THE EFFECT OF IN-ROW SEED PIECE SPACING AND HARVEST DATE OF THE TUBER YIELD AND PROCESSING QUALITY OF CONESTOGA POTATOES IN SOUTHERN MANITOBA

Conestoga was registered in Canada in 1982. It has been readily accepted by chip producers and processors in Manitoba, although little information on the effect of commercial production practices on the yield and processing quality under Manitoba conditions is available. In this study, the effect of within-row seed piece spacing at three harvest dates on Conestoga potatoes for the early-season chip processing market was evaluated under rainfed conditions in southern Manitoba in 1982, 1983 and 1986. Treatments consisted of spacings of 22, 30, 38 and 46 cm between seed pieces within the row, with 1 m between row centers, harvested at 10-d intervals starting at 75 +/- 5 d after planting (DAP) each year. As spacing between seed pieces increased, total, small and maingrade tuber yield and number, and specific gravity decreased. Large tuber yield and number increased. The number of mainstems per plant, the incidence of hollow heart and chip color were unaffected. Delaying harvest resulted in an increased yield of total and maingrade tubers, and higher specific gravity. The highest marketable yield (maingrade plus large tubers) resulted from the 22-cm in-row spacing. The total number of tubers harvested and the number of maingrade tubers increased between 75 and 85 DAP, but did not increase substantially after 85 DAP. Chip color and the incidence of hollow heart were not significantly affected by harvest date.