" The physiological seed quality attributes assayed in laboratory, are important components to extend the characterization of germplasm for use in a plant breeding program, to give information about plant emergency, field establishment, and competitive ability in different seed planting conditions. Seed physiological quality was evaluated in two improved maize landrace populations (early selection and original landrace); which were obtained in the spring-summer season in Celaya, Gto., Mexico in 2005, under different strategies of selection and genetic breeding approaches. The laboratory study was established under a completely randomized block design, the evaluated variableswere: normal plantlets at the first count, germination percentage, abnormal plantlets, ungerminated seeds, plantlets dry weight, and plumule and root average length. The variance analysis showed significant differences (p 0.05) among blocks for average plumule length, what justifies having employed this experimental design. There were also significant differences (p 0.01) between popula tions for physiological efficiency in germination, dry matter production and plumule average length, being the early selection the one with better performance; those differences between populations can be attributed to their germoplasmic conformation, so that the early selection has improved germplasm in its genetic constitution."