National Tropical Botanic Garden Kampong Science Teacher Enrichment Program Author: Jose Almeida Affiliation: TERRA Environmental Research Institute, Miami-Dade County Public Schools Target Grade: 9 through 12 Lesson Length: 2 hours (minimum) Title of Lesson: Allelopathy: How will leaf litter originating from 2 Everglades communities (hardwood hammock and rock pine lands) influence the ability of seeds to germinate? NGSSStandard/NGSS Standard: SC.912.N.1.1 Define a problem based on a specific body of knowledge, for example: biology, chemistry, physics, and earth/space science, and do the following: A. Pose questions about the natural world, (Articulate the purpose of the investigation and identify the relevant scientific concepts). B. Conduct systematic observations, (Write procedures that are clear and replicable. Identify observables and examine relationships between test (independent) variable and outcome (dependent) variable. Employ appropriate methods for accurate and consistent observations; conduct and record measurements at appropriate levels of precision. Follow safety guidelines). C. Examine books and other sources of information to see what is already known, D. Review what is known in light of empirical evidence, (Examine whether available empirical evidence can be interpreted in terms of existing knowledge and models, and if not, modify or develop new models). E. Plan investigations, (Design and evaluate a scientific investigation).
F. Use tools to gather, analyze, and interpret data (this includes the use of measurement in metric and other systems, and also the generation and interpretation of graphical representations of data, including data tables and graphs), (Collect data or evidence in an organized way. Properly use instruments, equipment, and materials (e.g., scales, probeware, meter sticks, microscopes, computers) including set-up, calibration, technique, maintenance, and storage). G. Pose answers, explanations, or descriptions of events. Generate explanations that explicate or describe natural phenomena (inferences), H. Use appropriate evidence and reasoning to justify these explanations to others, I. Communicate results of scientific investigations, and J. Evaluate the merits of the explanations produced by others. SC.912.N.1.2 Describe and explain what characterizes science and its methods. A. Scientific inquiry is a multifaceted activity; the processes of science include the formulation of scientifically investigable questions, construction of investigations into those questions, the collection of appropriate data, the evaluation of the meaning of those data, and the communication of this evaluation. B. The processes of science frequently do not correspond to the traditional portrayal of "the scientific method." C. Scientific argumentation is a necessary part of scientific inquiry and plays an important role in the generation and validation of scientific knowledge. D. Scientific knowledge is based on observation and inference; it is important to recognize that these are very different things. Not only does science require creativity in its methods and processes, but also in its questions and explanations. SC.912.N.1.4 Identify sources of information and assess their reliability according to the strict standards of scientific investigation. A. Scientific inquiry is a multifaceted activity; The processes of science include the formulation of scientifically investigable questions, construction of investigations into those questions, the collection of appropriate data, the evaluation of the meaning of those data, and the communication of this evaluation. B. The processes of science frequently do not correspond to the traditional portrayal of "the scientific method." C. Scientific argumentation is a necessary part of scientific inquiry and plays an important role in the generation and validation of scientific knowledge. D. Scientific knowledge is based on observation and inference; it is important to recognize that these are very different things. Not only does science require creativity in its methods and processes, but also in its questions and explanations.
NGSS Standard: SC.912.N.1.6 Describe how scientific inferences are drawn from scientific observations and provide examples from the content being studied. A. Scientific inquiry is a multifaceted activity; the processes of science include the formulation of scientifically investigable questions, construction of investigations into those questions, the collection of appropriate data, the evaluation of the meaning of those data, and the communication of this evaluation. B. The processes of science frequently do not correspond to the traditional portrayal of "the scientific method." C. Scientific argumentation is a necessary part of scientific inquiry and plays an important role in the generation and validation of scientific knowledge. D. Scientific knowledge is based on observation and inference; it is important to recognize that these are very different things. Not only does science require creativity in its methods and processes, but also in its questions and explanations. Objective(s): The students will be able to: 1. Objective should observable and measurable 2. The students will be able to define allelopathy and how allelopathy has the potential to inhibit the growth of nearby plants. 3. The students will be able to apply quantitative data collection procedures to set up an experiment Evaluation Question(s): Write at least one question to match each objective 1. Question should evaluate corresponding (#1) objective 2. Will allelopathic chemicals being released by leaf litter be effective in reducing the germination capacity of bean plants? 3. What volumetric and mass-measurement instruments are appropriate for this experiment? 4. Use tools to gather, analyze, and interpret data (this includes the use of measurement in metric and other systems, and also the generation and interpretation of graphical representations of data, including data tables and graphs). 4. How will you organize and collect data so that data representation and analysis will be facilitated? 5. Pose answers, explanations, or descriptions of events. Generate explanations that explicate or describe natural phenomena (inferences), 5. Were there any differences in the germination percentages of beans germinated from extract of different leaf litter media?
Where there any differences in the germination percentages of beans germinated from extract of different leaf litter media over time? 6. Use appropriate evidence and reasoning to justify these explanations to others, 7. Communicate results of scientific investigations, 6. What statistical test(s) should be used to determine if there were differences in the data from the 2 growth media? 7. Did the results demonstrate agreement or disagreement with the hypothesis or the central question? Abstract Please provide a brief overview (200-300 words) of your lesson. The lesson will have an introductory phase that will review the concept of allelopathy and will tie-in the chemistry-biology connection. Allelopathy is (usually) the inhibition of growth of one plant from the interaction of other plants. In this activity students will conduct an experiment that quantitatively compares the germination percentage of bean seeds exposed to allelopathic treatments. The allelopathic concentrates will be made by collecting leaf litter from 5 transects randomly tossed to the ground of a hardwood hammock and from the leaf litter collected from 5 random transects of the ground of rock-pinelands. The derived concentrate will be part of the growth medium used for seed germination. The percentage of seeds that germinate in the growth media over time will be used to determine the efficacy of each allelopathic solution. The activity is designed to explore how the 2 ecological communities differ in terms of allelopathic potential. The activity is also designed to allow students to quantitatively use lab procedures and to analyze and interpret chemical and biological data. Background Information Allelopathy refers to the effect that one plant has on the growth of another plant. Allelopathy can be beneficial or harmful to neighboring plants. Allelochemicals are the chemicals that are released by one plant and that affect other nearby plants. The chemicals could be released by leaching from the root, by the production of aromatic substances released into the air, and by the production of allelochemicals in the leaves, flowers, bark, and roots which could be in physical contact with other plants or the leaves could fall off to become toxic leaf litter. Allelochemicals are secondary metabolites and are not required for growth and development of the host plant. The allelopathic producing plant releases the chemical as a way to damage nearby plants and help with its survival. Allelopathic chemical making is energy and resource dependant and exerts a cost to the host plant.
Allelopathy can have an adverse effect in any garden or forest ecosystem, resulting in reduced seed germination and overall plant growth. Allelopathy is a natural weed killer. Most all allelopathic plants store their protective chemicals within their leaves, and the allelopathic properties can increase as there is an accumulation of leaf litter. As leaves drop to the ground, decompose and accumulate, the toxins can affect nearby plants. This experiment will utilize the theoretically allelopathic substances found in leaf litter to make a concentrated solution which students will use to test the efficacy of these chemicals on seed germination. Engagement Estimated Time: 10 minutes Brief description of the Engagement: A. Students will be shown pictures of a rock pine land and a hardwood hammock from South Florida. The pictures shown should include pictures of the understory so that the ground could be seen in both ecosystems. B. After the students have had time to take in and study the 2 ecosystems, they will be asked probing questions that lead towards understanding the concept that the ground in both ecosystems is not totally covered by plants but instead shows open spaces in the understory. Further questions will lead the students to hypothesize about possible mechanisms responsible for maintaining the openness in the ground of both ecosystems. C. The concept of allelopathy will be introduced. Allelopathy is the concept where parts of certain plant(s) chemically affect the growth of other nearby plants. D. Questions will be asked to students which probe possible ways that one plant (based on release of chemicals) can affect the growth of nearby plants. Examples of different strategies for inhibition could include toxins released from leaves, roots, and air borne chemicals. The teacher will: The students will: Select at least one of the 5E stems below and delete those that you will Select at least one of the 5E stems below and delete those that you will not use not use Piques students curiosity and interest Become interested in and curious about the concept/topic Determines students current understanding (prior knowledge) of a Express current understanding of a concept or idea concept or idea Raise questions such as, What do I already know about this? What do Invites students to express what they think I want to know about this? Invites students to raise their own questions
1. Students will be shown pictures of a rock pine land and a hardwood hammock from South Florida. The pictures shown should include pictures of the understory so that the ground could be seen in both ecosystems. 2. Ask probing questions that lead towards understanding the concept that the ground in both ecosystems is not totally covered by plants but instead shows open spaces in the understory. Further questions will lead the students to hypothesize about possible mechanisms responsible for maintaining the openness in the ground of both ecosystems. 1. After the students have had time to take in and study the pictures of the 2 ecosystems, 2. The students will answer probing questions that lead to understanding that the understory of both ecosystems show open spaces. Further questions will lead the students to hypothesize about possible mechanisms responsible for maintaining the openness in the ground of both ecosystems. List some possible questions to ask the students and give anticipated answers: Questions: Answers: 1. Describe observable differences about the types of vegetation that you see. 2. How relatively lush are the 2 communities? 3. Can you see the ground? 4. Is there a difference in the density of the plants between the 2 communities? 5. Can you see sunlight reaching the ground in each community? 6. Which has more light? 7. Do you see a difference in the substrate of the 2 communities. 8. Do you notice a difference in how separated the plants are in the ground between the 2 communities? 9. Summarize observable differences between the 2 communities. 1. In pine rock land the vegetation is dominated by slash pine and saw palmetto. In the hardwood hammock, the vegetation is varied, difficult to identify dominant species and dominated by broad leafed trees and shrubs. 2. On superficial observations, the hardwood hammock ecosystem looks much more complex and lush than the pine rock land. 3. The ground can be seen in both communities, indicating that plant density is controlled by some mechanism. 4. The plant density appears greater in the hardwood hammock; ground plant density appears to be about the same. 5. The hardwood hammock limits the amount of light hitting the ground. 6. The hardwood hammock has plants that are stratified vertically with multiple epiphytes attached to tree branches. 7. Hardwood hammock has a greater amount of leaf litter on the ground. Not all leaf litter has decomposed. Rock pine lands has less leaf litter and has exposed rock and holes on the ground. 8. On the ground plants have approximately the same amount of separation.
List resources and quantities needed for the Engagement: 1. A variety of multiple internet derived pictures from Google showing the 2 communities. 2. Ability to project the pictures on a screen. Describe any safety considerations for the Engagement: None
Exploration Estimated Time: 1.4 hours Brief description of the Exploration: The students will have an overview of needed vocabulary to understand the lab and its ideas. The students will need to develop a testable hypothesis. The students will need to follow the procedures of the lab while utilizing equipment and quantitative equipment so that qualitative and quantitative data could be collected. The teacher will: Select at least one of the 5E stems below and delete those that you will not use Encourages student-to-student interaction Observes and listens to the students as they interact Asks probing questions to redirect the students investigation when necessary Asks questions to help students make sense of their experiences Provides time for student to puzzle through problems A. Before the Lab Activity the teacher needs to collect the plant material: 1. The teacher will set out 5 random transects of 1 meter in area. 2. The transects used will come from Hula Hoops thrown so that they hit the ground randomly in 5 different parts of a hardwood hammock and 5 different parts of a rock pine land. 3. In each of the transects the teacher will fill out 1 large grocery bag s worth of leaf litter, so that we have a total of 5 bags of leaf litter from a hardwood hammock and 5 bags of leaf litter from a rock pine land. The students will: Select at least one of the 5E stems below and delete those that you will not use Mess around with materials and ideas Conduct investigations in which they observe, describe, and record data Try different ways to answer a question Acquire a common set of experiences so they can compare results and ideas Compare their ideas with those of others 1. Students will take notes in their note book OR students will write down the notes as part of their lab assignment. 2. Working definitions of allelopathy, hardwood hammock, rock pine lands, amounts of species found, density of plant populations in vertical stratification and horizontal spacing will be explored.
B. Before actually conducting the experiment and after the Engagement portion of the lesson, the teacher needs to introduce the needed concepts/vocabulary in order for students to understand the lab. 1. Allelopathy is defined 2. Brief history behind allelopathy in forest communities and in agricultural communities. 3. Why would plants allocate needed resources to produce chemicals that inhibit the growth of other plants? 4. Using the Engagement portion of the activity, students need to develop a testable hypothesis which relates to predicts which of the 2 ecosystems will have a greater allelopathic effect and why they believe that is so. 5. Students copy relevant parts of the experiment on their paper, including title, purpose, hypothesis, materials, procedures, data tables, format for the graphs and conclusions based on observable data. 3. The students will develop a quantitatively based hypothesis which could be tested through experimentation that aims to measure the allelopathic strength of a solution derived from each of the 2 communities. 4. Hypothesis should be written as: if we do this, then this will happen, because of this reason. 5. Once all relevant parts of the lab are copied, students will be responsible for being able to follow procedures and use lab apparatuses so that data collection could proceed in a precise manner. C. The Procedures of the experiment: 1. Label 2 weighing boats Hardwood Hammock and Rock Pine-land. 2. Mass out 5.0 grams each of leaf litter from Hardwood Hammock and Rock Pineland. 3. Using mortar and pestle pulverize the leaf litter. Carefully add 50 ml of distilled water to each mixture. 4. Using filter paper filter the distilled water and leaf litter mix and collect each liquid. 5. Make Nine 20 by 20 cm paper towel squares. 6. Label 3 Petri dishes as control, label 3 Petri dishes as hardwood hammock, and the last 3 as rock pine land. 7. Place each of the 20 by 20 cm paper towel squares into the bottom of a Petri dish 8. Thoroughly wet each paper towel using 10 ml of decanted liquid. 9. Place 5 seeds onto the wet paper towel. Fold the paper towel so that the seeds reside in pocket of wet paper towels. 10. Cover the top of each Petri dish.
D. Example for Analysis of Data: Source of Allelopathic solution: Days from time of planting 2 4 6 8 10 12 14 Number of seeds germinated Control 1 Control 2 Control 3 Hard wood 1 Hard wood 2 Commented [TA1]: Hard wood 3 Pine lands 1 Pine lands 2 Pine lands 3
List some possible questions to ask the students and give anticipated answers: Questions: Answers: 1. Do the 2 allelopathic solutions derived from the different 1. Answers will depend on what the data show. communities look and smell differently? How do the two 2. solutions differ? 2. Is there a total difference in the amount of seeds germinating from the 2 communities plus the control? Describe the differences if any? 3. Going back to the hypothesis, which community s allelopathic solution did you predict to have the greatest inhibition towards germination? 4. Did your experiment agree with or disagree with the hypothesis? Explain
List resources and quantities needed for the Exploration: 1. Multiple weighing boats 2. Leaf litter samples randomly collected and stored in paper grocery bags with litter from Hardwood Hammock and Rock Pine-land. 3. Electronic balances 4. 5.0 grams each of leaf litter from Hardwood Hammock and Rock Pine-land. 5. Using mortar and pestle 6. 50 ml of distilled water for each mixture. 7. Filter paper filter the distilled water and leaf litter mix and collect each liquid. 8. Nine 20 by 20 cm paper towel squares. 9. Label 3 petri dishes as control, label 3 petri dishes as hardwood hammock, and the last 3 as rock pine land. 10. Funnel 11. Green beans Describe any safety considerations for the Exploration: None
Explanation Estimated Time: 20 minutes (class time) additional time as homework Brief description of the Explanation: Students will make a data table, then the students will make a bar graph that shows the percent of seeds that germinated in each of the 3 allelopathic solutions through time. The students will compare the seed germination data with the hypothesis that they wrote and note agreement with the hypothesis or disagreement with the hypothesis, indicating that the results hypothesized did not match with the predicted results. If the results do not match the hypothesis, or if there was no allelopathy observed then other mechanisms to account for plant spacing needs to be considered. The teacher will: The students will: Select at least one of the 5E stems below and delete those that you will not use Encourages students to use their common experiences and data to develop explanations Ask questions that help students express understanding and explanations Requests justification (evidence) for students explanations Provides time for students to compare their ideas with those of others and perhaps to revise their thinking Introduces terminology and alternative explanations after students express their ideas 1. After looking at the data table, students will make a bar graph that shows the percent of seeds that germinated in each of the 3 allelopathic solutions through time. 2. The students will compare the seed germination data with the hypothesis that they wrote and note agreement with the hypothesis or disagreement with the hypothesis, indicating that the results hypothesized did not match with the predicted results. 3. If the results do not match the hypothesis, or if there was no allelopathy observed then other mechanisms to account for plant spacing needs to be considered. Select at least one of the 5E stems below and delete those that you will not use Explain concepts and ideas in their own words Base their explanations on evidence acquires during previous investigations Become involved in student-to-student conversations in which they debate their ideas Record their ideas and current understanding Reflect on and perhaps revise their ideas Express their ideas with what scientists know and understand 1. Definition of what constitutes seed germination based on actual observation of the lab seeds. 2. Students write in the observed germination results. 3. Students transfer the written data onto a bar graph that shows the percent of seeds that germinated for each solution for each day. 4. Students will use the percent germination data to accept or reject their hypothesis. 5. If allelopathy is not observed due to negligible differences in seed germination percentage between the prepared solutions and the control, then other mechanisms will need to be need explored to account for the observed spatial distribution pattern of plants.
List some possible questions to ask the students and give anticipated answers: Questions: Answers: 1. Did you observe a difference in the germination percentage 1. The answers are data driven based on experimental results. over time? 2. Were there significant differences in the germination 2. percentages between the 3 solutions tested? 3. Besides allelopathy, what other factors (2 more) could have reduced the capacity for seeds to germinate. List resources and quantities needed for the Explanation: 1. Continuation of the experiment. 2. Same as Exploration AND add graph paper to facilitate bar graph making. Describe any safety considerations for the Explanation: None Elaboration Estimated Time: 20 minutes (continued from explanation) Brief description of the Elaboration: The students will explain their observations of the spacing of ground plants in the 2 environments studied. The students will review the differences of biotic and abiotic factors in the 2 environments. The students will discuss the methods used in deciding how to write the hypothesis so that one environment is favored versus another in predicting more allelopathy. Seed germination criteria did you used during observations will be noted. Differences in seed germination percentages as time increased will be explained Students will explore criteria used to decide to accept or reject the hypothesis. Students will consider besides allelopathy, other factors in the environment that could lead to greater spacing of individuals. The teacher will: Select at least one of the 5E stems below and delete those that you will not use Focuses students attention on conceptual connections between new and past experiences The students will: Select at least one of the 5E stems below and delete those that you will not use Make conceptual connections between new and past experiences Use what they have learned to explain a new object, event,
Encourages students to use what they have learned to explain a new event or idea Reinforces students use of scientific terms and descriptions previously introduced Asks questions that help students draw reasonable conclusions for evidence organism, or idea Use scientific terms and descriptions Draw reasonable conclusions from evidence and data Communicate their understanding to others List some possible questions to ask the students and give anticipated answers: Questions: Answers: 1. What is allelopathy? 1. Students will redefine allelopathy and explain how the 2. Why did you decide to direct the hypothesis in the direction presence of allelopathic chemicals derived from 2 Everglades that you did so that X environment would tend to be more communities could inhibit seed germination. allelopathic? 2. Students will explain the though process used to develop a 3. What criteria did you use when observing seed germination? testable hypothesis. The hypothesis must address: if this is 4. Did you observe differences in seed germination percentages done then this happen because of this reason. as time increased? 3. Students will explain the data gathered through time for the 2 5. Why did you decide to accept or reject the hypothesis? allelopathic solutions made plus the control solution. 6. Besides allelopathy, what other factors in the environment 4. The results of the data will be explained. could lead to greater spacing of individuals? 5. The results of the data will indicate if the hypothesis is accepted or rejected and WHY. 6. If the data do not fit the original model for allelopathy, the students can speculate what other factors might be involved in the spacing of plants on the ground at both communities observed. 7. The group presentations will be done on either white boards or a larger poster sheet. 8. Lastly, if allelopathy worked, students could further design additional labs that look at other ecosystems in South Florida to determine if similar relationships exist. List resources and quantities needed for the Elaboration: 1. White boards and dry erase markers OR 2. White paper and markers
Describe any safety considerations for the Elaboration: None
Evaluation Estimated Time: 20 minutes (continued from explanation) plus homework time Brief description of the Evaluation: The teacher will: The students will: Select at least one of the 5E stems below and delete those that you will Select at least one of the 5E stems below and delete those that you will not use not use Observes and records as students demonstrate their understanding Demonstrate what they understand about the concepts and how of concepts and performance of skills well they can implement a thinking skill Provides time for students to compare their ideas with those of Compare their current thinking with that of others and perhaps others and perhaps to revise their thinking revise their ideas Interviews students as a means of assessing their developing Assess their own progress by comparing their current understanding understanding with their prior knowledge Encourages students to assess their own progress Ask new questions that take them deeper in a concept or topic area 1. The teacher will ask questions to the group presenting regarding the concept of allelopathy? 2. The teacher will check that the hypothesis allowed quantitative vetting, and included if we do this, then this will happen, because of this reason. 3. The teacher will check that all components of the lab are included as directed from directions offered the first day. 4. The teacher will check that the data table is complete. The table should include all labels of all quantifiable observations. 5. The table should include qualitative observations through time. 6. Criteria used when observing seed germination should be noted. 7. Graphical data showing quantities of seeds germinated through time should be included. 8. The graph needs to be titled, clear, perfectly organized and neat, and should include all labels and units used on each axis. 9. Observe differences in seed germination percentages as time increased should be noted so that hypothesis can be rejected or accepted with a description of WHY the hypothesis was accepted or rejected. 10. Sources of error should be noted. 1. Answer questions, and take notes that define key term and concepts needed to understand the lab. 2. The students will write the hypothesis so that it is testable and quantitative in nature. 3. The students will continue to write components of the lab from board notes. Components of the lab include the title, purpose, materials, procedures, data table, a space for graphs and conclusions. 4. Students perform the lab with the emphasis on systematic and replicatable data collection. 5. Students collect data through the various days, recording the amounts of seeds that germinated for each Petri dish. 6. Students make perfect bar graphs indicating percent seeds germinated per each allelopathic solution for each day. 7. Data is analyzed and compared to the original hypothesis for acceptance or rejection. 8. If the hypothesis was wrong, an analysis needs to occur to determine if: There was minimal allelopathy. The allelopathic solution preparation method needs to be revised. There are other factors at play in maintaining the plant
11. Besides allelopathy, what other factors in the environment could lead to greater spacing of individuals? 9. density at the level that were found in the habitats. What other factors could maintain plant density as were found? Future studies could look at other Everglades ecosystems to monitor and determine plant spacing and allelopathy. Biological and physical inhibitors to plant growth could be explored. Replace this text with your students second step here Formative Assessment List some possible questions to ask the students and give anticipated answers: Questions: Answers: 1. Were allelopathic effects minimal? 2. How would the allelopathic solution preparation method be revised? 3. What other factors could be at play in maintaining the plant density at the level that were found in the habitats? 4. What other factors could maintain plant density as were found? 5. What other Everglades ecosystems could be studied to monitor and determine plant spacing and allelopathy? 6. Could other biological and physical inhibitors to plant growth be explored? 7. What are some sources of error in the lab? 1. Answer depends on data 2. More concentration with more leaves, more time letting the leaves age, include some soil in the mix 3. Soil composition, ph, other nutrients, light availability, herbivores, plant parasites, insects, humans 4. Mangrove, ecotone communities, grasslands, costal prairie, bayheads 5. Light penetration, relative humidity, soil nutrients, salinity 6. Multiple sources of error are possible: leaf collection, making the solution, reducing possible infection of the seeds, maintaining precision throughout the lab, determining when seeds are considered to have germinated. Summative Assessment attach summative assessment and rubric at the end of lesson plan and hyperlink 1. Define concept of allelopathy (1 Pt) 2. The teacher will check that the hypothesis allowed quantitative vetting, and included if we do this, then this will happen, because of this reason. (2 Pts) 3. The teacher will check that all components of the lab are included as directed from directions offered the first day. (1 Pt)
4. The teacher will check that the data table is complete. The table should include all labels of all quantifiable observations. (2 Pts) 5. The table should include qualitative observations through time. (1 Pt) 6. Criteria used when observing seed germination should be noted (1 Pt) 7. Graphical data showing quantities of seeds germinated through time should be included. (3 Pts) 8. The graph needs to be titled, clear, perfectly organized and neat, and should include all labels and units used on each axis (2 Pt) 9. Observe differences in seed germination percentages as time increased should be noted so that hypothesis can be rejected or accepted with a description of WHY the hypothesis was accepted or rejected. (2 Pts) 10. Sources of error should be noted. (1 Pt) List resources and quantities needed for the Evaluation: None Describe any safety considerations for the Evaluation: None Resources Please provide resources for further information Jose, 1. Allelopathy: https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=3&cad=rja&uact=8&ved=0ahukewigtue36sfnahwfkiykhuj TCC4QFgg2MAI&url=http%3A%2F%2Fedis.ifas.ufl.edu%2Fhs186&usg=AFQjCNHxvpSdNalpRKtzKfljW_t6zQhJ5A&bvm=bv.1255967 28,d.eWE 2. Allelopathy CSIP Cornell https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=4&cad=rja&uact=8&ved=0ahukewigtue36sfnahwfkiykhuj TCC4QFgg8MAM&url=http%3A%2F%2Fcsip.cornell.edu%2FProjects%2FCEIRP%2FAR%2FAllelopathy.htm&usg=AFQjCNFJrItfYr3k Yu003PxqREG_4SHeyA&bvm=bv.125596728,d.eWE 3. URL I wish that I had access to the soils and other resources needed to do this in my part of the world. Please share any data or any other thoughts when you have done this.
David