Impact of seasonal, geographical and varietal variations on amino acid profile of Sri Lankan rice varieties (Oryza sativa L.)

Abstract

With the aim of assessing the feasibility of utilization of amino acid (AA) profiles in characterization of rice varieties grown under distinct influential conditions, the impact of seasonal, geographical and varietal variations on AA and organic acid profiles in rice was investigated. Seven traditional rice varieties with diverse grain and agronomic characteristics were cultivated in two major distinct agro ecological regions of Sri Lanka across the two major cultivation seasons. The AA and organic acid compositions were determined using liquid chromatographic technique. Rice grains contained twenty AAs (41.2–75.1 mg/100 g) including Gamma Amino Butyric Acid (GABA) in free form and sixteen AAs in bound form (70.0–105.4 g/kg). Rice grains contained low levels (4.3–103.3 mg/kg) of fumaric, succinic and malic acids while citric acid (314.6–534.5 mg/kg) being the major organic acid present. Wet agro-ecological conditions favored total AA formation in rice. The impact caused from the season was found pronounced over the impact arising from the geographical location on the AAs in free form in rice. Principal Component Analysis (PCA) indicated that AA profile could be used for differentiation of rice based on the season and the variety.