Title page for ETD etd-04112016-142710

Type of Document Master's Thesis
Author Agostinho, Flávia Bastos
Author's Email Address fagost2@lsu.edu
URN etd-04112016-142710
Title Evaluation of Absorption and Uptake of Soil- and Foliar-Applied Silicon in Rice and its Accumulation under Different Phosphorus Rates
Degree Master of Science (M.S.)
Department Plant, Enviromental & Soil Sciences
Advisory Committee
Advisor Name Title
Tubana, Brenda Committee Chair
Datnoff, Lawrence Committee Co-Chair
Harrell, Dustin Committee Member
Wang, Jim Committee Member
  • Oryza sativa
  • Si solution
  • foliar spray
  • silica deposition
Date of Defense 2016-03-10
Availability unrestricted
Silicon (Si) fertilization has gained attention in rice (Oryza sativa) production. However, the common soil-applied sources are amended at high rates, whereas the efficacy of foliar Si application is yet to be proven. A series of pot experiments were conducted to (1) elucidate the effects of different Si sources on grain yield and Si accumulation of rice supplied with varying P rates, and 2) evaluate Si absorption and uptake by rice via foliar- and soil-application of Si fertilizers. First, three phosphorus (P) rates (0, 112, and 224 kg P ha-1) and three Si sources: two soil-applied (wollastonite and silicate slag) and a liquid Si formulation applied as foliar spray at rates of 20, 40, and 80 mg Si L-1 were set as treatments. Silicon applied to soil (wollastonite and silicate slag) and leaves (Si solution) did not result in significant increase in rice P content and uptake in straw and grain. However, a corresponding increase in soil P content was observed with wollastonite application. Across all rice stages, wollastonite application consistently increased biomass Si content (P<0.05), but no significant increase in rice yield was observed with Si fertilization. For the second objective, two greenhouse experiments were conducted to determine if Si in solution can be absorbed through leaf surface and translocated within the plant. Three application rates of Si solution (20, 40, and 80 mg Si L-1) were sprayed to either whole rice plants or leaves of the primary third tiller of each plant, whereas for the second experiment, Si solution (80 mg Si L-1) was strictly applied to adaxial side of rice leaves, including two soil-sources and a check. The experiments were conducted in a randomized complete block design with at least four replications. There was no significant effect observed on rice growth and yield with Si fertilization. Foliar application of Si solution did not increase Si content of leaves, whereas wollastonite-treated rice attained the highest Si content (P<0.01). The outcomes of this series of greenhouse studies suggest that Si absorption on leaf surface did not take place as well as the translocation of Si within the plant.
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