Tamanho de parcela e número de repetições na cultura do milheto em épocas de avaliação

Abstract

ResumoOs objetivos deste trabalho foram determinar o tamanho ótimo de parcela (Xo) e o número de repetições para avaliar a massa verde de parte aérea de milheto em épocas de avaliação. Foram conduzidos 42 ensaios de uniformidade de 6 m×4 m (24 m 2 ), sendo cada ensaio dividido em 24 unidades experimentais básicas (UEB) de 1 m×1 m (1 m 2 ). Aos 52, 69 e 82 dias após a semeadura, foram avaliados, respectivamente 18, 6 e 18 ensaios, nos quais se pesou a massa verde das plantas de cada UEB. O Xo foi determinado pelo método da curvatura máxima do modelo do coeficiente de variação, e as comparações de médias entre as épocas de avaliação foram realizadas pelo teste t de Student. O número de repetições, para experimentos nos delineamentos inteiramente casualizados e blocos ao acaso, em cenários formados pelas combinações de i tratamentos (i=3, 4, ..., 50) e d diferenças mínimas entre médias de tratamentos a serem detectadas como significativas a 5% de probabilidade, pelo teste de Tukey, expressas em percentagem da média do experimento (d=10%, 12%, ..., 30%), foi realizado por processo iterativo até a convergência. O tamanho ótimo de parcela para avaliar a massa verde de parte aérea de milheto é de 4,46 m 2 , para as três épocas de avaliação. Para avaliar até 50 tratamentos, nos delineamentos inteiramente casualizados e blocos ao acaso, quatro repetições são suficientes para que diferenças entre médias de tratamentos de 28,75% da média do experimento sejam significativas, pelo teste de Tukey, a 5% de probabilidade.Palavras-chave: Pennisetum glaucum L., ensaio de uniformidade, planejamento experimental, precisão experimental. Plot size and number of repetitions in evaluation times in millet crop AbstractThe objectives of this work were to determine the optimum plot size (Xo) and number of repetitions, to evaluate the fresh weight of aerial part of millet, in evaluation times. Forty-two uniformity trials with 6 m×4 m (24 m 2 ) were conducted. Each trial was divided in 24 experimental units basic (UEB) with 1 m×1 m (1 m 2 ). At 52, 69 and 82 days after sowing were evaluated, respectively, 18, 6 and 18 trials, where the fresh weight of plants was weighed in each UEB. The Xo was determined by the method of maximum curvature of the model coefficient of variation and the means compared, among evaluation times, by Student's t test. The number of repetitions for experiments on completely randomized and randomized block designs, in scenarios of combinations of i treatments (i=3, 4, ..., 50) and d minimal differences between treatments means, to be detected as significant, 5% probability by Tukey test, expressed in percentage of the average of the experiment (d=10%, 12%, ..., 30%), was determined by iterative process until convergence. The optimum plot size to evaluate the fresh weight of aerial part of millet is 4.46 m 2 , to the three evaluation times. To evaluate up to 50 treatments, in completely randomized and randomized block designs, four replications are sufficient for differences between treatment means of 28.75% of the av...

Plot Size and Number of Replications for Evaluation of the Yield of Grains in Cultivars and Dates of Sowing of Rye

“…As the number of treatments is increased, the difference observed in the number of replications necessary for experiments in CRD and RBD is little expressive, until the moment in which the number of replications for experiments using the completely randomized and randomized block designs are virtually equal. These results agree with studies on crops of black oats (Cargnelutti Filho et al, 2014a), forage pea (Cargnelutti Filho et al, 2015a), canola (Cargnelutti Filho et al, 2015b), millet (Burin et al, 2015) and pigeonpea (Santos et al, 2016).…”

Comparison of Methods for Estimating the Optimum Plot Size for Pearl Millet, Slender Leaf Rattlebox, and Showy Rattlebox

“…This size can be calculated using data from uniformity trials (blank experiments) of this same crop by different methods. Plot size has been investigated in the common cultivar of pearl millet (Pennisetum glaucum L.) (BURIN et al, 2015(BURIN et al, , 2016 and sunn hemp (Crotalaria juncea L.) (FACCO et al, 2017) using the maximum curvature of the model of the coefficient of variation (PARANAÍBA; FERREIRA; , and in C. juncea (FACCO et al, 2018) using the modified maximum curvature method (MEIER; LESSMAN, 1971).…”

Plot size and number of repetitions in vetch

“…This wide variability scenario of ρ, s 2 , m, CV, Xo and CV Xo statistics among 48 uniformity trials is important for the properly dimensioning of plot size and number of repetitions. In field areas, this wide variability has also been observed in other cover crops, such as: black oat (Cargnelutti Filho et al 2014a), jack bean (Cargnelutti Filho et al 2014b), forage pea (Cargnelutti Filho et al 2015a), canola (Cargnelutti Filho et al 2015b), millet (Burin et al 2015;Burin et al 2016) and pigeonpea (Santos et al 2016).…”

“…Similar plot sizes to 4.52 m² were determined to evaluate the fresh matter weight of other cover crops. The determined sizes were: 4.14 m 2 for black oat (Cargnelutti Filho et al 2014a) (Burin et al 2015) and 8.39 m 2 for pigeonpea (Santos et al 2016). In researches carried out by Lithourgidis et al (2006), Tuna and Orak (2007) and Desalegn and Hassen (2015) to assess the fresh matter weight of vetch, the authors utilized plot sizes and useful area exceeding 4.52 m².…”

“…Dimensioning the optimum plot size based on the method of maximum curvature of the coefficient of variation model (Paranaíba et al 2009) and number of repetitions in combinations of treatments and precision levels have been carried out to measure fresh matter weight of cover crops, such as: black oat (Cargnelutti Filho et al 2014a), jack bean (Cargnelutti Filho et al 2014b), forage pea (Cargnelutti Filho et al 2015a), canola (Cargnelutti Filho et al 2015b), millet in evaluation times (Burin et al 2015), millet in sowing and cut times and pigeonpea (Santos et al 2016). For these crops, the optimal plot size oscillated between 4.14 m 2 for black oat (Cargnelutti Filho et al 2014a) and 8.39 m 2 for pigeonpea (Santos et al 2016).…”