Influencia de la semilla certificada de maíz en la productividad de los sistemas de producción de maíz en grano de los estados Portuguesa y Guarico

the development and use of new maize cultivars have increased the productivity and rentability of corn growers nationwide. the objetives of this research were to: evaluate the contribution of certified maize seed (cms) to the productivity of corn production systems of portuguesa and guarico states during the growing season of the year 2000; estimate the influence of cms upon crop rentability; and evaluate the roles played by growers？ associations on the negotiations with seed and other inputs suppliers. ninety maiz growers of portuguesa and 40 of guarico were surveyed. quantitative variables were evaluated by using principal components analisis (pca) and the upward hierarchical classifications (uhc). for qualitatives variables, descriptive analyses were used. results showed that in guarico the largest percentage of planted seed belonged to transnational companies, pioneer and cargill, with productivity 1.000 kg ha-1 higher than the obtained by hybrids of national seed companies. in contrast, at guarico locations, the yields of the hybrids to seflorca and himeca national seed companies were significant higher that those of pioneer. the main role of portuguesa growers？ associations was to strengthten producers？ negociation power with seed and inputs suppliers, as opposed to individual actions of guarico maiz growers. the pca for the 130 growers studied found that six variables: seed price, fertilizer, farming practices, labor, harvesting and transporting, accounted for 75% of the total variance (tv) for production costs. these variables were clustered in three principal components (pc1, 2 and 3), in which the cp1 formed by fertilizer, farming practices, and harvesting, accounted for 35.21.5 of tv; cp2 conformed by labor and harvest accounted for 22.12% of vt; and cp3 represented labor and transporting, accounted for 17.82% of tv. the uhc identified five groups for the 90 portuguesa growers, and two for the guarico growers; interestingly, one guarico grower was include