Direct and correlated responses to three S1-recurrent selection strategies for increasing protein yield in oat

Abstract

The objectives of this study were to evaluate the efficacy of S1-recurrent selection for increasing groat (caryopsis)-protein yield in oat (Avena sativa L.) and to compare the effects of three selection strategies on correlated responses in groat yield and groat-protein concentration. Three S1-recurrent selection programs were conducted for five cycles. Selection criteria in each program (line of descent) emphasized different components of protein yield; high grain yield in HG, both high grain yield and high groat-protein concentration in HP, and protein yield per se in HGP. Thirty to sixty random S0-derived lines from each cycle and ten check lines were evaluated in one year at two locations to estimate the response to selection. Groat-protein yield increased 4.4% cycle-1 in HG, 3.4% cycle-1 in HP, and 2.2% cycle-1 in HGP. Gains in groat yield were 7% cycle-1 in HG, 1% cycle-1 in HP, and 3% cycle-1 in HGP. Mean groat-protein yield and groat yield in the cycle 5 (C5) populations of all three lines of descent were equal to or slightly higher than those of high yielding cultivars. The HG line of descent showed a significant decrease from 193 to 175 g kg-1 groat protein, while the HP line of descent showed a significant increase from 202 to 218 g kg-1. The HGP line of descent showed a small but significant decline in groat protein from 200 to 192 g kg-1. In comparison, the high-protein commercial cultivars contained about 210 g kg-1 groat protein. The C5 population of the HP line of descent had a unique combination of high groat yield and high groat-protein concentration. Genotypic variances for groat-protein yield, groat yield, and groat-protein concentration were not always significant in the various cycles of the three lines of descent, but in no instance was there a consistent change from C0 to C5. S1-recurrent selection was effective for increasing groat-protein yield of oat, and with the proper germplasm and selection strategy both groat yield and groat-protein concentration can be improved simultaneously.