Agronomic value of alfalfa semi‐hybrids across contrasting Italian environments

Abstract Alfalfa ( Medicago sativa L.) semi‐hybrids of genetically distant material may display heterosis, but their agronomic value is hardly known. Our study evaluated two two‐way and one three‐way semi‐hybrids and two synthetic varieties for 3‐year herbage dry‐matter yield (DMY) in four agricultural environments of Northern Italy formed by the factorial combination of irrigated or rain‐fed cropping by pure stand (PS) or mixed stand (MS) with vigorous grasses to verify (1) the yield advantage of semi‐hybrid material and (2) the ability of a phenotyping platform with eight managed environments used in a prior study to reproduce the population adaptive responses in agricultural environments. The semi‐hybrids derived from putative heterotic populations selected from Italian germplasm, Egyptian germplasm, and a semi‐erect pool from Eastern Europe, Canada, and Spanish Mielga germplasm. The three‐way semi‐hybrid showed wide adaptation and over 17% greater DMY than a variety selected from the Italian genetic base (set as a reference for synthetic variety breeding). The two‐way semi‐hybrids showed specific adaptation to the irrigated MS environment (where alfalfa was outcompeted) or PS environments that agreed with features of their exotic parent population, and over 19% greater yield than the reference synthetic variety in the environments where they were specifically adapted. The phenotyping platform reproduced largely the population × environment interaction effects across agricultural environments.