Physiological effects of waterlogging on two lucerne varieties grown under glasshouse conditions

Abstract

Two lucerne (Medicago sativa) varieties, an anecdotally waterlogging-intolerant old New Zealand variety, Grasslands Wairau, and a reputedly waterlogging-tolerant new variety, Pioneer 54Q53, were subjected to waterlogging stress and a range of physiological and agronomic measurements performed. Waterlogging stress was characterized by measurement of soil oxygen depletion and soil carbon dioxide accumulation. Both varieties exhibited strong responses to waterlogging stress, including reduction in leaf soluble protein concentration, photosynthetic rate and tap root weight, but also exhibited differences in response, notably a decrease in carboxylation efficiency and in the steady-state quantum yield of electron flow through PSII (ΦPSII) in Wairau, but not in Pioneer. Implications for understanding of waterlogging effects on photosynthesis, and for field management of lucerne on wet soils are discussed. © 2007 The Authors.