Plant Tropic Movements and Allelopathy

Group Leader: Ron Michael L. Castillo Date Performed: September, 2011

Group Members: Jose Mario C. Espino, Jr. Date Submitted: October 17, 2011

Alyssa Nicole Y. Fermin

Melissa April D. Pajinag

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Experiment 10: Plant Movement and Allelopathy

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Abstract

Plant movement is not as discrete compared to animal movement yet plants do exhibit motion usually in response to certain stimuli. Plant movement may be describes as tropic movements or nastic movements. Tropic responses are responses which are directionally related to their stimuli,. Nastic responses, on the other hand are not related to any vector of the stimulus. The main concern of the researchers includes geotropism (growth response to gravity), thigmotropism (growth response to touch) and turgor movement, which are actually thigmonastic responses of the plant. The researchers observed that roots respond positively to gravity while shoots respond negatively. Moreover, the root and shoot systems were observed to grow parallel to the direction of gravitational pull. Thigmonasty was observed in Mimosa pudica through its closing response when disturbed mechanically. It was also observed that the responses of the M. pudica leaves were localized depending on the site of disturbance. Positive thigmotropism was observed for the tendrils of the plants examined while negative thigmotropism was exhibited by the trees monitored throughout the experiment. Plants also produce chemicals in response to the presence of other plants which might have a detrimental effect to the other plants functions. This is called allelopathy. It was observed that the germinating seeds of Raphanus sp. have inhibited the germination of the seeds of Lactuca sp.

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Results and Discussion

Geotropism

Figure 1. (a) Germinating seeds in Petri dish. (b) Close-up on seeds in set-up....