Implications of the clone by harvest interaction in the selection of sugarcane genotypes in a regionalized program.

The recommendation of sugarcane clones depends on several factors, as the response or performance of the clones over different cuts or harvests. The clone by harvest interaction might be difficult to identify superior clones in the final stages of the sugarcane breeding program. Thus, the objective of this study was to investigate and describe the implications of the genotype by harvest interaction in the adaptability and stability of genotypes and delineation of mega-environments from a set of multi-environment trials. Fifteen clones and four checks were evaluated in eight environments. The trait TPH (tons of pol per hectare) was evaluated in two harvests (plant cane and ratoon cane) in 2010 and 2011. The joint analysis showed significance for harvest (H), environment (E), and genotype (G) effects. The interactions GxE, ExH, GxH, and ExGxH were also significant. The last three-way interaction indicated the differential response of the genotypes over environments, and that it depends on the harvests. The overall mean of the trials was 12.77 TPH. The coefficient of variation was 8.70% and the selective accuracy was 98.63%, indicating high experimental precision. The genotypes G4, G14, and G16 were statistically superior to the check varieties used; however, these genotypes did not show high stability as described by the additive main effects and multiplicative interaction method. There was a specific adaptation between the E7 and E5 environments and the G4 and G5 genotypes, respectively. In general, the grouping of the environments was inconsistent throughout the harvests, except for the E1 and E4 environments, which exhibited similarities for the different genotypes.

Experimental optimization of the number of blocks by means of algorithms parameterized by confidence interval in popcorn breeding.

The objective of this study was to determine the optimal number of repetitions to be used in competition trials of popcorn traits related to production and quality, including grain yield and expansion capacity. The experiments were conducted in 3 environments representative of the north and northwest regions of the State of Rio de Janeiro with 10 Brazilian genotypes of popcorn, consisting by 4 commercial hybrids (IAC 112, IAC 125, Zélia, and Jade), 4 improved varieties (BRS Ângela, UFVM-2 Barão de Viçosa, Beija-flor, and Viçosa) and 2 experimental populations (UNB2U-C3 and UNB2U-C4). The experimental design utilized was a randomized complete block design with 7 repetitions. The Bootstrap method was employed to obtain samples of all of the possible combinations within the 7 blocks. Subsequently, the confidence intervals of the parameters of interest were calculated for all simulated data sets. The optimal number of repetition for all of the traits was considered when all of the estimates of the parameters in question were encountered within the confidence interval. The estimates of the number of repetitions varied according to the parameter estimated, variable evaluated, and environment cultivated, ranging from 2 to 7. It is believed that only the expansion capacity traits in the Colégio Agrícola environment (for residual variance and coefficient of variation), and number of ears per plot, in the Itaocara environment (for coefficient of variation) needed 7 repetitions to fall within the confidence interval. Thus, for the 3 studies conducted, we can conclude that 6 repetitions are optimal for obtaining high experimental precision.