Temperature-Associated Effects on Flavonol Content in Field-Grown Phaseolus vulgaris L. Zolfino del Pratomagno

Abstract

Combining the need to increase local Phaseolus vulgaris L. production, with the objective of identifying which abiotic inductors (irrigation and temperature) and/or elicitors (nitrogen fertilizer treatment) can be used as potential strategies to improve flavonol content, open-field experiments were conducted in Pisa and Bologna (Italy) over two years, using the local landrace of interest “Zolfino del Pratomagno”, and a commercial variety, Verdone. Full-irrigation and nitrogen treatment, individually, and in combination, increased yield and decreased flavonols, respectively, in both genotypes and locations. Yield, under all treatments, was significantly higher in Pisa (17.5–21.9 °C) than Bologna (21.4–24.8 °C) for Verdone, but was the equivalent for Zolfino. An inverse correlation between average mean temperature and flavonol content was evident only in Zolfino. The feasibility of increasing dietary flavonol production using decreasing temperature as a strategy with some degree of control was then tested by cultivating Zolfino at different altitudes (108 (24 °C) to 800 m a.s.l. (18 °C)) in Pratomagno. Increasing the altitude induced a significant 3-fold increase in seed-coat kaempferol glycosides, comprising more than 95% of the total flavonols. Temperature-associated effects on flavonol synthesis warrants consideration when selecting a cultivation environment to augment the kaempferol-based, anticarcinogenic benefits of Zolfino.