Melhoramento de milho para o cerrado do Estado de Tocantins

• Autor(a) principal: Fidélis, Rodrigo Ribeiro
• Data de Publicação: 2006
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/1264
• topic: Milho; Melhoramento genético; Recursos do germoplasma; Corn; Breeding; Germplasm resources; CNPQ::CIENCIAS BIOLOGICAS::GENETICA::GENETICA VEGETAL

The objectives of this work were to select corn progeny populations efficient in the absorption and use of phosphorus for grain production, under high temperature conditions in cerrado soil during the second corn crop; to evaluate the potential use of commercial corn cultivars as progenies in phosphorus stress breeding programs; to compare the genetic control of corn grain productivity in high and low phosphorus environments; to define the best strategy to develop cultivars for breeding purposes; and to select the genotypes most efficient in the absorption and utilization of phosphorus in cerrado soil. In order to obtain the hybrid combinations, nine commercial corn cultivars were selected, originated from different breeding programs, and classified as adapted to cerrado soil condition. The crosses were performed according to the paired row configuration, at the Diogo Alves de Mello Experimental Field of the Department of Plant Sciences of the Universidade Federal de Viçosa. The hybrid combination evaluation assay was conducted at the Experimental Area of Universidade Federal do Tocantins, Gurupi Campus. To simulate environments with low and high levels of phosphorus, doses of 25 and 113 kg ha-1 of P2O5 were used in seeding, respectively. The following traits were evaluated: grain weight, plant height, ear height, days for female flowering and number of ears per plot. In order to evaluate cultivar behavior, the traits were submitted to analysis of variance and the means were grouped by the Scott-Knott test. Individual diallelic analyses for each environment and combined analyses for all the traits were carried out by method 4, proposed by Griffin, using only the hybrid combinations. It was concluded that the cultivars most adapted to second corn crop conditions in southern Tocantins cerrado are UFVM77-0385, UFVM77-0367 and UFVM77-0349 and that the commercial cultivars are inadequate for drought stresses and high temperatures occurring during second corn crop in the state of Tocantins; among the cultivars tested, DKB 350 is the most indicated progeny in both environments; based on the traits evaluated, the additive genetic effects were more important than the non-additive genetic effects in the environment with high and low P; reciprocate recurring selection aimed at potential yield optimization is the best corn breeding strategy for the environments; Fageria and Kluthcouski methodology (1980) identified the efficient genotypes for phosphorus use and responsive to phosphorus application; the genotypes efficient in absorbing and utilizing phosphorus and responsive to P increase were UFVM77-0331, UFVM77-0307, UFVM77-0333, UFVM77-0381, UFVM77-0313, UFVM77-0305, UFVM77-0377 and UFVM77-0345.