Lotus corniculatus
L. is a perennial forage legume species highly-adapted to growth under drought conditions. However,
the genetic and physiological mechanisms involved in its adaptive capacity have not been elucidated. The role of osmotic
adjustment (OA) and water-use efficiency (WUE) on the drought tolerance of
L. corniculatus was studied in a greenhouse
experiment. Seven cultivars of different origin were subjected to two contrasting treatments of available soil water: No
water stress (NWS) and with water stress (WWS). Xylem water potential (Ψ
x), osmotic potential (Ψ
π), pressure potential
(Ψ
p), relative water content (RWC), stomatal conductance (g
s), shoot DM production, water transpiration (T), and WUE
(shoot DM/T) were measured. Water treatments significantly (P < 0.05) affected plant water status, which was reflected
in reduced Ψ
x, RWC, g
s, and transpiration rate in the WWS treatment compared with the NWS treatment. All cultivars
showed a high capacity for OA under WWS treatment because Ψ
π decreased by approximately 60% and Ψ
p increased by
approximately 30%, compared with the NWS treatment. Cultivars with a higher solute accumulation (low Ψ
π value) had
the lowest DM production under WWS treatment. In contrast, WUE varied greatly among cultivars and was positively
associated (
R2
= 0.88; P < 0.01) with DM production under drought conditions.
