Resource Allocation in Breeding for Fatty Acid Composition of Soybean Oil1

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Abstract
The objective of this study was to determine the allocation of testing resources that would provide the greatest genetic improvement for fatty acid composition in soybean [Glycine max (L.) Merr.] oil. Twenty random lines of maturity groups I to III were evaluated in two replications at seven environments in Iowa and Puerto Rico. The percentages of palmitic, stearic, oleic, linoleic, and linolenic acid were determined for two consecutive injections (analyses) of oil into a gas chromatograph from two 20‐seed samples from each of two plants per plot. Heritability estimate averages across fatty acids were 49% on a seed‐sample basis, 55% for plants, 63% for plots, and 93% for entry means. Two consecutive analyses were of little or no value for increasing the heritability of the five fatty acids compared with one analysis of an oil sample. The heritabilities for individual plant evaluation were effectively increased by analyzing more than one seed sample per plant. Evaluation of one sample from multiple plants in a plot was more effective than multiple samples from one plant when evaluating a pure line. Plot‐to‐plot variation was so small that evaluation of multiple plants in one plot was as effective as evaluation of multiple replications. The use of multiple environments was effective for increasing the heritabilities of the five fatty acids.