Since the first discovery and reporting of high stearic acid composition of germ oil in PI 175334 (Nepal), W. Agric. Food Chem. 18:365-370, 1970), selfing in an ear-to-row breeding procedure has resulted in a uniform plant type with various levels of stearic acid. A number of closely related lines derived from PI 175334 were grown in 1982, from which 250 selfed ears were obtained and analyzed for fatty acid composition. The majority of ears (240) had kernels with germ oil ranging from 13 to 19.8% stearic acid composition. Only 10 ears had less than 13% stearic acid composition of oil, and these were discarded. Seed of the 240 ears was combined into seven populations based on stearic acid levels as shown in Table 1. The average fatty acid composition of these populations shows a strong inverse relationship between stearic acid and linoleic acid. An increase in stearic acid resulted in a corresponding decrease in linoleic acid. The overall correlation coefficient was -0.87 between stearic and linoleic acid in these populations. There was a small but consistent increase in palmitic acid and decrease in oleic acid associated with an increase in stearic acid.
Seed from the 34 ears with stearic acid composition between 18 and 19% of total oil was combined and released as GE180. Since GE180 has an 8 to 9-fold increase in stearic acid percentage as compared to most maize germplasm, it was released for use in oil genetic, physiology, and biochemistry studies. Seed from the other populations with 1% increments of stearic acid between 13 and 18% was not released, but will be made available to anyone wishing to study these lines.
Table 1. Average fatty acid Composition of oil from various high stearic acid populations.
M. D. Jellum
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