Effects of Herbicides on Raphanus sativus Plant

Growth

Allison Paige Provey

Undergraduate Student (Biology, Pre-Pharmacy)

Department of Biology

Tennessee Tech University

Cookeville, TN 38505

IntroductionIntroduction• Herbicides are defined as any chemical Herbicides are defined as any chemical

substance that is used to destroy or inhibit substance that is used to destroy or inhibit the growth of plants, mostly weeds. the growth of plants, mostly weeds.

• They can be divided into two different They can be divided into two different categories; selective and non-selective categories; selective and non-selective herbicides (McCourt 2005). herbicides (McCourt 2005).

• 2,4 dichlorophenoxyacetic acid or 2,4-D is a 2,4 dichlorophenoxyacetic acid or 2,4-D is a common selective herbicide that is toxic to common selective herbicide that is toxic to plants, but less harmless to grasses (Winder plants, but less harmless to grasses (Winder 2006). 2006).

IntroductionIntroduction

The reason some plants are able to The reason some plants are able to overcome elimination by inheriting herbicide overcome elimination by inheriting herbicide tolerance or resistance, which is the ability of tolerance or resistance, which is the ability of a species to survive following a herbicide a species to survive following a herbicide treatment (Ward 2006). treatment (Ward 2006).

The wild radish population is phenoxy The wild radish population is phenoxy herbicide resistant (Pryor 2002). Meaning, it herbicide resistant (Pryor 2002). Meaning, it can survive the toxins of the herbicide 2,4-D. can survive the toxins of the herbicide 2,4-D.

Objective/ HypothesisObjective/ Hypothesis• My objective was to see how plants will react My objective was to see how plants will react

once specific herbicides are added during once specific herbicides are added during germination.germination.

• My hypothesis is that at least one of the My hypothesis is that at least one of the radish plant groups will have a hormetic radish plant groups will have a hormetic effect.effect.

• My null hypothesis is that none of the groups My null hypothesis is that none of the groups will have a beneficial effect.will have a beneficial effect.

Methods and MaterialsMethods and Materials• Eleven cups prepared for planting; each cup Eleven cups prepared for planting; each cup

had the same amount of potting soil and had the same amount of potting soil and radish seeds added to it.radish seeds added to it.

• According to Manuja (2005), packing the soil According to Manuja (2005), packing the soil down onto the seed could cause problems in down onto the seed could cause problems in the sprouting process the sprouting process

• Plants were watered consistently, until Plants were watered consistently, until germination occurred.germination occurred.

Methods and MaterialsMethods and Materials

2,4-D herbicide concentrations were prepared 2,4-D herbicide concentrations were prepared with appropriate mix of clean, diluted water and with appropriate mix of clean, diluted water and the herbicide.the herbicide.

The mixtures were then applied to the specific The mixtures were then applied to the specific plant groups (Exp: herbicide mixture 1 only for plant groups (Exp: herbicide mixture 1 only for plant cup #1)plant cup #1)

Plant cup #11 was the control group, and it was Plant cup #11 was the control group, and it was given no herbicidal concentrations.given no herbicidal concentrations.

Methods and MaterialsMethods and MaterialsTable 1.0- 2,4-D Herbicide Solution Mixtures

Solution #1 10%= 1.6 ppm 2,4-D

Solution #2 20%= 3.1 ppm 2,4-D

Solution #3 30%= 4.7 ppm 2,4-D

Solution #4 40%= 6.2 ppm 2,4-D

Solution #5 50%= 7.8 ppm 2,4-D

Solution #6 60%= 9.4 ppm 2,4-D

Solution #7 70%= 10.9 ppm 2,4-D

Solution #8 80%= 12.5 ppm 2,4-D

Solution #9 90%= 14.0 ppm 2,4-D

Solution #10 100%= 15.6 ppm 2,4-D

Solution #11 No herbicide added

Methods and MaterialsMethods and Materials

Over the next six weeks, the plants were Over the next six weeks, the plants were watered and observed.watered and observed.

After the growth had occurred in all the plants, After the growth had occurred in all the plants, the height and weight was measured for each the height and weight was measured for each plant. plant.

The recovered data from this experiment was The recovered data from this experiment was then recorded, and determined that the then recorded, and determined that the hypothesis was accepted.hypothesis was accepted.

Methods and MaterialsMethods and Materials

Plant Group #2- 3.1ppm Controlled Plant Group- No herbicide

ResultsResults

• As I had expected some of the plants did show As I had expected some of the plants did show some beneficial effects with the addition of 2,4-D some beneficial effects with the addition of 2,4-D herbicide. herbicide.

• Group #2 (3.1 ppm herbicide) grew to average Group #2 (3.1 ppm herbicide) grew to average height of 4.18cm, while the controlled group only height of 4.18cm, while the controlled group only grew to 3.75cm. grew to 3.75cm.

• Group #3 (4.7 ppm herbicide) weighed in at 1.9 Group #3 (4.7 ppm herbicide) weighed in at 1.9 grams and the controlled group weighed only 1.6 grams and the controlled group weighed only 1.6 grams.grams.

Tables and GraphsTables and Graphs

Tables and GraphsTables and Graphs

DiscussionDiscussion

After performing this experiment, I confirmed Winder’s After performing this experiment, I confirmed Winder’s statement that the herbicide 2,4-D is indeed a selective statement that the herbicide 2,4-D is indeed a selective herbicide.herbicide.

Raddish plants must inherit some herbicide tolerance Raddish plants must inherit some herbicide tolerance and resistance, because the harmful effects were and resistance, because the harmful effects were limited in this case. limited in this case.

The remark from Pryor supported my hypothesis, that The remark from Pryor supported my hypothesis, that at least one of the radish plant groups would have a at least one of the radish plant groups would have a beneficial effect from the herbicides. beneficial effect from the herbicides.

ConclusionsConclusions I concluded that with the addition of certain I concluded that with the addition of certain

herbicide concentrations, radish plants can have a herbicide concentrations, radish plants can have a hormetic or beneficial growth effect. hormetic or beneficial growth effect.

The results indicated that the plants in Group #2 The results indicated that the plants in Group #2 (3.1ppm) and Group #3 (4.7 ppm) had significantly (3.1ppm) and Group #3 (4.7 ppm) had significantly more growth over the controlled group in height more growth over the controlled group in height and weight. and weight.

Therefore, the hypothesis that at least one group Therefore, the hypothesis that at least one group would have a hormetic effect, was proven true and would have a hormetic effect, was proven true and the experiment rejected the null. the experiment rejected the null.