Caio Césio Salgado

Genetic gains in physic nut using selection indexes

Abstract – The objective of this work was to estimate genetic gains in physic nut ( Jatropha curcas ) using selection indexes and to establish the best selection strategy for the species. Direct and indirect selection was carried out using different selection indexes, totalizing 14 strategies. One hundred and seventy five families from the active germplasm bank of Embrapa Agroenergy, Brasilia, Brazil, were analyzed in a randomized complete block design with two replicates. The evaluated traits were: grain yield; seeds per fruit; endosperm/seed ratio; seed weight, length, width, and thickness; branches per plant at 0.5, 1.0, and 1.5 m; plant height; stem diameter; canopy projection on rows and between lines; canopy volume; juvenility (days to the first flowering); and height of the first inflorescence. Evaluations were done during the second year of cultivation. The use of selection indexes is relevant to maximize the genetic gains in physic nut, favoring a better distribution of desirable traits. The multiplicative and restrictive indexes are considered the most promising for selection.Index terms:

Artificial neural networks for adaptability and stability evaluation in alfalfa genotypes

The purpose of this work was to evaluate a methodology of adaptability and phenotypic stability of alfalfa genotypes based on the training of an artificial neural network considering the methodology of Eberhart and Russell. Data from an experiment on dry matter production of 92 alfalfa genotypes (Medicago sativa L.) were used. The experimental design constituted of randomized blocks, with two repetitions. The genotypes were submitted to 20 cuttings, in the growing season of November 2004 to June 2006. Each cutting was considered an environment. The artificial neural network was able to satisfactorily classify the genotypes. In addition, the analysis presented high agreement rates, compared with the results obtained by the methodology of Eberhart and Russell.

Biometrics Applied to Molecular Analysis in Genetic Diversity

Studies about genetic diversity have been of great importance for the purposes of genetic improvement and to evaluate the impact of human activity on biodiversity. They are equally important in the understanding of the microevolutionary and macroevolutionary mechanisms that act in the diversification of the species, involving population studies, as well as in the optimization of the conservation of genetic diversity. They are also fundamental in understanding how natural populations are structured in time and space and the effects of anthropogenic activities on this structure and, consequently, on their chances of survival and/or extinction. This information provides an aid in finding the genetic losses generated by the isolation of the populations and of the individuals, which will be reflected in future generations, allowing for the establishment of better strategies to increase and preserve species diversity and diversity within the species.

Pólen 2n e mecanismos meióticos de formação em Solanum commersonii ssp

Solanum commersonii subsp. commersonii Dun. e Solanum commersonii subsp. malmeanum Bitt. (2n=2x=24 - 1EBN) nao podem ser diretamente cruzadas com a batata cultivada de S. tuberosum subsp. tuberosum L. (2n=4x=48 -4 EBN) em razao da barreira da ploidia e do numero de equilibrio do endosperma (EBN). No entanto, a producao de polen nao reduzido por S. commersonii ssp. (2x=2n=24 - 1EBN), permite o cruzamento desta com dihaploides de batata e com as especies diploides S. phureja Juz. & Bukasov. e S. chacoense Bitt., que possuem 2 EBN. Conduziu-se este trabalho, com o objetivo de determinar o mecanismo meiotico e a frequencia dos graos de polen nao reduzidos em cinco clones de Solanum commersonii ssp. Foram avaliados tres clones de S. commersonii subsp. commersonii (SCC) e dois de S. commersonii subsp. malmeanum (SCM). Nas avaliacoes, duzentos graos de polen viaveis foram corados (carmim acetico 2%) e mensurados, sendo considerados nao reduzidos aqueles com o diâmetro igual ou superior a 25 µm. O clone Solanum commersonii subsp. commersonii Dun. (SCC 100) produz 26.1% de polen nao reduzido, por fusos fundidos e fusos paralelos, o qual pode ser utilizado em programas de melhoramento.