QUANTITATIVE GENETIC ANALYSIS OF TOTAL GLUCOSINOLATE, OIL AND PROTEIN CONTENTS IN ETHIOPIAN MUSTARD (BRASSICA CARINATA A. BRAUN)

Abstract

Cultivars of Ethiopian mustard are agronomically robust, but have very high levels of
total glucosinolates, which impair feed value of the meal though it is rich in protein of balanced amino
acids. This experiment was undertaken to assess the level of natural variation in total glucosinolate, and
study its inheritance together with that of oil and protein from a diallel cross of six inbred lines which
were field-tested in a randomized block design at two locations in Ethiopia. Seeds were analyzed using
HPLC (glucosinolates), NMR (oil) and NIRS (protein). Analyses of variance, Hayman’s method of diallel
analysis and a mixed linear model of genetic analysis were employed to estimate and predict genetic
parameters and interactions. There were significant differences among the parental lines as well as their
hybrids. The additive, dominance and cytoplasmic effects were highly significant for all the traits. The
additive component of variance, accounting for about 40% of the total variations in all the traits, was
twice as much as the dominance, which in turn was also about twice as much as the variation
accounted by the cytoplasm. A clear-cut case of inbreeding depression was evident with oil content.
Partial dominance was most prevalent in governing total glucosinolate although some levels of overdominance
were also noticed. It appeared that in addition to nuclear genes, cytoplasmic components,
which could be persistent or transient maternal effects, are also of significance in the inheritances of
these quantitative traits in B. carinata. There were at least two dominant genes with decreasing effect on
total glucosinolate for every single recessive gene of counter actions. The predominant additive
component of variation coupled with the high narrow-sense heritability may allow fixation of low
levels of total glucosinolate in recombinant inbred lines by selection.