Biochemical Changes during Germination of the Tung Seed.

Abstract

The changes in chemical composition, respiratory gas exchange and enzymatic activities were followed through the germination of dry-stored and stratified tung seeds. The stratified seeds germinated more rapidly and uniformly than did the dry seeds. This effect of treatment was associated with the earlier absorption of water and activation of the enzymes, lipase and amylase in the stratified seeds. The higher enzyme activity in turn was reflected in a more efficient utilization of oil reserves as indicated by a more rapid drop in RQ values following planting and by the absence of free fatty acids in either the endosperm or the embryo oil of the stratified seeds until the seedlings had reached the stage preceding dissolution of the endosperm. As soon as the dry-stored seeds sprouted, free fatty acids were found, and the quantity increased rapidly as germination proceeded. The formation of saturated intermediates during the process of oil utilization was evident earlier in the oils of dry-stored seeds than in those of the more efficient stratified seeds. One end product of oil utilization was starch, which increased rapidly in the developing seedling while the oil of the endosperm decreased at a corresponding rate. At all stages of germination, irrespective of treatment, the embryo oil had a lower percentage of unsaturated glycerides than the endosperm oil. This indicates that the fatty acid radicals remain essentially unchanged in molecular weight prior to utilization with no detectable accumulation of lower molecular weight intermediates during their utilization.