Potato Seed Piece Size, Spacing, and Seeding Rate Effects on Yield, Quality and Economic Return

It has been observed that potato producers often focus more on the quantity of potato seed pieces being planted per unit area than on seed piece size and placement within the row. This study compared the effects of seed quantity per unit area (Mg ha−1) or seed piece size and in-row spacing on potato yield and quality. Hand-cut certified seed of three potato cultivars (Alturas, Russet Norkotah, Ranger Russet) of three size classes (42, 64 or 85 g) were planted at in-row seed piece spacings of 20, 30 or 40 cm. Three of the treatments (42-g seed pieces planted at 20 cm, 64-g seed pieces planted at 30 cm, and 85-g seed pieces planted at 40 cm) resulted in equal weights of seed planted (2.28 Mg ha−1). Increasing seed piece size from 42 to 85 g resulted in higher total yield regardless of in-row spacing. U.S. No. 1 yield was increased only at the 40-cm in-row spacing when 42- and 85-g seed pieces were planted. Increasing seed piece spacing from 20 to 40 cm resulted in lower total and U.S. No. 1 yields at all three seed piece size treatments. However, equal seeding rates of 2.28 Mg ha−1 resulted in equal total and U.S. No. 1 yields. Altering seed piece size or in-row spacing had little effect on tuber yields in the 285–397-g size category. A fresh-pack economic gross returns analysis of Russet Norkotah based on tuber size distribution less seed costs resulted in higher gross returns per ha only for 85-g seed pieces planted at 40 cm compared with planting 42- or 64-g seed pieces at a the 40 cm. At an equal seeding rate of 2.28 Mg ha−1, paired t-tests indicated there were no differences in gross returns per ha. However, the effects of seed piece size and spacing on economic return will depend on cost of seed and the selling price of the harvested potatoes.