Yield-stability selection index applied to identify top genotypes in a Hevea brasiliensis segregating population in Antioquia, Colombia

Abstract

Rubber (Hevea brasiliensis) production in Colombia has been primarily dependent on three predominant genotypes for over five decades. However, challenges such as disease susceptibility and low yield and quality underscore the need for increased genetic variability. Yield-stability indexes are essential tools for identifying superior genotypes in Hevea breeding programs. In 1999, a segregating rubber plantation with 3395 trees was established at the Agrosavia El Nus Research Center. Georeferencing, tapping data, and total solids yield were assessed through 10 evaluations per tree. This study aimed to identify high-performing rubber genotypes using an adjusted total solids yield-stability index. Phenotypic values were adjusted to account for microclimate effects and temporal variation. The resulting index, applied through stratified mass selection, provided a closer approximation of genotypic performance. Based on the index, the top 50 and bottom 10 genotypes were identified, offering insights into elite individuals' contributions to total solids production. Notably, genotypes 2a13, 2a317, and 3a89 exhibited higher predicted yield-stability ($\hat{p}$) index values, with ${\hat{p}}_{2a13}=87.03,{\hat{p}}_{2a317}=78.50,$ and ${\hat{p}}_{3a89}=39.79$, reflecting superior performance and stability, making them valuable candidates for rubber breeding programs aimed at improving total solids production. Additionally, the index facilitated the identification of genotypes with high phenotypic values but marked production instability, as observed in genotype 3c355 (${\hat{p}}_{3c355}=-404.35)$.