Analysis of the relationships of environmental factors with seed oil and fatty acid concentrations of wild annual sunflower

Abstract

Seed oil and fatty acid concentrations of wild annual sunflower ( Helianthus annuus L.) seed vary greatly depending on the environmental conditions during development. Previous research has shown seed oil and fatty acid concentrations' response to temperature has been variable in wild and cultivated sunflower. The objective of the present study was to examine environmental factors, specifically temperature (maximum and minimum), total solar radiation and daylength for their direct and indirect effects on seed oil and fatty acid concentrations in seed oil of wild annual and cultivated sunflower using correlation and path-coefficient analyses. Ten populations of wild annual sunflower indigenous to areas from 29° to 46° N Lat. and 81° to 122° W Long. were grown in a randomized block design with three replications on Pullman clay loam (fine, mixed, thermic Torrertic Paleustoll) soils in 1980 and 1981. Three heads per genotype at early anthesis were sibbed or interpollinated at six different dates, and mature seeds were collected 28 days after sibbing for determination of seed oil and fatty acid concentrations. Hybrid ‘894’ was grown as a check for comparisons. Path-coefficient analyses indicated that minimum temperature and total solar radiation have the greatest direct effect on seed oil concentration in wild annual sunflower, though the influence was very low. In the cultivated hybrid, minimum temperature and daylength had the highest direct effect on seed oil concentration. Path-coefficient analyses also indicated that minimum temperature and solar radiation had the primary influence on oleic acid concentration in the wild and cultivated sunflower, with maximum temperature being less important. Linoleic acid concentration was primarily influenced (negatively) by minimum temperature and solar radiation as indicated by path-coefficient analyses in the wild and cultivated sunflower. The highest indirect effects of other environmental factors on fatty acid concentrations in the wild and cultivated sunflower were via minimum temperature followed by total solar radiation. There was a strong negative relation between linoleic and oleic fatty acid concentrations in the study. Path-coefficient analyses indicated that the wild annual sunflower reacted similarly to the cultivated sunflower to the environmental factors examined. This information will be useful to sunflower plant breeders when they incorporate the wild germplasm into commercial sunflower breeding lines.