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‘ND Henson’ soybean [Glycine max(L.) Merr.] (Reg. No. CV‐517, PI 675334) was first tested as ND09‐5604 and was released in January 2015 by the North Dakota Agricultural Experiment Station, North Dakota State University (NDSU), to provide producers with Maturity Group 0 conventional cultivar (relative maturity 0.0), generally adapted as a full‐season cultivar from 48 to 49° N latitude. ND Henson was evaluated by the NDSU soybean breeding program in advanced yield trials for a total of 27 location‐years that included 2011 to 2014. Testing for iron‐deficiency chlorosis (IDC) was conducted from 2012 to 2014 at a total of 10 sites located in eastern North Dakota, based on four replicates per site. Screening for resistance to races 3 and 4 of Phytophthora sojae(M.J. Kaufmann and J.W. Gerdemann) was conducted using the hypocotyl‐injection method. ND Henson was released because it has (i) resistance to races 3 and 4 of P. sojae, (ii) high yield in North Dakota environments, (iii) lodging resistance, and (iv) tolerance to IDC.

If recurrent selection methods are effective, the frequency of favorable alleles is expected to increase in the population. Random changes in gene frequency will also occur, if effective population size is small, due to the effect of sampling. In maize (Zea maysL.), where dominance gene action is positive in direction for traits such as grain yield, genetic drift results in inbreeding depression. Genetic drift is the change in gene frequency due to sampling in a finite population. Two major processes are expected to be operating to change the mean over cycles of recurrent selection in a population of finite size, selection acting to increase the mean and inbreeding depression due to genetic drift acting to decrease the mean. Estimation of the effects of genetic drift may be useful because the choice of what constitutes adequate effective population size may be altered, on the basis of empirical results. The objectives of the current study were to compare progress between reciprocal recurrent selection (RRS) and intrapopulation selection that included half‐sib (HT) and S2(S) selection in ‘Iowa Stiff Salk Synthetic’ (BSSSC0), and to separate the effects of selection from those of genetic drift. Effects due to selection for grain yield improvement of populations on a per‐cycle basis were not significantly different between methods of recurrent selection. When advanced cycles were evaluated for grain yield in crosses with an unrelated inbred line (Mo17), improvements paralleled improvement in the populations. The improved populations crossed to an unrelated population [BSCB1(R)Cn], which was used reciprocally as the tester for BSSS(R)Cn, suggested that response to RRS in improving the population cross mean was similar to the populations improved by either HT or S methods of selection. Effects of genetic drift were significant and should be considered in long‐term selection programs. Differences among selection methods for genetic drift were not significant.

Progress from selection is dependent on the additive variance within the population. Selection and genetic drift are two biological processes that can change gene frequencies and thus change the magnitude of the genetic variance of a breeding population over cycles of a recurrent selection program. Our objective was to determine if changes in genetic variance had occurred after recurrent selection primarily for grain yield in two maize (Zea maysL.) selection programs originating from ‘lowa Stiff Stalk Synthetic’ (BSSSCO). One program consisted of reciprocal recurrent selection and the second program consisted of seven cycles of half‐sib followed sequentially by three cycles of S2per se recurrent selection. Nonselected S2progenies from each of five populations [BSSSCO, BSSS(R)CS, BSSS(R)C9, BSI3(S)C0=BSSS(HT)C7, and BSI3(S)C3] were evaluated in a replications‐within‐sets experiment conducted in six environments. Average grain yield of the nonselected S2progenies relative to the original BSSSCO population increased 62% after nine cycles of reciprocal recurrent selection and 81% after seven cycles of half‐sib followed by three cycles of S2recurrent selection. Evidence suggests that genetic variance decreased in the population improved using reciprocal recurrent selection but not in the population improved by using the sequential half‐sib and S2recurrent selection methods. Estimates of genetic variance among random S2progenies decreased in the BSSS(R)C9 population, when compared to the BSSSCO, for stalk lodging; dropped ears; grain yield; and grain moisture at harvest, and increased for root lodging. Genetic variance estimates among random S2progenies increased for root and stalk lodging, and grain yield, but decreased for dropped ears and moisture at harvest for BSI3(S)C3 relative to BSSSCO.