Peer review

The development of corn containing proportionately large quantities of amylose starch initiated considerable interest during the past decade. Starch in commercial dent hybrids consists of two components, amylopectin and amylose. The amylose component is a straight-chain, or linear -type, compound formed by the chemical dehydration of a large number of glucose or dextrose units. In contrast. the amylopectin component has a branched, or nonlinear molecular, structure. The total endosperm starch of commercial dent hybrids consists of approximately 27% amylose and 73% amylopectin. Several genetic factors have been identified ( 1, 4, 8, 9, 1 2) which are associated with an increase in the amylose-starch synthesis of corn endosperm. In the amylose breeding program at Missouri, experimental hybrids which contain as much as 70% amylose have been developed. Previous information from the breeding of high-amylose corn suggested that variation in amylose content of relatively homozygous lines was environmentally induced . For example, at the Missouri Agriculture Experiment Station it was found that high-amylose lines grown in the Florida winter nursery were higher in amylose content than the same lines grown in Missouri the following summer. The present study was subsequently initiated to evaluate the possible influence of environment on the amylose content of corn endosperm. Experiments were designed to determine whether differences in amylose content within relatively homozygous inbred lines might be due to climatic and edaphic factors associated with various geographical regions, as well as these factors associated with year effects. Affirmative results would be in general agreement with numerous earlier studies on the influence of environment on the chemical components of other crop plants.

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