Date of Award:

5-1979

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Biology

Committee Chair(s)

George W. Welkie

Committee

George W. Welkie

Committee

Gene W. Miller

Committee

Ronald V. Canfield

Abstract

Halogeton glomeratus (M. Bieb) C.A. Mey when grown in nutrient solution, caused the solution pH to decrease very rapidly as plants increased in size, especially during the fifth week of growth. This might be attributed to hydrogen ion exchange for cations. Also, the cation uptake, especially K and Na, may exceed that of the major anions. The control of pH is effective in increasing shoot weights markedly.

In general there was no difference between plants grown at the same NaCl concentration at low and high relative humidity. An increase in plant size, shoot weights, leaf length and diameter was detected for plants receiving NaCl at both levels of relative humidity. The highest shoot weights were obtained at the highest NaCl concentrations used in this experiment; 0.3 and 0.2 M NaCl at low and high relative humidity, respectively.

When both K and Na were varied at low relative humidity, and normal K concentration was 0.006 moles/1, an increase of 0.016 moles K/1 with no NaCl was as effective in increasing most plant measurements as was the corresponding concentration of 0.01 moles Na/1 at normal 1 K concentration. The shoot fresh weight was maximum at 0.1 M NaCl and 0.006 moles K/1 and was significantly different at 95% confidence from all the other treatments. Sodium was inhibitory for plant growth at 0.5 moles/1, while K was moderately inhibitory at 0.106 moles/1 and this inhibition was reduced by the addition of low or medium concentrations of sodium up to 0. 1 M NaCl.

Chlorophyll content expressed on leaf fresh weight basis decreased with increased salinization. Values were lower with Na at 0. l moles/1 than the corresponding K concentration of 0.106 moles/1. The decrease in chlorophyll content can be attributed to the greater increase in size and number of nonchlorophyll containing cells with salinization than those containing chlorophyll, and no increase in chloroplasts per cell. On a dry weight basis there was no decrease of chlorophyll with salinization, and no significant differences were noted.

Water utilized by plants, as expressed on shoot fresh weight basis, decreased markedly by increasing Na, and slightly by increasing K with no or low Na. The results suggest but does not confirm that inadequate sodium may promote excessive transpiration leading to decreased leaf water potentials, reduced photosynthesis and reduced growth.

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