Deficit Irrigation and Nitrogen Application Rate Influence Growth and Yield of Four Potato Cultivars (Solanum tuberosum L.)

Potatoes have high nitrogen (N) and irrigation requirements. Increasing water scarcity and environmental concerns highlight the need for efficient resource management. This study evaluated the effects of deficit irrigation and reduced N on yield and growth parameters in four potato cultivars (Canela Russet, Mesa Russet, Russet Norkotah3, and Yukon Gold) at Colorado State University’s San Luis Valley Research Center over two growing seasons. Three irrigation levels (~70%, ~80%, and 100% ET replacement) and two N rates (165 and 131 kg/ha) were evaluated. Measurements included total and marketable yield, tuber size distribution, tuber bulking (TB), leaf area index (LAI), and stem and tuber numbers. Yield losses were absent with ≤18% irrigation reduction in Canela Russet, Mesa Russet, or Yukon Gold but occurred with larger deficits. Russet Norkotah3 experienced yield decline with 16–23% reductions in irrigation. A twenty percent reduction in N application had no effect on Mesa Russet or Russet Norkotah3 yields, while the other varieties experienced a yield decline in one out of two years. Early-season LAI and late-season TB were positively correlated with yield, particularly for Canela Russet and Russet Norkotah3. These findings suggest irrigation and N inputs can be reduced without compromising productivity, but reductions must be determined on a cultivar-by-cultivar basis.