Abstract
The optimum plot size for ‘Gigante’ cactus pear can be estimated by several methods; thus, ultimately aiming for efficiency, simple use and high precision, the objective of this study was to compare methods for estimating plot sizes: modified maximum curvature method, Hatheway’s convenient plot size method, linear and quadratic response plateau models, and comparison of variances method for evaluating phenotypic characteristics in experiments with ‘Gigante’ cactus pear. Plot sizes were estimated by conducting a uniformity trial. Estimated optimum plot sizes varied with the method and vegetative characteristic. The quadratic response plateau regression estimated the largest plot sizes, whereas Hatheway’s method estimated the smallest plot sizes. Comparison of variances method estimated intermediate plot sizes in comparison with the other methods for most measured characteristics. Plots sizes estimated by modified maximum curvature method are more consistent with results reported by studies on ‘Gigante’ cactus pear. 10 basic unit plot sizes estimated by the linear response plateau model can be used with high precision and practical feasibility for growing cactus pear, thereby improving the use of resources.
Highlights
‘Gigante’ cactus pear (Opuntia ficus indica Mill) is considered the forage crop with the highest productivity, yields recorded in Brazil do not reach satisfactory levels (Marques et al, 2017)
Based on the soil heterogeneity coefficient (b), the experimental area was classified as heterogeneous, with regression coefficients higher than 0.7 for all evaluated traits. These experimental conditions indicate that increasing plot size is more effective than increasing the number of replicates when aiming at higher experimental precision (Hou et al, 2015)
Once the optimum plot size is determined, further increases in precision may be obtained by using more replicates (Souza et al, 2018)
Summary
‘Gigante’ cactus pear (Opuntia ficus indica Mill) is considered the forage crop with the highest productivity, yields recorded in Brazil do not reach satisfactory levels (Marques et al, 2017). Field trials with ‘Gigante’ cactus pear are conducted in several Brazilian regions with the objective of improving production, decreasing costs and increasing efficiency of agricultural inputs, thereby providing minimum conditions for feasible farming (Dantas et al, 2017). Finding out the suitable size and shape of the experimental plot is necessary so as to lessen the experimental error (Cargnelutti Filho et al, 2018). Adopting a suitable plot size has a direct impact on the precision and quality of the experimental data (Cargnelutti Filho et al, 2014; Schmildt et al, 2016; Lavezo et al, 2017)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
