Effect of crop maturity on leaf lipids.

Abstract

AbstractStudies extending throughout a period of 100 days' growth have been made on the total lipids of ryegrass, kale and fodder radish. Expressed in terms of % dry matter, lipids are at a maximum of about 10 to 11% during the period of vegetative growth. Lipid yields in absolute terms are maximal at 200–300 kg/ha after 56 to 70 days from sowing, at which stage lipids have fallen to 7 to 9% of total dry matter, according to species.Considering the fatty acids as a whole, dominant components are linolenic and palmitic, the latter rising and the former falling as maturation progresses. Minor fatty acids show no clear trend. More specific changes in fatty acid profiles are revealed when individual lipid classes are studied separately.Lipid classes display a predictable change in pattern as maturation progresses. New growth is rich in partial glycerides and free sterols, and particularly in mono‐ and digalactosyl diglycerides and sulphoquinovosyl diglyceride. Leaves from mature or senescing crops show progressive falls in these components, accompanied by the appearance of triglycerides, free fatty acids and steryl glycosides. In the case of fodder radish the accumulation of the hydrocarbon, n‐nonacosane, is a noteworthy feature. The principal phospholipids do not change appreciably with maturation.The trends observed on maturation show common general patterns for all the leafy crops so far studied. They do emphasise, however, the crucial importance of specifying both species and duration of growth when quoting data on leaf lipid compositions.