The Use of the WOFOST Model to Simulate Water-Limited Yield of Early Potato Cultivars

In this work, an attempt was made to use the WOFOST (WOrld FOod Studies) model to simulate the potential and water-limited yield of early potato cultivars Lord and Denar. Data from cultivar experiments carried out at the Polish Research Centre for Cultivar Testing in 2004–2013 were used in the study. The Lord cultivar yielded 22.4–67.8 t fresh tuber weight per ha and 3.8–11.5 t ha−1 dry tuber weight during the study period. The highest tuber yields (over 10 t ha−1 dry weight) were obtained in 2009, 2011 and 2012, and the lowest in 2005 (3.8 t ha−1) and 2006 (2.65 t ha−1). The water-limited tuber yield simulated by WOFOST ranged from 3.6 to 10.9 t ha−1 dry weight and was about 0.45 t ha−1 higher on average than the actual yield. The planting period each year was between days 104 and 120 of the year, and harvesting took place between days 216 and 232. Water availability was a factor limiting the yield. The yield limited by water deficiency was 38.7% lower (irrespective of the cultivar) than the potential yield. The WOFOST model was sensitive to water deficiency, and the simulated (water-limited) yields were close to the actual yield or showed a clear downward trend indicating evident rainfall shortages in 2005 and 2006.