Genetics of nitrate accumulation in lettuce.

This study evaluated the prospects of breeding for low nitrate content in lettuce ( Lactuca sativa L.). A lettuce collection was screened and accessions with low nitrate content were identified. These were used to study the genetics of nitrate accumulation. Nitrate accumulation inherited quantitatively, in a mainly additive fashion with only minor effects of dominance. No important maternal effects were detected. Estimates of the additive genotypic variance and the environmental variance were used to evaluate the prospects of introgression of the low-nitrate trait in modern lettuce cultivars and of a further reduction of the nitrate level by combining genes from two low-nitrate accessions. Nitrate content in lettuce showed important genotype x environment interactions. Genotypes responded differentially to changing environmental conditions related to the daylength or light-intensity at harvest. In a detailed study of two low-nitrate accessions this interaction was shown to be related to differences in the rate change of dry matter content under changing daylengths