Studies on the Fat Metabolism of Light‐ and Dark‐Germinated Seeds of Scots Pine (Pinus silvestris L.)

Abstract

The aim of the present investigation has been to study whether the light factor influences the fat metabolism in the scots pine seeds in any way which could be correlated with its effect on the germination. The studies have been made on petroleum ether extracts. Gravimetric determinations showed small increases of extractable material during the first 24 hours of the germination process. After a longer time there was a small but insignificant consumption (72 hours). No effects of the light factor could be found. Investigations with gas‐liquid chromatography on the corresponding extracts did not reveal any influence on the fatty acid composition, either of the light factor or of the germination period. The main identified fatty acids were linoleic, oleic, palmitic and stearic acid. One of the unidentified components (“c”) was also present in a large amount. Principally the same acids were found as free fatty acids but in different proportions: oleic, palmitic, linoleic and stearic acid. After the onset of the imbibition the linoleic acid appeared in the largest proportion. The total content of free fatty acids increased with increasing germination period. This was found both in titration experiments and in gas‐liquid chromatography with an internal standard. The latter method permitted studies on the content of the individual acids. During the period 0–21 hours there were no evident differences between the content in light‐ and dark‐germinated seeds, during the period up till 48 hours there was lower content in the light‐germinated seeds concomitant with the onset of the mitotic activity in these seeds and after 48 hours there was a rapid increase in the same ones corresponding to the opening of the seed coats and the incipient protrusion of the rootlets. Thus changes of free fatty acid content were found only after the start of the light‐induced growth but not under the preliminary phase, which earlier has been shown to be the determinative one in the light control of the germination.

Appearance of the zeatin riboside type of cytokinin inPinus sylvestrisseeds after red light treatment

“…It is therefore tempting to suggest a role for the ZRtype cytokinins in the embryo mitoses, which according to Nyman (1963) takes place just prior to the protrusion of the Scots pine radicle, a hypothesis long put forward for various species (see Van Staden, 1983). Furthermore, there was also a transient increase in endogenous indoleacetic acid content in the Scots pine seed at the stage of radicle protrusion (Tillberg, 1977).…”

“…3) soaked with 10 ml tap water. Seeds were held in darkness and imbibed with water for 5 h to increase their photosensitivity (Nyman, 1963). They were then irradiated with either R for 15 min or with R for 15 min followed by FR for 5 min.…”