Assessing genetic variation, genotype-environment interactions, and genomic prediction for cassava garri quality

Abstract

In this study, we assessed the genetic and genotype by environment interaction variation and genomic prediction of the garri quality traits of cassava (Manihot esculenta Crantz). The study was conducted in the National Root Crop Research Institute experimental sites in Umudike and Otobi, Nigeria, in two planting seasons of 2021 and 2022. We estimated the broad and narrow-sense heritability and correlation among measured physicochemical parameters on the garri and dried cassava roots (chips). A fivefold cross-validation scheme was used to calculate the accuracy of the genomic prediction. A significant negative correlation was observed between dry matter content, swelling index, water absorption capacity, and amylose content in garri. The swelling index had a significant negative correlation with swelling power, bulk density, amylose content of cassava chips, crude fiber, and dry matter content. Bulk density had a significant negative correlation with the crude fiber of garri and a positive correlation with the amylose content of cassava chips, the crude fiber of cassava chips, and the dry matter content. Broad-sense heritability ranged between 0 and 0.19 for garri traits and 0.02 and 0.49 for chips. Narrow-sense heritability ranged between 0 and 0.18 for garri quality traits and 0 and 0.20 for chips. A significant genotype × environment effect was observed for most of the evaluated traits of chips and garri quality. The predictability of the sugar content, swelling index, swelling power, and water absorption capacity of garri was higher than that of the amylose content, bulk density, and starch content of garri. There was low predictive accuracy for the quality traits garri studied. The sugar content, swelling power, and water absorption capacity of cassava chips averaged approximately 20%. This study provides valuable insights into assessing the genetic variation, correlation, and genomic selection within breeding programs aimed at enhancing the quality traits of cassava for end users.