Effect of Drought Stress on Bioactives and Starch in Chilean Potato Landraces

Abstract

Despite the importance that environmental stress plays in the agronomic performance of plants, there is little agreement on its effect on bioactive compounds in tuber crops. A field study was carried out with eight diverse Chilean potato landraces and the commercial variety Desiree. Plants were subjected to drought stress for 6 weeks starting at 88 or 110 days after planting. As expected, the treatments had a strong impact on the yield and the number of tubers produced per plant (P<0.01). Surprisingly, there was no significant effect of the treatments on the content of phenolic compounds, anthocyanins or antioxidant activity (P>0.05). Resistant starch content is reported for the first time in these landraces, with values between 26 and 44% DW for raw samples and 5 and 7% DW for boiled samples in plants under well-watered conditions. Bioactive content in general was genotype-dependent and it changed significantly after boiling. Furthermore, our results suggest that bioactive content in raw samples is not necessarily a good predictor for the composition of boiled samples. This is highly relevant considering that screening of varieties with high bioactive content is often carried out in raw tubers. Our results provide valuable information regarding the effect of drought stress in tuber composition and highlight the unexplored potential of the Chilean potato gene pool in the development of varieties with higher bioactive content.