction of microtubers in tissue culture for 30 varieties. Potato microtubers could then be harvested and vernalized year-round for planting in the Virgin Islands. Virus-free potato germplasm was obtained from the USDA as in vitro plants. The tissue culture medium contained MS salts and Gamborg vitamins, 8% agar and 10% sucrose. Single nodal sections were placed in 8 dram shell vials and grown under 16 hr photoperiod at 25C. Data was collected weekly on microtuber formation. After four weeks, ten varieties started to form microtubers but at a low percentage per variety. Within eight weeks, 18 varieties had formed microtubers and 28 varieties by 12 weeks. ‘Red Pontiac’ and ‘Tasty’ produced no microtubers while ‘Cruza 148’ had 100% microtuberization. The microtuberization rate varied between the other varieties. Microtubers can be induced from potato cuttings for 60% of the varieties tested after eight weeks in vitro on 10% sucrose. Further studies will be developed to enhance microtuberization efficiency incorporating reduced light and plant growth regulators.