Abstract

The present study assessed the impact of moderately high temperatures (3-4°C above ambient temperature) during tuber bulking on yield and physiological traits of Chilean native (Chona) and commercial varieties of potato (Karú-Desiree) under different water regimes. During two growing seasons, four treatments were applied for 40-days from the beginning of tuber bulking under field conditions: ambient temperature without irrigation (T0H0) and with irrigation (T0H1), temperature increase without irrigation (T1H0) and with irrigation (T1H1). Plots were heated using polyethylene chambers equipped with thermostatic electric heaters. Plots were arranged in a split-plot design with 3 replicates (blocks). The yield increased with irrigation but not with temperature, whatever the genotype. The harvest index, average tuber weight, tuber number and dry matter content varied mainly depending on water availability and genotype. In Chona, T1H1 increased the photosynthesis rate by 30% and the RuBisCo content by 680% compared to T0H1. Karú showed lower concentrations of foliar pigments than Chona which maintained its green foliage for longer time under T1H0 and T1H1 treatments. Proline concentration increased in leaves and tubers of plants without irrigation, showing that it contributed to osmotic adjustment in potato. The concentrations of MDA and total ascorbate content of leaves varied mainly depending on water availability and genotype, showing that oxidative stress was observed without irrigation. In conclusion, the moderate increase in ambient temperature projected for southern Chile will not adversely affect potato production, however water availability will play an important role in productivity increase under climate change conditions.