GENOTYPIC VARIATION IN KERNEL CADMIUM CONCENTRATION IN SUNFLOWER GERMPLASM UNDER VARYING SOIL-CONDITIONS

Production of nonoilseed sunflower (Helianthus annuus L.) on certain soil series yields kernels with cadmium (Cd) concentration in excess of international market Cd limits. This study was conducted to determine if genetic variability exists among sunflower germplasm for low kernel Cd accumulation, and to select genotypes under varying soil conditions for breeding low kernel Cd cultivar(s). Two-hundred sunflower genotypes were evaluated at four different soil series in North Dakota and Minnesota. Large genetic variation in Cd content was found among genotypes. Kernel Cd concentrations showed continuous variation across the range of 0.31 to 1.34 mg/kg (average for four locations), Although Genotype x Location effect exists, genotypes were ranked similarly in Cd concentration at the four locations. Concentrations of Cd for the genotypes were highly correlated among locations, indicating genotypes performed consistently across the four environments. Results clearly show that genotypes for sunflower differ significantly in kernel Cd concentration, and it appears that this evaluation of 200 genotypes has identified sufficient low Cd germplasm for breeding low kernel Cd genotypes. Soil properties played an important role in Cd uptake and accumulation in sunflower. Data from the four soil series showed that fine textured soils from the Fargo and Grandin locations contained higher levels of diethylenetriaminepentaacetic acid (DTPA) extractable Cd and total Cd, and caused significantly higher sunflower kernel Cd across genotypes. Regressions for kernel Cd on soil measurements were all significant except for pH measures in deeper layer soil. The highly correlated relationship could be used to predict kernel Cd for some soil series which were not part of this study.