Date of Award

4-17-1990

Document Type

Thesis

Abstract

An instrumentation and control system was built to maintain a constant nutrient supply to plants in flowing solution culture. The microcomputer based system controls the concentration of mineral nutrients, pH, root temperature, and water level. The nutrient ion concentrations controlled by the computer are nitrate, potassiuum, and ammonium. Ion-specific electrodes used as sensors are automatically calibrated before each measurement. Computer controlled valve manifolds and a 16-channel peristaltic pump mix aliquots of nutrient solution with ionic strength adjuster for improved electrode operation. A mathematical analysis of the performance of the Nutrient Flow System shows how the error introduced in system components contributes to error in measurements, and how experimental parameters affect accuracy. Results of plant growth trials are given, and statistical techniques for evaluating growth trial results are discussed. Over a sixteen day experiment with a target concentration of 1.0 $\times$ 10$\sp{-4}$-M NO$\sbsp{3}{-}$, the variance of the concentration was 2.4 $\times$ 10$\sp{-6}$. The uptake over the experiment was 91.6 grams of nitrate. There was a 1.5% discrepancy between actual uptake and the uptake calculated by the system.

Handle

http://hdl.handle.net/11122/8498

Download

Share

COinS