Effects of soil pH and soil water potential on arbuscular-mycorrhizal fungal colonization of soybean

Development and consequences of arbuscular-mycorrhizal (AM) fungal colonization of plants are highly affected by the conditions in the growth medium. The effect of extreme soil pH and moisture conditions on AM fungal development and plant-growth enhancement has been well documented independently. However, the soil factors that influence the survival and success of fungi may not act independently. We have conducted a greenhouse experiment to determine the interactive effects of soil pH and moisture level on root colonization and growth of soybean (Glycine max L. Merr.) inoculated with Glomus etunicatum and Glomus mosseae in two common Iowa soils (Webster and Clarion). Soils were adjusted to pH 5.5, 7.0, and 8.2 by adding the appropriate quantities of A12 (SO4)3 or Ca (OH)2. Three different soil moisture potentials, -7.5, -33.3, and -100 kPa, were used in this experiment. There was a significant (P<0.001) interaction of soil moisture potential and pH on AM fungal root colonization and plant growth. Soil types also significantly (P<0.001) influenced fungal colonization of roots and plant growth. While the percentage colonization of G. etunicatum was 45.3% in Webster soil, the percentage colonization of G. mosseae was only 9%. The fungal colonization and plant growth increased markedly with increasing soil moisture potentials. Root colonization by G. etunicatum was the highest at soil pH 5.5 and decreased with increasing pH, but differences were less between soil pH 7.0 and 8.2. In contrast, percentage root colonization of G. mosseae was the highest at pH 8.2 and decreased significantly with decreasing soil pH. Fungal inoculation improved the plant's resistance to extremes of soil pH, soil moisture levels, and their interactions. A highly significant (P<0.001) positive correlation was found between colonization levels and plant growth: however, a very strong negative correlation was found between root-by-shoot ratios and fungal colonization. Glomus species showed different adaptation to soil types, extremes of soil pH, moisture, and their interactions. Between these fungal species, G. etunicatum showed higher colonization and greater plant growth for each treatment level.

Name thesis:degree_name

Master of Science

Level thesis:degree_level

Masters

Discipline thesis:degree_discipline

Soil Science

Year dc:date.issued

1998

Author dc:creator

• Ozbek, Mine

Advisor dc:contributor.advisor

• Loynachan, Thomas E.

Language dc:language.iso

en

Repository record dc:identifier.uri

https://dr.lib.iastate.edu/handle/20.500.12876/7vdX228v

OAI identifier oai:identifier

oai:dr.lib.iastate.edu:20.500.12876/7vdX228v