Juanico, Sami Clarisse T., Romero, Mark Angelo R., Tulio, Jessa Airiz G. (March 2008)
Philippine Science High School Western Visayas Campus – Department of Science and Technology (DOST-PSHS WVC), Brgy. Bito-on, Jaro, Iloilo City 5000, Philippines
ABSTRACT
This study applies the phenomenon called allelopathy on the problem of rice weeds. Allelopathy, caused by allelochemicals like tannin, is a plant’s chemical mechanism that stunts the emergence and/or growth of another plant like the rice weeds. Thus, in the first phase of this study, extracts of mahogany (Swietenia macrophylla) roots, bark and leaves were tested for allelopathy. The rice weeds used were Ischaemum rugosum, Echinocloa oryzoides and Leptochloa chinensis.
Rice germination inhibition percentages for the mahogany root extracts were lowest as compared the rice germination inhibition in mahogany leaf and mahogany bark extracts. Mahogany roots have no significant effect on the height of rice and on the germination of different weed seeds.
The second phase of the study tested the herbicide potential of mahogany root extract under field conditions. Plots were treated as follows: with rice seeds, with extracts; with rice seed, without extracts; without rice seeds, without extracts; and, without rice seeds, with extracts. One-way ANOVA and LSD were used to compare weed populations among different treatments of extract-treated and untreated rice plots (a=0.05). The second phase also ascertained whether or not the extract is detrimental to rice by comparing rice heights among different treatments through independent t-test.
Although the rice heights of the different setups proved the extract’s safety on rice, results also showed no significant difference between weed populations of the different plots. Therefore, the allelopathy S. macrophylla root extract is not enough to make it organic alternative to commercial herbicides.