Irrigation and nitrogen effects on tuber yield and water use efficiency of heritage and modern potato cultivars

•Modern potatoes were more responsive to irrigation and N than heritage potatoes.•More than 80kgNha−1 decrease yield in heritage potato whilst increasing modern potato yield.•Partial irrigation and 80kgNha−1 improved yields in heritage potatoes.•WUE based on crop water use is high in modern potatoes but that based on economical water use is high in heritage potatoes.•Heritage potato tolerates water stress and require more water due to late maturity. There is renewed interest in heritage potatoes in New Zealand, USA and Europe because of their natural flavour and the premiums farmers receive in niche markets. However, a dearth of information on irrigation and nitrogen limit their successful management. This research investigated irrigation and N effects on yield and water use efficiency of heritage and modern potatoes. The 2009/2010 experiment was a split-plot and the 2010/2011 was a Split–Split-Plot with water regimes as the main treatments, four cultivars as sub-treatments and two nitrogen (N) levels, as sub-sub-treatments. The N treatment in 2010/2011 was 20 and 180kgNha−1 of urea at top dressing. Both experiments were basal dressed with 500kgha−1 of 12N:5.2P:14K6:S+2Mg:Ca at planting. The 2009/2010 was top dressed with 100kgNha−1. Data collected was subjected to analysis of variance (ANOVA), using general Linear Model procedure (PROC GLM) in statistical analysis system (SAS). Modern potatoes (Moonlight, Agria) were more responsive to irrigation and N than heritage potatoes (Moe Moe, Tutaekuri). Moe Moe produced as much marketable yield as modern cultivars while Tuteukui had low yields. Application of more than 80kgNha−1 decreased yield in heritage potatoes whereas, it increased the yield of modern potatoes. Full irrigation and 80kgNha−1 improved Moe Moe yields whereas partial irrigation and less than 80kgNha−1 improved Tutaekuri yields. Water use efficiency was high in modern potatoes whereas economic water productivity was high in heritage potatoes. Heritage potatoes tolerated water deficit although they required more water due to late maturity. It was concluded that premium market prices are important to the success of heritage potatoes whereas modern potatoes might use irrigation water more efficiently. It is evident that heritage potatoes can be grown successfully, and that on occasions they use valuable resources efficiently; however a price premium is required to maintain viability.