Differences in potato development (Solanum tuberosum cv. Maris Piper) in zero and conventional traffic treatments are related to soil physical conditions and radiation interception

Penetration resistance, potato (Solanum tuberosum cv. Maris Piper) root, tuber, and top growth, and leaf nutrient concentrations were compared between a conventional traffic (CTr) and a zero traffic (ZTr) treatment. Plants grown under ZTr had a 19.4% greater yield (P < 0.001), and throughout the growing season leaf area, stem dry weight, stolon and tuber dry weight, were consistently greater for ZTr plants. On three occasions during the growing season penetration resistance was greater in CTr furrow subsoil than in ZTr furrow subsoil, as a result of the drier conditions in CTr soil. ZTr soil in the ridge had greater air-filled porosities throughout the growing season, although between mid-May and mid-July the furrow subsoil of both ZTr and CTr were at or near saturation. Although no significant differences in root distribution of plants were observed between treatments, all roots growing within the subsoil were elongating in cracks and biopores. Determination of radiation interception values from leaf area and radiation data, showed that between 5 July and 20 August ZTr plants were intercepting 5% more radiation (P < 0.01) than CTr plants. No differences in light conversion coefficients were observed for plants in either traffic treatment. The observed yield differences are linked primarily to the differences in radiation interception between the two treatments. © 1993.