Generalizations On the Use of Leaf Element Concentrations to Accelerate Improvement of Rice Grain Nutritional Quality.

Traditional breeding approaches to develop rice genotypes with improved grain element composition require analyzing grain element concentrations of large numbers of genotypes. The study evaluated if the vegetative phenotype could be used to predict grain concentrations. Results indicate that vegetative-stage leaf concentrations have potential to be used for indicating genotype grain concentration differences of some elements. As a group, genotypes selected for high grain-cadmium, -cobalt, -molybdenum, and -strontium harvested from flooded field plots, and selected for high grain-cadmium, -molybdenum, -rubidium, and -sulfur from unflooded field plots showed higher leaf-element concentrations as well. No leaf-grain associations were obtained for copper or nickel concentrations. For a particular element, when selected genotypes as a group showed excellent agreement between leaf and grain element concentrations, the plausibility of using vegetative-stage leaf element concentrations for screening diverse germplasm collections is indicated. Speculation concerning chemical, physical, and physiological bases for the potential of vegetative leaf concentrations to predict rice grain concentrations of some elements will be provided.