Effects of In-Row Spacing on Yield, Tuber Size Profiles, Bruise Damage, and Crop Values for Cultivars Alturas, Clearwater Russet and Ranger Russet in the Columbia Basin

Abstract

Variety selection and cultural management practices are the most common considerations for improved profitability in potato production systems. Planting density investigations have led to both within and between-row spacing recommendations to maximize profitability for commonly grown potato cultivars. Planting density can significantly alter tuber set, tuber size distribution, yield and profitability depending on end-use of the crop. However, rarely have such investigations included an assessment of the residual effects of changes in tuber size distribution on tuber bruising (blackspot and shatter bruise) and associated financial returns. The physics of impact injury suggests that larger tubers are more prone to tuber bruising than smaller tubers when dropped from a similar height. In this study we varied the in-row spacing of seed to investigate the extent to which the associated changes in tuber size distribution affect tuber bruising and crop values. The results demonstrated that: (1) the extent of tuber bruising was directly correlated with total marketable yield as altered by in-row spacing; (2) marketable yields decreased as in-row spacing increased; (3) while the absolute yield (MT ha⁻¹) of bruised tubers increased with closer in-row spacing, the spacing-induced shifts in tuber size distribution had no effect on the percentage of bruised tubers as a proportion of total yield; (4) larger tubers were more prone to bruising; and (5) closer in-row spacing significantly improved financial returns for both processing and seed contracts despite the increase in bruise yield.