The role of root zone temperature on physiological and phytochemical compositions of some pigmented potato (Solanum tuberosum L.) cultivars

Abstract

A greenhouse study was conducted to evaluate the effects of three root zone temperatures (20, 24 and 28°C) on growth and chemical compositions in seed mini tubers of four pigmented Solanum tuberosum cultivars (Non-pigmented control (BP1), Salad Blue (SB), Pink Fir Apple (PFA) and Highland Burgundy Red (HBR)). The results indicate that RZT 24°C significantly increased plant height and tuber weight. RZT 28°C increased polyphenols (mg GA/g) in cv. BP1 (1.47) and PFA (2.09). Cultivars BP1, SB and PFA recorded 84.37, 83.08 and 124.86 µg/g ascorbic acid, respectively. The highest caffeic acid content was reported in cv. HBR (1380.74 µg/g) under the control RZT and lowest in the non-pigmented BP1 (40.48 µg/g) at 20°C RZT. In similar manner, the highest chlorogenic acid (µg/g) value was reported in cv. HBR (426.20 µg/g) under the control RZT and lowest in the non-pigmented BP1 (6.79 µg/g) at 20°C RZT. DPPH activity was highest in cv. SB (26.43 µmol TE/g) under the control RZT. Although these results indicate a variable response of various parameters to different root zone temperatures, the high values recorded under the control RZT presumably show the natural concentrations of the phytochemicals at room temperature without heat application. The RZT recommendations would therefore be based on specific needs. Furthermore, the secondary metabolites reported in the pigmented cultivars SB, PFA and HBR and their associated potential health benefits offer a substantial basis for their inclusion in the diet, regardless of their low yielding capacity.

Keywords

• antioxidants
• ascorbic acid
• phenolic acids
• root zone temperature
• seed tuber potatoes