Nitrogen use efficiency of irrigated dry bean (Phaseolus vulgaris L.) genotypes in southern Alberta

Although dry bean (Phaseolus vulgaris L.) is a legume capable of fixing nitrogen, fertilizer N is usually recommended for its production in Canada because it is believed to be an inefficient N fixer. Using genotypes with high N use efficiency (NUE) would reduce the amount of applied N, which usually has deleterious environmental effects. We evaluated 22 bean genotypes for N uptake efficiency (NUpE) in a greenhouse trial and 16 genotypes for N use efficiency (NUE) and its components: NUpE and N utilization efficiency (NUtE) in two seasons (2012 and 2013) of a field trial at 30 kg N ha(-1) (30N) and 100 kg N ha(-1) (100N) soil levels. Root biomass and surface area were highly correlated with NUpE in the greenhouse, where NUpE at 100N was 48% lower than that at 30N. In the field trial, grain yield was highly correlated with NUpE and NUtE at both 30N and 100N. The NUpE at 100N was 65% lower than that at 30N, and NUE at 100N was 68% lower than that at 30N. The low NUE at 100N in the field trial was mainly due to the difference in NUpE. This study also identified nine genotypes, including five germplasm lines (PI 136692, GH-196, UNS-117, UI-239, and LEF2RB) and four cultivars (Othello, Viva, AC Redbond, and Island), that were both N-efficient (at 30N) and N-responsive (to 100N).