Quantifying genetic and nongenetic improvement for grain yield in faba bean breeding

Abstract

Faba Bean ( Vicia faba ) is a cool season legume crop, often grow as a rotation crop to improve sustainability of the farming systems. The Australian faba bean breeding program is publicly funded, with improving grain yield as a key breeding objective to increase grower profitability. In this study, we aimed to quantify the genetic and nongenetic improvement for grain yield using historical multi‐environment trial data collected from 2018 to 2024, comprising 1985 breeding lines evaluated in 158 field trials across 25 locations in southern Australia. Genetic gain estimates varied with the method used. Best linear unbiased estimates–based analyses showed negative gain with different breeding stages populations, whereas best linear unbiased prediction–based estimates indicated small but significant gains ranging from −1.6 to 7.8 kg/ha per cycle. With a subset data from 2020 to 2024 and pedigree information, genetic gain calculated via estimated breeding values–based method showed consistent positive gain across all populations, ranged from 7.6 to 15.3 kg/ha per cycle. Nongenetic trends estimated from check varieties (9 kg/ha/year) or using the single check PBA Samira (30 kg/ha/year) were positive but statistically insignificant. Environmental covariates analysis further suggested that water availability was the key driver of grain yield variation among breeding trials in faba bean. Despite the short timeframe, this study provided an evidence‐based evaluation of grain yield gain for the current breeding program and laid the foundation for future breeding program optimization.