An experimental neighborhood analysis of intraspecific competition in Oryza sativa L. and Echinochloa crus-galli (L.) Beauv. at opposite ends of a fertility gradient

Date

4-1993

Degree

Bachelor of Science in Biology

College

College of Arts and Sciences (CAS)

Adviser/Committee Chair

Marissa P. Caldas

Abstract

To test whether competition would be more intense in productive or unproductive habitats, changes in the intensity of intraspecific competition in rice and barnyard grass at contrasting levels of fertility were determined using neighborhood analysis. Plant height, tiller number, and seed number of target plants increased as a response to fertilization, but was greatly reduced in the presence of neighbors. This was true for both species, except for Echinochloa height. ANOVA results showed that while competition and fertilization clearly affected plant size and fecundity independently, there was no significant effect of competition by fertilization interaction (except for Oryza tiller number), which implied that density affected plant success similarly across the contrasting fertilizer levels. Comparison of values of competitive indices (absolute and standardized) also yielded similar results. Thus, results of this study have provided enough evidence to support the prediction that competition intensity is approximately equal across a fertility gradient. Fertilization allowed greater above-ground growth which led to intense competition for light. On the other hand, competition was also more intense in the unfertilized plots since there may have been a major shift from competition for light to competition for below-ground resources,. since nutrients were more limited.

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

Thesis

Document Type

Thesis

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