Date of Award:

5-1991

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Plants, Soils, and Climate

Advisor/Chair:

Lynn M. Dudley

Abstract

Soil salinity is a major concern to agriculture in arid and semiarid regions, where evapotranspiration causes salts originating from irrigation water (or sometimes naturally from the soil) to become concentrated in the rooting zone. In some areas, with good management, it has been economically feasible to ameliorate a sodic soil with Ca. The objective of this study was to investigate the effects of Ca amelioration of salinity (sodicity) on biomass, number of nodules, number of pods, weight of pods, ion uptake, and photosynthesis of Phaseolus vulgaris L.

Pl ants were grown in one liter styrofoam pots under greenhouse conditions. In the first experiment, Na stress was accomplished by adding NaCl and Na2S04 at concentrations of 0, 20, 40, 60 , and 80 mmolcfl. The second and third experiments used concentrations of 0, 15, 30, 45, and 60 mmolc/1 NaCl or Na2S04 , combined with two levels of 15 and 30 rnrnolc/1 of either caso4 or cac12. Each styrofoam pot was irrigated with 300 ml of salt solution with a 0.25 leaching fraction on every fourth day for four weeks.

Increasing Na concentration decreased biomass, number of nodules, number of pods, and weight of pods but increased ion uptake. Addition of NaCl in the substrate increased shoot Na, Ca, and Cl content, while Na2SO4 increased shoot S content. The photosynthesis rate was affected by all levels and types of sodium salts. Calcium sulfate treatments had a greater ameliorating effect than CaCL2 on Na induced salinity in snapbeans.

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