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

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 180 kg N ha−1 of urea at top dressing. Both experiments were basal dressed with 500 kg ha−1 of 12N:5.2P:14K6:S+2Mg:Ca at planting. The 2009/2010 was top dressed with 100 kg N ha−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 80 kg N ha−1 decreased yield in heritage potatoes whereas, it increased the yield of modern potatoes. Full irrigation and 80 kg N ha−1 improved Moe Moe yields whereas partial irrigation and less than 80 kg N ha−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.