João Batista Lopes Silva

Cluster evaluation of Brazilian and Moroccan goat populations using physical measurements

The aim of this study was to compare the genetic diversity of 12 populations of goats in Brazil and Morocco (n = 796) through the use of physical measurements and different multivariate techniques. Traits measured included wither height (WH), distance from the brisket to the ground (BH) and ear length (EL). The standardized Euclidean distance (D) was adopted. The D values were submitted to clustering analysis using hierarchical methods (from nearest neighbor and UPGMA - Unweighted Pair Group Method with Arithmetic Mean) and the numbers of clusters were analyzed using the Tocher optimization method. The population clustering was different depending on the method of analysis used. Among the hierarchical methods, UPGMA showed the best fit (CCC = 0.82). The Tocher method enabled the formation of four different clusters. Although the hierarchical and Tocher methods resulted in different cluster formations, both contributed to the interpretation of the genetic cluster divergence. The results obtained through UPGMA and Tocher optimization enable their use for future studies that may include a larger number of biometric variables on greater numbers of individuals and additional populations.

Biometric variability of goat populations revealed by means of principal component analysis

The aim was to analyze variation in 12 Brazilian and Moroccan goat populations, and, through principal component analysis (PCA), check the importance of body measures and their indices as a means of distinguishing among individuals and populations. The biometric measurements were wither height (WH), brisket height (BH) and ear length (EL). Thorax depth (WH-BH) and the three indices, TD/WH, EL/TD and EL/WH, were also calculated. Of the seven components extracted, the first three principal components were sufficient to explain 99.5% of the total variance of the data. Graphical dispersion by genetic groups revealed that European dairy breeds clustered together. The Moroccan breeds were separated into two groups, one comprising the Drâa and the other the Zagora and Rhâali breeds. Whereas, on the one side, the Anglo-Nubian and undefined breeds were the closest to one another the goats of the Azul were observed to have the highest variation of all the breeds. The Anglo-Nubian and Boer breeds were similar to each other. The Nambi-type goats remained distinct from all the other populations. In general, the use of graphical representation of PCA values allowed to distinguish genetic groups.

Influência dos métodos para cálculo de graus-dia em condições de aumento de temperatura para as culturas de milho e feijão

O presente estudo foi realizado com o objetivo de se avaliar diferentes metodos para o calculo de graus-dia (GD). Foram comparados quatro metodos de soma termica, frequentemente usados no calculo de GD: Ometto, Snyder, Dufault e metodo residual de Arnold. Esses metodos foram aplicados as culturas do milho e do feijao. As simulacoes foram feitas com as temperaturas observadas em Vicosa, MG no ano de 2011, e temperaturas simuladas (com acrescimo aleatorio entre 0 a 5oC em cada dia do periodo). As respostas dos quatro metodos de calculo dos GD foram similares para as temperaturas observadas (reais). Para as temperaturas elevadas, os metodosnao apresentaram respostas similares. Fixando os graus-dia em 1.600 oC dia para a cultura do milho e 1.300 oC dia para o feijao, os metodos estudados reduziram de forma diferente o ciclo das culturas. As maiores reducoes foram obtidas pelo metodo Arnold e Snyder, reduzindo igualmente o ciclo em 28 e 17 dias para as culturas do milho e do feijao, respectivamente. No metodo de Ometto, foram observadas as menores reducoes, de 12 (milho) e 11 (feijao) dias, pois, nesse caso utilizam-se as temperaturas basais superior e inferior e considera-se uma penalizacao maior em dias em que a temperatura maxima ultrapassa a temperatura basal.

Influences of two CO2 concentrations and water availability on bean crop

This study was carried out to determine some physiological and phenological responses of the bean under high [CO2] and drought stress. The experiment was conducted from April to July 2009 in Vicosa, Brazil. The open-top chambers were used to enrich the air with CO2, whereas the drought stress was applied between the flowering and the ripening. The randomized block design was used, with four replicates in the subplots. The following plots were [CO2] at 700ppm (F1) and [CO2] environmental (F2) and the subplots were well watering (S1) and drought stress (S2). The results were subjected to Anova and the Tukey test (P < 0.05). For the treatments F1S1 and F1S2 the photosynthetic rate showed increments of 59% and the transpiration reduction of 12%. The yield, leaf temperature and stomatal conductance were not significant different to high [CO2], different from the dry matter, who showed increment of 20% (F1S1) and the water use efficiency who showed increase of 90% for high [CO2]. The osmotic potential was lower in plants under drought stress (F2S2 and F1S2), followed by plants under high [CO2] (F1S1). Despite the increment in photosynthesis, high [CO2] does not guarantee higher yield.

Leaf concentrations of nitrogen and phosphorus in phaseolus vulgaris l. Plants under high CO2 concentration and drought stress

This study aims to evaluate the leaf concentration of nitrogen and phosphorus correlated to the production of photoassimilates in beans plants (Phaseolus vulgaris L.) under high [CO2] and drought stress. The experiment was conducted in Vicosa (Brazil), during the period from April to July 2009, by using open-top chambers equipped with CO2 injection system. The drought stress was applied, through the irrigation suspension, during the period from flowering to maturation. The experimental design was randomized blocks in split-plot scheme with four replication, where the plots with plants grown in [CO2] of 700 mg L-1 and [CO2] environment of 380 mg L-1 and the subplots with plants with and without drought stress. The results were submitted to ANOVA and Tukey test (p < 0.05). In the plants under high [CO2] with and without drought stress, the photosynthetic rate increased by 59%, while the dry matter presented an increment of 20% in the plants under high [CO2] without drought stress. Reductions in [N] and [P] occurred in plants grown under high [CO2], resulting in greater efficiency in nitrogen use for photosynthesis. The high [CO2] increase only the total dry matter and not the total mass of grains. The drought stress reduces the dry matter and mass of grain, even at high [CO2].