Interpopulation recurrent selection methods can be used for developing new heterotic patterns and enhancing those identified previously. The objective of this research was to estimate the direct and indirect responses to eight cycles of reciprocal full‐sib recurrent selection in maize (Zea mays L.) populations BS10 and BS11. The populations and their crosses corresponding to Cycles 0, 2, 4,6, and 8 were evaluated at two levels of inbreeding (F = 0 and F = 0.5), and populations also were testcrossed to the respective Cycle 0 populations and unrelated inbred lines. Entries were evaluated in eight environments. Eight cycles of selection were effective for increasing grain yield of the population cross (6.5% cycle−1), BS10 (3.0% cycle−1), and BS11 (1.6% cycle−1). Standability, prolificacy, and grain moisture also were changed in the desired directions, and, in most instances, the responses were linear across cycles of selection. Direct responses were greater than indirect responses for grain yield and Standability. The selected populations also performed better than did the unselected populations in crosses with unrelated testers. Changes in inbreeding depression and heterosis were associated with selection. Rates of direct and indirect responses for grain yield in the inbred populations tended to be greater than the rates of responses in the noninbred populations. Reciprocal full‐sib selection increased the frequency of homozygotes for favorable alleles in the BS10 and BS11 populations, which would be improved sources of vigorous inbred lines with good general combining ability. Reciprocal full‐sib selection seems to have increased the frequency of heterozygotes in the population crosses.

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A better understanding of the physiological processes related to nitrogen (N) metabolism in maize (Zea mays L.) inbred lines is important for increasing the efficiency of breeding programs targeting low-N environments. This study analyzed the response to contrasting N availability of morphophysiological traits in a set of 12 maize inbred lines, from different origins (USA and Argentina) and breeding eras (from 1952 onward). Traits included in the analysis were related to canopy structure, light interception, shoot biomass production, and grain yield. Our results indicate that (i) the start of N effects on canopy size was more related to a threshold crop leaf area index (about 2) than to a given leaf stage (i.e., V n ), (ii) the light attenuation coefficient value was not affected by N availability, (iii) variations in kernel number per plant were explained by prolificacy (r 2 5 0.59), and (iv) differences in harvest index were related to kernel number per plant (r 2 5 0.77). The most important finding of our research was the detection in some inbreds of a particular response of kernel number to plant growth rate around silking, different from the general model established for hybrids. In these inbreds an additional effect of N availability was detected as reduced kernel set at a given plant growth rate under N deficient conditions (i.e., reduced reproductive efficiency). This result highlights the need of more research on reproductive sink development in this type of germplasm.

The objective of this study was to determine the relationship between the amount and type of lipids, starch composition and structure, and storage proteins on popcorn expansion and to evaluate whether popcorns could be discriminated from other types of corn based on the protein elution parameters. Seven commercial Argentinean popcorn samples were used in the study and significant differences were observed in the popping volume of these popcorns. A significant negative correlation was observed between oleic acid and popping volume and a positive correlation was observed between linoleic acid and popping volume. Popcorn starch properties were significantly different from normal corn but no particular measured attribute of starch correlated with popping volume. α‐Zein proteins and glutelins significantly correlated with popcorn expansion volume with R2 = 0.963 and 0.744, respectively. The elution patterns of corn proteins could also be used to discriminate between different types of corn including popcorn, dent, and flint corns.

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