Selection index and prediction of genetic values in cassava via reml/blup

Abstract

Cassava, an important subsistence crop in tropical countries, represents the third most important source of starch worldwide. Espírito Santo (Brazil) presents predominance of family farming, where table cassava is cultivated as a food crop. The objective of the study was to evaluate the genetic diversity, estimate the genetic parameters and quantify gains with the selection of traditional cassava genotypes collected in different regions of the state of Espírito Santo, using the methodology of the mixed models (REML/BLUP). A total of 106 genotypes were evaluated in three locations. Each planting date was considered an environment, totaling six environments. The evaluated traits were: shoot height (APH), total number of tuberous roots (NR); weight of commercial roots (WCR); total root weight (TWR), marketable root weight/total root ratio (MRTR); root cortex color (RCC), root pulp color (PC) and cooking time (CT). The studied cassava genotypes presented genetic diversity and selection potential. The highest heritabilities (h² = 0.90; 0.75 and 0.75) were recorded for the traits NRT, WCR and TWR, respectively. Gains from selection were positive for all of the traits evaluated. Higher selection gains (GS = 21.77% and 20.15%) were observed for the WCR and TWR traits, considering animal and human consumption and (GS = 10.89% and 17.45%) for NRT and WCR, when intended for human consumption only. Genotypes 82, 76, 46, T3 and 2 stood out for selection purposes for animal and human consumption. Genotypes 2, 81, 69, 12 and 49 stood out for selection purposes for human food. The assessment of the diverse genotypes has uncovered a selection of superior candidates with tremendous potential for commercial crops, catering to both human and animal consumption markets.