Cut seed tubers – benefits and constraints

The influence of seed cutting of over-size seed tubers was examined in field and on farm experiments. Agria, the most important variety of Switzerland was used. Whole tubers of the same origin served as control. Compared to whole tubers seed weight of cut pieces declined on average by 52 % to 54 g. This leads to a reduction of 35 % in seed weight per hectare. Seed pieces developed 45 % less sprouts per piece than whole tubers. 63 % of the sprouts present at planting time emerged later as stems. For whole seed the ratio was 54 %. For cut seed the stem number per unit area was 16 % lower at Reckenholz and 25 % lower at Changins respectively. Tuber number per stem slightly increased for cut seed. On average cut seed yielded 92 % at Reckenholz and 89 % at Changins respectively compared to whole tubers. Also marketable yield was on average reduced by 9 % and 15 % respectively. In on farm experiments yield differences were estimated to 7 %. Differences in stem number and in individual tuber weight were responsible for the lower yield of cut seed. The starch content was not influenced by seed cutting and fulfilled in all seasons the demanded starch content of 14 % for the processing to French fries. Seed pieces decay was never observed neither during the wound healing period nor at the field during emergence. Economic advantages of seed cutting are mainly influenced by the prices of over-size seed tubers. Until know, no prices were fixed. Due to phytopathological reasons seed cutting should be performed by the seed producing establishments, because they are able to select the best origins and guaranty the professionalism in the handling of cut seed. This ensures also the best follow during the whole seed processing.