Seed Germination Response of Rapid-Cycling Brassica oleracea Grown Under Increasing Sodium Selenate

Breeding plants to be more efficient at micronutrient accumulation is a proposed strategy for fighting worldwide malnutrition of humans. Selection for increased selenium (Se) in Brassica oleracea L. is possible. However, when present at high levels, micronutrients such as Se can affect seed germination and subsequently hamper breeding efforts. The objectives of this study were: (1) to evaluate the accumulation of Se in seeds of B. oleracea; and (2) to determine effects that Se accumulation may have on seed germination. Plants of a rapid-cycling B. oleracea population were grown in nutrient solutions with sodium selenate (Na₂SeO₄) concentrations up to 7 mg L^-1 (2.93 mg Se L^-1). Seeds and leaves were harvested from the selenized plants and analyzed for Se content using atomic absorption spectrophotometry. Germination percentage and rate were determined by sowing seeds in moistened towels, placing them in an incubator at 21°C, and observing radicle emergence. Selenium accumulated in the seeds, but at a lower level than in the leaves. Seed Se content increased linearly with increasing Na₂SeO₄ in solution culture. A significant difference in germination percentage occurred if Na₂SeO₄ was in solution at 5 mg L^-1 or higher. However, even at the higher selenate treatments, germination percentage never fell below 94%. Germination rate was little affected by the Se content in the seeds. These observations provide evidence that Se accumulation in seeds is not likely to hamper breeding efforts for Se enrichment in B. oleracea at Se levels similar to this study.