Yield Component Responses Associated with Increased Groat Yield after Recurrent Selection in Oat
Analysis of yield into components may provide information for devising efficient selection strategies for improving yield or traits correlated with yield in cereal crops. Our objective was to analyze changes in yield components associated with increased groat yields observed within three S1-recurrent selection programs for high protein yield (grain yield × groat-protein concentration) in oat (Avena sativa L.). Selection emphasized high protein yield per se (HGP), with no restrictions in grain yield or groat-protein concentration; high protein yield due only to high grain (HG) yield; and high protein yield due to both high groat-protein concentration and high grain yield (HP). Responses of yield components to these selection criteria were evaluated by growing 30 to 60 random S0-derived lines from each selection cycle (C) in a hill plot experiment at two Iowa locations in 1989. Above ground biomass increased 7%, vegetative growth index (vegetative yield/number of days to heading) increased 9%, and groat index (groat yield/biomass) increased 8% from C0 to C5 in HGP. Changes in biomass, vegetative growth index, and groat index from C0 to C5 of HG were similar to those of HGP in direction, but were greater in magnitude (15,13, and 17% increases, respectively). Biomass increased by 5% from C0 to C5 in HP, but vegetative growth index and groat index did not change significantly. Seed number per plot increased in HGP by 16.6%, in HG by 28.2%, and in HP by 11.4%. Groat weight remained unchanged in all three lines of descent. Thus, the increased groat yields in all lines of descent were due first to greater biomass and second to high seed numbers.
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