Charissa J. Matiling (February 2009)
Philippine Science High School Western Visayas Campus – Department of Science and Technology (DOST-PSHS WVC), Brgy. Bito-on, Jaro, Iloilo City 5000, Philippines
ABSTRACT
Dispersal is a way for the seed to find a suitable place away from its parent plant to maximize its chance for survival. Mahogany fruits are an example of samaras, fruits that disperse from their parent plant through autorotation. Dispersion is affected by environmental factors and the physical structure of the fruit. the longer it stays airborne, the farther way it can be dispersed by the wind. Thus this study aims to determine the structural characteristics of a mahogany fruit that may influence its flight time.
Fruits that were newly released from the pod were collected. Then the following physical characteristics of each fruit were determined: length, total surface area, fruit mass, seed mass, and wing mass. From these the square root of the wing loading and the ratio of the wing mass. and seed mass were computed. The flight time was determined by dropping the seeds from a constant height. The relationship between flight time and seed’s physical and aerodynamic properties were then investigated.
The flight time of the mahogany fruit range from 0.97 to 2.02 seconds. Pearson r correlation showed that individually, each of the following is not significantly correlated with flight time: length (r=0.133, p=0.483, min=5.80 cmm, max-10.70cm), fruit mass (r=-0.238, p=0.205, min=0.2464g, max=0.8007g) and total surface area (r=0.018, p=0.925, min=20.96 cm2,51.81 cm2). However, flight time is negatively correlated with the square root of the wing loading (r=-0.578, p=0.001, min=0.3127 gcm/s2, max=0.4086 gcm/s2) and positively correlated with the ratio of the wing mass and seed mass (r=0.633, p=0.001, min=0.0811, max=0.1667). Furthermore, one-way analysis of variance also showed that there is no significant difference between the mean flight times of mahogany fruits with different curvatures (a=0.05).
Within the confines of the physical characteristics under investigation, it can be concluded that to stay airborne longer, the seed must have high ratio of wing mass to seed mass and low wing loading. This information might be useful to botanists who study seed dispersal or engineers who wish to develop new technology based on natural phenomenon.