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was carried out on a 250 × 4.6-mm, 5-μm column (Diamonsil C18; Dikma Technologies, Foothill Ranch, CA). Detection was operated at 214-nm wavelength with 0.1 mmol·L −1 KH 2 PO 4 (pH = 2.6) as mobile phase passed through a 0.45-μm membrane filter. The

(pH 2.0, using 6 M HCl). With a separatory funnel, the free phenolic compounds were extracted with diethyl ether (5 × 20-mL portions). The extractant was composed of acetone, water, and acetic acid. The organic phase (acetone) was removed using the

remaining pellet was again resuspended in 40 mL of HCl, pH 2.5, and incubated for 90 min at 60 °C. The extract was centrifuged and filtered to obtain the acid-soluble pectin (ASP). The remaining pellet was resuspended in 40 mL of 0.05 m NaOH and incubated

) 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

Detector set at 210 nm using an X-bridge C18 column (4.6 × 250 mm, 5 μm, Waters Corporation) operated at 30 °C. The elution solvent was 0.01 mol·L −1 sulfuric acid (pH 2.6) passed at a rate of 0.5 mL·min −1 . The quantity and type of organic acids were

  =   0.8780   ×   Δ pH 3 +   1.3369   ×   Δ pH 2 +   9.9856   ×   Δ pH −   0.2569 [1] Plant growth was measured as root and shoot dry weight gain during the experiment. Root and shoot tissue from seedlings and from final replicates was oven-dried for 48 h

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

of 5 m m potassium phosphate monobasic (KH 2 PO 4 ), pH 2.65, with 0.1% of formic acid (solution A) and methanol with 0.1% of formic acid (solution B). The linear gradient of the mobile phase was programmed as follows: 5% to 15% B for 1 min, followed

20 m m potassium phosphate (pH 2.5 by phosphoric acid) at a flow rate of 1 mL/min and were detected at 210 nm. L-Proline (Sigma) dissolved in the 20 mm potassium phosphate solution was used to calibrate the standard curve. The amount of proline in

. 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