Crop response to silicon supplements in New Jersey

Silicon has been shown to benefit plants by suppressing disease and insect herbivory, decreasing lodging of grasses, reducing the effects of abiotic stresses and assisting in plant growth and mineral nutrition. However, response to silicon supplements varies by species, growth medium, product used, rate, and timing of application. Silicon is essential for rice production in Japan and Brazil, and is routinely applied during sugarcane production in Florida. The effects of silicon supplements on crops grown in temperate regions, such as New Jersey, have not been widely investigated. The purpose of the research presented in this dissertation is to contribute to the understanding of silicon’s effects on crops grown in temperate regions. The specific objectives were to (i) compare the effects of calcium silicate with calcium carbonate on yields and powdery mildew disease expression of field-grown winter wheat (Triticum aestivum); (ii) evaluate the effects of calcium silicate and dolomitic limestone soil amendments on white grub densities in a cool-season turfgrass stand; (iii) compare the response of Kentucky bluegrass (Poa pratensis), seeded to 16 different New Jersey soils amended with either calcium silicate slag or dolomitic limestone, when subjected to powdery mildew disease pressure; (iv) evaluate the effects of foliar and soil drench potassium silicate on seedling flowering dogwoods (Cornus florida) subjected to powdery mildew disease pressure in a greenhouse environment. Our results demonstrated that crops grown in New Jersey can benefit from silicon supplements. These benefits included: reduced powdery mildew disease and increased yields of winter wheat; reduced white grub densities in cool-season turfgrass, similar to limestone during the first year of application; increased density and clipping yields of Kentucky bluegrass under powdery mildew disease pressure; and increased leaf number and reduced powdery mildew severity of flowering dogwood seedlings. However, response varied by soil, soil pH, soil silicon levels, and application method. Additionally, acetic acid-extractable soil silicon levels did not correlate well with Kentucky bluegrass silicon uptake. In summary, crops grown in New Jersey may benefit from silicon supplements, but additional research is needed in order to predict crop responses to silicon supplements considering the varied growth environments in New Jersey.Ph.D.Includes bibliographical referencesIncludes vitaby Mary C. Provance-Bowle