Variability dynamics of morphological characters in backcrosses of distant hybrids between maize (Zea mays L.) and teosinte (Zea mexicana (Schrad.) Kuntze)

Background. Maize breeding involving the crop’s wild relatives contributes to the broadening of its genetic polymorphism. However, in addition to useful agronomic traits, maize also receives from its wild relatives features unfavorable for breeding. The process of selection in a splitting progeny of distant maize hybrids requires thorough assessment of agronomic characters and removal of undesirable or harmful traits.

Materials and methods. The studies were conducted in the steppe zone of the North Caucasus Federal District (town of Prokhladny) in 2020–2024. The work involved 150 samples of the BC₁ and BC₅ populations obtained by hybridizing the 633MV and P346zakM maize lines with Zea mexicana (Schrad.) Kuntze from the VIR collection. Stimulation of flowering and hybridization of teosinte with maize were conducted with a short 10-hour day, using photoinsulators for 35–40 days, followed by a transition to a longer day (16 hours).

Results. The dynamics of variability was monitored for 9 important agronomic characters of the maize plant and ear in the segregating populations BC₁ and BC₅. An increase in the share of the maize genome in backcrosses was found to induce improvement in the ear structure more than in the structure and architectonics of the plant. Samples were identified in the BC₁ progeny that had pronounced bushiness and branching, high leafiness and stem pubescence, a long ear stalk, and abundant formation of primitive ears with 2–4 rows of grains and 6–8 grains in a row with asynchronous flowering. Plants in the BC₅ progeny exhibited less bushiness and leafiness, an ear stalk shorter than in BC₁, and a tendency to form 2 to 3 ears with synchronous flowering. Their ears consisted of 14–16 rows of grains, having 28–35 grains in a row.

Conclusion. The results of the studies confirm the transfer of valuable agronomic traits from teosinte, such as prolificacy, stem pubescence (trichomes), increased stem lignification, and resistance to dense sowing.

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