Optimal plot size in single or intercropping sorghum and showy rattlebox

Abstract

The objective of this study was to determine the optimal plot size to evaluate fresh matter productivity of sorghum (Sorghum bicolor (L.) Moench) and showy rattlebox (Crotalaria spectabilis Roth.). Fifteen uniformity trials (blank experiments) with sorghum and showy rattlebox, in single or intercropping, were carried out. The fresh matter productivity was evaluated in 540 basic experimental units (BEU) of 1 × 1 m (15 trials × 36 BEU per trial). The plot size was determined by the method of Hatheway (1961), in scenarios formed by combinations of treatment numbers, repetitions numbers, and levels of experimental precision. To evaluate the fresh matter productivity of sorghum and showy rattlebox, in single or intercropping, with 5 to 30 treatments and with five repetitions, plots of 10 m² of useful area are sufficient for differences between treatments of 24% of the overall average of the experiment to be considered significant at 0.05 probability.