Got Water? Testing for Hydrotropism in Certain Garden Plants

Overview

Objectives/Goals The objective is to determine if hydrotropism of roots differs depending on whether plants have a fibrous or taproot system and how much water the pant uses. I predicted that species with taproots would show less hydrotropism because they are more gravitropic and that the more water a species uses the more hydrotropic it would be. Methods/Materials I used six species of garden plant, three with fibrous root systems and three with taproot systems. I germinated the seeds and studied the roots when they were several days old. I measured hydrotropism by the angle of the roots curve towards a hydrostimulant (wet floral oasis) from downward growth. I put the floral oasis with the germinating seeds attached to its edge over a saturated salt solution to give a gradient of water towards the hydrostimulant (experimental) or over water so there was no gradient of water (control). To measure the water lost through the leaves of the plants, I took seedlings of each species and wrapped the pots in plastic to prevent water loss. I weighed the pot and left it outside for a day and then weighed it again. Results All the species showed deviation of the root towards the hydrostimulant. The average angle of deviation was greater in fibrous root systems than taproot systems. There was a negative relationship between the amount of water a plant used and its hydrotropism. Plants with fibrous roots used less water than taproot plants. Conclusions/Discussion Based on the species I looked at, it seems that all plants are hydrotropic. I suggest this because the angle of deviation was greater for experimental than control roots. My hypothesis that fibrous root systems would show more deviation than taproots was also correct; the fibrous root species showed a greater angle of deviation. I did not expect the negative relationship between hydrotropism and water use because I thought if a plant used a lot of water it would need to search for water. A plant that uses a lot of water might occur in an environment where there is a lot of water, and not need to search for water.

Awards (1)

• Honorable Mention

Competition history

• CSEF 2008 Plant Biology · Entry J1733

Resources

• CSEF project summary ↗

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