In Fall 2001 in Nova Scotia's Annapolis Valley (Canada), several million kilograms of processing and table-stock potatoes (Solanum tuberosum L.) were affected by a severe “musty” “off” flavor and “off” odor that persisted after cooking. 2,4,6-Trichloroanisole (TCA), a potent musty flavor/odor compound that is not known to be a potato metabolite was detected in samples of three potato lots rejected by consumers. To determine the role and source of TCA in the affected crop, samples of tubers from 30 fields were evaluated, including examination of production inputs and industry estimation of the “off” flavor, expert organoleptic assessment of flavor–odor intensity, and analytical quantitation of the TCA content of affected tubers, followed by a soil challenge to provoke TCA production. Production of “musty” potatoes was associated with unusually hot (>30 °C) soil temperatures during the 2001 growing season, and in some cases with γ-cyclohexane hexachloride (CHC) applied to control soil wireworm (putatively Limonius agonus Say). TCA quantitation and organoleptic assessment were in general agreement. Samples of soils from “idle” fields (no agricultural inputs for at least 8 years) and “production” fields (produced “off”-flavor potatoes in 2001) were subjected to several factors: 1) presence or absence of potato tubers; 2) preheating at 30 °C for 3 days, or no preheating; and followed by 3) no pesticides, or γ-CHC, chlorothalonil, chlorpyrifos, fludioxonil, imidacloprid, or linuron applied singly, or all six pesticides applied together. After incubation for 2 weeks at 22 °C day/14 °C night with a 14-hour photoperiod, solid-phase microextraction/gas chromatographic–mass spectrometric analysis revealed that untreated soils released small quantities of TCA (2.8 mol·kg−1) whereas higher quantities of TCA were present in soils treated with pesticides (3.8–6.6 mol·kg−1). The quantity of TCA released was not significantly affected by the presence or absence of potato tubers, but it was increased by preheating the soil sample, regardless of the other two factors, and by an interaction between pesticides and soil source. The quantity of TCA from both “idle” and “production” soils was highest when γ-CHC was added alone (214% and 284% of checks respectively). TCA production increased in the presence of the other five pesticides applied singly in “production” soils, but not in “idle” soils. Application of the six pesticides together increased TCA in both soils. Such an association of TCA-based “musty” “off” flavor with field soils containing γ-CHC and other pesticides combined with high soil temperature had not been reported previously.
Effects of soil temperatures on the rooting of cut-sprouts of sweet potato (Ipomoea batatas Lam.). I. Optimum soil temperature for rooting and effects of high soil temperatures on the physiological and anatomical characteristics of roots.