Variation of Functional Materials and Antioxidant Activity as Affected by Cultivation Environment in Pigmented Rice Varieties

Production of high quality pigmented rice contained with high content of anthocyanin, and polyphenol was significantly influenced by cultivation environments like transplanting date and cultivation location. This study was carried out to establish an optimum transplanting date and cultivation region to produce maximum content of anthocyanin, polyphenol and antioxidant activity of pigmented rice varieties (black, red colored). Three transplanting times (May 20, June 5, June 20) and four different sites (Miryang, Uiseong, Sangju, Bonghwa) were evaluated with five pigmented rice cultivars. Anthocyanin and total polyphenol index to average temperature during 30 days after heading (DAH) of black, red pigmented rice varieties showed that anthocyanin and total polyphenol contents were decreased by 10% and 9%, respectively, with increasing average temperature of 1 Celsius. The optimum ripening temperature of the 30 DAH for the production of high anthocyanin and total polyphenol was 22 to 23 Celsius for early maturity black rice, 21 to 22 Celsius for mid-late maturity of black and red rices, respectively. On the other hand, an estimated heading date of pigmented rices in return according to the optimum ripening temperature of the 30 DAH was ranged Aug. 11 to 17 for early maturity black rice, Aug. 25 for mid-late maturity black, red rice variety in Jecheon, Aug. 27 to Sep. 2 for early maturity type, Sep. 3 to 6 for mid-late type in Daegu. It seemed that Jecheon, Boeun, Mungyeong, and Yeongju were optimum regions for cultivation of pigmented rices. The estimated sowing date of pigmented rices for high anthocyanin and total polyphenol production based on the optimum heading date was May 18 to 26 for early maturity black rice variety, April 11 for mid-late black, red variety in Jecheon, May 23 to 28 for early type, April 9 to 26 for mid-late type in Boeun, respectively.