described by Nour et al. (2010) . Chromatographic separation was performed with an HPLC system (1260 Series; Agilent Technologies, Santa Clara, CA), using 50 m m potassium dihydrogen orthophosphate buffer, pH 2.8, as a mobile phase (flow rate of 0.7 mL
ruthenium red for 20 min and observed for red color ( Jensen, 1962 ). A 1% Alcian blue 8GX solution in 3% acetic acid (pH 2.5) was applied to tissue sections for 20 min, rinsed with water, and the sections were examined for blue color under visible radiation
dihydrogen phosphate (H 2 PO 4 − ) and then to hydrogen phosphate (HPO 4 2− ) occurs at pH 2.1 and 7.2, respectively ( Schachtman et al., 1998 ). Plants can only absorb P as the free orthophosphate ions H 2 PO 4 − and HPO 4 2− ( Becquer et al., 2014
, trachelium, and zinnia stems. Control solutions. Cut stems were held in DI water (pH 3.1–4.2; EC 0 dS·m −1 ), DI water supplemented with 200 mg·L −1 8-HQC (pH 2.8–3.1; EC 0.12–0.15 dS·m −1 ), tap water (pH 6.3–7.1; EC 0.18–0.23 dS·m −1 ), or tap water with 8
. The chromatographic column (3 μm, 150 × 3 mm) was an Acclaim 120 C18 (Dionex, Sunnyvale, CA), and the column temperature was 30 °C. Mobile phase A was acetonitrile, mobile phase B was water (adjusted to pH 2.6 with acetic acid), and the flow rate was 0
temperature ( WSU AgWeatherNet, 2019 ). During the growing season, the average RH is 80%, while total precipitation is 39 mm per month. The soil is Skagit silt loam, a fine-silty mixed nonacid mesic Typic Fluvaquents, with 6.5 pH, 2.7% organic matter, and is
pH using a pH meter (Model 215; Denver Instrument, Bohemia, NY). We extracted P, K, Ca, Mg, Na, and S using the Mehlich III extractant (a dilute acid-fluoride-EDTA solution of pH 2.5 that consists of 0.2 N CH 3 -COOH, 0.25 N NH 4 NO 3 , 0.015 N NH 4 F
thawed, placed in cheesecloth, and squeezed to extract the juice from the berries. Titratable acidity and pH were measured by an 877 Titrino Plus (Metrohm AG, Herisau, Switzerland) standardized to pH 2.0, 4.0, 7.0, and 10.0 buffers. Titratable acidity was
) with an automated titrimeter and electrode standardized to pH 2.0, 4.0, 7.0, and 10.0 buffers. Titratable acidity was determined using 6 g of juice diluted with 50 mL of deionized, degassed water by titration of 0.1 N sodium hydroxide to an endpoint of
monobasic (KH 2 PO 4 , 0.5%, w/v) at pH 2.5 with metaphosphoric acid (HPO 3 , 0.1%, w/v). The retention time of the AA peak was 2.5 min. After comparison of retention time with the AA standard, the peak was identified. The amount of total AA content in