Research on potato seed-use practices: planting times and seed tuber weight in relation to cultivar.

Research on potato was carried out near Naples (southern Italy) to obtain the so-called seed-use tubers starting from certified seeds. One experiment was carried out in 2003 to compare three planting times (January 19, February 18 and March 20) in factorial combination with three cultivars (Adora, Spunta and Timate), arranging a split-plot design with three replicates. Planting time influenced productive results: tuber yield and number showed increases with the planting delay, whereas their mean weight had the opposite trend. Cultivar Adora was found to be the most productive. A second experiment was carried out in 2004 to compare three seed weights (40±2, 50±2 and 60±2 grams) in factorial combination with three cultivars (Adora, Spunta and Timate), according to a split-plot design with three replicates. Tuber yield and number decreased with the reduction in seed tuber weight. ‘Spunta’ performed best and ‘Adora’ produced the smallest seed-use fraction (28-45 mm tubers). Results indicate that while planting delay gives seed tubers a higher probability of reaching physiological ripening, it causes a later harvest, which is more exposed to viral infections, reduces the time interval between two subsequent cycles and thus gives rise to quiescent tubers for subsequent summer planting. With regard to optimal seed tuber weight, 60 g was the most effective for yield performance and 50 g the most suitable for seed-oriented production.