Regulation of anthocyanin accumulation in rice (Oryza sativa L. subsp. indica) using MgSO4 spraying and low temperature

Pericarp pigmented grains of rice have been reported as anthocyanin enriched source of antioxidants. The aim of this investigation was to regulate anthocyanin accumulation in pericarp pigmented rice cv. ‘Hom Nil’ using 0, 10, 50, and 100 mM MgSO₄ foliar spray. The level of magnesium content in the leaf tissues treated with 100 mM MgSO₄ for 2 d increased 2.6 times over control (0 mM MgSO₄). After growing the treated plants under 16°C for 28 d, photosynthetic abilities were reduced by 17?93%, leading to retarded plant height (39?42% less than control). In addition, grain yield per panicle of the plants grown under 16°C for 28 d was reduced by 26?75% compared to the plants grown under 32°C.Total anthocyanin concentration, cyanidin-3-glucoside and peonidin-3-glucoside in the pericarp of the grains derived from the rice treated with 100 mM MgSO₄ was increased 3.8 times over the control. Peonidin-3-glucoside, a dominant compound was reported for the first time. The study concludes that Mg?enrichment may play a key role as a metalloid in stabilizing anthocyanin, a secondary metabolite in the leaf sheath tissues and pericarp of grains in ‘Hom Nil’ rice cultivar.