EFFECT OF PLANTING TIME AND LOCATION ON THE ISOFLAVONE CONTENT AND PROFILE OF DIFFERENT SOYBEANS [Glycine max (L.) MERRILL] CULTIVARS

Abstract

Isoflavones found in high concentrations in soybeans have received great attention due to their potential beneficial effects in human health. The effects of soybean planting time, location and seed type on isoflavone content and profile were evaluated using 40 cultivars.

Isoflavones were extracted with 80% methanol and analyzed by HPLC. Conditions were optimized to separate all reported soybean isoflavones plus an additional acylated genistein-related peak. Genistein derivatives were most abundant, followed by daidzein and glycitein-related isoflavones. Total isoflavone content varied greatly among cultivars, from 212 (Black Jet) to 3056 mg/Kg seed (Stressland). Planting time and location affected the isoflavone content. Soybeans planted at Poplar Hill in a double crop system exhibited higher isoflavone concentrations than soybeans planted during the full season at Wye Farm. Plants exposed to low temperatures and precipitation exhibited higher isoflavone content. It may be possible to select cultivars and growing conditions to obtain isoflavone rich seeds.