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

Abstract

The objective of this work was to determine the optimal plot size to evaluate the fresh weight in buckwheat (Fagopyrum esculentum Moench) of the IPR91-Baili and IPR92-Altar cultivars, in scenarios formed by combinations of numbers of treatments, numbers of replicates, and levels of experimental precision. Sixteen uniformity trials (blank experiments) were carried out, eight with cultivar IPR91-Baili and eight with cultivar IPR92-Altar. The trials were performed in eight sowing dates. The fresh weight was evaluated in 576 basic experimental units (BEU) of 1 m x 1 m (36 BEU per trial). The soil heterogeneity index of Smith (1938) was estimated. The plot size was determined by the method of Hatheway (1961) in scenarios formed by combinations of i treatments (i = 5, 10, 15, and 20), r replicates (r = 3, 4, 5, 6, 7, and 8), and d precision levels (d = 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, and 20%). To evaluate the fresh weight in buckwheat of the IPR91-Baili and IPR92-Altar cultivars, in experiments under completely randomized and randomized block designs, with 5 to 20 treatments and eight replicates, plots of 8 m3of useful area are sufficient to identify significant differences between treatments, at 5% probability level, of 15% of the overall mean of the experiment.

Optimal plot size in single or intercropping sorghum and showy rattlebox

“…In the five compositions of S and CS sowing densities, it is observed that with fixed values of i and r, Xo increased with increasing precision (d); with fixed values of i and d, Xo decreased with increasing r; and with fixed values of r and d, there was a decrease in Xo with increasing i (Figures 2 and 3). This pattern is in agreement with the results obtained by Cargnelutti Filho et al (2020aFilho et al ( , 2020bFilho et al ( , 2021aFilho et al ( , 2021bFilho et al ( , 2022.…”

“…Thus, it is suggested to use plots up to 10 m 2 , because the gain in experimental precision (decrease of VU (X) ), from ten BEU, was inexpressive. Similar pattern was observed in buckwheat (Cargnelutti Filho et al, 2020a);black oat + common vetch (Cargnelutti Filho et al, 2020b); millet + slender leaf rattlebox (Cargnelutti Filho et al, 2021a); millet + showy rattlebox (Cargnelutti Filho et al, 2021b); and black oat + common vetch + forage turnip (Cargnelutti Filho et al, 2022).…”

“…The averages of b, from the three trials for each composition were 0.8179, 0.8514, 0.8350, 0.9899, and 0.7345 for the compositions of 100% of S, 75% of S + 25% of CS, 50% of S + 50% of CS, 25% of S + 75% of CS, and 100% of CS, respectively. Values of b close to unity were also obtained in grain sorghum (Lopes et al, 2005;Brum et al, 2008), sunflower (Sousa et al, 2016), forage palm (Guimarães et al, 2020), and in species with potential for ground cover, such as: buckwheat (Cargnelutti Filho et al, 2020a); black oat + vetch (Cargnelutti Filho et al, 2020b); millet + slender leaf rattlebox (Cargnelutti Filho et al, 2021a); millet + showy rattlebox (Cargnelutti Filho et al, 2021b); and black oat + common vetch + forage turnip (Cargnelutti Filho et al, 2022).…”

“…Methodologies from Smith (1938) and Hatheway (1961) can be applied to calculate the optimal plot size according to the number of treatments, number of repetitions, and experimental precision. These methodologies have been used in grain sorghum (Lopes et al, 2005;Brum et al, 2008), sunflower (Sousa et al, 2016), banana (Donato et al, 2018), forage palm (Guimarães et al, 2020), buckwheat (Cargnelutti Filho et al, 2020a), and tomato (Oliveira et al, 2021). It has still been used, in single and intercropped cultivation of black oat + vetch (Cargnelutti Filho et al, 2020b), millet + slender leaf rattlebox (Cargnelutti Filho et al, 2021a), millet + showy rattlebox (Cargnelutti Filho et al, 2021b), and intercropping of black oat + common vetch + forage turnip (Cargnelutti Filho et al, 2022).…”