Comparative analysis of potato hail recovery by cultivars differing in time to maturity and agroecological adaptability under different hail severity conditions

Abstract

Hailstorms are projected to intensify under climate change, posing a severe and unpredictable threat to potato production. The physical impact of hail disrupts canopy development, reduces photosynthetic capacity, and subsequently limits carbohydrate assimilation necessary for tuber growth and quality. This presents severe economic consequences for farmers, as yield reductions are coupled with quality downgrades that reduce marketability and processing potential. This necessitates the development of effective mitigation strategies to reduce hailstorm risks. Current mitigation strategies are expensive and often impractical. Cultivar selection has emerged as an affordable, practical, and environmentally friendly strategy for hail mitigation. The overall aim of the study was to assess the recovery responses of selected potato cultivars to simulated hail damage, to inform cultivar-based tactical decision-making for minimising hail-related losses. A literature review was first conducted to evaluate the effectiveness, affordability, scalability, and accessibility of existing hail mitigation strategies. The review confirmed the limitations of current practices and recommended the combination of strategies in mitigating hail damage as well as the use of other cultural strategies, such as cultivar selection. Field trials were conducted in the 2023/24 and 2024/25 seasons at the University of Limpopo Experimental Farm (Syferkuil). The trials were laid out in a randomised complete block design, arranged in a 5 × 4 factorial design. The experimental factors comprised five canopy disruption levels (0%, 25%, 50%, 75% and 100%) applied to four cultivars (Sababa – early, Mondial – mid, Tyson – mid, and Panamera – late maturing) prior to tuber initiation. Yield, canopy cover, and time to maturity were recorded in the field. Post-harvest analysis was conducted using a completely randomised design in a 5 × 4 factorial arrangement, where tuber size, dry matter, and starch content were recorded to evaluate tuber quality under hail stress. Yield and tuber quality characteristics were statistically similar across the seasons (p > 0.05), indicating that seasonal variation did not influence yield or quality traits. Therefore, values were averaged across the two seasons to provide a single comparative estimate for each cultivar. Panamera, the late-maturing cultivar, exhibited the highest recovery across all parameters, with yield recovery of 63.75%, large tuber recovery of 88.61%, tuber dry matter recovery of 66.36%, and starch recovery of 57.81% compared to the other tested cultivars. This superior performance was attributed to its longer maturity period, higher yield base, and a taller, narrower leaf phenotype that enabled the development of a large canopy capable of sustained regrowth. However, regression analysis indicated that Panamera experienced a higher rate of starch loss compared to Sababa. This indicated a physiological strategy in which Sababa prioritises starch accumulation following hail damage. However, its overall starch recovery was limited due to its relatively low baseline starch content of 13.4% (Table 4.1). The results of this study indicate that cultivar selection is a practical solution for mitigating hail damage in potatoes. Traits such as a late-maturing period, larger canopy size, higher yield base, and higher starch content base should be prioritised when breeding for hail resilience. Farmers in hail-prone regions can adopt cultivars such as Panamera to minimise losses and maximise yield and tuber quality. However, since yield and tuber quality losses still occur, it is recommended that early warning systems be strengthened and that planting dates be adjusted to avoid peak hail periods. Future research should expand the sample of early-, mid-, and late-maturing cultivars to confirm these findings.