Análisis agroeeonómico del uso de semilla mejorada de maíz en los valles altos de México.

The productive capacity of fue generations F1 (commercial seed) and F2 (recycled seed) from the H-34, H- 33, H-68, and H-36 corn hybrids, produced for high valleys of Mexico by the Centro Nacional de Investigaciones Forestales y Agropecuarias (lNIFAP) was evaluated. The simple cross of CIMMYT, and as a reference, of an open pollinated corn variety from INIFAP (V-23) were also evaluated. An analysis of yield and other agronomic characteristics of the materials was performed. Likewise, an economic analysis to determine the optimal alternative for growers concerning the use of seeds during two cycles, was undertaken. All of the hybrids showeda yield decrease when using F2 seed, compared to the use of F2 seed, with the decrease varying from 5.5% to 51.3%. The greatest yield decrease due to use of seed F2 corresponded to the simple hybrid H-34 (F2), which only yielded 4.327 kglha, as compared to 8.892 kg/ha for the corresponding F1 seed. Yield of the V-23 variety was 7.488 kg/ha, which was statistically surpassed by the CIMMYT F1 simple cross (9.930 kglha), and was not significantly different from H-34 (F1), H-33 (F1) - 8.887 kglha; H-36 (F1) - 9.133 kglha; and F2 CIMMYT simple crosses (8.999 kglha). Excluding the latter, no other genotype surpassed the yield of the F2 seed variety. Economic analysis was based on the yields' trial results, on information about prices of seeds and grains, and the seed/hectare rateo The best option for corn producers of the region is to use double hybrid commercial seeds (F1) in both years, which provides a marginal return rate of over 1.500%.