Rhizosphere bacterial species diversity in two rice cropping systems under three different nutrient management schemes

Date

4-2014

Degree

Bachelor of Science in Biology

College

College of Arts and Sciences (CAS)

Adviser/Committee Chair

Charina Gracia B. Banaay

Restrictions

Restricted: Not available to the general public and to those bound by the confidentiality agreement. Access is available only after consultation with author/thesis adviser.

Abstract

The effect of the two factors, the different cropping systems (paddy rice-Aerobic rice and paddy rice-maize cropping systems), and crop nutrient management (Conventional, Zero Nitrogen and Site Specific Nutrient Management Schemes) to the dynamics of the rhizosphere bacterial community was examined using culture-independent methods. DNA was extracted from the rhizosphere soil samples of the rice and maize plants harvested at different stages of development. Nested PCR was used to amplify the 16S ribosomal RNA gene and the products were subjected to Denaturing Gradient Gel Electrophoresis (DGGE). Results showed that in all treatments, there is high diversity of rhizosphere bacterial species, ranging from 2.31 to 3.58 as computed using the Shannon Index of Diversity. There were rise and decline of diversity in each treatment throughout every sampling season showing fluctuations in evenness of different species. Differences on the trends is probably the result of the different maturation stages specific to each treatment which may have influenced the different types and amounts of root exudates specifically during Booting and Milking Stages. But generally, the differences in the diversity, evenness and banding patterns among different nutrient management schemes are minimal. The patterns were relatively stable suggesting that plant root only caused subtle changes instead of complete shifts in the community structure and that it is not the amount of nutrient that primarily determines the assemblage of rhizosphere microorganisms. However, the observations in this study may hold true only for the first year of cropping.

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

LG 993.5 2014 B4 /P48

Notes

Major in Ecology

Document Type

Thesis

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