Estabilidade e adaptabilidade de híbridos de milho utilizando a abordagem AMMI-bayesiano

Biplot graphics are widely employed in the study of the genotypeenvironment interactions, but they are only a graphical tool without a statistical hypothesis test. The singular values and scores (singular vectors) used in biplots correspond to specific estimates of its parameters, and the use of uncertainty measures may lead to different conclusions from those provided by a simple visual evaluation. The aim of this work is to estimate the genotype-environment interactions, using AMMI analysis, through Bayesian approach. Therefore the credibility intervals can be used for decision-making in different situations of analyses. It allows to verify the consistency of the selection and recommendation of cultivars. Two analyses were performed. The first analysis looked into 10 regular commercial hybrids and all possible 45 hybrids obtained from them. They were assessed in 15 locations. The second analysis evaluated 28 hybrids in 35 different environments, with imbalance data. The ellipses were grouped according to the standard of interaction in the biplot. The AMMI analysis with a Bayesian approach proved to be a complete analysis of stability and adaptability, which provides important information that may help the breeder in their decisions. The regions of credibility, built in the biplots, allow to perform an accurate selection and a precise genotype recommendation, with a level of credibility. Genotypes and environments can be grouped according to the existing interaction pattern, which makes possible to formulate specific recommendations. Moreover the environments can be evaluated, in order to find out which ones contribute similarly to the interaction and those to be discarted. The method makes possible to deal with imbalanced data in a natural way, showing efficiency for multienvironment trials. The prediction takes into account instability and the interaction standard of the observed data, in order to establish a direct comparison between genotypes of both 1st and 2nd seasons.

Capacidade combinatória de linhagens e seleção de híbridos de sorgo sacarino

Sweet sorghum figure as an alternative feedstock for ethanol production. The establishment of this culture in Brazilian production chain depends on the development of more productive and adapted cultivars. The aim of this study was to evaluate the general combining ability (GCA) of sweet sorghum lines and specific combining ability (SCA) of hybrid combinations as the agronomic and technological traits, and additionally to identify promising hybrid combinations for evaluation in advanced trials. Five restorer lines (R) and four male-sterile lines (A) were used in a partial cross diallel yielding 20 hybrids. The parental lines, hybrids and one check were evaluated in experiments carried out in a rectangular lattice design 5x6 with three replicates in two locations. The following traits were measured: flowering time, plant height, green mass yield, dry matter percentage, dry matter yield, juice extraction, total soluble solids content, sucrose content, purity, reducing sugars content, fiber content, sugars reducing total content, total recoverable sugars, hydrous ethanol, tons of per hectare, and ethanol production. There were differences between locations and genotypes for the traits. There was a significant effect of the genotype by environment interaction for most characters, except juice extraction, purity and reducing sugars content. There were a significant effect of GCA and SCA for most traits, indicating that additive and non-additive effects affect the phenotypic expression. Considering the effects of the GCA, the A line 201402B022-A, and R lines BRS 511, CMSXS643, and CMSXS646 were considered promising for exploration as parents in breeding programs of sweet sorghum in order to increase the ethanol production and the quality of the feedstock.The hybrids 201402B010-A x BRS 511, 201402B010-A x BRS 508, 201402B010-A x CMSXS646, 201402B022-A x BRS 511, 201402B022-A x CMSXS643, 201402B022-A x CMSXS646, 201402B022-A x CMSXS647 were the most promising for ethanol yield.

Avaliação do potencial de uso agrícola da fluorita com óxido silício (AgroSiCa), derivado da fabricação de fertilizantes fosfatados

Phosphate fertilizers are critical for crop production in tropical soils, which are known for having high phosphate-fixing capacity and aluminium saturation, as well as low pH and calcium contents. Fluorine is a component of many phosphate rocks used to make phosphate fertilizers, via a process that generates hexafluorosilicic acid (H2SiF6). While many treatment technologies have been proposed for removal of fluorine in industrial facilities, little attention has been given to a process of neutralizing H2SiF6 with calcium oxide aiming to find out an alternative and sustainable use of a by-product with a great potential for beneficial use in tropical agriculture. This study evaluated the effect of a by-product of phosphoric acid production (fluorite with silicon oxide, hereafter called AgroSiCa) in levels of phosphorus (P), calcium (Ca), silicon (Si), aluminum (Al) and fluorine (F) and some others parameters in soils as on growth of soybean and corn. Experiments were conducted in a greenhouse condition at the Federal University of Lavras (UFLA), Lavras, Minas Gerais, using different types of soils in tropical regions and different doses of AgroSiCa. The application of AgroSiCa resulted in a slight increase in soil pH and significant increases in calcium, phosphorus and silicon in the soil solution and the shoots of corn and soybeans. We also found very low levels of fluoride in all soil leachates. A significant reduction of labile aluminum levels found in all soils after the cultivation of corn and soybeans. In sum, AgroSiCa improved soil properties and contributed to better growth of both cultures. In sum, AgroSiCa improved soil properties and contributed to a better growth of both crops. Our results show that reacting H2SiF6 derived from the wet-process phosphoric acid production with calcium oxide leads to a by-product with potential for agricultural use, especially when applied in highly-weathered soils. Besides providing calcium and silicon to plants, the use of such by-product in soils with high phosphate-fixing capacity and high aluminium saturation delivers additional benefits, since fluoride and silicon can play an important role in improving soil conditions due to the formation of less plant-toxic forms of aluminium, as well as upon decreasing phosphate fixation, thus improving root development and making fertilizer-derived phosphate more available for plant growth.