Synthetic Varieties of Sweet Corncob Derived from Mixtures of Lines and Single Crosses.

In a maize breeding program that includes the development of synthetic varieties (SVs), due to the availability of lines and single crosses, the need to save resources in the prediction step of the usually very numerous SVs that are possible even for a small number of potential parents (with n, the number of potential SVs is 2ⁿ-n+1), etc., it may be desirable to develop varieties with mixtures of L lines and s single crosses. In relation to such varieties, theoretical studies on their inbreeding coefficient and genotypic mean have been carried out; however, they have not been evaluated in the field. The aim of this study was to develop and experimentally evaluate a set of SVs formed with L lines and s single crosses [SV_{(L  s)}] to help determine their relevance. L and s take values that include zero [SV_{(0  s)} and SV_{(L  0)}, respectively]. In total, 34 SVs [20, 10 and 4 of the forms (0  s), (L  s) and (L  0), respectively] and 3 controls were assessed. The evaluation was performed in three locations. According to the combined analysis, the three types of SVs and the controls were not statistically different (α≤0.05) in total corncob yield (TCY), and first corncob (FCYQ) and second corncob (SCYQ) yield quality. This statistical equality extended to the rest of the variables studied (17). At location level, however, there were contrasting results due to the strong interaction between genotypes and environments detected (α≤0.05). For example, while in Zacatepec, the controls yielded more FCYQ than the SVs of the types (0  s), (L  s) and (L  0), in 4, 3 and 3 cases, respectively (α≤0.01 or α≤0.05), in San Martin, they had a similar behavior to that of Zacatepec; the controls were never higher in the 10 significant contrasts detected (α ≤ 0.05) involving 4, 4 and 2 SVs of the types (0  s), (L  s) and (L  0), respectively. The best yield of the SVs in San Martín is due to their better adaptation to this location, being their place of origin.