The aim of this work was to evaluate the influence of year condition, variety and fertilization treatments on content of isoflavones genistein and daidzein in soy seeds. Four soybean varieties Korada, Supra, Alma Ata and OAC Vision were growing at experimental farm Oponice (south-western Slovakia) in 2007-2008. The experimental site belongs to warm and moderate arid climatic region. Soybean was growing after sugar beat forecrop each year. The conventional tillage practices were used. Fertilization treatments were as follows: I. Non-fertilized control, II. LAV 27 % (40 kg ha -1 N) in growing stage of first pair of true leaves (BBCH 101), III. Humix komplet (rate 8 L ha -1 ) applied in growing stage of first pair of true leaves (4 L ha -1 ) and before flowering (4 L ha -1 ), IV. DAM 390 (20 kg ha -1 of N) applied in growing stage before flowering (BBCH 501). Seeds were inoculated by HiStick preparation. Concentration of daidzein and genistein were determined using a high-performance liquid chromatography. All nitrogen fertilization treatment significantly increases the yield of soy seeds. High significant correlation between daidzein concentration and genistein was confirmed. The positive correlation of daidzein with seed yield suggests that daidzein concentration significantly increased as seed yield went up. In contrast, application of different fertilizers at two development stage of soy plant (BBCH 101 and BBCH501) consistently decreased the daidzein content, except OAC Vision variety with very low content of daidzein, with comparison to variety Supra. Averaged over fertilization treatments content of daidzein and genistein were decrease by nitrogen input relative to  zero nitrogen as follows: in LAV treatment  27% of daidzein and 21.9% of genistein; after Humix application daidzein/ genistein  content decrease amount   22.3/36.8%  and DAM application have decreased the content of daidzein  of 8.0% and genistein content  of 20.9%  soy seeds. On the other hand nitrogen input increased the total production of isoflavones due to significant increasing in soy seeds yield. Appropriate nitrogen management may be among the important factors controlling isoflavones concentration and production.

soybean, variety, fertilization, yield, daidzein, genistein, correlation

Presentation: oral