Document Type

Thesis

Date of Award

5-1996

School/College

College of Science, Engineering, and Technology (COSET)

Degree Name

MS in Chemistry

First Advisor

Professor Ray F. Wilson

Abstract

From the knowledge of Chelation Chemistry of plants we can predict the composition and function of metals in green plants. Hydroponic plant growth technologies are developed to accommodate the need for food production during long duration space missions. Controlled environment agricultural systems such as the hydroponic system provide out of season, top quality produce. The continued delivery of ions in hydroponic systems ensures that the leaves are supplied with the mineral nutrient essential to the growth and development of plants. The metals required for the growth of plants exists in cells and tissues as complexes and especially as chelates. Iron is an essential element for growth, metabolism and survival of plants. Low affinity chelators such as EDTA help keep iron soluble and available for cell growth in plants. Chelators added to the growth medium promote iron uptake. Severe iron deficiency can occur if pH is out of the 5 .8 to 6.5 range. The study of inorganic nutrient requirements of green plants is easier than that of other kinds of organisms. The reason is that green plants require very little in the way of organic growth factors so that growth media may be prepared in high state of purity. The uptake and translocation of inorganic solutes within the whole plant is an essential and major aspect of the process of plant nutrition. Iron is taken up and transported more readily when supplied as chelated complexes, such 1 2 chlorophyll synthesis, and many other enzymatic activities. In EDTA Fe chelate complex, the six donor atoms bond to the central atom. A ligand capable of binding Fe3+ and Fe2+ will bind the Fe3+ more tightly than it will bind with Fe2+. The Stock solution I was Prepared by dissolving 5.05g KN03, 0.012 g MnSO".H20, 0.OO2g CuSO".5H10, O.OOSg ZnSO".7H10, 1.36g KH2PO", 4.92g MgSO".7H20 and 0.58 g NaCI in DI water and the volume was made up to l00ml. Stock solution II was prepared by dissolving O.44g Na1EDTA and ll.8g of Ca(NOJ1.4H20 in SOml Deionized water. Excess FeCl3 (100 ppm) solution was added to stock solution II. The volume was adjusted to 100 mi. Working nutrient solution was prepared by adding 20 ml each of stock solutions I and II to 3000ml D I water and diluting to 4 liters. The pH was adjusted to 6.0. At 15 days the plants looked healthy. They were 5" tall. Halogen lamps were used as light source for photosynthesis. pH was maintained between 5.8 and 6.3. The ionic strength was measured regularly. Stock refill nutrient solution was prepared by dissolving 12.1g KN03, 2.04g KH1PO", 4.80g MgSO".7H10, 0.S8g NaCI, O.Olg MnSO".H10, 0.002g CuSO".5H10, and O.OOSg ZnSO".7H10 in DI water and the volume was adjusted to 100m}. The volume of nutrient solution was maintained at two liters. An air pump was used to circulate air through the medium. The plant roots were protected from light after observing algae growing in the medium. Forty five days after germination, the plants were 12" tall. At sixty days, flowering buds were observed. Small beans were seen on the plants on October 20, 1995. On November 6 1995, the beans were ready to be picked. The matured beans were picked. The beans ,...cighed 10.5 grams. On November 13, beans were picked again and the beans weighed 8.5 grams. All the reagents and chemicals used were of analytical grade. A stock standard solution was prepared by dissolving one gram NazEDTA in one liter deionized water. From this solution, calibration standards ranging 10 to 80 .umol/L EOTA were prepared. One milliliter FeCl3 solution (lOOppm) was added before the last dilution. The chelated EOTA in the standards were analyzed by HPLC using the BAS 200A analyzer and the calibration graph was obtained. The original concentration of EDTA in the sample was 60 .umol. Four samples were collected from the nutrient 3 concentration of EDTA in the sample was 60 Jmlol. Four samples were collected from the nutrient medium at two weeks interval. They were filtered using 0.02 Jml filter paper. To one ml of each sample, one ml FeCIJ solution (100 ppm) and three ml mobile phase solution were added. Twenty four hours after mixing the samples with FeCIJ solution, they were analyzed using the BAS 200A HPLC analyzer. The instrument was allowed to reach equilibrium prior to analysis. The injection volume was 20,ul and the detection wave length was 254 nm. The electro chemical cell temperature was 30' C. The temperature of mobile phase in bottle A was set at SO'C and the temperature of mobile phase in bottle Band C were 3S·C. The pressure was monitored during analysis and was between 2310 and 2350. The recovery of EDTA from the sample ranged from 84.0S% to 91.879'0. From these result it can be concluded that EDTA concentration does not decrease significantly during and after plant nutrient uptake. EDTA can be considered as an efficient chelating agent. The advantage of this method for analysis are the low cost, lower limit of detection and the good reproducibility.

Download

Share

COinS