Tamanho de parcela e número de repetições para avaliar a massa verde de parte aérea em feijão guandu

Abstract

A good planning of experiment should be related to the optimization of the size of the plots and the number of repetitions. Thus, the objectives of this study were: determine the portion size and the number of repetitions to evaluate the green mass of pigeonpea shoots and compare estimates of the size of portion between times of assessment in the same year and between years. Two tests were conducted of uniformity with pigeonpea (Cajanus cajan (L.) Millsp.) cultivar BRS Mandarin in two years 2011/2012 and agricultural 2012/2013. In the year 2011/2012, agricultural to 127 days after sowing (DAS), the evaluation was conducted of the first season, where they were evaluated 16 tests with 36 basic experimental units (UEB) of 1 m² were weighed in grams, plants were cut along the surface of the ground to evaluate the aboveground green mass in grams m-² in digital electronic personal scale. This methodology was used in all evaluations. The second time was evaluated to 139 of, with 24 essays composed 36 UEB of 1 m². In the year 2012/2013 agricultural assessments were conducted in 10 seasons to163, 167, 170, 174, 177, 181, 184, 188, 191 and 195 of, each season was rated 4 trials with 36 UEB of 1 m². For each test, were determined the spatial autocorrelation coefficient of first order (ρ), variance (s²), medium (m), the coefficient of variation (CV) assay, the great size of plot (Xo) and the coefficient of variation in size of parcel (CVXo) as Paranaíba; Ferreira; Morais (2009a). The comparison of the averages statistics ρ, s², m, CV, Xo and CVXo, between the times of assessment in each year between agricultural and agricultural, regardless of time, was accomplished using student's t test for independent samples, the 5% probability of error using bootstrap with 10000 simulations. The number of repetitions was determined by iterative process for experiments in completely randomized design (DIC) and random blocks design (DBA). The great size of plot to evaluate the green mass of aerial part of pigeonpea differs between seasons in the same year assessment and does not differ between the years, regardless of the time of evaluation. Because there are significant differences between the eras of evaluation within each year, the great size of plot to evaluate the green mass of aerial part of pigeonpea was estimated at 8.39 m ², contemplating this way, every season for the evaluation of two years. To evaluate the green mass of aerial part of pigeonpea with CVXo = 18.76% and Xo = 8.39 m², seven repetitions are enough in experiments in DIC and DBA with up to 50 treatments to identify the 5% probability, by Tukey test, significant differences between averages of treatments of 40% of the average of the experiment.