RESUMO -Esta pesquisa foi conduzida com o objetivo de avaliar a precocidade, a produtividade e as características do dossel de 12 genótipos de seis espécies de cereais de inverno de duplo propósito (forragem e grãos) submetidos ao corte na região da Depressão Central do Rio Grande do Sul. As espécies e os genótipos testados foram: trigo BRS 277, BRS Guatambu, BRS IntroduçãoNo Sul do Brasil, uma das maiores limitações da atividade pecuária é a carência de forragem no período entre o outono e início do inverno, que ocasiona quedas na produção de leite e de carne. Para diminuir este problema, normalmente adota-se a suplementação com silagem, feno ou concentrados , que implica maiores custos de produção. Neste sentido, a utilização de pastagens anuais de inverno é uma alternativa de produção de forragem precoce com menor custo.Os cereais de inverno normalmente são cultivados com o objetivo de produzir grãos para a alimentação humana e animal ou como forrageiras para formação de pastagens. As espécies mais cultivadas são a aveia-branca (Avena sativa L.), a aveia-preta (Avena strigosa Schreb.), o centeio (Secale cereale L.), a cevada (Hordeum vulgare L.), o triticale (X Triticosecale Wittmack) e o trigo (Triticum sativum L.), R. Bras. Zootec., v.41, n.4, p.873-882, 2012

The objectives of this study were to determine the optimum plot size (Xo) and the number of replications to evaluate grain yield and verify the variability of Xo among oat cultivars. Thirtytwo uniformity trials of 3 × 3 m were performed, being 8 from each cultivar (URS Charrua, URS Taura, URS Estampa, and URS Corona). Each uniformity trial was divided in 36 basic experimental units (BEU) of 0.5 × 0.5 m. Grain yield was determined in each BEU. The Xo was determined by the method of maximum curvature of the coefficient of variation model. Mean comparisons among cultivars were performed by the Scott-Knott test via bootstrap. The number of replications was calculated by an iterative process until convergence for experiments in completely randomized design (CRD) and randomized block CRop pRoduCTion And MAnAgeMenT-Article

RESUMO -Esta pesquisa foi conduzida com o objetivo de avaliar o valor nutritivo da forragem de 12 genótipos de seis espécies de cereais de inverno de duplo propósito (forragem e grãos), submetidos ao corte, na região da Depressão Central do Rio Grande do Sul. As espécies e genótipos testados foram: trigo (BRS 277, BRS Guatambu, BRS Tarumã, BRS Umbu); aveia-preta (Agro Zebu, UPFA 21 -Moreninha e Comum); aveia-branca (UPF 18); centeio (BR 1 e BRS Serrano); Cevada

Studies on growth models for productive character of sunn hemp are important to know the behavior of the culture. Therefore, the objective of this research was to adjust non-linear models, Gompertz and Logistic, in the description of productive traits of sunn hemp in two sowing periods. Two uniformity trials were performed. The evaluations began on October the 29 th 2014 and December the 16 th 2014, totaling 94 and 76 evaluation days for periods 1 and 2, respectively. After the emergence of the seeds of sunn hemp, for first period from 7 days after sowing, and from 2 to 13 days after sowing, on each day, they were collected randomly four plants. The traits: fresh matter leaf, stem, root, shoot, and total, and dry matter leaf, stem, root, shoot, and total. For both models the confidence interval was calculated of parameters a, b and c. The adjustment quality of the Gompertz and Logistic models was verified by the determination coefficient, the Akaike information criteria, residual standard deviation, mean absolute deviation, mean absolute percentage error and mean prediction error. The Gompertz model when compared between the sowing periods through the confidence interval of the parameters, for the productive traits, differs. The same result was found for the Logistic model. The growth models of Gompertz and Logistic presented good adjustment quality.

The objectives of this study were to determine the optimum plot size (X o ) and the number of replications to evaluate the grains yield of rye (Secale cereale L.) and investigate the variability of X o between two cultivars and three sowing dates. Eighteen uniformity trials were conducted with rye. The X o was determined by the method of maximum curvature of the coefficient of variation model. The number of repetitions was determined in scenarios formed by combinations of i treatments (i = 3, 4, ... 50) and d minimum differences between means of treatments to be detected as significant at 0.05 of probability, by Tukey test, expressed in percentage of the average of the experiment (d = 10, 12, ... 30%). There is variability in optimum plot size to evaluate the grains yield among the cultivars BRS Progresso and Temprano and among sowing dates in the rye crop. The optimum plot size to evaluate the grains yield of rye is 6.08 m 2 . Seven replicates are sufficient to evaluate the grains yield of rye in experiments with up to 50 treatments, and identify, as significant at 5% probability by Tukey test, differences among averages of treatments of 29.65% of the mean of the experiment in designs completely randomized and randomized block.

The objectives of this study were to determine the sample size (number of plants) required to estimate the mean of morphological traits of rye (Secale cereale L.) and verify the sample size variability between the traits, cultivars, sowing dates, and evaluation times for distincts mean estimation errors. Ten uniformity trials were performed with two rye cultivars (BRS Progresso and Temprano) in five sowing dates (05/03/2016, 05/25/2016, 06/07/2016, 06/22/2016 and 07/04/2016). Evaluations of traits plant height, number of leaves, and number of stems were performed during the development of the crop. In order to verify the difference of the traits between cultivars and between sowing dates and evaluation times, the F-test was applied to test the hypothesis of homogeneity of variances and the Student's t-test was used to test the hypothesis of equality of means. The sample size of each trait was calculated for distincts mean estimation errors. There is sample size variability between the traits, cultivars, sowing dates, and evaluation times. In order to estimate the mean of plant height with the same precision, smaller sample sizes are required at the intermediate and final evaluation times compared to initial evaluation times. For the traits number of leaves and stems, smaller sample sizes are required in the initial evaluation times than in the final evaluation times. For mean estimation of traits with maximum estimation error of 15% between sowing dates and evaluation times, 83 and 103 plants are required respectively for cultivars BRS Progresso and Temprano. Key words: Sampling planning. Sampling precision. Secale cereale L. ResumoOs objetivos deste trabalho foram determinar o tamanho de amostra (número de plantas) para a estimação da média de caracteres morfológicos de centeio (Secale cereale L.) e verificar a variabilidade do tamanho de amostra entre caracteres, entre cultivares, entre épocas de semeadura e de avaliação, para distintos erros de estimação da média. Foram conduzidos dez ensaios de uniformidade, com duas cultivares de centeio (BRS Progresso e Temprano) em cinco épocas de semeadura (03/

-The objective was to evaluate elephant grass (Pennisetum purpureum Schum.) pastures, under the agroecological and conventional systems, as forage mass and stocking rate. In the agroecological system, the elephant grass was established in rows spaced by 3.0 m from each other. During the cool season ryegrass (Lolium multiflorum Lam.) was established between these rows, which allowed the development of spontaneous growth species during the warm season. In the conventional system the elephant grass was established singularly in rows spaced 1.4 m from each other. Organic and chemical fertilizers were applied at 150 kg of N/ha/year with in the pastures under agroecological and conventional systems, respectively. Lactating Holstein cows which received 5.0 kg/day supplementary concentrate feed were used for evaluation. The experimental design was completely randomized, with two treatments (agroecological and conventional systems) two replications (paddocks) and independent evaluations (grazing cycles). The pastures were used during the whole year for the agroecological system and for 195 days in the conventional year. The average values of forage mass were 3.5 and 4.2 t/ha and the stocking rates were 2.08 and 3.23 AU/ha for the respective systems. The results suggest that the use of the elephant grass under the agroecological system allows for best distribution of forage and stocking rate to be more uniform throughout the year than the use of elephant grass in conventional system.

The objective of the present study was to fit Gompertz and Logistic nonlinear to descriptions of morphological traits of sunn hemp. Two uniformity trials were conducted and the crops received identical treatment in all experimental area. Sunn hemp seeds were sown in rows 0.5 m apart with a plant density of 20 plants per row meter in a usable area of 52 m × 50 m. The following morphological traits were evaluated: plant height (PH), number of leaves (NL), stem diameter (SD), and root length (RL). These traits were assessed daily during two sowing periods—seeds were sown on October 22, 2014 (first period) and December 3, 2014 (second period). Four plants were randomly collected daily, beginning 7 days after first period and 13 days after for second period, totaling 94 and 76 evaluation days, respectively. For Gompertz models the equation was used y=a*e^((?-e?^((b-c*xi))and Logistic models the equation was used yi= a/(1+e^((-b-c*xi)). The inflection points of the Gompertz and Logistic models were calculated and the goodness of fit was quantified using the adjusted coefficient of determination, Akaike information criterion, standard deviation of residuals, mean absolute deviation, mean absolute percentage error, and mean prediction error. Differences were observed between the Gompertz and Logistic models and between the experimental periods in the parameter estimate for all morphological traits measured. Satisfactory growth curve fittings were achieved for plant height, number of leaves, and stem diameter in both models using the evaluation criteria: coefficient of determination (R²), Akaike information criterion (AIC), standard deviation of residuals (SDR), mean absolute deviation (MAD), mean absolute percentage error (MAPE), and mean prediction error (MPE).