This study aimed to estimate genetic parameters and correlations between morphological, agronomic and root quality traits of cassava plants, as well as to study cause and effect relationships through path analysis. A total of 814 genotypes were evaluated from 2011 to 2015. The joint analysis of the data was performed by the mixed models approach. The predicted genetic values of the genotypes were used to estimate the genetic correlations among as well the path analysis. The estimates of heritability of the genotype means ranged from 0.31 (commercial fresh root yield - CRY) to 0.62 (plant height - PLH). The highest genetic correlation coefficient estimates were observed for starch yield (STY) × total fresh root yield (FRY) (0.97). The results of the path analysis showed that FRY had the highest direct effect on STY, but the indirect selection based on FRY was not efficient to improve the gain of STY. The joint analysis of the data for the 21 environments was performed using the linear mixed model for incomplete block design in several locations: y=Xr+Zg+Wb+Ti+e.
Figure 1: Pairwise genotypic correlation coefficients between eight agronomic traits evaluated in cassava genotypes.
VIG: plant vigor; LFR: leaf retention; AGY: above-ground yield; PLH: plant height; CRY: commercial fresh root yield; DMC: dry matter content; FRY: total fresh root yield; STY: starch yield.