The influence of environment upon the composition of sunflower seed oils. II.—Composition of the seed oils of sunflowers grown in English gardens from five specimens of different African sunflower seed

Abstract

Five specimens of sunflower seeds from Africa, the oils in which varied widely in composition (44-72% linoleic acid), were grown in three English gardens in West and East Cheshire and Kent. The composition of the resulting English-grown seed oils was broadly the same in all cases, irrespective of the seed sown. Most of the oils contained, on an average, 68-70% of linoleic acid, but the extreme range of linoleic acid varied from about 60 t o 7j7,. The apparent rxplanation of these subordinate differences may lie in the cffect of direct sunlight on the ripening seed heads, since flower-heads that became completely inverted and faced downwards gave the oils with highest linoleic acid content ; others, in which the stems turned more or less through go" so that the lieads were more freely exposed to direct light, gave oils with somewhat reduced linoleic acid content. It is concluded that varietal factors play little part in determining the composition of sunflower seed oils. The main effect is that high linoleic content is conditioned by slow development and ripening of the seed, and rice z w s a ; climatic (temperature) conditions and also, probably, the degree of incidence of light on the ripening seed heads are tlie factors which control the rate of development of the sect1 and also the relative unsaturation of the seed oil.

The Effect of Temperature on the Oil Content and Fatty Acid Composition of the Oils From Several Oil Seed Crops

“…This conclusion was largely based on the analysis of the seed oils from plants grown a t different geographical locations (7). However, no record of te~nperatures were available, no consideration was given to the possible effect of photoperiod and except for flax (7) and sunflowers (1,2), little consideration was given to the variety of the crop involved. I t is now well ltnown that considerable variation in fatty acid composition can exist between varieties of safflower (9) and rape (1 1).…”