Optimum plot size for experiments with the sunflower1

Abstract

-The aim of this study was to determine a suitable plot size for field experiments with the sunflower. An experiment was carried out in a randomised complete block design with 14 sunflower cultivars and 10 replications. The plots consisted of four rows, six metres in length, spaced 0.7 m apart with 0.3 m between plants. The working area of the plot (7.56 m 2 ), consisting of the two central rows, was divided into 12 basic units, each consisting of three plants per row (0.63 m 2 ), from where the yield of the sunflower seeds was obtained. Suitable plot size was estimated using the intraclass correlation coefficient method. The detectable difference between treatments was also estimated (d). The optimum plot size for the evaluation of grain yield in the sunflower was 2.52 m 2 (working area), considering a boundary of one row on each side. Greater gains in experimental precision (16%) with increases in plot size, occurred up to eight basic units (5.04 m 2 ) using seven replications. Increasing the number of replications and the plot size was more efficient in increasing experimental precision, than increasing the number of cultivars.

Plot Size, Number of Treatments and Replicates and Experimental Precision in Buckwheat

“…In an analysis of variance, the greater the number of treatments and the number of replicates, the greater the number of degrees of freedom of the error and, consequently, the lower the mean square of the error (residual variance), that is, the higher the experimental precision. However, in this context, Sousa et al (2015) concluded that the increase in the number of replicates and plot size were more efficient to increase experimental precision than the increase in the number of cultivars (treatments).…”

“…Applying the methodologies of Smith (1938) and Hatheway (1961) in a set of uniformity trials conducted in different sowing periods and with different cultivars makes it possible to generate useful information to be used as a reference in the planning of experiments with buckwheat crop, aiming at higher experimental precision. These methodologies have been used in beans (MAYOR -DURÁN; BLAIR; MUÑOZ, 2012), sunflower (SOUSA et al, 2015;SOUSA;SILVA;ASSIS, 2016), banana (DONATO et al, 2018, cactus pear (GUIMARÃES et al, 2019;GUIMARÃES et al, 2020) and in species with potential for soil cover, such as: velvet bean (CARGNELUTTI FILHO et al, 2014a); forage turnip (CARGNELUTTI FILHO et al, 2014b); and flax (CARGNELUTTI FILHO et al, 2018).…”

Optimum Size and Shape of Experimental Units for Cassava Cropping

“…For the choice of different types of plots, we used only the groupings of BUs with parcel sizes that allowed the use of 100% of the area of uniformity test. In this way, the number of repetitions of each plot was limited by the respective total area, and the BUs were grouped in 31 different ways: 1x1, 1x2, 1x4, 1x5, 1x8, 1x10, 1x20, 1x40, 3x1, 3x2, 3x4, 3x5, 3x8, 3x10, 3x20, 3x40, 5x1, 5x2, 5x4, 5x5, 5x8, 5x10, 5x20, 5x40, 15x1, 15x2, 15x4, 15x5, 15x8, 15x10, and 15x20, thus obtaining 23 different plot sizes (X): 1, 2, 3, 4, 5, 6,8,10,12,15,20,24,25,30,40,50,60,75,100,120,150,200, and 300 UBs, which corresponded respectively to areas of 0.60, 1.20, 1.80, 2.40, 3.00, 3.60, 4.80, 6.00, 7.20, 9.00, 12.00, 14.40, 15.00, 18.00, 24.00, 30.00, 36.00, 45.00, 60.00, 72.00, 90.00, 120.00, and 180.00 m².…”

“…Several studies report the optimal size of the experimental unit for different situations and different crops, such as for tomato [14,15], lettuce [16], candeia [17], bean [18], rice [6], coffee [5], and sunflower [19,20,21]. However, there is little information about the size and shape of the experimental unit for cassava.…”

Experimental dimensions and precision in trials with millet and slender leaf rattlebox

“…The application of the methodologies of Smith (1938) and Hatheway (1961) in a set of uniformity trials conducted with millet and slender leaf rattlebox, in single cropping or intercropping, makes it possible to calculate the optimal plot size according to the experimental design, number of treatments, number of replicates and experimental precision. These methodologies have been used in common bean (MAYOR-DURÁN; BLAIR; MUÑOZ, 2012), in sunflower (SOUSA et al, 2015; SOUSA; SILVA ; A S SIS, 2016), banana (DONATO et al, 2018), cactus pear (GUIMARÃES et al, 2019(GUIMARÃES et al, , 2020 and in species with potential for soil cover, such as: turnip (CARGNELUTTI FILHO et al, 2014a); velvet bean (CARGNELUTTI FILHO et al, 2014b); flax (CARGNELUTTI FILHO et al, 2018) and black oats with common vetch (CARGNELUTTI FILHO et al, 2020).…”