<span name="style_bold">Seed vigor and productivity of maize varieties. </span>In Cuautitlán Izcalli, Mexico (FESC-UNAM), during the 2004 spring-summer season, in order to determine the effect of harvest time on the vigor of maize seeds, the productivity of four early-maturing, yellow-grain maize varieties, harvested at five different times and stored until spring-summer 2007 was determined. For two varieties, seed germination and vigor were measured, as well as the differences in vigor due to seed size (small and large, smaller than or larger than 7 mm, respectively) during each harvest time. The percentage of dry matter, grain ratio and yield were measured for the four genotypes. In the field, a randomized complete block design with three replications was used for treatment distribution. Statistical analysis was performed as a factorial, considering the factors genotype, harvesting dates, and the interaction genotype x harvesting date. The highest yields (6541 kg/ha, 7335 kg/ha and 7550 kg/ha) were obtained at harvesting dates of 149, 152 and 156 days after planting, when the varieties had reached physiological maturity. The three maize varieties with flint grain: golden ultra 1C (6477 kg/ha), Golden Ultra 2C (6242 kg / ha), and Golden Ultra 3C (6210 kg/ ha) had better yield than the variety Gold Plus 1D (4575 kg/ha), with dented grain. No differences in seed vigor were detected in the varieties studied. Larger seeds produced seedlings with higher dry weight.In Cuautitlán Izcalli, Mexico (FESC-UNAM), during the 2004 spring-summer season, in order to determine the effect of harvest time on the vigor of maize seeds, the productivity of four early-maturing, yellow-grain maize varieties, harvested at five different times and stored until spring-summer 2007 was determined. For two varieties, seed germination and vigor were measured, as well as the differences in vigor due to seed size (small and large, smaller than or larger than 7 mm, respectively) during each harvest time. The percentage of dry matter, grain ratio and yield were measured for the four genotypes. In the field, a randomized complete block design with three replications was used for treatment distribution. Statistical analysis was performed as a factorial, considering the factors genotype, harvesting dates, and the interaction genotype x harvesting date. The highest yields (6541 kg/ha, 7335 kg/ha and 7550 kg/ha) were obtained at harvesting dates of 149, 152 and 156 days after planting, when the varieties had reached physiological maturity. The three maize varieties with flint grain: golden ultra 1C (6477 kg/ha), Golden Ultra 2C (6242 kg / ha), and Golden Ultra 3C (6210 kg/ ha) had better yield than the variety Gold Plus 1D (4575 kg/ha), with dented grain. No differences in seed vigor were detected in the varieties studied. Larger seeds produced seedlings with higher dry weight.

Zea mays; flint varieties; dent varieties; physiological maturity