Alfalfa (Medicago sativa L.) is the most important cultivated forage crop in the world. However, large proportions of alfalfa acreage in the western USA experience water deficit on a regular basis. Consequently, the current studies investigated the application of both molecular and conventional plant breeding approaches to improve alfalfa productivity under limited water conditions. The objectives of these studies were to: i) conduct marker assisted selection for favorable biomass QTL and to select against unfavorable biomass QTL that were segregating in three different elite alfalfa genetic backgrounds, ii) assess the impact of one cycle of phenotypic selection for drought resilience on frequencies of marker alleles linked to biomass QTLs, iii) determine the productivity of 24 elite alfalfa germplasms under fully irrigated, chronic (deficit irrigation throughout the season) and acute (mid-summer irrigation termination) water stress conditions, and iv) determine if elite alfalfa populations vary in their response to variable irrigation management regimes.