Fig. 2. Relation between normalized ARA measured 5 d after ureide treatment and leaf Mn concentration (µg g^-1 DW). The plants of Biloxi (A) and Jackson (B) were 5 wk old and grown hydroponically under various Mn nutrition levels in Exp. 1 and 2. The equation of the regression for Biloxi was y = 0.46 + 0.00086 x [Mn], R² = 0.29 (P < 0.01). The slope of the regression equation for Jackson was not significantly different from 0 (P < 0.05).