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

Production of nonoilseed sunflower (Helianthus annuus L.) on certain s oil 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 kerne l Cd accumulation, and to select genotypes under varying soil conditio ns for breeding low kernel Cd cultivar(s). Two-hundred sunflower genot ypes were evaluated at four different soil series in North Dakota and Minnesota. Large genetic variation in Cd content was found among genot ypes. Kernel Cd concentrations showed continuous variation across the range of 0.31 to 1.34 mg/kg (average for four locations), Although Gen otype x Location effect exists, genotypes were ranked similarly in Cd concentration at the four locations. Concentrations of Cd for the geno types were highly correlated among locations, indicating genotypes per formed consistently across the four environments. Results clearly show that genotypes for sunflower differ significantly in kernel Cd concen tration, and it appears that this evaluation of 200 genotypes has iden tified sufficient low Cd germplasm for breeding low kernel Cd genotype s. Soil properties played an important role in Cd uptake and accumulat ion in sunflower. Data from the four soil series showed that fine text ured soils from the Fargo and Grandin locations contained higher level s of diethylenetriaminepentaacetic acid (DTPA) extractable Cd and tota l Cd, and caused significantly higher sunflower kernel Cd across genot ypes. Regressions for kernel Cd on soil measurements were all signific ant 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.