Stability analysis of forage yield of Iranian and exotic alfalfa (Medicago sativa L.) genotypes using genotype plus genotype-by-environment interaction biplot method

Abstract

Importance of the work: The stability of forage yield under variable climate conditions is
increasingly important for sustainable alfalfa production under climate change scenarios.
Objectives: To assess the genotype × environment interaction for the prediction of differential
genotype responses and to support the selection of superior, low-risk genotypes.
Materials and Methods: The stability was evaluated of the forage yield of nine Iranian and
international alfalfa genotypes over 2 y (2021–2022) in a randomized complete block design,
with three replications across four agricultural research stations in Iran (Karaj, Dezful, Yazd, Jiroft).
Results: Combined analysis of variance for dry forage yield and plant height revealed significant
effects of environment, genotype and their interaction. Stability analyses using Shukla’s
stability variance and Lin and Binns’ superiority coefficient identified the Omid genotype
as an optimal combination of high dry forage yield with 21.34 t/ha and acceptable stability.
Furthermore, the genotype plus genotype-by-environment biplot analysis showed that Omid and
Baghdadi (located closest to the ideal genotype) combined superior yield with stability across
environments. The commercial CUF101 genotype, despite a moderate forage yield (20.62 t/ha),
had favorable stability under unpredictable environmental conditions and was recommended for
stress-prone areas.
Main finding: These results show that the applied method was reliable for selecting and
deploying stable, high-yielding alfalfa cultivars adapted to diverse climatic regions of Iran.