Genotype by environment interaction influence on functional molecules (tocopherols and sterols) accumulation in sunflower oil

Tocopherol and sterol are non-dietary functional molecules in sunflower oil, which act as antioxidants, reduce cholesterol and improve immunity against diseases. The present study was designed to determine tocopherol and sterol contents in 13 high and two low oleic acid sunflower hybrids across two seasons (spring and autumn) and four locations under subtropical conditions of Pakistan with contrasting reproductive phase temperatures. The results showed that tocopherol and sterol contents varied across the seasons and locations. Autumn planting produced high tocopherol content. Moreover, locations under high temperature during reproductive phase negatively affected the sterol and tocopherol contents. High oleic acid hybrids yielded 38% higher tocopherol content than low oleic acid hybrids. High oleic acid hybrids produced higher sterol contents at all locations and seasons. Hybrids such as H4 and H5 are considered stable due to comparatively close values of tocopherol and sterol contents across the four locations when compared with standard checks and other hybrids during spring season as indicated from various stability parameters. Hybrids H8, H4 and H5 also manifested higher magnitude of heterosis for tocopherol and sterol contents that may be due to overdominance gene action. Breeding lines such as B.116.P, B.112.P and RH.365 were positive combiners for the investigated traits, thus likely carrying positive alleles for both tocopherol and sterol traits.