PROGRESSO GENÉTICO E SELEÇÃO PRECOCE EM GENÓTIPOS DE PINHÃO-MANSO EM FASE JUVENIL

O pinhão manso (Jatropha curcas L.) é uma euforbiácea utilizada na produção de biodiesel. A espécie possui base genética estreita o que dificulta o processo de lançamento de cultivares. Caracterizar precocemente os genótipos constitui etapa importante no melhoramento da cultura. Objetivou-se com este estudo realizar uma seleção precoce em caracteres morfoagronômicos, predizer o progresso genético de tais caracteres e indicar genitores potenciais para obtenção de progênies. O delineamento experimental utilizado foi o de blocos casualizados com 26 tratamentos e três repetições. As variáveis morfoagronômicas foram analisadas via modelos mistos e o progresso genético obtido pela seleção direta, indireta e índices de seleção. A dissimilaridade genética foi determinada pela distância de Mahalanobis, com agrupamento hierárquico UPGMA e coeficiente de correlação cofenética adquirido de 1.000 permutações. As estimativas demonstraram variabilidade genética, com identificação de genótipos juvenis promissores. Os genótipos JCCE034, JCCE014 e JCCE103 apresentam melhores progressos genéticos e os genótipos JCCE036 e JCCE86 apresentam maiores divergências genéticas, formando clusters individuais. Os genótipos de pinhão-manso são promissores na seleção precoce e possuem satisfatórios ganhos com a seleção para os caracteres avaliados. Os genótipos apresentam boa capacidade para compor grupos de genitores em cruzamentos direcionados, constituindo populações-base no melhoramento de J. curcas. Palavras-chave: Jatropha curcas; diversidade genética; ganhos com a seleção; índices de seleção. Genetic progress and early selection of juvenile physic nut genotypes ABSTRACT: Physic nut (Jatropha curcas L.) is a euphorbia used in the production of biodiesel. The species has a narrow genetic base which the process of launching cultivars is difficult. Early characterization of the genotypes is an important step in crop breending. The aims of this study were to perform an early selection in morpho-agronomic traits, to predict the genetic progress of such traits and to indicate potential parents for progeny development. The experimental design used for the randomized blocks with 26 treatments and three replications. The morpho-agronomic traits were analyzed via mix models and the genetic progress added by direct, indirect selection and selection indexes. The genetic dissimilarity was provided by the Mahalanobis distance, with UPGMA hierarchical grouping and co-phenetic correlation coefficient acquired from 1,000 permutations. The indicators demonstrated genetic variability, with the identification of promising juvenile genotypes. The genotypes JCCE034, JCCE014 and JCCE103 show better genetic progress and the genotypes JCCE036 and JCCE86 show greater genetic divergences, forming individual clusters. J. curcas genotypes are promising in early selection and have satisfactory genetics gains for the traits. The genotypes have a good ability to compose groups of parents in targeted crosses, constituting base populations in the improvement of J. curcas. Keywords: Jatropha curcas; genetic diversity; selection gains; selection indexes.

Indexes of Natural Selection, Migration and Reproductive Characteristics in Lutsk Population, West Ukraine

In human populations natural selection is shifting to the side of prenatal development and appears as negative outcomes of pregnancies such as spontaneous abortions, ectopic pregnancies and stillbirths. Therefore, it is important to study dynamics of changes in reproductive characteristics and selection indexes of the populations in order to predict possible problems and numbers of genetic burden in the populations. Ukraine is poorly studied in this area. The aim of the study was to investigate indicators which characterize the population structure of Lutsk city, the intensity of natural selection, migration and their dynamics in two generations. 583 post-reproductive age females were anonymously questioned. Age, places of birth of the couple, the number of pregnancies and their outcomes were considered. Results show that natural selection indexes (Crow’s indexes) are decreasing from the first generation (0,26) to the second (0,20). Migration coefficients in the population of Lutsk decreased from 0.89 to 0.82 per generation and show intensive urbanization of the city for the studied time. The efficiency of the migration is low, since the biggest number of migrants come from the villages of the Volyn region (45% for first generations and 64% for the second one), or adjacent regions of Ukraine (35% and 27%, respectively). The population of Lutsk has a narrowed type of reproduction, where average number of offspring per female equal 1,86 for the first generation and 1,73 for the second generation.

Evaluation of high-concentrate diets that vary in physically effective neutral detergent fibre for finishing lambs

The objective of this research was to evaluate lamb diets with a high proportion of concentrate and various levels of physically effective neutral detergent fibre (NDF) using tropical ingredients. Four diets were formulated: D1 with 16.5% physically effective NDF (peNDF), D2 with 21.4% peNDF, D3 with 23.3% peNDF, and D4 with 24.6% peNDF. Twenty male Santa Inês lambs at four months old with an average liveweight (LW) of 18.6 ± 3.4 kg were fed for 49 days. There were no differences (P >0.05) among the diets in dry matter (DM) intake. Crude protein (CP) intake, relative to either LW or metabolic live weight (LW0.75) or LW, was greater (P ≤0.05) for D2 and D3 than for D1 or D4. Lower (P ≤0.05) NDF intake, relative to LW0.75 or LW, was lower for D1 than for the other diets. Selection indexes (SIs) were similar (P >0.05) among diets. Animals that consumed D1 had less (P ≤0.05) rumination time per bolus. Meaningful variations were not observed in performance and efficiency of finishing lambs that were related to differences in peNDF among the diets. Santa Inês lambs were able to adapt to diets with low levels of peNDF by increasing rumination time as a consequence of increased fibre consumption and greater particle size selection.

Dialell Analysis for Morphoagronomic Descriptors in Physalis Angulata L. Hybrids

Physalis angulata L. is an American species with edible fruits that stands out for having high nutritional and pharmaceutical value. The species is found in almost the entire Brazilian territory but the consumption of its fruits is not widespread. Genetic improvement is one of the main factors that can make P. angulata a crop in Brazil. The aim of this work was to evaluate the existence of heterosis and heterobeltiosis for morphoagronomic descriptors, to estimate correlations, and to select the best hybrids in P. angulata in a full diallel with five accession. Twenty plant, fruit and seed descriptors were evaluated, and plant height and total soluble solids showed significant genetic variation. Positive heterobeltiosis for total soluble solids was observed in hybrids Pi x G53, Can x Pi and Can x LG, while negative heterobeltiosis for plant height was observed in G53 x LG, Pi x Laj e Can x Laj hybrids. Heterosis was also observed for both descriptors. Using selection indexes, Can x G53, Can x LG, Pi x G53, Can x Pi and G53 x Pi were selected as the best hybrids, expressing smaller plant height and higher total soluble solids.

Selection Response Due to Different Combination of Antagonistic Milk, Beef, and Morphological Traits in the Alpine Grey Cattle Breed

Selection in local dual-purpose breeds requires great carefulness because of the need to preserve peculiar traits and also guarantee the positive genetic progress for milk and beef production to maintain economic competitiveness. A specific breeding plan accounting for milk, beef, and functional traits is required by breeders of the Alpine Grey cattle (AG), a local dual-purpose breed of the Italian Alps. Hereditability and genetic correlations among all traits have been analyzed for this purpose. After that, different selection indexes were proposed to identify the most suitable for this breed. Firstly, a genetic parameters analysis was carried out with different datasets. The milk dataset contained 406,918 test day records of milk, protein, and fat yields and somatic cells (expressed as SCS). The beef dataset included performance test data conducted on 749 young bulls. Average daily gain, in vivo estimated carcass yields, and carcass conformation (SEUROP) were the phenotypes obtained from the performance tests. The morphological dataset included 21 linear type evaluations of 11,320 first party cows. Linear type traits were aggregated through factor analysis and three factors were retained, while head typicality (HT) and rear muscularity (RM) were analyzed as single traits. Heritability estimates (h2) for milk traits ranged from 0.125 to 0.219. Analysis of beef traits showed h2 greater than milk traits, ranging from 0.282 to 0.501. Type traits showed a medium value of h2 ranging from 0.238 to 0.374. Regarding genetic correlation, SCS and milk traits were strongly positively correlated. Milk traits had a negative genetic correlation with the factor accounting for udder conformations (−0.40) and with all performance test traits and RM. These latter traits showed also a negative genetic correlation with udder volume (−0.28). The HT and the factor accounting for rear legs traits were not correlated with milk traits, but negatively correlated with beef traits (−0.32 with RM). We argue that the consequence of these results is that the use of the current selection index, which is mainly focused on milk attitude, will lead to a deterioration of all other traits. In this study, we propose more appropriate selection indexes that account for genetic relationships among traits, including functional traits.

Selection of tomato genotypes for drought tolerance and agronomic potential through different selection indexes

ABSTRACT The selection of genotypes with agronomic potential associated with drought tolerance is considered of high complexity. An alternative could be the use of selection indexes that can evaluate multiple characteristics simultaneously. This study aimed to select tomato genotypes with agronomic potential and drought tolerance by selection indexes. The experiment was conducted in a randomized block design with three replications. Ten treatments were evaluated: seven genotypes F2RC3, donor genitor (Solanum pennellii), recurrent genitor (UFU-040), and cv. Santa Clara. The irrigation was suspended until the substrate reached a matric potential of ≤-25 kPa for water stress simulation during the tomato cycle at 45, 60, 80 and 100 days after sowing. The control treatment (donor genitor) and cv. Santa Clara, were resistant and susceptible to water deficit, respectively. The UFU-102-RC3#91335 genotype presented agronomic potential and satisfactory tolerance level to water deficit and presented 58.2% higher production than the recurrent genitor (UFU-040). The genotype-ideotype distance selection index was the most appropriate for the selection of tomato genotypes for agronomic potential allied to drought tolerance.

SELECTION IN HEREFORD CATTLE I. SELECTION INTENSITY, GENERATION INTERVAL AND INDEXES IN RETROSPECT

Selection intensity and generation interval were evaluated in a Hereford cattle herd of 14 inbred lines and 14 linecross groups corresponding to the lines of inbred sire at the San Juan Basin Research Centre, Hesperus, Colorado. Selection indexes practised were calculated in retrospect. The records analysed were weaning weight and postweaning traits in males and females collected from 1946 through 1973. Analyses were performed by line for the inbreds and pooled analyses for the inbred and linecross populations. From records of 1,239 calves weaned, age of sire averaged 3.75 years compared with 4.52 years for age of dam, showing faster generation turnover for sires than for dams. Generation interval determined 98 actual age of midparent was 4.13 years.Selection applied, evaluated as annual selection differentials within inbred lines and then pooled over all lines, averaged .55 standard deviations per generation for sires for weaning weight. Selection of females was much less. Midparent selection differential amounted to .33 standard deviations per generation. Pooled standardized selection differentials per generation over all lines for sires were .49, .46, 40, -.20, -.10, and .69, respectively, for initial weight, final weight, feed consumption, unadjusted feed efficiency, adjusted feed efficiency, and average daily gain. Selection of females for postweaning traits was not intense. Selection Indexes actually practiced in retrospect were: for sires, IS = .4661(WW) -.0092(FE) + .6126(ADG); for inbred dams, ID = .1824(WW) -.0284 (12W) + .0736 (18W) - 1097 (SPW) -.1097 (FAW); for linecross dams, ID= .2693 (WW) - 2960 (12W) + .0147 (18W) + 1185 (SPW) -.0354 (FAW). The corresponding index selection differentials were .818, 203, and .209. Sire index selection differentials represent about 79 percent of the total selection differentials.