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Michael Raviv

Agricultural Research Organization of Israel, Newe Ya'ar Research Center, Faculty Member

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An Emeritus Professor in agriculture, dealing mainly with the following sugjects:1. Using soilless media to improve plant productivity2. Composting and compost uses, especially in order to suppress soil-borne pathogens

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Kansas State University

Jayanta Kumar Saha

Indian Institute of Soil Science, Bhopal

Prof. Nasser Elgizawy

Benha University

Darwin H . Pangaribuan

The University Of Lampung

Sheikh Muhammad Masum

Sher-e-Bangla Agricultural University, Dhaka

Sharad C. Phatak

The University of Georgia

Prof Manjit S Kang

Kansas State University

Azarian Journal of Agriculture (AJA)

University of margheh

University of Iqra Buru

York University

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Books by Michael Raviv

Composting municipal biosolids in polyethylene sleeves with forced aeration: Process control, air emissions, sanitary and agronomic aspects

Composting in polyethylene sleeves with forced aeration may minimize odor emissions, vectors attr... more Composting in polyethylene sleeves with forced aeration may minimize odor emissions, vectors attraction and leachates associated with open windrows. A disadvantage of this technology is the lack of mixing during composting, potentially leading to non-uniform products. In two pilot experiments using biosolids and green waste (1:1; v:v), thermophilic conditions (>45 °C) were maintained for two months, with successful control of oxygen levels and sufficient moisture. Emitted odors declined from 1.5–3.8 Â 10 5 to 5.9 Â 10 3 –2.3 Â 10 4 odor units m À3-air in the first 3 weeks of the process, emphasizing the need of odor control primarily during this period. Therefore, composting might be managed in two phases: (i) a closed sleeve for 6–8 weeks during which the odor is treated; (ii) an open pile (odor control is not necessary). Reduction of salmonella, E. coli and coliforms was effective initially, meeting the standards of ''Class A " biosolids; however, total and fecal coliforms density increased after opening the second sleeve and exceeded the standard of 1000 most probable number (MPN) per g dry matter. Compost maturity was achieved in the open piles following the two sleeves and the final compost was non-phytotoxic and beneficial as a soil additive.

Soilless Culture: Theory and Practice

Papers by Michael Raviv

Detecting Activity of Juvenile Phase-Specific Translocatable Substances that Influence Rooting Potential Using In Vitro Rooting Assays and Expression of a Specific Gene

The objectives of the project for which substantial effort was put forth were to: 1) Verify the r... more The objectives of the project for which substantial effort was put forth were to: 1) Verify the relationship between expression of a cDNA clone (HW103) and the rooting potential of reciprocally grafted cuttings of juvenile and mature lamina and petioles of Hedera helix L. 2) Detect rooting promoter fractions in exudates from the juvenile leaves of H. Helix by assaying for rooting with leaf petioles of juvenile and mature plants. 3) Isolate, purify and identify compounds which show activity in assays for rooting potential. Some objectives or aspects of the objectives of the original proposal were not pursued for the reasons put forth in the body of the report. The most significant findings of the project are: 1) The MS medium is a better medium than Romberg medium for performing the leaf petiole rooting assay. 2) HW103 gene expression is cell-type specific with higher levels of expression in mature than juvenile phase H. Helix petioles as evidenced by in situ hybridization which sugg...

Transpirational Cooling of Greenhouse Crops

Background Transplanting vegetable seedlings to final spacing in the greenhouse is common practic... more Background Transplanting vegetable seedlings to final spacing in the greenhouse is common practice. At the time of transplanting, the transpiring leaf area is a small fraction of the ground area and its cooling effect is rather limited. A preliminary modeling study suggested that if water supply from root to canopy is not limiting, a sparse crop could maintain about the same canopy temperature as a mature crop, at the expense of a considerably higher transpiration flux per leaf (and root) area. The objectives of this project were (1) to test the predictions of the model, (2) to select suitable cooling methods, and (3) to compare the drought resistance of differently prepared seedlings. Procedure Plants were grown in several configurations in high heat load environments, which were moderated by various environmental control methods. The difference between the three experimental locations was mainly in terms of scale, age of plants, and environmental control. Young potted plants wer...

Greenhouse Operation for Best Aerial Environment

Progress report to the International Cut Flower Growers Association

Calorespirometry: a novel approach to predicting energy requirements of greenhouse flower crops

The 9 th meeting of the IOBC / WPRS Working Group Integrated Control in Protected Crops , Mediterranean Climate Working Group Meeting Pest Management in an Ever-Changing World 11-15 October 2015 The

We are happy to welcome you to the 9th meeting of the Working Group on the campus of the R.H. Smi... more We are happy to welcome you to the 9th meeting of the Working Group on the campus of the R.H. Smith Faculty of Agriculture, Food and Environment of the Hebrew University of Jerusalem in Rehovot, Israel. The theme we chose for the meeting, Pest Management in an Ever-Changing World, reflects the constant changes in climate, consumer demand, economy, regulations, technology, as well as invasions of new pest species, that continuously challenge researchers, extension officers, growers and the agro-businesses. These changes are evidenced throughout the meeting program. The four days of the meeting will include keynote talks by leading scientists, oral research reports, three guest speakers that will explore new approaches and ideas, discussion sessions, and a full day field trip to a major greenhouse production region in the Arava valley. We also allowed ample of time for informal interaction during breaks, field trip, and evening events. Now it is really over to you, the participant. How you benefit from the meeting will depend not only on your listening to the talks but also on your active participation; we encourage you to ask questions and actively participate in discussions. We trust you will take the opportunity to approach people you haven't met before and then network further over dinner, wine, and coffee, or on the bus on Tuesday. We worked hard to create the best possible scientific, professional and personal experience for you. Please feel free to approach any of us for assistance or with suggestions. We will do our best to help.

Fungal Photomorphogenesis: A Basis for the Control of Foliar Diseases Using Photoselective Covering Materials for Greenhouses

HortScience, 1998

The Effect of Physical Properties of Soilless Media on Plant Performance - a Review

Acta Horticulturae, 2004

Moderate matric potential and oxygen deficiency reduce leaf water potential, net assimilation rat... more Moderate matric potential and oxygen deficiency reduce leaf water potential, net assimilation rate and transpiration and thus negatively affect plant productivity. Moderate matric potential in the porous media, usually accompanied by a sharp decrease in unsaturated hydraulic conductivity, leads to localized zones of very low matric potential adjacent to the root-medium interface. This phenomenon cannot be easily characterized using tensiometers and is the main limiting factor to water uptake by plant roots. Restricted water uptake results in low leaf water potential, leading to cessation of leaf and shoot expansive growth. Oxygen deficiency restricts root respiration, thus negatively affects water and nutrient uptake. If it persists, temperal loss of ion selectivity of the root membranes may occur, resulting in increased uptake of non-essential ions such as sodium. Water and oxygen status of the root zone can be manipulated at two stages. Firstly, they are affected by the choice of the medium, in respect to the crop needs, available management practices and climatic conditions, and secondly by the chosen strategy of irrigation control. The main physical properties of the medium that affect plant performance are discussed in the following review, as well as methods to affect the actual status of water and oxygen in the medium.

Soil suppressiveness against Macrophomina Phaseolina s.l. as affected by cyclic temperature regimes

Phytoparasitica, 2016

Effect of temperature on the survival of Macrophomina phaseolina s.l. (Mp) was tested under labor... more Effect of temperature on the survival of Macrophomina phaseolina s.l. (Mp) was tested under laboratory conditions using an incubation system programmed for a cyclic temperature regime, simulating soil solarization. Mp culture and soil with and without Mp were incubated under two cyclic temperature regimes, with maximum temperatures of 50°C or 52°C, simulating solarization processes, and at a constant temperature of 25°C, as a control. Total fungal community and Mp levels were not affected negatively by constant temperature of 25°C. However, total soil fungal community was significantly decreased at temperature regime of 50°C, whereas Mp did not change significantly whether in soil mixture or as pure propagules culture. In Mp-amended soil treated by temperature regime of 50°C, total fungal community decreased while Mp CFU number did not change significantly. However, temperature regime of 52°C almost completely eradicated total fungal community, as well as that of Mp. When Mp was amended to soils after being treated at 50°C and 52°C temperature regimes and incubated for two additional weeks at 25°C, an indirect temperature effects on Mp survival were apparent. The 50°C pretreatment did affect significantly neither the total fungal nor Mp levels. In soil previously treated by 52°C, total fungal growth was somewhat decreased while Mp growth was promoted. The results suggest that Mp survival may be affected by temperature directly as well as indirectly via effects on total fungal population. Studying these biological factors may contribute to the control of Mp pathogen using environment-friendly methods.

Slurry Produced by Methanogenic Fermentation of Cow Manure as a Growth Medium for Some Horticultural Crops *

Acta Horticulturae, 1984

Composting Olive Mill Waste and Assessment of Its Horticultural Value

International Symposium on Growing Media 2007, 2009

Survival of Macrophomina phaseolina s.l. and Verticillium dahliae during solarization as affected by composts of various maturities

Crop Protection, 2015

Abstract Solarization is commonly used against several soilborne pathogenic fungi, and is an effe... more Abstract Solarization is commonly used against several soilborne pathogenic fungi, and is an effective, environmental-friendly substitute for chemical control or soil steaming. This study aimed to verify solarization effectiveness as a control measure against the pathogens Macrophomina phaseolina s.l. (sensu lato) (MP) and Verticillium dahliae (VD) when combined with compost of various maturity levels. This assumes that immature compost can help to eradicate the pathogens as its degradation can raise the temperature below the tarp. The survival rates per gram of MP and VD were tested at depths of 10 and 20 cm. At both depths in the solarized treatments, VD was eradicated during the first 2 weeks, whereas in the non-solarized treatments the level of VD incidence decreased but not to total elimination. Four weeks after the beginning of the experiment, about 5000 colony forming units (CFUs) of VD survived in the non-solarized treatment. MP survived the solarization process. The presence of compost of any maturity level did not contribute to a temperature increase in the solarized part during the day. At night, in the non-solarized treatments, the average minimal temperature rose by almost 1.4 °C in the immature-compost-treated soil. Solarization at a maximal temperature of almost 48 °C, as found in the field experiment, could eradicate VD, but this temperature was not sufficiently high to eradicate MP. We also aimed to determine the minimal threshold temperature for eradication of MP. For this we used an incubator with cycling temperatures, to simulate the daily cycles of soil temperature during solarization. MP survived a maximal temperature of 52 °C during a 4-week laboratory experiment with cycling temperatures; it was totally eliminated after 4 weeks at a maximal temperature of 54 °C and after 2 days at a maximal temperature of 56 °C.

Inorganic and Synthetic Organic Components of Soilless Culture and Potting Mixes

Soilless Culture, 2008

The components of soilless growing media and potting mixes used in horticulture are primarily sel... more The components of soilless growing media and potting mixes used in horticulture are primarily selected based on their physical and chemical characteristics and, in particular, their superior ability to provide simultaneously sufficient levels of oxygen and water to the roots. There is a lot of variability in the origin and physical and chemical characteristics of the substrates used by the horticultural industry. Substrates are divided into inorganic and synthetic organic materials. The organic materials comprise synthetic substrates and natural organic matter. The inorganic substrates can be classified as natural unmodified materials and processed materials. This chapter provides the description of each substrate, which includes information on its production and origin, general information on its applications as a growth medium, or for other purpose. It sheds light on the physical characteristics, such as bulk density (BD), water retention, and hydraulic conductivity, as these properties are essential for proper irrigation management. Furthermore, it describes the chemical characteristics, i.e., composition, stability as affected by pH, cation exchange capacity (CEC), pH, and salinity, as these basic data are required for the proper management of fertilization and irrigation. In addition, it presents information on substrate sterilization, as disease control is a major factor in the successive use of substrates. Finally, it provides information on waste treatment since the potential for environmental contamination is becoming a central issue in intensive soilless cultivation.

Organic Soilless Media Components

Soilless Culture, 2008

This chapter deals with the organic materials used in soilless production: peat, coir, bark, wood... more This chapter deals with the organic materials used in soilless production: peat, coir, bark, wood products, and compost. It describes their physical and chemical properties and their effect on plant performance. It also discusses the composting process and reviews the biological stability of growing media and disease suppression. Peat has long been used as a component of potting mixes and has become the most widely used growing medium for containers as a complete growing medium by itself. However, the use of peat in horticulture has recently been questioned from an environmental standpoint, since peat is a non-renewable resource and since it plays a major role in atmospheric CO2 sequestration. Alternative organic substrates in organic--inorganic media mixes include waste organic by-products, such as wood industry wastes, urban wastes, cork, wood fibers, livestock manure composts, coconut wastes, etc. While some of these have been in use for a long time, others, such as coir and coconut wastes, have been tried more recently, sometimes with promising results. Alternative organic substrates that are well characterized and corrected by suitable blending with inorganic components make it possible to produce high-quality horticultural plants and contribute to the reduction of overexploitation of natural peat-lands. Chief among replacement materials has been bark and wood fiber from forestry and the wood industry. There is also increasing interest in coconut fiber (coir dust), green waste, and other plant and animal residues.

Sustainability of Organic Horticulture

Horticultural Reviews, 2010

Page 1. 6 Sustainability of Organic Horticulture Michael Raviv Ministry of Agriculture Agricultur... more

The effect of medium disinfestation on cut rose productivity and on some chemical properties of tuff

Scientia Horticulturae, 1998

Peat in the inoculation medium induces fusarium susceptibility in melons

Plant Breeding, 2008

ABSTRACT The effect of peat moss on fusarium wilt of melon (Cucumis melo L.) was studied in order... more ABSTRACT The effect of peat moss on fusarium wilt of melon (Cucumis melo L.) was studied in order to improve the selection process of resistant melons during breeding programmes. Disease symptoms were evident earlier and disease progress was faster in seedlings that were transplanted to peat following inoculation than in those transplanted to sand. The resistant breeding line used as a control did not show any wilt symptoms in either medium. Mixing the peat with sand or perlite reduced the disease development rate and the final disease incidence. The effects of peat and sand on disease progress were evaluated with two segregating melon populations in which the expected susceptible : resistant ratio was 25 : 75. In both populations, disease incidence was higher in the peat, which enables breeders to identify resistant plants and to lower the risk of using escapees as resistant plants. The mechanism of disease enhancement may include both biotic and abiotic components. There is an indication that peat induces plant susceptibility before inoculation. Melon seedlings germinated in peat and transplanted into sand exhibited significantly greater wilt incidence than those that germinated in sand and were transplanted into sand following the inoculation. Disease progress in sterile peat was significantly slower than that in non-sterile peat, which suggests the possible involvement of microbial activity.

The absolute configuration effect on the activity of the avocado rooting promoter

Phytochemistry, 1990

Heptadecyn-1,2,4-trio1 is the most active component of the avocado rooting promoter (ARP). All fo... more Heptadecyn-1,2,4-trio1 is the most active component of the avocado rooting promoter (ARP). All four diastereoisomers of this compound have been synthesized. Their root promoting activity was determined over the physiologically active concentration range. It was found that the (2R,4R)-stereoisomer exerts a rooting activity similar to that of the extracted and purified compound from avocado tissues. The (2R,4S), and (2S,4R)-stereoisomers had lower activity and the (25,4S)-stereoisomer had the lowest activity. It is concluded that the natural form, (2R,4R), acts in the rooting process either in its original structure or after reaction which does not alter its chiral centres.

Effects on chemical surface properties of tuff by growing rose plants

Hydrobiologia, 1996

... Alva AK, Edwards DG and Blarney FPC 1986 Relationships between root length of soybean and cal... more

Composting municipal biosolids in polyethylene sleeves with forced aeration: Process control, air emissions, sanitary and agronomic aspects

Composting in polyethylene sleeves with forced aeration may minimize odor emissions, vectors attr... more Composting in polyethylene sleeves with forced aeration may minimize odor emissions, vectors attraction and leachates associated with open windrows. A disadvantage of this technology is the lack of mixing during composting, potentially leading to non-uniform products. In two pilot experiments using biosolids and green waste (1:1; v:v), thermophilic conditions (>45 °C) were maintained for two months, with successful control of oxygen levels and sufficient moisture. Emitted odors declined from 1.5–3.8 Â 10 5 to 5.9 Â 10 3 –2.3 Â 10 4 odor units m À3-air in the first 3 weeks of the process, emphasizing the need of odor control primarily during this period. Therefore, composting might be managed in two phases: (i) a closed sleeve for 6–8 weeks during which the odor is treated; (ii) an open pile (odor control is not necessary). Reduction of salmonella, E. coli and coliforms was effective initially, meeting the standards of ''Class A " biosolids; however, total and fecal coliforms density increased after opening the second sleeve and exceeded the standard of 1000 most probable number (MPN) per g dry matter. Compost maturity was achieved in the open piles following the two sleeves and the final compost was non-phytotoxic and beneficial as a soil additive.

Soilless Culture: Theory and Practice

Detecting Activity of Juvenile Phase-Specific Translocatable Substances that Influence Rooting Potential Using In Vitro Rooting Assays and Expression of a Specific Gene

The objectives of the project for which substantial effort was put forth were to: 1) Verify the r... more The objectives of the project for which substantial effort was put forth were to: 1) Verify the relationship between expression of a cDNA clone (HW103) and the rooting potential of reciprocally grafted cuttings of juvenile and mature lamina and petioles of Hedera helix L. 2) Detect rooting promoter fractions in exudates from the juvenile leaves of H. Helix by assaying for rooting with leaf petioles of juvenile and mature plants. 3) Isolate, purify and identify compounds which show activity in assays for rooting potential. Some objectives or aspects of the objectives of the original proposal were not pursued for the reasons put forth in the body of the report. The most significant findings of the project are: 1) The MS medium is a better medium than Romberg medium for performing the leaf petiole rooting assay. 2) HW103 gene expression is cell-type specific with higher levels of expression in mature than juvenile phase H. Helix petioles as evidenced by in situ hybridization which sugg...

Transpirational Cooling of Greenhouse Crops

Background Transplanting vegetable seedlings to final spacing in the greenhouse is common practic... more Background Transplanting vegetable seedlings to final spacing in the greenhouse is common practice. At the time of transplanting, the transpiring leaf area is a small fraction of the ground area and its cooling effect is rather limited. A preliminary modeling study suggested that if water supply from root to canopy is not limiting, a sparse crop could maintain about the same canopy temperature as a mature crop, at the expense of a considerably higher transpiration flux per leaf (and root) area. The objectives of this project were (1) to test the predictions of the model, (2) to select suitable cooling methods, and (3) to compare the drought resistance of differently prepared seedlings. Procedure Plants were grown in several configurations in high heat load environments, which were moderated by various environmental control methods. The difference between the three experimental locations was mainly in terms of scale, age of plants, and environmental control. Young potted plants wer...

Greenhouse Operation for Best Aerial Environment

Progress report to the International Cut Flower Growers Association

Calorespirometry: a novel approach to predicting energy requirements of greenhouse flower crops

The 9 th meeting of the IOBC / WPRS Working Group Integrated Control in Protected Crops , Mediterranean Climate Working Group Meeting Pest Management in an Ever-Changing World 11-15 October 2015 The

We are happy to welcome you to the 9th meeting of the Working Group on the campus of the R.H. Smi... more We are happy to welcome you to the 9th meeting of the Working Group on the campus of the R.H. Smith Faculty of Agriculture, Food and Environment of the Hebrew University of Jerusalem in Rehovot, Israel. The theme we chose for the meeting, Pest Management in an Ever-Changing World, reflects the constant changes in climate, consumer demand, economy, regulations, technology, as well as invasions of new pest species, that continuously challenge researchers, extension officers, growers and the agro-businesses. These changes are evidenced throughout the meeting program. The four days of the meeting will include keynote talks by leading scientists, oral research reports, three guest speakers that will explore new approaches and ideas, discussion sessions, and a full day field trip to a major greenhouse production region in the Arava valley. We also allowed ample of time for informal interaction during breaks, field trip, and evening events. Now it is really over to you, the participant. How you benefit from the meeting will depend not only on your listening to the talks but also on your active participation; we encourage you to ask questions and actively participate in discussions. We trust you will take the opportunity to approach people you haven't met before and then network further over dinner, wine, and coffee, or on the bus on Tuesday. We worked hard to create the best possible scientific, professional and personal experience for you. Please feel free to approach any of us for assistance or with suggestions. We will do our best to help.

Fungal Photomorphogenesis: A Basis for the Control of Foliar Diseases Using Photoselective Covering Materials for Greenhouses

HortScience, 1998

The Effect of Physical Properties of Soilless Media on Plant Performance - a Review

Acta Horticulturae, 2004

Moderate matric potential and oxygen deficiency reduce leaf water potential, net assimilation rat... more Moderate matric potential and oxygen deficiency reduce leaf water potential, net assimilation rate and transpiration and thus negatively affect plant productivity. Moderate matric potential in the porous media, usually accompanied by a sharp decrease in unsaturated hydraulic conductivity, leads to localized zones of very low matric potential adjacent to the root-medium interface. This phenomenon cannot be easily characterized using tensiometers and is the main limiting factor to water uptake by plant roots. Restricted water uptake results in low leaf water potential, leading to cessation of leaf and shoot expansive growth. Oxygen deficiency restricts root respiration, thus negatively affects water and nutrient uptake. If it persists, temperal loss of ion selectivity of the root membranes may occur, resulting in increased uptake of non-essential ions such as sodium. Water and oxygen status of the root zone can be manipulated at two stages. Firstly, they are affected by the choice of the medium, in respect to the crop needs, available management practices and climatic conditions, and secondly by the chosen strategy of irrigation control. The main physical properties of the medium that affect plant performance are discussed in the following review, as well as methods to affect the actual status of water and oxygen in the medium.

Soil suppressiveness against Macrophomina Phaseolina s.l. as affected by cyclic temperature regimes

Phytoparasitica, 2016

Effect of temperature on the survival of Macrophomina phaseolina s.l. (Mp) was tested under labor... more Effect of temperature on the survival of Macrophomina phaseolina s.l. (Mp) was tested under laboratory conditions using an incubation system programmed for a cyclic temperature regime, simulating soil solarization. Mp culture and soil with and without Mp were incubated under two cyclic temperature regimes, with maximum temperatures of 50°C or 52°C, simulating solarization processes, and at a constant temperature of 25°C, as a control. Total fungal community and Mp levels were not affected negatively by constant temperature of 25°C. However, total soil fungal community was significantly decreased at temperature regime of 50°C, whereas Mp did not change significantly whether in soil mixture or as pure propagules culture. In Mp-amended soil treated by temperature regime of 50°C, total fungal community decreased while Mp CFU number did not change significantly. However, temperature regime of 52°C almost completely eradicated total fungal community, as well as that of Mp. When Mp was amended to soils after being treated at 50°C and 52°C temperature regimes and incubated for two additional weeks at 25°C, an indirect temperature effects on Mp survival were apparent. The 50°C pretreatment did affect significantly neither the total fungal nor Mp levels. In soil previously treated by 52°C, total fungal growth was somewhat decreased while Mp growth was promoted. The results suggest that Mp survival may be affected by temperature directly as well as indirectly via effects on total fungal population. Studying these biological factors may contribute to the control of Mp pathogen using environment-friendly methods.

Slurry Produced by Methanogenic Fermentation of Cow Manure as a Growth Medium for Some Horticultural Crops *

Acta Horticulturae, 1984

Composting Olive Mill Waste and Assessment of Its Horticultural Value

International Symposium on Growing Media 2007, 2009

Survival of Macrophomina phaseolina s.l. and Verticillium dahliae during solarization as affected by composts of various maturities

Crop Protection, 2015

Abstract Solarization is commonly used against several soilborne pathogenic fungi, and is an effe... more Abstract Solarization is commonly used against several soilborne pathogenic fungi, and is an effective, environmental-friendly substitute for chemical control or soil steaming. This study aimed to verify solarization effectiveness as a control measure against the pathogens Macrophomina phaseolina s.l. (sensu lato) (MP) and Verticillium dahliae (VD) when combined with compost of various maturity levels. This assumes that immature compost can help to eradicate the pathogens as its degradation can raise the temperature below the tarp. The survival rates per gram of MP and VD were tested at depths of 10 and 20 cm. At both depths in the solarized treatments, VD was eradicated during the first 2 weeks, whereas in the non-solarized treatments the level of VD incidence decreased but not to total elimination. Four weeks after the beginning of the experiment, about 5000 colony forming units (CFUs) of VD survived in the non-solarized treatment. MP survived the solarization process. The presence of compost of any maturity level did not contribute to a temperature increase in the solarized part during the day. At night, in the non-solarized treatments, the average minimal temperature rose by almost 1.4 °C in the immature-compost-treated soil. Solarization at a maximal temperature of almost 48 °C, as found in the field experiment, could eradicate VD, but this temperature was not sufficiently high to eradicate MP. We also aimed to determine the minimal threshold temperature for eradication of MP. For this we used an incubator with cycling temperatures, to simulate the daily cycles of soil temperature during solarization. MP survived a maximal temperature of 52 °C during a 4-week laboratory experiment with cycling temperatures; it was totally eliminated after 4 weeks at a maximal temperature of 54 °C and after 2 days at a maximal temperature of 56 °C.

Inorganic and Synthetic Organic Components of Soilless Culture and Potting Mixes

Soilless Culture, 2008

The components of soilless growing media and potting mixes used in horticulture are primarily sel... more The components of soilless growing media and potting mixes used in horticulture are primarily selected based on their physical and chemical characteristics and, in particular, their superior ability to provide simultaneously sufficient levels of oxygen and water to the roots. There is a lot of variability in the origin and physical and chemical characteristics of the substrates used by the horticultural industry. Substrates are divided into inorganic and synthetic organic materials. The organic materials comprise synthetic substrates and natural organic matter. The inorganic substrates can be classified as natural unmodified materials and processed materials. This chapter provides the description of each substrate, which includes information on its production and origin, general information on its applications as a growth medium, or for other purpose. It sheds light on the physical characteristics, such as bulk density (BD), water retention, and hydraulic conductivity, as these properties are essential for proper irrigation management. Furthermore, it describes the chemical characteristics, i.e., composition, stability as affected by pH, cation exchange capacity (CEC), pH, and salinity, as these basic data are required for the proper management of fertilization and irrigation. In addition, it presents information on substrate sterilization, as disease control is a major factor in the successive use of substrates. Finally, it provides information on waste treatment since the potential for environmental contamination is becoming a central issue in intensive soilless cultivation.

Organic Soilless Media Components

Soilless Culture, 2008

This chapter deals with the organic materials used in soilless production: peat, coir, bark, wood... more This chapter deals with the organic materials used in soilless production: peat, coir, bark, wood products, and compost. It describes their physical and chemical properties and their effect on plant performance. It also discusses the composting process and reviews the biological stability of growing media and disease suppression. Peat has long been used as a component of potting mixes and has become the most widely used growing medium for containers as a complete growing medium by itself. However, the use of peat in horticulture has recently been questioned from an environmental standpoint, since peat is a non-renewable resource and since it plays a major role in atmospheric CO2 sequestration. Alternative organic substrates in organic--inorganic media mixes include waste organic by-products, such as wood industry wastes, urban wastes, cork, wood fibers, livestock manure composts, coconut wastes, etc. While some of these have been in use for a long time, others, such as coir and coconut wastes, have been tried more recently, sometimes with promising results. Alternative organic substrates that are well characterized and corrected by suitable blending with inorganic components make it possible to produce high-quality horticultural plants and contribute to the reduction of overexploitation of natural peat-lands. Chief among replacement materials has been bark and wood fiber from forestry and the wood industry. There is also increasing interest in coconut fiber (coir dust), green waste, and other plant and animal residues.

Sustainability of Organic Horticulture

Horticultural Reviews, 2010

Page 1. 6 Sustainability of Organic Horticulture Michael Raviv Ministry of Agriculture Agricultur... more

The effect of medium disinfestation on cut rose productivity and on some chemical properties of tuff

Scientia Horticulturae, 1998

Peat in the inoculation medium induces fusarium susceptibility in melons

Plant Breeding, 2008

ABSTRACT The effect of peat moss on fusarium wilt of melon (Cucumis melo L.) was studied in order... more ABSTRACT The effect of peat moss on fusarium wilt of melon (Cucumis melo L.) was studied in order to improve the selection process of resistant melons during breeding programmes. Disease symptoms were evident earlier and disease progress was faster in seedlings that were transplanted to peat following inoculation than in those transplanted to sand. The resistant breeding line used as a control did not show any wilt symptoms in either medium. Mixing the peat with sand or perlite reduced the disease development rate and the final disease incidence. The effects of peat and sand on disease progress were evaluated with two segregating melon populations in which the expected susceptible : resistant ratio was 25 : 75. In both populations, disease incidence was higher in the peat, which enables breeders to identify resistant plants and to lower the risk of using escapees as resistant plants. The mechanism of disease enhancement may include both biotic and abiotic components. There is an indication that peat induces plant susceptibility before inoculation. Melon seedlings germinated in peat and transplanted into sand exhibited significantly greater wilt incidence than those that germinated in sand and were transplanted into sand following the inoculation. Disease progress in sterile peat was significantly slower than that in non-sterile peat, which suggests the possible involvement of microbial activity.

The absolute configuration effect on the activity of the avocado rooting promoter

Phytochemistry, 1990

Heptadecyn-1,2,4-trio1 is the most active component of the avocado rooting promoter (ARP). All fo... more Heptadecyn-1,2,4-trio1 is the most active component of the avocado rooting promoter (ARP). All four diastereoisomers of this compound have been synthesized. Their root promoting activity was determined over the physiologically active concentration range. It was found that the (2R,4R)-stereoisomer exerts a rooting activity similar to that of the extracted and purified compound from avocado tissues. The (2R,4S), and (2S,4R)-stereoisomers had lower activity and the (25,4S)-stereoisomer had the lowest activity. It is concluded that the natural form, (2R,4R), acts in the rooting process either in its original structure or after reaction which does not alter its chiral centres.

Effects on chemical surface properties of tuff by growing rose plants

Hydrobiologia, 1996

... Alva AK, Edwards DG and Blarney FPC 1986 Relationships between root length of soybean and cal... more

The chemical identification of root promoters extracted from avocado tissues

From the Avocado Rooting Promoter (ARP) 4 compounds were isolated and identified as:

Cocomposting – A Method to Improve Results of Poultry Manure Composting

Compost Science & Utilization, 1999

Composting of poultry manure (initial C:N ratio - 11.3) in a thermostatically aerated pile result... more Composting of poultry manure (initial C:N ratio - 11.3) in a thermostatically aerated pile resulted with overheating (>65°C) and rapid loss of Total Volatile Solids (TVS) and of nitrogen. Adding five percent (on a dry weight basis) of squeezed grapefruit peels (initial C:N ratio of the mixture - 12.4) lowered the pH of the aqueous phase of the raw materials from 6.6 to 5.8 (in a 1:10 extract). This enabled controlling the pile temperature below 60°C and increased the amount of conserved N by ca. 80 percent. Nitrogen was conserved more than the TVS on a relative basis in this mixture but conserved less than the TVS in the poultry manure alone. This suggests that previously released NH4+ was biologically immobilized in the mixture. Although the effect of the added acidic carbon source was apparent until the end of the composting period on the above mentioned parameters, a sharp rise in pH and a decline in C:N ratio occurred after less than 12 days and less than 39 days, respectively. This suggests that addi...

Organic management effects on the short- and long-term dynamics of soil organic carbon and nitrogen pools

by Nativ Rotbart and Michael Raviv

Compost application increases soil organic matter (SOM) content and is particularly beneficial in... more Compost application increases soil organic matter (SOM) content and is particularly beneficial in arid and semi-arid agroecosystems, often impoverished in SOM. The hypotheses of the research were: 1. compost application would increase SOM and microbial biomass; 2. This increase will be bigger in soils with low content of SOM and 3. The absorbance at 254 nm (A254) which is an indicator of the aromatic level of the dissolved organic matter would increase with SOM content in the soil. The general objective was to characterize the effect of organic vs. inorganic fertilization management on the short and long-term dynamics of SOM's quantity, its pools and properties of two different soils in Mediterranean and semi-arid climates. The specific objectives were to explore the effects of compost application rates on: Multi-years accumulation of total organic C (TOC) and total N (TN); and the short-term dynamic of SOC and TN, including dissolved cold and hot-water-extractable organic C and N (DOC, DN, HWDOC and HWDN) and microbial biomass C and N (MBC, MBN) pools. A long-term field experiment, conducted in two locations, in Izrael Valley and in the Northern Negev, compared the application of a cattle manure-based compost (at rates of 20, 40 or 60 m/ha/ yr) with urea fertilization. The organic fertilization management induced significant long-term (6 years) increases in TOC and TN and in DOC, DN, HWDOC and HWDNpositively related to compost application rates. Compost application dose also affected the properties of the short-term dynamic of SOC and TN including MBC and MBN pools. DOC concentrations in both soils were similar despite of the bigger SOM content in the semi-arid area, probably due to the initial low SOM and the positive effect of irrigation on the OM capacity of the soil. Therefore, DOC is a good parameter for evaluating the short-term effects of compost application on SOM. While the DOC and DN pools showed a highly fluctuating seasonal pattern, the much larger HWDOC and HWDN pools were stable with time, suggesting that the latter pools represent a relatively stabilized SOM fraction. The Mic C and N similarly increased with compost application rates. Seasonal dynamics of MBC and MBN showed a fluctuating pattern with microbial growth phases following compost and urea applications as well as temporary increases in response to rain events. An increase in A254 in both soils was measured following compost application in the soil extractions (cold and hot). Moreover, values of A254 were sensitive to compost dose and demonstrated stability along the sampling dates. The specific ultraviolet absorbance (SUVA = A254/DOC) of both DOC and HWDOC was higher for the compost-treated soils compared with the urea treatment, indicating the higher level of aromaticity of the extracts from compost-treated soils. While the SUVA of DOC showed a fluctuating seasonal pattern, the SUVA of HWDOC was stable with time, implying that the latter pool represents stabilized, aromatic SOM. DOC concentration was in good correlation with compost load in Gilat soil. MBC pool size was found to be a useful early indicator of changes in TOC contents in poor OM soil. The best characteristic index for compost dose effect on OM was the A254. This outcome indicates the strong effect of compost application on the properties of the DOC in addition to its quantity.