Resumo

LEON-VELASCO, Humberto et al. Evaluation of two generations of cold tolerant sorghum hybrids and parental lines. I: genetic variability and adaptability. Agrociencia [online]. 2009, vol.43, n.5, pp.483-496. ISSN 2521-9766.

In 1990, the first generation of cold tolerant experimental sorghum [Sorghum bicolor (L.) Moench] hybrids adapted to the Mexican High Central Valleys was evaluated, and in 1995, the second generation of hybrids was developed, with new B-and R- lines. With the purpose of evaluating genetic variability and adaptability of the two generations of hybrids and parental lines for grain yield and other traits, five experiments (three irrigated and two under rain fed conditions) were set up in 1996, in contrasting environments at 2250 m of altitude. Each experiment included 12 hybrids from the 1^st generation, 80 from the 2^nd, their corresponding parental lines and four testers, in an 11X11 square lattice with four repetitions. The experimental plot had two rows (3 m long, 0.7 wide) with one plant each 10 cm. The 2^nd generation hybrids had earlier flowering, greater yield and better agronomic characteristics than those from the 1^st generation and the cv. VA-110 (the best tester). The 2^nd generation R- lines had earlier flowering and higher yields than those from the 1^st; the 2^nd generation B- lines, with yields that were statistically similar, had earlier flowering than those of the 1^st and VA-110. The average yield of the ten top 2^nd generation hybrids was 7.97 t ha^-1 in the irrigated experiments and 2.49 t ha^-1 under rain fed. In the 1^st generation, the R- lines were stable for yield and hybrids were for early flowering; the R-lines and the hybrids of the 2^nd generation showed a stable and desirable yield.

Palavras-chave : Sorghum bicolor L. Moench; hybrids; parental lines; cold tolerance.

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