Scheduling Reduced Irrigation on ‘Atlantic’ Potato for Minimal Effect

Droughts are common in the US High Plains, causing declining water availability and lowering water allocations. The objective of this 4-year field study was to identify a period of water deficit least detrimental to potato production. Fully irrigated ‘Atlantic’ potato received 62–63 cm of applied water. Total applied water was reduced by 25 % in three seasonal periods, 50 % water from emergence to 8 weeks after emergence (WAE) (early stress), 50 % water from 8 to 13 WAE (late stress), and 50 % from 0 to 5 WAE and again from 10 to 13 WAE (outer stress). Main plots were irrigation regime and split with three N levels, 101, 168, and 235 kg/ha. Soil and petiole N were higher when applied water was reduced. Lower irrigation inhibited growth, i.e., canopy height (10–20 %), weight (20–30 %) and leaf area index (50–70 %). Yield decreased 25 % and 13 % with early and outer stress, respectively. Chip color was darkest with early stress compared to fully irrigated plots. Common scab occurrence was greater in early stress than with other regimes. N rate had no effect on canopy growth, yield, chip color, or common scab. If applied water is reduced 15 cm, it is best late in the season and worst between 5 and 8 WAE compared to fully irrigated plants