Identificação de genitores e controle genético da eficiência no uso de nitrogênio e fósforo em milho

• Autor(a) principal: Silva, Júlio César do Vale
• Data de Publicação: 2011
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/1161
• topic: Zea mays L.; Estresse abiótico; REML/BLUP; Zea mays L.; Abiotic stress; REML/BLUP; CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::FITOTECNIA::MELHORAMENTO VEGETAL

In recent years, interest in sustainable agriculture has encouraged plant breeding programs to develop genotypes more efficient use of resources, especially those non-renewable. Among the main strategies is to improve nitrogen (N) and phosphorus (P) use efficiency and phosphorus through the acquisition efficiency and utilization efficiency of these nutrients. However, knowledge of the inheritance of these traits is essential to guide breeders in the most appropriate method to be used for improvement. Thus, the aimed to identify: (i) contrasting maize parents to N and P acquisition and utilization efficiencies, in high and low availability these nutrients to be used in a study of inheritance; (ii) the relative importance of the components of nutritional efficiency, in contrasting conditions of availability N and P; (iii) the relationship of system root and shoot dry mass with nutritional efficiency, in contrasting conditions of availability N and P; (iv) the genetic control of traits associated with N and P use efficiency. Initially were evaluated 15 inbred lines in two experiments, the first to N and second to P, in high and low availability of these nutrients. The nutrients were supplied by way of nutrient solution from the seventh day after germination. Were used a randomized block design with two replications in factorial simple (hybrid combination x availability of N or P). Were measured shoot dry mass, N and P acquisition and utilization efficiencies and, lengths of axial and lateral roots. Statistical analysis was performed using the mixed model equations. It was observed genetic variability for almost all of the traits evaluated. Were observed that is possible to identify contrasting parents to components of N and P use efficiency to study of inheritance. Later, were conducted a factorial interpopulation involving 14 of these 15 inbred lines, in two groups of parents. Group I was composed of seven contrasting parents for P use efficiency. Group II was composed of seven contrasting parents for N use efficiency. Posteriorly, were obtained 41 experimental hybrid combinations that were evaluated in two experiments, the similarities of which conducted to identify parents. Independently of the availability N and P, the acquisition efficiency was the most important component for the both nutrients use efficiency. The shoot dry mass allows indirect selection of genotypes more efficient in the use of N and P. Interactions hybrid combinations x availability N or P are predominantly of the simple type, so the selection can be performed on a single availability of these nutrients. The genetic control of N use efficiency is mainly additive, so the selection can be performed by the individual inbred lines performance. The controlgenetic of P use efficiency is predominantly non-additive, so that the selection should be carried out by the hybrids performance.