1 Reflections Regarding Plant-Plant Interactions, Plant-Plant Communications and Plant-Plant Allelopathic Interactions with an Emphasis on Plant-Plant Allelopathic Interactions
1.1 Plant-Plant Interactions
1.1.1 Direct Transfer between Plants
1.1.2 Plant-Plant Communications
1.1.3 Plant-Plant Allelopathic Interactions
1.1.4 Relationships
1.2 Defining the Boundaries of Plant-Plant Allelopathic Interactions
1.2.1 Plant-Plant Allelopathic Interactions and the Biotic and Physicochemical Environment
1.2.2 Boundaries for Plant-Plant Allelopathic Interactions
1.2.3 Terminology
1.3 Approaches
1.4 References
2 General Background for Plant-Plant Allelopathic Interactions
2.1 Introduction
2.2 Sources of Available (Free) Organic Compounds in the Field Environment
2.2.1 Living Plants
2.2.2 Litter, Residues, and Organic Matter
2.2.3 Residual Available Organic Compounds and Recalcitrant Organic Matter
2.2.4 Formation of Available Secondary, Tertiary, etc. Organic Compounds
2.3 Sinks for Available Organic Compounds
2.4 Sources (Input)-Sink Relationships for Available Organic Compounds
2.4.1 Sources (Inputs)-Sink Relationships
2.4.2 Turnover Rates of Available Organic Compounds
2.5 When is an Organic Compounds an Allelopathic Compound?
2.6 Identified Putative allelopathic (IPA) Compounds
2.6.1 Effects for Identified Putative Allelopathic (IPA) Compounds
2.6.2 Modifying Elements for the Effects of IPA Compounds
2.6.3 Time Frame for the Effects of IPA Compounds
2.6.4 Mobility and Distribution of IPA Compounds in the Environment
2.6.5 Fractions of IPA Compounds
2.6.6 Available/Active Fractions, Uptake, Depletion, Turnover Rates and Residual Concentrations
2.7 Modeling
2.8 References
3 Conceptual Models for Soil Systems and Physicochemical Properties of Organic Compounds
3.1 Introduction
3.2 Sources (Inputs) and Transport
3.2.1 Hydrophilic Organic Molecules (All Non-Gaseous Water-Soluble Molecules No Matter their Classification)
3.2.2 Hydrophobic Organic Molecules (All Non-Gaseous Water-Insoluble Molecules No Matter their Classification)
3.2.3 Volatile Organic Molecules (All Gaseous Molecules No Matter their Classification)
3.3 Sinks
3.3.1 Hydrophilic Organic Molecules (All Non-Gaseous Water-Soluble Molecules No Matter their Classification)
3.3.2 Hydrophobic Organic Molecules (All Non-Gaseous Water-Insoluble Molecules No Matter their Classification)
3.3.3 Volatile Organic Molecules (All Gaseous Molecules No Matter their Classification)
3.4 Conceptual Models for Source (Potential Inputs)-Sink Relationships
3.5 Physicochemical Properties for Individual Organic compounds
3.6 Linkages between Physicochemical Properties of Organic compounds
3.7 References
4 Simple Phenolic Acids in Solution Culture I: pH and pKa
4.1 Introduction
4.2 Simple Phenolic Acids
4.3 Physicochemical Properties of Phenolic Acids in Solution Cultures
4.4 pK
a Values of Phenolic Acids
4.5 Calculating Neutral and Negative Fractions
4.6 Depletion (Uptake) of Neutral and Negative Fractions of Individual Phenolic Acids
4.7 Effects of Neutral Fractions of Individual Phenolic Acids on Growth
4.8 Neutral Fractions and Mixtures of Phenolic Acids
4.9 The Neutral fraction vs the Negative fraction as Causative Agents
4.10 Final Comments
4.11 References
5 Simple Phenolic Acids in Solution Culture II: Log P, Log D and Molecular structure
5.1 Introduction
5.2 Log P
5.3 Log D (i.e., pH adjusted Log P)
5.4 Potential Roles of Log P and Log D
5.4.1 Log P and Individual Phenolic Acids
5.4.2 Outliers
5.4.3 Log D and Individual Phenolic Acids
5.4.4 Log P and Concentrations of the Neutral Molecules
5.4.5 Mixture of Phenolic Acids
5.5 Molecular Structure
5.6 Roles of Microorganisms
5.7 Final Comments
5.8 References
6 Simple Phenolic Acids in Soil Culture I: Sorption, Kd and KOC
6.1 Introduction
6.2 Sorption and Sorption Coefficients
6.2.1 Definitions
6.2.2 Sorption of Phenolic Acids in Soil Systems
6.2.3 Soil-Water (Kd) and Soil Organic Carbon-Content (Koc) Coefficients
6.3 Soil Sorption of Phenolic Acids Based on Batch Equilibrium-Desorption Techniques and Water and Neutral EDTA Extractions
6.3.1 Percent Sorption, K
d and K
oc of Phenolic Acids in Cecil and Portsmouth Soils
6.3.2 Percent E-Sorption
6.4 Final Comments
6.5 References
7 Simple Phenolic Acids in Soil Culture II: Biological Processes in Soil
7.1 Introduction
7.2 Utilization and Responses of Microorganisms to Phenolic Acids
7.2.1 Soil-Non-Mycorrhizal Root Systems
7.2.2 Mycorrhizosphere, Rhizoplane and Endorhizosphere of Mycorrhizal Roots
7.2.3 Nodulation
7.2.4 Field vs Laboratory Systems: Microbial Populations Based on Colony-Forming Units
7.3 Uptake of Phenolic Acids by Roots and Mycorrhizae
7.3.1 Root Uptake
7.3.2 Mycorrhizal Uptake
7.4 References
8 Hypothetical Solution-Culture System Sub-Models
8.1 Introduction
8.2 General Background
8.2.1 Features of the Nutrient-Culture System
8.2.2 The Conceptual Model
8.2.3 Physicochemical Properties of Phenolic Acids and Phenolic Acid Effects
8.3 Hypothetical Models: Exploring the Source (Input)-Sink Relationships and Effects of Phenolic acids by Means of the Conceptual Model
8.3.1 Depletion of Ferulic Acid, p-Coumaric Acid, and Vanillic Acid and Their Effects on Net Phosphorous Uptake (see Lyu et al. 1990)
8.3.2 Depletion of ferulic Acid, vanillic Acid and an Equal-Molar Mixtures of Ferulic Acid and Vanillic Acid and Their Effects on Net Phosphorous Uptake (see Lyu et al. 1990)
8.3.3 Depletion of Ferulic Acid from Treatment Solutions and Effects of Ferulic Acid on Absolute Rates of Leaf Expansion as Modified by pH over a 48-hr Treatment Period (see Blum et al. 1985b)
8.4 Final Comments
8.5 References
9 Hypothetical Soil-Culture System Sub-Models
9.1 Introduction
9.2 Features of Soil and Soil-Sand Cultures
9.2.1 Basic Systems
9.2.2 Media, Roots, Microorganisms, Treatment Solutions and Effects
9.3 Measurements, Coefficients, and Relationships
9.3.1 Determining Depletion, Sorption and Residual Concentrations of Phenolic Acids in Soil and Soil-Sand Systems
9.3.2 Sorption, Kd, Kf and Koc Coefficients
9.3.3 pKa, Log P and Log D
9.3.4 Colony-Forming Units (CFU) of Microorganisms
9.3.5 Seedling Effects
9.3.6 Cause and Effect Relationships
9.4 Hypothetical Models: Fundamentals of Cecil and Portsmouth Soil Systems
9.4.1 Phenolic Acid Input
9.4.2 Processes that Determine Available and Unavailable Phenolic Acids
9.4.3 Available (Free and Reversibly Sorbed) and Unavailable Phenolic Acids
9.4.4 Seedling Effects and Some Modifying Factors
9.5 Final Comments
9.6 References
10 Quantitative Hypothetical System Models for Cecil Soil-Sand Systems
10.1 Introduction
10.2 The Systems and their Hypothetical Models
10.2.1 Continuous-Input Column Open Systems
10.2.2 Single and Multiple Input Closed Systems
10.3 References
11 Quantitative Hypothetical System Model for Portsmouth Soil-Sand System and Potential Modifying Factors
11.1 Introduction
11.2 Quantitative Data Available for Portsmouth Soil and Soil-Sand Systems
11.2.1 Physicochemical Processes in Soil
11.2.2 Physicochemical Processes and Microbial Populations and Utilization in Soil-Sand Systems
11.2.3 Rhizosphere Microbial Populations and Utilization in Cucumber Seedling-Soil-Sand Systems
11.2.4 Seedling Inhibition
11.3 Hypothetical Model for Portsmouth Soil-Sand Systems
11.3.1 Systems
11.3.2 Potential Modifiers of Black Box Values
11.4 References
12 Epilog: Assumptions, Models, Hypotheses and Conclusions
12.1 Introduction
12.2 Physicochemical Properties of Phenolic Acids
12.2.1 Solubility and vapor Pressure
12.2.2 pK
a
12.2.3 Log P
12.2.4 Molecular Structure
12.2.5 Sorption Coefficients (K
d, K
f and K
oc)
12.2.6 Can Physicochemical Properties of Phenolic Acids be Used as Tools to Help Understand the Complex Behavior of Phenolic Acids and the Ultimate Effects of Phenolic Acids on Sensitive Seedlings?
12.3 Other Tools
12.3.1 Soil Extractions
12.3.2 Plate-Dilution Frequency technique
12.3.3 Leaf Area and Leaf Area Expansion
12.3.4 Water Utilization, Evapotranspiration and µM and mM of Phenolic acids in Soil
12.4 Assumptions for Model Systems
12.4.1 Nutrient Culture Systems
12.4.2 Continuous-Input Systems
12.4.3 Single and Multiple Input Closed Systems
12.5 Summary of Observations for Seedling-Microbe-Soil Systems
12.5.1 Physicochemical Processes
12.5.2 Root Uptake and Microbial Utilization
12.5.3 Seedling Effects
12.5.4 Partitioning of Phenolic Acids
12.6 What insights do the laboratory bioassays and the conceptual and hypothetical models of laboratory systems tell us about the potential behavior and effects of phenolic acids in field systems?
12.6.1 Similarities for Laboratory and Field Systems
12.6.2 Differences for Laboratory and Field Systems
12.6.3 Conclusions
12.7 References
