Effects of Production History and Gibberellic Acid on Seed Potatoes

In the present study effects of production history on tuber sprout, root, stem development and crop yield of seed potato cultivars Fambo and Van Gogh were investigated in the High Grade Area of Finland (64.9 N, 25.4 E). The haulms of seed potatoes were destroyed at the time of flowering (50 days after planting, DAP), three weeks after flowering (75 DAP) and as a control the haulm was left to natural death until harvest (95 DAP). The temperature sum accumulation of the seed potatoes was recorded for the growing season and storage period. In addition, the use of plant hormone gibberellic acid (GA) in sprout control was also investigated. The results indicated that cultivar properties had a greater effect on the sprouting and crop yield of seed potatoes than production-phased haulm killing or temperature sum accumulation. Haulm killing carried out at three weeks after flowering (75 DAP) accelerated the emergence of both cultivars significantly compared to killing at 50 DAP or 95 DAP. Gibberellic acid (GA) treatments significantly increased the number of sprouts and at lower concentration (100 mM) GA increased the number of tubers in the cultivar Fambo. Thus, the timing of haulm killing and in the case of Fambo, GA treatment influenced the characteristics of seed potatoes produced in the present study, revealing methods to improve seed potato production in the northern latitudes.