Rockwool Slab Research Articles

Fire Safe Interior Surface Finishes : A Selection Guide

The main focus of this article was to mitigate the fire hazards occurring from the internal furnishing materials widely used in buildings. To enhance the safety of life and property inside buildings, internal material selection guide characteristics were developed. The internal furnishing materials used in the buildings were initially characterized as non-combustible and combustible materials based on the ignitability properties of materials as per Indian Standard, IS: 3808 – 1979. The combustible materials were further classified as Class 1 – 4 based on the surface spread of the flame (SSF) as per British standard BS 476 : Part 7. With these specifications and standard test methods, the internal furnishing materials such as gypsum board, rock wool slab, deodar wood, Polyvinylchloride structural foam, Phenol formaldehyde foam, particleboard, rice husk board, and particleboard, etc. were characterized. Recommendations were prepared on their usage of the materials for selection and application at a suitable location, with respect to ceiling height, and any fire-retardant treatment. These internal furnishing materials selections/recommendations guide will help to improve fire safety in buildings.

Application of automatic system for water stress treatment to produce high soluble solids tomato (Solanum lycopersicum Mill. cv Rinka 409)

The objectives of this study were to confirm the application of automatic system for detecting the water stress and the compatibility of the water stress treatment system for producing high soluble solids tomato fruits in high technology greenhouse. The tomato variety used, “Rinka 409”, was grown hydroponically with a high-wire system in high technology greenhouse in Faculty of Agriculture, Ehime University, Japan. The greenhouse has a full controlling system (temperature, relative humidity, carbon dioxide, and light intensity) to support the seasonal change and was adjusted to the real-time condition. Water stress condition of the tomato plant in the high technology greenhouse was detected by measuring the water content in the rockwool slab and by using visual monitoring system. The result showed that the automatically nutrient supplying system using visual monitoring system based on speaking plant approach technology could be used for the detection of water stress in the tomato plant. Using this system, water stress tomato cultivation was detected and the high soluble solids tomato fruits could be produced continuously to fulfill consumer expectation.

The effect of growing media on the nutritional value of cherry tomato

The aim of this paper is to demonstrate how certain growing media (rockwool slab, coco slab, and coco substrate in window box) can change nutritional values of different tomato cultivars in hydroponic system. The test took place at the Study Garden of Faculty of Horticulture and Rural Development, John von Neumann University in the summer of 2018. The paper shows the role of growing media and particular tomato cultivars in the development of sensory and biochemical characteristics.

Relationships between Yield, Mineral Content of Fruits, and Sap Bleeding Rate in Dutch and Japanese Tomato Cultivars

We present the relationship between yield, mineral content, and the sap bleeding rate (SBR) caused by root pressure as an indicator of root activity in eight Dutch and eight Japanese tomato cultivars (including popular Japanese cultivar ‘Momotaro’) grown in a hydroponic system. Root dry weight in the rockwool slab was positively correlated with stem and leaf fresh weight. In the Dutch cultivars, the SBR remained high (over 20 mL∙h-1) as the root dry weight increased. In contrast, the SBR of Japanese ‘Momotaro’ series cultivars decreased. Ca in the tomato fruits and the SBR were higher in the Dutch cultivars than in the ‘Momotaro’ series. The SBR was found to positively correlate with fruit or total fresh weight. The higher SBR, which supports Ca transport to the fruits, probably led to the higher yields. The SBR might be a simplified indicator of selecting high-yielding cultivars in long-term cultivation.

Effect of Salt Stress on Three Green Bean (<i>Phaseolus vulgaris </i>L.)<i> </i>Cultivars

Agriculture is increasingly forced to utilize marginal waters to meet its increasing demands, which in turn increases the risks of soil salinization and yield reduction in the arid and semi-arid areas of the Mediterranean basin. Given that the bean is an extremely salt sensitive species, the purpose of the present work was to study the effect of 0 and 75 mM sodium chloride (NaCl) on leaf characteristics, growth, pod yield and ion accumulation of three green bean (Phaseolus vulgaris L.) cultivars ('Corallo Nano, 'Romano Bush Plaja' and 'Starazagorski'), widely used in Greece. Plants were grown in a greenhouse of Technological Educational Institute of Peloponnese in Messinia, Southern Greece, from April to June 2014, in hydroponics. The experimental design was the factorial completely randomized one with five replications; each replication consisted of the three plants grown on the same rockwool slab. The results of the majority of growth and yield parameters determined showed the superiority of 'Corallo' over 'Romano' whereas 'Starazagorski' tolerance was found to be intermediate. 'Corallo' tolerated NaCl salinity better due to its capacity for Na retention in the roots and maintaining appropriate K/Na and Ca/Na ratios, limiting the accumulation of toxic ions into actively growing shoots. The salt sensitivity of 'Romano' was related to its higher concentration of Na in the leaves and lower in the roots, to the greater decrease of the leaf number and leaf water content, as well as to the specific leaf area increase compared to the other two cultivars under saline conditions.

Effect of Salt Stress on Three Green Bean (<i>Phaseolus vulgaris </i>L.)<i> </i>Cultivars

Agriculture is increasingly forced to utilize marginal waters to meet its increasing demands, which in turn increases the risks of soil salinization and yield reduction in the arid and semi-arid areas of the Mediterranean basin. Given that the bean is an extremely salt sensitive species, the purpose of the present work was to study the effect of 0 and 75 mM sodium chloride (NaCl) on leaf characteristics, growth, pod yield and ion accumulation of three green bean (Phaseolus vulgaris L.) cultivars (‘Corallo Nano’, ‘Romano Bush Plaja’ and ‘Starazagorski’), widely used in Greece. Plants were grown in a greenhouse of Technological Educational Institute of Peloponnese in Messinia, Southern Greece, from April to June 2014, in hydroponics. The experimental design was the factorial completely randomized one with five replications; each replication consisted of the three plants grown on the same rockwool slab. The results of the majority of growth and yield parameters determined showed the superiority of ‘Corallo’ over ‘Romano’ whereas ‘Starazagorski’ tolerance was found to be intermediate. ‘Corallo’ tolerated NaCl salinity better due to its capacity for Na retention in the roots and maintaining appropriate K/Na and Ca/Na ratios, limiting the accumulation of toxic ions into actively growing shoots. The salt sensitivity of ‘Romano’ was related to its higher concentration of Na in the leaves and lower in the roots, to the greater decrease of the leaf number and leaf water content, as well as to the specific leaf area increase compared to the other two cultivars under saline conditions.

Flower yield and quality of two rose cultivars grown in phenolic foam LC slab and phenolic foam RC slab in comparison to perlite and rockwool slab

Two standard cut rose (Rosa hybrida) ‘Rock Fire’ and ‘Feel Lip’ were propagated by single nodal cuttings. Each cutting with a five-leaflet leaf was stuck in a rockwool cube (Delta, 5 cm × 5 cm × 5 cm, Grodan Co., Ltd., Denmark) on May 16, 2011. After 32 days, rooted uniform saplings were transplanted onto the four different growing media, perlite (Pergreen, No. 1, G-Biotech Co., Ltd., Korea), rockwool slab (Delta, 100 cm × 20 cm × 7.5 cm, Grodan Co. Ltd., Denmark), phenolic foam LC slab (100 cm × 20 cm × 7.5 cm, Smithers Oasis Co., Ltd., Korea), or phenolic foam RC slab (100 cm × 20 cm × 7.5 cm, Smithers Oasis Co., Ltd., Korea), laid out in a completely randomized design on a bench in a commercial grower’s plastic house. The nutrient solution was supplied uniformly through a drip irrigation system. The irrigation frequency was dependent on amount of solar radiation. Yield and quality of harvested flower stems were measured for five successive harvests during a period of 11 months. Growth parameters measured were stem length, stem diameter, number of five-leaflet leaves per stem, stem fresh weight, number of harvested cut flowers per ten plants by grade, total yield, and tissue contents of inorganic elements. Measured growth parameters, such as stem length, number and quality of harvested stems, and contents of inorganic elements, were similar in all the tested growing media, except perlite in which these values were the lowest. The results obtained suggests that the widely used rockwool slab can be replaced with the new phenolic medium such as phenolic foam LC slab for commercial scale hydroponic productions of cut roses.

Rockwool과 Phenolic Foam 배지에서 양액공급 방법이 프리카(Capsicum annuum) 'Veron'의 생육과 수량에 미치는 영향

파프리카 수경재배용으로 사용되고 있는 암면을 대체하기 위해 개발 배지인 Phenolic foam(LC, Oasis Co.)의 물리특성에 맞는 양액공급방법을 구명하기 위해 양액공급 방법을 누적일사량 <TEX>$100J{\cdot}cm^{-2}$</TEX>에 주당 1회 공급량 100mL(100-100)를 대조구로 <TEX>$90J{\cdot}cm^{-2}$</TEX>에 주당 1회 공급량 90mL(90-90), <TEX>$90J{\cdot}cm^{-2}$</TEX>에 주당 1회 공급량 80mL(90-80) 등 3처리를 두고 Rockwool 배지와 함께 비교하였다. 양액공급 방법별 배액률은 100-100이 Rockwool에서 33.8%, LC에서 36.7%로 높았고 90-80이 Rockwool에서 30.4%, LC에서 33.7%로 낮았다. Rockwool 배지의 함수률과 EC는 63.6-68.9%, <TEX>$4.4-5.dS{\cdot}m^{-1}$</TEX>, LC 배지는 52.9-58.8%, <TEX>$5.5-6.5dS{\cdot}m^{-1}$</TEX>를 유지하였다. 100-100과 90-90 처리는 90-80 처리보다 생육이 촉진되어 과실이 크고 평균과중이 무거웠다. 착과수는 90-80 처리가 Rockwool 배지에서 주당 8.0개, LC 배지에서 8.3개로 가장 많았다. 상품과수는 90-90 처리가 가장 많았고 비상품 과수는 90-80 처리가 소과와 배꼽썩음과의 발생이 많아 주당 1.7-1.8개로 가장 많았다. 수량은 90-90 처리가 높았다. This study was carried out to find a reasonable irrigation method of a nutrient solution for the phenolic foam slab (foam LC) used in a trial experiment to substitute the rockwool slab in the production of paprika (Capsicum annuum 'Veyron'). 100, 90, and 80 mL of a nutrient solution was supplied per plant each time when the accumulated radiation reached to 100, <TEX>$90J{\cdot}cm^{-2}$</TEX>, and they were named as the 100-100, 90-90, and 90-80 treatment, respectively. The drain percentage per plant of the 100-100 treatment was high by 33.8% in rockwool and 36.7% in foam LC (Lettuce Cube) and that of 90-80 treatment was low by 30.4% and 33.7%. The water content and EC of the rockwool slab were maintained in the range of 63.6-68.9% and <TEX>$4.4-5.1mS{\cdot}cm^{-1}$</TEX>, while those of the foam LC slab were in the range of 52.9-58.8% and <TEX>$5.5-6.5mS{\cdot}cm^{-1}$</TEX>. The plant height and leaf size of the 100-100 and 90-90 treatments increased in a similar manner, while those of the 90-80 treatment decreased and those of the rockwool were greater than those of the foam LC. The fruit size and weight of the 100-100 and 90-90 treatments were similarly bigger and heavier than those of the 90-80 treatment. The number of fruits harvested per plant was the greatest in the 90-80 treatment with 8 and 8.3 fruits in the rockwool and foam LC. The number of marketable fruits in the rockwool and foam LC was the greatest with 18.1 and 18.2, respectively, in the 90-90 treatment, while that in the 90-80 treatment was 17.2 and 16.8, respectively. The number of unmarketable fruits of the 90-80 treatment was the greatest (1.7-1.8 fruits per plant) in both the rockwool and foam LC, and most of them were small sized or blossom end rot fruits. The yield of the 90-90 treatment was the greatest among the irrigation.

Study of a Nutrient Solution Flows in a Saturated Rockwool Slab Using the Model of Sources and Sinks

An analytical study of saline solution flows in a saturated rockwool slab, which represents a growing substrate, was developed to account for actual flow visualizations with dies and predict the solution concentration at any point of the growing substrate. Darcy flows corresponding to an injection point and to a drainage point were analytically treated by a linear superposition of periodic sources and sinks. This model was validated by the experimental results. The model of sources and sinks is simple and it gives an idea on the evolution of the nutrient solution inside the substrate.

Pseudomonas corrugata and Pseudomonas marginalis associated with the collapse of tomato plants in rockwool slab hydroponic culture

Plant pathogenic species Pseudomonas corrugata and P. marginalis were detected and determined in collapsed tomato plants in rockwool slab hydroponic culture in southern Moravia, Czech Republic. Surprisingly, P. marginalis was also determined before planting in apparently healthy grafted tomato transplants grown in hydroponic culture. Moreover, non-pathogenic P. fluorescens, P. putida, P. synxantha, and Stenotrophomonas malthophilia were identified. The Biolog Identification GN2&amp;nbsp;MicroPlate&amp;trade; System System (Biolog, Inc., Hayward, USA) was used for identification of bacterial isolates. Cultures of P. corrugata and P. marginalis were used in a greenhouse pathogenicity experiment. Seven weeks old tomato plants of cv. Moneymaker grown in sterilised perlite were inoculated into the stem with a hypodermic needle at one point above the cotyledon node. In inoculated tomato plants, disease symptoms were observed that included external and internal dark brown lesions around the inoculation site, watering and collapse of pith and sometimes also vascular browning and wilting of leaves. In comparison with P. marginalis, P. corrugata appeared to be a much stronger pathogen. Both tested Pseudomonas species were recovered from inoculated tomato plants. P. corrugata was found to move both upwards to the apex of the stem and downwards from the site of the inoculated stem into roots. When inoculated into potato tuber slices, some tomato strains of P. marginalis, P. fluorescens, P. synxantha, and Pseudomonas sp. produced soft rot. However, other strains of the same species were not able to macerate the potato tissue. It is concluded that P. corrugata and P. marginalis can be associated with the collapse of tomato crop in soilless culture grown in a greenhouse. This is the first report on P. corrugata in tomato plants in the Czech Republic. The role of plant pathogenic bacteria, fungal root rot and vascular pathogens and Pepino mosaic virus in the collapse of tomato plants is discussed.

GROWTH AND YIELD OF TOMATO GROWN ON REUSED ROCKWOOL SLABS

Rockwool is the most used substrate for soilless culture in Croatia. Multiple use would greatly contribute to the waste management of the rockwool slabs. The aim of the research was to determine the influence of rockwool slab age on tomato plant growth and marketable yield. In the trial reported, new, one and two year old slabs were used. Different age of rockwool slabs did not significantly affect plant height and leaf number. The harvest periods in 2005 and 2006 lasted 171 and 168 days respectively. For early yield, defined as yield during first 10 days of harvest, total yield and fruit weight were determined. In 2005 early yield achieved on new rockwool slabs (0.99 kg plant-1) was 10.4 % lower, and total yield (12.95 kg plant-1) 6.8 % higher than on one year old slabs. During 2006 the highest early yield (1.76 kg plant-1) obtained on two year old rockwool slabs was 6.4 % higher than on one year old slabs, and 10.1 % higher than on new slabs. The highest marketable yield (12.86 kg plant-1), significantly higher than the yield on two year old slabs (11.09 kg plant-1), was obtained on new rockwool slabs. Throughout the harvest period fruit weight varied from 183 to 186 g during 2005 and between 161 to 164 g in 2006. Because new and one year old slabs achieved statistically identical values of researched parameters, but lower values during the third year of use, biennial use of rockwool slabs could be recommended.

Irrigation Strategies for Greenhouse Tomato Production on Rockwool

To address the concern that irrigation provides sufficient water to match the crop needs, while not impeding oxygen availability to the roots, we conducted an experiment to develop suitable irrigation schedule(s) for greenhouse tomato (Lycopersicon esculentum Mill.) on rockwool. The experimental treatments incorporated the electrical conductivity (EC) of the nutrient solution in the rockwool slab (slab-EC) along with the water content (WC) in the rockwool slab (slab-WC) as the irrigation decision-making variables. They were: slab-WC ≤ 70% or slab-EC ≥ 1.4× normal or more (T1), slab-WC ≤ 70% or slab-EC ≥ 1.7× normal or more (T2), slab-WC ≤ 80% or slab-EC ≥ 1.4× normal or more (T3), slab-WC ≤ 80% or slab-EC ≥ 1.7× normal or more (T4), and the combined weight loss (WL) 700 g or more (T5) and WL 500 g or more (T6), in which “normal” means the feed solution EC as recommended in the seasonal fertigation schedule for a spring–summer tomato crop. The data on early-season marketable yield, total seasonal marketable yield, and fruit grades indicated the superiority of treatments T1, T2, and T6 over T3, T4, and T5. Better root growth was observed with T1, T2, and T6 and this was also associated with minimized nutrient solution leaching; furthermore, these plants had an abundance of coarse and fine roots, higher photosynthesis and transpiration, higher marketable yield, and a higher water use efficiency. Our results thus established that irrigation based on either a slab water content 70% or less or a 500-g weight loss is the best strategy for rockwool-grown greenhouse tomatoes in the spring–summer season. A variation in slab-EC between 1.4 and 1.7× normal, at a slab-WC of 70% or less, would have no significant effect on root growth, water use, marketable yield, or fruit grades.

Growth of sweetpotato cultured in the newly designed hydroponic system for space farming

Life support of crews in long-duration space missions for other planets will be highly dependent on amounts of food, atmospheric O 2 and clean water produced by plants. Therefore, the space farming system with scheduling of crop production, obtaining high yields with a rapid turnover rate, converting atmospheric CO 2 to O 2 and purifying water should be established with employing suitable plant species and cultivars and precisely controlling environmental variables around plants grown at a high density in a limited space. In this study, we developed a new hydroponic method for producing tuberous roots and fresh edible leaves and stems of sweetpotato. In the first experiment, we examined the effects of water contents in the rooting substrate on growth and tuberous root development of sweetpotato. The rooting substrates made with rockwool slabs were inclined in a culture container and absorbed nutrient solution from the lower end of the slabs by capillary action. Tuberous roots developed on the lower surface of the rockwool slabs. The tuberous roots showed better growth and development at locations farther from the water surface on the rockwool slabs, which had lower water content. In the second experiment, three sweetpotato cultivars were cultured in a hydroponic system for five months from June to November under the sun light in Osaka, Japan as a fundamental study for establishing the space farming system. The cultivars employed were ‘Elegant summer’, ‘Kokei-14’ and ‘Beniazuma’. The hydroponic system mainly consisted of culture containers and rockwool slabs. Dry weights of tuberous roots developed in the aerial space between the rockwool slab and the nutrient solution filled at the bottom of the culture container were 0.34, 0.45 and 0.23 kg/plant and dry weights of the top portion (leaves, petioles and stems) were 0.42, 0.29 and 0.61 kg/plant for ‘Elegant summer’, ‘Kokei-14’ and ‘Beniazuma’, respectively. Young stems and leaves as well as tuberous roots of ‘Elegant summer’ are edible and palatable. Therefore ‘Elegant summer’ would be a promising crop to produce large amounts of food with high nutritional values in the present hydroponic system in space farming.

Water dynamics in two rockwool slab growing substrates of contrasting densities

It is important to determine the dynamics of water and nutrients in the growing substrate used for soil-less cultivation because this allows better time and space management of the water and nutrient supply according to plant needs during each step of the crop cycle. In this study, we focus on the motion of water in rockwool slabs used as growing substrate for a sweet pepper crop. The transport equation is first quoted and root absorption described by a sink term for which the absorption law was experimentally determined. Control volume methods by means of commercial computer fluid dynamics (CFD) software were used to solve the water movement equations numerically in three dimensions. However, as Richards’ equation describing water movements in the substrate is quite different from the Navier–Stokes equations used by the CFD, considerable modifications of the standard transport equations were required. The numerical results were then compared with experimental results and, once validated, the model was reused for a sensitivity analysis with respect to various physical parameters of the substrate. Based on this study, we propose an alternative substrate design more suitable for closed systems.

Effects of Potassium Silicate on the Growth of Miniature Rose 'Pinocchio' Grown on Rockwool and its Cut Flower Quality

The effects of root and foliar applications of potassium silicate on the growth and quality of hydroponically-grown cut flower miniature rose Rosa hybrida ‘Pinocchio’ were evaluated. In a hydroponic system that uses rockwool slabs as a growing medium, the growth and quality of plants in four treatments, including the control (untreated), root feeding, foliar spray, and root feeding + foliar spray of a 200 mg · L−1 potassium silicate solution, were examined. The treatments were laid out in a randomized block design with four replicates per treatment. Four rooted cuttings per treatment started on rockwool cubes were planted on a rockwool slab on Aug. 7, 2000 and grown for 413 days. The mean flower stem length, mean yield by grade, and total yield were significantly greater in the root feeding treatment than in the others; likewise, fresh and dry weights of roots were significantly heavier. Stem diameter, number of branches, dry matter, and shoot fresh and dry weights significantly increased in the root feeding + foliar spray plot as compared to the control. Stem flexibility, measured as the modulus of elasticity was greatest in the root feeding + foliar spray treatment. Photomicrographs taken with a scanning electron microscope showed the formation of a film of glass on the leaf surface in the foliar spray treatment. From these results, we concluded that the applications of potassium silicate proved to have beneficial effects on the growth and quality of cut flower miniature rose ‘Pinocchio’ in the rockwool culture system.

RESPONSE OF TOMATO TRANSPLANT TO NITRATE PHOSPHATE CONDITIONING: EFFECTS ON DEVELOPMENT, GROWTH AND EARLY YIELD

RESPONSE OF TOMATO TRANSPLANT TO NITRATE PHOSPHATE CONDITIONING: EFFECTS ON DEVELOPMENT, GROWTH AND EARLY YIELD

The effect of split-root salinity stress on tomato leaf expansion, fruit yield and quality

SummaryA crop-scale experiment between March and October 2000 investigated the effects of split-root salinity stress and rooting volume on the expansion of leaves, fruit yield and quality in two standard round fruited cultivars of tomato (Lycopersicon esculentumMill) Solairo and Espero, grown in rockwool. To implement the treatments, a split-root method was utilized whereby different levels of salinity (expressed as EC), adjusted by the addition of NaCl, was administered to two halves of a root system. The split-root high EC (2.8/8.0 dS m–1) treatment enhanced fruit quality by increasing the concentrations of sugar, acid, total soluble solids and reducing the incidence of visual defects such as uneven ripening and gold-spot. Split-root high EC did however reduce leaf area that corresponded with low K concentration in the leaf tissue. The split-root method utilized doubled the rooting volume compared with the standard single rockwool slab, but this extra rooting capacity had no detectable effect on leaf expansion, yield or fruit quality. Although there was little impact on yield for ten weeks after the imposition of the high EC split-root treatment, mean reductions in weekly yield occurred thereafter and were of the order of 9 and 13% for ‘Solairo’ and ‘Espero’ respectively through to the end of the experiment. The fall in yield was due, in part, to a decrease in fruit size. Whilst water uptake was reduced it was unclear how the effects on leaf growth and fruit yield were mediated in the shoot. Possible processes that coordinate responses to root-zone salinity stress are discussed. The potential use of the split-root system in commercial production is considered.

Root mat of tomato caused by rhizogenic strains of Agrobacterium biovar 1 in the UK

Since 1993 many hydroponic cucumber (Cucumis sativus) crops in the UK have been affected by a root disorder known as root mat, a condition first described in soil and straw bed crops in the 1970s. The predominant symptom is extensive root proliferation within the rockwool propagation cube and across the rockwool slab surface. In severe cases a loss in marketable yield has been reported. Recently, the causal agent of this disease was shown to be wild-type Agrobactrium biovar 1 strains harbouring an Ri-plasmid (Weller et al. 2000). Since 1997, sporadic cases of a similar disorder have also been observed in commercial tomato (Lycopersicon esculentum) crops. Tomato plants affected by root mat were collected from crops across the UK. All crops were grown hydroponically in rockwool and the incidence of affected plants ranged from < 1% to 50%. Rhizogenic strains of Agrobacterium biovar 1 were isolated from affected but not from healthy roots, of symptomatic crops. Suspensions of three isolates of the bacterium (NCPPB 4060, 4061, 4062–National Collection of Plant Pathogenic Bacteria. Central Science Laboratory, Sand Hutton, York YO41 1LZ.) were inoculated, as in previous experiments on cucumber (Weller et al. 2000), onto six rockwool slabs each containing four young plants of one of two tomato varieties (cv. Pronto – a round variety; cv. Favorita – a cherry variety). Symptoms were initially seen five weeks after inoculation and at three months 16 plants from five of the six slabs were symptomatic. Symptoms were observed as increased root production across the propagation cube surface and swelling of the cube and/or root proliferation across the slab surface. Although root growth was excessive compared with normal tomato plants, it was less than that seen in root mat affected cucumbers. Rhizogenic Agrobacterium bv. 1 strains were re-isolated from four of the five slabs with symptoms and from the one slab without symptoms. No symptoms developed and no rhizogenic Agrobacterium strains were isolated from uninoculated control plants. Investigations on a heavily infected cherry tomato crop (cv. Favorita) at a commercial nursery indicated that fruit diameter was reduced by 2–3 mm in infected compared with healthy crops, leading to a higher proportion of unmarketable fruit (< 28 mm). Fruit numbers did not appear to be affected, although overall fruit yield was reduced by 15%. This is the first UK record of rhizogenic Agrobacterium causing root mat symptoms in tomato. Although tomato is susceptible to crown gall producing Agrobacterium strains, crown gall is a rare disease of glasshouse tomatoes. Non-pathogenic strains of Agrobacterium (without the plasmid) are commonly found on hydroponic tomato crops. This work was funded by the Horticultural Development Council (HDC) Project PC 149.

Hydroponic Greenhouse Production of Fresh-market Basil in Colorado

Fresh-market basil has become a viable greenhouse commodity in Colorado. Marketing pressures and profit advantages also encourage the production of certified organic produce. The research objectives were to determine the length of time basil plants were productive in the greenhouse and to compare the production of fresh-market basil grown with three root zone systems and two fertilizer treatments. The three systems were hydroponic rockwool slab culture, hydroponic perlite raised bed culture, and hydroponic peat/perlite/compost bag culture. The two types of hydroponic fertilizer treatments were a salt-based formulated nutrient solution and an organic solution consisting of fermented poultry compost, hydrolized fish emulsion, and soluble kelp. The plants were harvested once per week for fresh weight determination. The results from the two runs show greater productivity for the plants in the perlite system as well as the bag mix system when fertilized with the organic fertilizer compared to salt-based fertilizer. However, productivity of the plants in the rockwool system was greater with the salt-based treatment compared to the organic treatment.

Distribution of nutrients and water in rockwool slabs

During the 1980s, soilless cultures expanded enormously. Since then, several kinds of substrates, both biodegradable and non biodegradable, have been developed. In this research, the physicochemical characteristics of one of the most commonly used chemical inert substrates `rockwool' is investigated. The flow patterns occurring in rockwool slabs under both laboratory and practical situations were investigated, using a pigmented nutrient solution. As the rockwool slabs became more saturated, flow patterns were spread more horizontally. The horizontal and vertical EC and pH gradients present in rockwool slabs under practical situations are represented in figures for a tomato crop. Both horizontal and vertical EC gradients with a magnitude of 4 mS/cm are present. Below the plants, the pH in the slabs is lower, while there is almost no pH gradient in the vertical direction. The distribution of ions in rockwool was studied under laboratory circumstances as a function of the moisture content of the slab, the fertigation time, the fertigation volume and the vertical position in the rockwool slab. The moisture content of the slab, the fertigation volume and the vertical position in the rockwool slab affect the distribution of ions in the slab.