Márcio Henrique Pereira Barbosa

Avaliação da divergência nutricional de genótipos de cana-de-açúcar (Saccharum spp.)

The objective of this trial was to study the nutritional divergence of sugarcane genotypes for feeding ruminants. The following sugarcane genotypes were evaluated: RB72454, RB835486, SP80-1842, IAC86-2480, RB977512, RB867515, RB935566, RB925345, RB977625, SP79-1011, SP80-1816, SP81-3250, and SP91-1049 all harvested at 11 months of age. The discriminatory variables were: neutral detergent fiber (NDF), hemicellulose, lignin, NDF to soluble carbohydrate ratio, NDF undegradable fraction, and rates of NDF and DM degradation. Application of the cluster analyses according to the Tocher approach, using the mean Euclidian distance matrix, yielded three groups of genotypes. Neutral detergent fiber and DM degradation rates were the most important variables for group discrimination contributing individually with 25.64% of the total discrimination power while the least contribution was observed with NDF undegradable fraction (11.54%). The variables NDF, NDF undegradable fraction, hemicellulose, and rates of DM and NDF degradation all showed to be effective to evaluate sugarcane nutritional divergence. Group III formed by the clone RB977512 showed the best responses for the studied variables and as such can be considered of higher nutritional quality for ruminants.

Avaliação da divergência nutricional de variedades de cana-de-açúcar (Saccharum spp.)

The objective of this work was to evaluate the nutritional divergence of the sugarcane varieties, using the principal components analysis, to select three representative varieties of that divergence. The sugarcane varieties (Saccharum spp.) evaluated in this study were: RB855113, RB765418, RB855536, SP79-2233, RB845257, SP80-180, RB855453, RB855336, SP80-1842, SP81-1763, SP80-4445, SP79-1011, RB739359, RB867515 and SP80-3280, harvested at 426, 487 and 549 days post planting. Neutral detergent fiber (NDF), hemicellulose, lignin, undegradable NDF fraction and degradation rate of the potentially degradable NDF fraction were the evaluated discriminatory variables. Differences were observed for all the studied variables, except for the undegradable NDF fraction. The evaluation of the nutritional divergence of the sugarcane varieties based on the first three principal components, that explained 87.8% of the total variation. The NDF and the undegradable NDF fraction were the variables of smaller importance to explain the nutritional variability of the varieties. The SP80-1842 variety, harvested at 426 days post planting, and SP79-1011 variety, harvested at 549 days, were the ones that showed greater score dispersions for the first three principal components, being considered the most dissimilar, while the RB845257 variety, harvested at 487 days post planting, was located in the intermediary position between both. The principal components analysis was also efficient in selecting varieties with different harvesting times.

Composição químico-bromatológica de variedades de cana-de-açúcar (Saccharum spp L.) com diferentes ciclos de produção (precoce e intermediário) em três idades de corte

The objectives of this work were to determine the chemical composition, the potentialy degradable fraction of NDF (B2) and undegradable fraction (C) and to estimate the ruminal fill of sugar cane with different cycles of production (early and intermediate), in three cut times (426, 487 and 549 days). The laboratorial analysis consisted in dry matter (DM), organic matter, ash, crude protein (CP), ether extract, lignin, neutral detergent fiber (NDF), neutral detergent fiber corrected for ash and protein, acid detergent fiber (ADF), neutral detergent insoluble protein, acid detergent insoluble protein and neutral detergent protein soluble. The TDN was calculated by chemical composition. The degradable and undegradable fractions, and fiber digestion rate, as well as the ruminal fill were estimated by kinetic parameters obtained throught in situ incubation. The advanced cut time increased the DM in 9.5%. The intermediate varieties presented higher TDN than early varieties, which had the highest contents of NDF and ADF, whose respective values were 487.56 and 471.03, and 287.87 and 247,54 g/kg DM for the early and intermediate varieties, respectively. The TDN increased linearly with the cut time, varying from 62.45 to 63.50%; however the NDF and ADF contents presented quadratic behavior. The early varieties presented higher content of CP than the intermediate only in the cut time of 549 days; contrarily, the brix of the sugar cane was superior to the intermediate varieties in the last cut. The early varieties presented larger total ruminal fill and lower fiber digestion rate. The degradable fraction of the fiber was reduced and the undegradable fraction was linearly increased with the age of the plants.

Genetic improvement of sugar cane for bioenergy: the brazilian experience in network research with RIDESA

In this paper, it is presented RIDESAs model for sugar cane breeding to ethanol, and its scientific, technological and human resources training contributions. RIDESA is an inter-university network for the development of sugar cane industry in Brazil, and was formed by a technical cooperation agreement between ten public universities. The model of network management is presented in this study, which involves, among other things, the public-private partnership (Universities-Mills) for the development of cultivars. RIDESA has produced 59 cultivars since 1990 and is now responsible for 59% of the total area cultivated with this plant in Brazil. In the last five years, 286 agronomists were trained in breeding programs at universities that comprise RIDESA. In this same period, the network formed 35 professors, 24 doctors and 7 post-docs in researches with this crop. It is also presented a conceptual approach on methods of sugar cane breeding involving families and genome-wide selection.

Sample size for full-sib family evaluation in sugarcane

The objective of this study was to determine the minimum number of plants per plot that must be sampled in experiments with sugarcane (Saccharum officinarum) full-sib families in order to provide an effective estimation of genetic and phenotypic parameters of yield-related traits. The data were collected in a randomized complete block design with 18 sugarcane full-sib families and 6 replicates, with 20 plants per plot. The sample size was determined using resampling techniques with replacement, followed by an estimation of genetic and phenotypic parameters. Sample-size estimates varied according to the evaluated parameter and trait. The resampling method permits an efficient comparison of the sample-size effects on the estimation of genetic and phenotypic parameters. A sample of 16 plants per plot, or 96 individuals per family, was sufficient to obtain good estimates for all traits considered of all the characters evaluated. However, for Brix, if sample separation by trait were possible, ten plants per plot would give an efficient estimate for most of the characters evaluated.

Repeatability of full-sib sugarcane families across harvests and the efficiency of early selection

This study was designed to estimate the repeatability coefficient of traits of the plant-cane and first rattoon in a large number of full-sib sugarcane families and to select the superior families based on their predicted genotypic values. The population used in this study consisted of 190 families, and crossing was performed at the Federal University of Alagoas, in Murici, Alagoas, Brazil, in 2007. Five experiments, each with 22 families, took place at the Centro de Pesquisa e Melhoramento da Cana-de-Açúcar (CECA), in Oratórios, Minas Gerais, while four experiments, each with 20 families, took place at the Volta Grande mill (VGM), in Conceição das Alagoas, Minas Gerais. Each experiment took the form of a randomized complete block design with six replications. The following traits were determined from the plant-cane and first rattoon: percentage of soluble solids w/w in the juice (Brix), tons of stalks per hectare (TSH) and tons of brix per hectare (TBH). Statistical analyses were performed using the mixed model methodology. Variance components were estimated by restricted maximum likelihood (REML) and the genotypic values of families were predicted by best linear unbiased prediction (BLUP). The moderately high estimates of repeatability for TSH and TBH and the high rates of coincidences of the families selected in both plant-cane and first rattoon indicate that selection of families using repeated measures across the first two harvests combined with individual clone selection at the rattoon stage may be efficient in sugarcane breeding programs, increasing the efficiency of obtaining new cultivars.

Repetibilidade e número de colheitas para seleção de clones de cana-de-açúcar

This work aimed at the establishment of the repeatability coefficients (r), determination of the predictability degree (R2) and the needed measurement numbers for tons of cane per hectare, percentage of pol (sucrose) in the juice of cane and tons of pol in the juice of cane per hectare in sugarcane genotypes. A randomized block experimental design, with three replicates in four experiments and four replicates in the other experiments was used. The repeatability estimates were obtained by the statistical methods: anova; main components based on correlation matrix; and structural analysis (correlation, average r). The estimates of the repeatability coefficients showed values with very similar magnitude. The general average repeatability for those three traits was above 0.60, therefore showing regularity in the genotype performance at several measurements (cuts) and reliability in the genotype discrimination that was higher than 87%. The results showed that for those three traits there is a need for the use of, at least, three cuts so that the selection can be accomplished with predictability of a real value above 80% for the genotype.

Composição químico-bromatológica, fracionamento de carboidratos e cinética da degradação in vitro da fibra de três variedades de cana-de-açúcar (Saccharum spp.)

The objectives of this work were to determine the chemical-bromatological composition, to determine the carbohydrates fractions and to estimate the kinetic variables of degradation of the fibrous (FC) and no-fiber carbohydrates (NFC), of three nutritional divergence sugarcane varieties. The studied varieties were SP80-1842, SP79-1011 and RB845257. The varieties of intermediary production cycle showed greater values of NDF and ADF compared to the variety of early cycle. The observed FDN/Pol (sucrose index) ratio was, respectively, 2.73; 2.82 and 2.25 for the SP80-1842, RB845257 and SP79-1011 varieties. The SP79-1011 variety presented smaller C and greater B2 carbohydrate fractions (27.78 and 33.26%). It was possible to observe difference, using the gravimetric technique, for the lag time and the effective degradation of NDF, with higher values for SP 791011 variety (7.90 h and 10.30%, respectively). However, for the gas production technique, there was only a significant effect, for the estimate of the maximum gas volume parameter for NFC, with higher values for the varieties SP79-1011 and RB845257 of intermediary production cycle. The SP79-1011 variety was the one that showed better productive characteristic, composition chemical-bromatological, besides better values of the kinetics variables of degradation of the fiber (FC) and non fiber (CNF) carbohydrates. The gas production technique was more reliable than the results observed by the gravimetric technique.

Análise dialélica em clones de cana-de-açúcar

Aiming at the evaluation of the gene action predominant in sugarcane characters of economic importance and the identification of crossing with favorable genetic potential to the development of new cultivars, eight genotypes were evaluated according to the unbalanced diallel cross scheme. Progenies obtained from 44 crosses were evaluated on a 7 x 7 lattice experimental design with three replications at the Centro de Pesquisa e Melhoramento da Cana-de-acucar (CECA) of the Universidade Federal de Vicosa. The following characters were studied: juice Brix %, stalk number, average stalk weight, tons of stalks per hectare, tons of Brix per hectare and flowering percent. The results emphasized the importance of either the additive and the non-additive genetic effects in the expression of those characteristics. The genotypes SP82-6108 and IAC86-2210 showed potential for increasing the sugarcane productivity, that is also valid for the following crossing combinations: SP82-6108 x SP88-754, SP82-6108 x SP87-365, SP81-1763 x SP82-6108, IAC86-2210 x SP88-754, IAC86-2210 x SP86-96, IAC86-2210 x SP81-1763, SP88-819 x SP87-365, SP84-2029 x SP87-365 and SP88-754 x SP87-365.

Determination of Sugarcane Bagasse Lignin S/G/H Ratio by Pyrolysis GC/MS

Abstract In this work, analytical pyrolysis (Py-GC-MS) was employed to identify lignin markers derived from H, S, and G phenylpropanoid units in sugarcane bagasse. Temperatures of 450 and 500°C allowed the detection of key products that were informative on the bagasse lignin composition. The method was validated by comparing the S/G ratio as determined by the nitrobenzene oxidation (NBO) standard method for five sugarcane varieties. The S/G ratio as determined by Py-GC-MS, taking into consideration all known lignin markers in the analysis, resulted in a correlation coefficient of 0.85 with a linear regression coefficient of 0.74. When a group of selected markers (M2) was used, the correlation coefficient between methods was improved to 0.95 and the linear regression coefficient was adjusted to 0.92. M2 markers consisted of five syringyl markers (syringol, 4-methylsyringol, 4-ethylsyringol, 4-vinylsyringol, and trans-4-propenylsyringol) and four guaiacyl markers (guaiacol, 4-vinylguaiacol, 4-methylguaiacol, and vanillin). Importantly, Py-GC-MS allowed for the study of lignin composition in sugarcane bagasse without the need to remove the extractives, minimizing the work with sample preparations.