Silicon Fertilization on Productivity and Leaf Rust Disease Management in Wheat Production in Louisiana: A Case Study.

Silicon (Si) is not considered as an essential nutrient for plant function, yet its uptake is beneficial in plant tolerance to stresses. Wheat is known to be capable of accumulating fairly large concentrations of Si and to respond well to Si treatment. The causal agent of wheat leaf rust, Puccinia Triticina, is a fungal pathogen causing significant wheat yield losses throughout the world. A field study was conducted at two locations in Louisiana since 2014 to evaluate the effect of Si fertilization on wheat productivity using yield, Si uptake, and disease severity as metrics. Treatments included two nitrogen (N) fertilizer rates (100 and 145 kg N ha^-1) and for each N rate, the following treatments were included: three rates of Si solution (120, 240, and 480 mg Si L^-1) as foliar spray, two Si granular sources (wollastonite – 23% Si and slag – 12% Si) applied at 250 kg Si ha^-1, a foliar spray with carrier solution, and a check plot. All treatments were replicated four times and arranged in a randomized complete block design. Disease severity was assessed over five weeks following modified Cobb's scale. Wollastonite and slag treated plants showed a significant reduction in disease severity in 2015, but the reduction was not statistically significant (p<0.05) in 2016 in both sites. The concentration of Si determined by wet digestion in biomass samples was significantly higher in Si treated plants than the non-Si treated plants. The distribution of silica bodies based on SEM/EDX analysis showed that plants treated with Si had significantly higher Si bodies than the control. The results suggested that Si application may be considered as a sustainable management strategy against plant disease. Future research is needed to investigate whether or not Si application can be integrated with other management strategies to reduce disease development in plants.