Jm. Bell et al., Comparisons of amino acid and protein levels in oil-extracted seeds of Brassica and Sinapis species, with observations on environmental effects, CAN J ANIM, 80(1), 2000, pp. 169-174
Seeds from 21 selections of Brassica and Sinapis were analyzed for crude pr
otein (CP; N x 6.25) and amino acid content following oil extraction and gr
inding. In exp. 1 three cultivars of B. napus, B. rapa and B. juncea were g
rown in four locations in 4 successive years, with duplicate samples taken
from each plot. Brassica juncea contained more CP (P < 0.001) than B. napus
or B. rapa (44.6 > 40.1 > 38.8%, respectively). Location affected CP level
but not the ranking among cultivars. Year-to-year effects on CP levels (P
< 0.001) were of lower magnitude than location effects. Treatments (cultiva
r, location, year) affected CP and amino acid levels differently. Amino aci
d levels expressed as percent of CP differed among many cultivars (P < 0.01
). Threonine, valine, histidine, lysine and arginine were strongly influenc
ed by location (P < 0.001), as were the dispensable amino acids serine, glu
tamine and tyrosine. In exp. 2, 10 cultivars and strains grown in one locat
ion and in three replicates resulted in greater CP levels in two B. juncea
cultivars than in B. napus and B. rapa (42.9 and 43.2 vs. 39.7 and 38.8%),
respectively, but lower levels of lysine and threonine in the CP (lysine: 5
.4 vs. 6.3; threonine: 3.5 and 3.7 vs. 3.8 and 4.0%). Brassica napus and B.
rapa ranked among the lowest in percent CP. In exp. 3, comparisons of eigh
t samples from B. napus, B. rapa and Sinapis alba plots revealed a CP range
of 38.1 to 45.0% but differences in amino acid content of the CP were rela
tively small.