Yield potential and tuber-size distribution using EVIKA multiplication methods

Abstract

A plant-multiplication technique developed at the Department of Plant Biotechnology EVIKA of the Estonian Research Institute of Agriculture involves multiplying plantlets in plastic rolls on peat before transplanting them onto the field, where the first generation of seed tubers will be grown. Four possible multiplication methods of potato meristem plants were compared from the aspect of obtaining optimal-sized, disease-free seed tubers. The plants grown from tip- and stem-cuttings and truncated plants were considered in relation to the plants multiplied by the in vitro micro-plant cultivation in plastic rolls. The main objective of this paper is to analyse how the tubers' mass per plant and their size distribution depend on the multiplication method, experimental year, and potato variety. Two local late-maturing potato varieties, Ants and Vigri, were used in the study, carried out in 2005–2007. A significant influence of multiplication method and experimental year on tuber weight and tuber-size distribution throughout the growing period was found. While plants multiplied by in vitro micro-cuttings produced substantially lower tuber mass per plant, also their tuber-size distribution was considerably inclined towards smaller dimensions – more tubers with <30 mm diameter (Ø) and fewer tubers with >60 mm diameter were formed. Compared with plants multiplied by the in vitro micro-plants method, significantly fewer tubers within the most proper seed-tuber size range (Ø 30–60 mm) were received for plants multiplied from tip- and stem-cuttings, while the plants grown from truncated seedlings provided about the same yield as micro-plants in this size interval. All stated differences were magnified by unfavourable growing years, whereas in favourable conditions the differences were almost non-existent. The influence of potato variety on tuber mass and their size distribution was not proved. All described EVIKA multiplication methods achieve quite similar tuber yields and seed-production potential, comparable to those obtained by in vitro methods.