Thomas Newton Martin

Plano amostral em parcelas de milho para avaliação de atributos de espigas

In agricultural experiments good sampling techniques are important to reduce costs and labor, and guarantee adequate experimental precision. The objective of this research was to study a sampling methodology of experimental plots to evaluate morphologic characteristic and corn yield in maize spikes. Single (DAS 9560), double (AG 6018) and triple (AG 303) crosses corn hybrids and an open pollinated variety (BR 202) were ev aluated. The experiment design was a randomized complete block with four replications and was conducted in the experimental area of the Crop Science Department of the Federal University of Santa Maria (UFSM), Brazil. The main plot was divided in 96 sub plots with one meter of length. In each plot, the spikes of five sub-plots were sampled and length, diameter, grain yield and the mass of one hundred grains of each spike was measured or weighted. It was concluded that the sample size within plots is related to the characteristic to be evaluated in the maize spikes and there are genetic and environment factors that interfere on estimation of sample size of maize spikes. A sample of 24 spikes, one for each split-plot, and six replications for each genotype, results in a considered appropriate precision (less than 10% from the mean) for length and width of spikes, grain yield and mass of one hundred grains.

Tamanho ótimo de parcela e número de repetições em soja (Glycine max (L.) Merril)

With the objective of verifying if different cultivars of soybean modify the estimates of the optimum plot size and of the numbers of replications, an experiment was conduced in the agriculturist year of 2000/01 in area pertaining to the Department of Crop Science in Santa Maria University Campus. Two cultivars of soybean were used (BRS 137 and Fepagro-RS10), conducted in a randomized block design with three replications. The size of plot was evaluated through the method of maximum modified bending. The test of parallelism of SEBER (1976), was used to verify the heterogeneousness of reply among tested cultivars. The number of replications was estimated through the described methodology for HATHEWAY (1961). It can be concluded that to cultivars studied the number of replications that confers an adequate accuracy is equal to seven and the optimum plot size is 3.96m2.

Análise de coeficiente de trilha para os componentes de produção em arroz

Eighty eight rice genotypes were evaluated during four years aiming to study the relationship among yield components. In each year, the experimental design was a completely randomized block design with four replications and the variables studied were: plant height, seed yield, spikelet sterility, number of seeds per panicle, 1000 seeds weight and head grains. The estimation of correlations and the path coefficient analysis were conducted with the GENES software. The genotypes showed significant variability for all the variables analyzed within each one of years. It was concluded that variable selection must be carried out among the cultivars that are more similar and using a greater number of variables allows better inferences about rice yield components. Grain weight was the yield of component that most affected seed yield rice plants.

Simulação estocástica de atributos do clima e da produtividade potencial de milho utilizando-se distribuição triangular

Abstract – The objective of this work was to simulate the potential productivity of maize, through Monte Carlomethod, using an agrometeorological stochastic model. The experiment was conduct in Piracicaba, State of SaoPaulo, Brazil, at 22 o 4230S, 47 o 3830W, and 546 m altitude, the climate of the region is Cwa type, tropical humid.Daily average values of temperature (from 1917 to 2002) and global solar radiation (from 1978 to 2002) were used.Statistical performance index was used to compare observed and simulated data. The probabilistic modelsdeveloped to simulate temperature and solar radiation averages produced similar values to observed data throughtriangular distribution, and it can be used in stochastic models to predict maize potential productivity in differentdates of sowing.Index terms: Zea mays , probability distribution, method of Monte Carlo. O milho, em razao de seu potencial produtivo,composicao quimica e valor nutritivo, e um dos maisimportantes cereais cultivados e consumidos no mundo.Gracas a sua multiplicidade de aplicacoes, quer naalimentacao humana quer na alimentacao animal, temrelevante papel socioeconomico, alem de constituir-seem indispensavel materia-prima impulsionadora decomplexos agroindustriais diversificados (Fancelli &Dourado Neto, 2003). A produtividade de uma cultura(potencial genetico de producao) e resultante do usoadequado de insumos tecnologicos de producao e decondicoes ambientais determinadas por fatoresclimaticos, durante o ciclo cultural. Entre os fatores doclima utilizados para se avaliar a viabilidade e a estacaopara a implantacao das mais diversas atividadesagricolas, a temperatura, a radiacao solar e aprecipitacao sao os mais estudados (Fancelli & DouradoNeto, 2003).

Dados climáticos simulados e produtividade potencial do milho

The objective of this work was to evaluate a methodology to estimate (proceed referred to obtain the estimated values and the estimative) maize potential productivity according to daily average values of air temperature and solar radiation, using a stochastic model. Thexa0values of 86xa0years for daily average air temperature and 25xa0years for daily global solar radiation were supplied by Piracicaba Meteorological Station (Esalq/USP). Potential productivity values were simulated 1,000xa0times for each one of the considered dates of sowing (Octoberxa015th, Februaryxa015th and Augustxa015th). Twoxa0cases for the normal truncated probability distribution were considered (extreme values: average distribution - 1.96xa0standard deviation and average distribution + 1.96xa0standard deviation): average temperature daily variable and global solar radiation daily constant, and average temperature daily constant and global solar radiation daily variable. Thexa0esteem methodology allows defining the magnitude order of the maize potential productivity for one locality (on the basis of temperature and solar radiation data). Thexa0stochastic procedure allows associating maize potential productivity to a probability of occurrence.

Adubação nitrogenada na cultura do feijoeiro em plantio convencional

The beans varietes, x91TPS Nobrex92 and x91Perolax92 were grown during the summer season of 2001/2002, in Santa Maria, State of Rio Grande do Sul, Brazil, with the objectives of study the application timing and spplitting of nitrogem in conventional tillage. The nitrogen was applied at planting (15kg ha-1 in all treatments) a single rate at 14, 21, 28 and 35 DAE and at the same times in two applications: 50% + 50% of the dose, 30% + 70% of the dose, 70% + 30% of the dose. The experimental was in randomized blocks design with four replications, with split-plot. It was not verified interaction between time and nitrogen portionin. Moreover, x91TPS Nobrex92 grain yield was 49% higher than variety Perola. Higher grain yield was obtained through the application of nitrogen full rate at 21, however good results were obtained with the portionong of the nitrogen fertilization (50% 14 DAE + 50% 21 DAE), (70% 14 DAE + 30% 28 DAE) e (30% 21 DAE + 70% 28 DAE). The nitrogen application after 28 DAE did not provided high grain yields.