Stability of phenotypic variation of root length over environmental conditions in the seedling generation of potato

We examined the stability of phenotypic variations of root length (RL) in t he seedling generation of a cross between Norin 1 (large RL) and Konafubuki (small RL) in different growing seasons and soil water conditions. Seedlin gs were grown in pots in a greenhouse, and RL was measured when six leaves were expanding. Mean RL largely differed among the environments, i.e., larg er in the summer crop season than in the winter crop season and larger in t he moderate water condition than in the dry or wet soil condition. The patt ern of phenotypic variation of RL was similar, however, in all environments . The distribution of RL had a large peak in the smaller side, and the seed lings seemed to be separated into two groups, small RL and large RL. These results indicate that the pattern of phenotypic variation of RL in the seed ling generation of the hybrid population is relatively insensitive to growi ng seasons and soil water conditions, suggesting that a selection of RL in the seedling generation may be possible in any of these growth conditions.