Silicon Concentration, Disease Response, and Yield Components of Rice Genotypes Grown on Flooded Organic Histosols

Abstract

On silicon‐deficient soils, fertilization with silicon (Si) has reduced disease severity and increased yield of rice (Oryza saliva L.). Breeding rice genotypes with greater Si concentration has been proposed, and some African and Asian rices have been evaluated for variability of Si concentration on upland and flooded mineral soils. This experiment investigated the variability and relation of Si concentration in rice plant tissue with disease severity and yield components of selected U.S. rice genotypes grown on flooded organic soils. Ten rice genotypes were grown at two Florida locations on Si‐deficient organic Histosols. Plots were replicated five times in each of two Si treatments: Siamended soil with silicon added at 2 Mg ha‐1, and an unamended control. Plots were rated for disease severity at growth stage 8 to 9 (dough to mature) and sampled for determination of Si concentration in plant tissue (leaves and straw). Genotypes differed for Si concentration and disease severity at each location and for each Si treatment. Among genotypes, disease severity was negatively correlated with Si concentration in plant tissue. Increases in yield with added Si were attributable to a greater number of grains per panicle, whereas weight per 100 seed and panicles per square meter exhibited less change. Results indicated that although Si concentration varies among genotypes and is negatively correlated with disease severity, the strength of this association is mitigated by other genotypic factors which also affect response to disease.