Photosynthesis and Growth of Camelina and Canola in Response to Water Deficit and Applied Nitrogen

ABSTRACT Nitrogen (N) and water availabilities are two important environmental factors affecting crop growth and yield. Effects of applied N and water deficit imposition on photosynthesis rate (Pn), transpiration rate ( E ), stomatal conductance ( g s ), and shoot and root biomass accumulation in camelina [ Camelina sativa (L.) Crantz] and canola ( Brassica napus L.) were compared in a greenhouse. Water deficit significantly decreased Pn, E , g s , and shoot/root biomass ratio in both crops. The relative reduction of Pn, E , and g s caused by water deficit was greater in canola than in camelina. Under drought conditions, applied N enhanced Pn and g s but had less pronounced effects on E in camelina. Camelina maintained higher Pn at N levels >125 kg N ha −1 under water deficit. In contrast, when exposed to drought, applied N decreased Pn, E , and g s in canola. The shoot/root ratio was more responsive to applied N in camelina, whereas applied N did not affect the shoot/root ratio in canola. Under drought conditions, camelina maintained a higher shoot/root ratio than canola. These results suggest that camelina is more tolerant to drought stress and potentially has greater adaptability to dryland production than canola.