Improving emergence and early vigor in alfalfa (Medicago sativa L.) with seed and seedling-based selections
Alfalfa (Medicago sativa L.) is an important perennial forage crop, providing nutritional and ecological benefits to the dairy industry in the United States. Despite this, production of alfalfa and other perennial forages across the United States has been declining over the past few decades. Considering the need for resilient, sustainable cropping systems in the face of climate change, perennial crops like alfalfa play vital carbon-sequestration, soil-protection and yield-stability roles, warranting the development of new agronomically competitive varieties suited for a changing climate. This report examines preliminary results from a breeding project for improved alfalfa establishment and seedling vigor. Poor establishment and early performance remain significant challenges for growers in the first production year. During the 2023 field season, three selection strategies employed in the first selection cycle were evaluated under field conditions, comparing five selected populations alongside their respective base populations. Various vigor and root traits were compared 29 days after planting, and no significant differences were observed across the experimental populations. Several correlations among traits were observed; taproot and shoot length were positively correlated. Nodule count per plant was positively correlated with branching complexity, taproot length, and shoot length. Differences across populations are expected to increase in future selection cycles. Correlations between traits offer insight into important seedling-root traits related to emergence and early vigor. Nodule count may be an indicator of high vigor above and belowground, and should continue to be examined in future breeding cycles and in alfalfa breeding at large.