The 2012 ASHS Annual Conference

Western Nebraska undergoes periodic severe and prolonged droughts. Recently irrigation restrictions were enacted in several areas to preserve the aquifer. These restrictions limit the amount of seasonal water to be pumped from wells. A 4-year study began 3 years ago to determine when, during the potato production season, would reducing irrigation by 15 cm have the least impact on marketable yield of the potato (Solanum tuberosum) chip cultivar Atlantic. Trial results to date will be presented. Planted in May, 'Atlantic' was exposed to full irrigation, 61 cm total adjusted for rain, or to a limited irrigation regime when 15 cm of water were withheld in the first half of the season, second half of the season, and some at the start and some at the end of the season. Plots were subdivided by three N levels, 101, 168, and 235 kg/ha. Soil water was directly correlated to irrigation regime. Soil N and petiole N were higher under reduced irrigation indicating low N uptake and low N use. Vine growth was inhibited when water was limited but partially recovered when full watering returned; N level showed no mitigating influence. Tuber yield was reduced by all three limiting regimes but less so when the 15 cm were withheld between 8 and 13 weeks after emergence (WAE). Stress between 3 and 8 WAE resulted in the greatest yield loss. Increased N partially overcame yield losses. Limiting water between 5 and 8 WAE resulted in lower tuber specific gravity, darker chips and greater incidence of common scab. These results will promote a better understanding of water and N interaction on market yield of potato in semi-arid environments. Growers forced to reduce irrigation of potato will know better how to manage the available water.