Modeling the impact of climate warming on potato phenology

Understanding the influence of thermal trends, crop management practices, and genetics on the crop developmental stages and phases is critical to develop adaptation strategies in the face of warming trends. The specific study objectives were to determine the correlation between observed potato phenology with the trends of rising temperature, and to investigate the impacts of thermal trend, crop management practices, and changes in cultivars using a modeling approach. The study was conducted at 12 sites in Punjab, Pakistan from 1980 to 2018 using phenological observations for both the spring and autumn potato crop. For the stages observed during spring, there was an average advance of 6.2 days decade(-1) for sowing, 6.0 for emergence, 3.8 for tuber initiation, and 2.0 for maturity. However, for the stages observed during autumn, there was an average delay of 5.2 days decade(-1) for sowing, 5.1 for emergence, 3.3 for tuber initiation, and 2.3 for maturity. The average phase duration decreased on average by 2.4 days decade(-1) for sowing to tuber initiation, 1.8 days decade(-1) for tuber initiation to maturity for spring, and 4.2 days decade(-1) for sowing to maturity. The average autumn phase duration decreased on average by 1.9 days decade(-1) for sowing to tuber initiation, 1.0 days decade(-1) for tuber initiation to maturity, and 2.9 days decade(-1) for sowing to maturity. With respect to the local weather observation, the average air temperature had increased 0.8 degrees C decade(-1) for spring and autumn from 1980 to 2018. The differences in spring and autumn phenology had a statistically significant negative correlation with the increase in temperature from 1980 to 2018. When the CSM-SUBSTOR-Potato model was used for a standard variety across locations and years, the predicted phenological stages, on average, occurred earlier due to increase in temperature from 1980 to 2018, while there was less impact on the observed phenological stages. This indicated that during the last four decade, adaptation strategies such as earlier planting for spring potato, and later planting for autumn, as well as the release of new cultivars that require more thermal time compared to the traditional cultivars have been implemented by growers have compensated for some part of temperature induced warming trends of spring and autumn potato phenology.