Testcross Response to Four Cycles of Half‐sib and S₂ Recurrent Selection in the BS13 Maize (Zea mays L.) Population

Abstract

Inbred progeny recurrent selection has been shown to be theoretically superior to several forms of noninbred‐progeny recurrent selection. However, recent improvements to theory and empirical evidence suggest that inbred‐progeny recurrent selection is not a superior method of recurrent selection. In the BS13(S) population, inbred‐progeny recurrent selection has not been effective at improving population per se performance. However, no other selection programs have been evaluated in BS13(S), so there is no basis to compare inbred‐progeny recurrent selection in BS13(S) to other methods to determine if other methods might be more effective. Four cycles of half‐sib selection with inbred line B97 as tester have been completed. The first four cycles of half‐sib selection and first four cycles of inbred‐progeny selection were testcrossed to B97 and evaluated in a replicated experiment in 2007 and 2008. Half‐sib selection improved grain yield, grain moisture, stalk lodging, root lodging, test weight, and final plant density, whereas inbred‐progeny selection did not improve any of these traits. This study adds to growing empirical literature suggesting that inbred‐progeny recurrent selection is inferior to noninbred‐progeny selection methods. A hypothesis has been put forth that pseudo‐overdominance caused by linkage disequilibrium may have limited response to inbred‐progeny recurrent selection in BS13(S) as well as other maize populations.

Genetic Variances and Heritabilities of Traits of an Early Yellow Maize Population after Cycles of Improvement for Striga Resistance and Drought Tolerance

“…They concluded that the selection method involving inbred progenies was responsible for the superior gains from selection in BS11 compared with other selection methods. Contrary to theoretical arguments that recurrent selection involving inbred progenies is superior to mass selection and the half-sib recurrent selection methods, it has been demonstrated empirically that S 1 or S 2 family selection is not always superior (Coors, 1999;Wardyn et al, 2009;Edwards, 2010). For example, Wardyn et al (2009) demonstrated that predicted responses to S 1 or S 2 family selection did not show any advantages over half-sib methods in three maize populations.…”

“…They concluded that dominance genetic variance was equally important and needed to be considered in future selection programs. Contrary to theoretical arguments that recurrent selection involving inbred progenies is superior to mass selection and the half-sib recurrent selection methods, it has been demonstrated empirically that S 1 or S 2 family selection is not always superior (Coors, 1999;Wardyn et al, 2009;Edwards, 2010). In the absence of over dominance, the S 1 or S 2 family selection method is superior to other population improvement methods (Lamkey, 1992).…”

“…Weyhrich et al (1998) investigated the responses to selection of a maize population using seven methods of recurrent selection and showed that all the methods were effective in improvement of population performance per se for yield. Similarly, Edwards (2010) indicated that pseudo-overdominance because of linkage disequilibrium may limit responses to S 1 or S 2 family selection in maize breeding populations. They concluded that the selection method involving inbred progenies was responsible for the superior gains from selection in BS11 compared with other selection methods.…”

Genotype × Environment Interaction for Plant Density Response in Maize (Zea mays L.)

“…Although data are not available on the scale of the present study to speculate on how G ´ E will affect plant density response curves in modern elite hybrids, the present study suggests additional work should be conducted to address that question. Additional work is planned for the data set in the present study to model G ´ E using climatic and environmental information in addition to phenotypic knowledge of the populations from other studies (Brekke et al, 2011a(Brekke et al, , 2011bEdwards, 2010) in a modeling framework. Even if the G ´ E does not affect plant density response curves in modern hybrids to the extent observed in the present study, the data described here will provide an invaluable resource for future work to better understand how plant density response curves are affected by G ´ E. Typical breeding programs do not have the resources to grow all materials at several plant densities in all environments.…”

“…Inbred line Mo17 was grown at all locations in 2011, B73 at all locations in 2011 and 2012, and B97 at all locations in 2010, 2011, and 2012. The data set in this study was the result of two experiments with treatments that changed across Penney and Eberhart (1971); Keeratinijakal and Lamkey (1993) BSSS(HT)C7 Seven cycles of half-Sib recurrent selection initiated in BSSS with IA 13 as a tester Eberhart et al (1973) BS13(S)C0 Recombination of 29 S 1 lines from BSSS(HT)C7 Lamkey (1992) BS13(HI)C5 Five cycles of half-sib recurrent selection starting with BS13(S) C0 with B97 as a tester Edwards (2010) BSSS(R)C17 Seventeen cycles of reciprocal recurrent selection with BSCB1(R) population Penny and Eberhart (1971); Eberhart et al (1973); Keeratinijakal and Lamkey (1993)…”