DIAGNOSIS OF ZINC-DEFICIENCY IN PEANUT (ARACHIS-HYPOGAEA L) BY PLANT ANALYSIS

Critical values of zinc (Zn) concentration in young leaves were established for the diagnosis of Zn deficiency in peanut by examining the relationship of Zn concentration in leaves to shoot dry matter (DM) at two growth stages of plants grown in pots of Zn deficient sand at seven levels of Zn supply (0, 67, 133, 200 267, 533, and 1067 Lig Zn/kg soil). Zinc deficient peanut accumulated reddish pigments in stems, petioles and leaf veins in addition to the more common symptoms of Zn deficiency in plants. Zinc concentrations increased with increasing Zn supply in the blades of the youngest fully expanded leaf (YFEL) and in the blades of the leaves immediately older (YFEL+1) and younger (YFEL-1) than it: They also increased with increasing Zn supply in the petioles of the YFEL+1 and YFEL and in the basal stem internode but their Zn concentrations were always much lower than those in the blades. Critical Zn concentrations in the blades of the YFEL and YFEL+1 were 8–10 mg Zn/kg DM at early pegging and mid pod filling: Values for YFEL-1 were similar but more variable. The blade of the YFEL is recommended for diagnosis of Zn deficiency in peanut and 8–10 mg Zn/kg DM as its critical value. © 1990, Taylor & Francis Group, LLC. All rights reserved.