Plot size and number of replications for ryegrass experiments

Abstract

The objective of this research was to determine the optimal plot size and the number of replications to evaluate the fresh matter of ryegrass sown to haul. Twenty uniformity trials were conducted, each trial with 16 basic experimental units (BEU) of 0.5 m2. At 117, 118 and 119 days after sowing, the fresh matter of ryegrass in the BEUs of 5, 10 and 5 uniformity trials, respectively, were determined. The optimal plot size was determined by the maximum curvature method of the variation coefficient model. Next, the replications number 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 5% of probability by the Tukey test, expressed in experimental mean percentage (d = 10, 11, ... 20%). The optimal plot size to determine the fresh matter of ryegrass seeded at the haul is 2.19 m2, with a variation coefficient of 9.79%. To identify as significant at 5% probability, by the Tukey test, differences between treatment means of 20%, are required five, six, seven and eight replications, respectively, in ryegrass experiments with up to 5, 10, 20 and 50 treatments.

Plot size and number of replicates for ryegrass experiments sowed in rows

“…Ryegrass (Lolium multiflorum L.) is one of the most cultivated forage species, and it can be used either alone or in mixtures to eliminate the lack of forage in southern Brazil, during the winter (Flores et al, 2008). The expansion of research on ryegrass is significant because of the importance of this crop to phytotechnology, soil conservation, phytosanitary defense, and animal nutrition (Flores et al, 2008;Agostinetto et al, 2017;Vizioli et al, 2018;Salazar et al, 2019;Toebe et al, 2020a). In this sense, it is important to define experimental protocols, to optimize the quality and reliability of research, as well as to minimize expenditures with financial, human, and time resources.…”

“…These two methods have been applied in experimental planning to determine the fresh weight of forage crops (Cargnelutti Filho et al, 2014a, 2020Burin et al, 2015;Chaves et al, 2018;Lavezo et al, 2018;Toebe et al, 2020b). These methods have been also applied for the determination of plot size and the number of replicates, to evaluate the fresh weight of broadcastseeded ryegrass (Toebe et al, 2020a).…”

“…In this sense , Cargnelutti Filho et al (2014b) identified differences in the experimental design of turnip sowed both in rows and broadcasted. Thus, although the number of replicates and the plot size for ryegrass sowing by broadcast have already been carried out by Toebe et al (2020a), this information for ryegrass experiments sowed in rows has not been reported in the literature yet.…”

“…The comparisons of means of the statistics ρ, s 2 , m, CV trial , Xo, and CV Xo among the evaluation days were performed using Tukey's test via bootstrap with 10,000 resamplings, at 5% probability, as detailed and applied by Toebe et al (2020a).…”

“…The number of replicates (r) was determined for experiments with completely randomized design and randomized block design, by an iterative process until convergence, using the mean of CV Xo among the evaluation days. The r was determined in scenarios formed by combinations of i treatments (i = 3, 4, ..., 50) and d minimum differences among means of treatments to be detected as significant by Tukey's test at 5% probability, expressed as a percentage of the experimental mean (d = 10%, 11%, ..., 20%), according to Cargnelutti Filho et al (2014a) and Toebe et al (2020a), in ryegrass sown to haul. Statistical analyses were performed with Microsoft Office Excel, R (R Core Team, 2020), and Sisvar softwares (Ferreira, 2014).…”