Effect of handweeding on population dynamics of weeds in the lowland ricefields.

Date

5-1993

Degree

Bachelor of Science in Biology

College

College of Arts and Sciences (CAS)

Adviser/Committee Chair

Marissa P. Caldas

Abstract

ADIILLA, DELILAH C. University of the Philippines at Los Banos. Bachelor of Science in Biology (Ecology). April 1993. EFFECT OF HANDWEEDING ON POPULATION DYNAMICS OF WEEDS IN THE LOWLAND RICEFIELD.

ADVISER: DR. MARISSA PANTASTICO-CALDAS

A study was conducted to determine the general pattern of weed emergence througout a single growing season of rice and the effect of two handweeding methods on emergence after handweeding, survival and reproduction. It also evaluated in the unweeded quadrats the effect of time of emergence on weed survival and reproduction. Implications on the use of weed demography on weed management were discussed. The experiment was carried out from December 1991 to April 11, 1992 in a lowland ricefarm in Bangias, Laguna, Four blocks consisting of three horizontally arranged 1m2 quadrats and three handweeding treatment levels (HO or "control", Hi or "hila" and H2 or "lubog") were used in the analyses. Results showed that almost 50% of the total number of weeds throughout the growing season emerged during the first six weeks. These weeds were: Ammania baccifera L., Echinochloa crus galli Beauv., E. indica Beauv., Hydrolea zeylanica (L.) Vahl., Fimbristylis miliaceae (L.) Vahl., Scirpus cernus (L.) Vahl., and Sphenochloa zeylanica Gaertn. The bulk of the population of each species (more than 78% ) except for Sphenocloa had germinated before they were handweeded. The absence of late emergence was hypothesized to be mainly the result of the limited amount of viable seeds after the initial germination at the start of the season. Other possible reasons such as changes in canopy structure and water level were mentioned.

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

Thesis

Document Type

Thesis

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