Present addresses: 1Central Potato Research Station, Kufri.
Studies on the shift of clonal selection from stage II and stage I of variety Kufri Jyoti for production of disease free nucleus seed potatoes showed that the clonal selection from stage I improved the disease freedom from viruses PVX, PVS, PVY, and purple top roll (PTR) and registered an increase of 33.3% in the number of tubers and 47.4% in yield per hill in stage I as compared to clonal selection from stage II. None of the two seed sources could reduce the incidence of marginal flavescence (MF) in stage I or II except in stage III by seed source stage II. The seed requirement through indexed tubers was fulfilled up to 125% in comparison with 80% by the clonal selection from stage II.
