Abstract
Potato microtubers (MT) (about 1 gram fresh weight) are mass-produced under in vitro conditions, and are used as seed tubers in field. We previously found that potato varieties were divided into two types, larger tuber number with lighter individual tuber weight (type 1), and smaller tuber number with heavier individual tuber weight (type 2) in the plants from MT. The purpose of this study is to ascertain whether the effects of seed tuber size and planting density on the tuber number and individual tuber weight of MT plants vary with the type of varieties. In type 1 variety Norin 1, the plants from MT had larger number of tubers than those from conventional seed tubers (CT). On the other hand, in type 2 variety Nishiyutaka, the plants from MT had heavier individual tuber weight than those from CT. High planting density caused a larger tuber number per unit area and lighter individual tuber weight in both types of varieties, i.e., type 1 variety Irish Cobbler and type 2 variety Toyoshiro. We concluded that planting small size MT at a high density will be useful for the seed tuber production system in fields regardless of variety type.
