Breeding for low nitrate content in radish (Raphanus sativus L.)

Abstract

To study prospects of reducing nitrate content of radish roots by breeding, plants with varying nitrate content were selected from four populations of the diploid cultivar Robijn (two populations with a low, one with an intermediate and one with a high nitrate content) and from two tetraploid cultivar, ‘Boy’ and ‘Oscar’, with low nitrate contents. Correlation coefficients between nitrate contents of parent plants and their I1's were generally significant, but rather small (between 0.48 and 0.78), as were the parent-offspring regression coefficients (between 0.18 and 0.54). Significant differences in nitrate content occurred between I1's of each of the parent populations, I1's were also present with significantly higher or lower nitrate contents than the corresponding parent populations. Genetic variation for nitrate content was still present within I1's. I2's could be selected with a significantly lower or higher nitrate content than their I1's. It is possible to select radish cultivars with less than 2.0 mg nitrate per gram fresh weight of root under low light conditions in winter. As appeared from crosses with cytoplasmic-genetic male sterile plants, their was no relationship between cytoplasmic-genetic male sterility and nitrate content, indicating that hybrid cultivars with low nitrate contents can also be selected.