Screening Common Bean Genotypes for Tolerance to Low Zinc Availability Using a Chelate-Buffered Hydroponics System

A chelate-buffered hydroponics system was assessed for its ability to induce zinc (Zn) deficiency in common bean and for its usefulness as a tool to select genotypes tolerant of Zn deficiency stress. Twenty-two common bean genotypes were evaluated for tolerance to Zn deficient conditions using the buffered hydroponics system. Relative yield (comparing growth under low Zn to adequate Zn conditions) and Zn and phosphorus (P) accumulation in plants were measured. Significant Zn deficiency stress was induced in all of the genotypes with relative yields ranging from 11.5 to 52.6%. Six genotypes were identified as being tolerant to low Zn. These six genotypes (E 101, AND 684, LSA 102, SUG 55, PVA 773, and CENTRO) all had relative yields >29%, were able to accumulate >60 μg Zn per plant from solution and were better able to regulate P uptake to avoid excessive P accumulation than the other genotypes. In a second experiment, a subset of seven genotypes grown in the chelate-buffered hydroponics systems were compared directly to plants grown in field soil. The two systems correlated well for total dry weight (r = 0.57, P < 0.001), shoot Zn content (μg g^-1) (r = 0.58, P < 0.001), and total Zn content (μg g^-1) (r = 0.64, < 0.001) when plants were grown under low Zn conditions.