Experimental plan for oilseed flax in multi-environment trials

The importance of the cultivation of oilseed flax has increased in the Brazilian agricultural scenario, and therefore, research must be carried out to have better recommendations for cultivation. For research to be reliable, there is a need for adequate experimental planning. In this context, the objective of this work is to propose an experimental plan, with estimates of plot size, sample size, and the number of replicates, to increase the precision and reliability of experiments carried out with the oilseed flax crop. The experiments were carried out in three environments and two agricultural years, in a randomized block design with four replicates and two varieties of oilseed flax, totaling eleven experiments in six different environments. In both years, plants were sampled in the plot and measured for: total height, technical length, productive length, main branch diameter, number of capsules per plant, number of seeds per capsule, and grain mass per plant. From these data, the plot size was estimated using the Pimentel-Gomes method, and it was verified that 30 plants, arranged in 6 rows of cultivation, are needed to compose the usable area of the plot, with 2 border rows, totaling 90 plants per plot. Differently, with the grain yield data, in which the effects of the parameters of the mathematical model of each experimental trial were removed, the plot size was estimated through the Paranaíba method, and it was identified that the plots must be 9.86 m². For sampling, an optimal size of 5.4 m² was observed, considering a semi-amplitude of the confidence interval (D%) equal to 20% of the mean. Also, the need to use five replicates per plot was verified, considering a least significant difference in the Tukey test expressed as a percentage of the mean of 25%.