All registered chemicals in South Africa are published in a two-volume guide viz. Guide to Hydroponic Vegetable Production You may be trying to access this site from a secured browser on the server. Please enable scripts and reload this page. Turn on more accessible mode. Turn off more accessible mode. Skip Ribbon Commands. Skip to main content. Turn off Animations. Turn on Animations.
Sign In. It looks like your browser does not have JavaScript enabled. Please turn on JavaScript and try again. Page Content. About hydroponic vegetable production. Hydroponically produced vegetables can be of high quality and need little washing. Soil preparation and weeding is reduced or eliminated.
One does not need good soil to grow vegetables. Water is used efficiently. Pollution of soil with unused nutrients is greatly reduced.
Hydroponic production is management, capital and labour intensive. A high level of expertise is required. Daily attention is necessary. Specially formulated, soluble nutrients must always be used. Pests and diseases remain a big risk. Finding a market can be a problem. Good topsoil is required. Plants are irrigated automatically. No water stress.
Plants need to be irrigated to minimise water stress Nutrients are available at all times Only soluble fertilizers are used. Hydroponic fertilizer formulations contain a balanced nutrient content Nutrients must be added to soil. Unless a laboratory analysis is done, too much or too little nutrients can be added.
Soil borne diseases can be eliminated Soil borne diseases can build up in the soil. Quality, quantity and reliablity A market. Know what, where and when to market your crop Hydroponics is labour intensive. Symptoms of nutrient deficiency can easily be mistaken for disease symptoms. Which crop should I grow? Garden units: Depends on the choice of the family and the type of unit.
Seed is available in small or large packages. Large packets, suitable for commercial scale production are available from seed companies. In South Africa the following are popular: Shadenet structures: Flat roof, pitch roof and tunnel type Plastic: Tunnels and multi-spans Greenhouse choice depends on the crop, market and financing available How do we create a more favourable climate in our greenhouses? Shadenetting offers protection in the following ways: Cuts out a certain amount of sunlight, in particular harmful UV rays.
Protects plants against winds, rain, hail, animals, birds and large insects Allows for natural ventilation and air circulation. Hydroponics Field production No soil is required.
Plants need to be irrigated to minimise water stress. To provide proper drainage holes trays were fed with nutrient enrich solution. The sowing of water so submersible water was not required lettuce in border soil and in net-pots using in this system.
Performance of static Lettuce crop was grown in static hydroponic hydroponic system was monitored and its system and in geoponics. T5 were Plant height Table 1 was measured in static measured.
Data measured in different treatments for Average plant height in treatment T1, T2, T3, various crop growth parameters were T4, and T5, was recorded In all 8.
Plant height in treatment T2 Results and discussion Various crop growth parameters probability. Plant height in treatment T5 measured during experiment were The experiment was performed under technique than geoponics which is in greenhouse conditions so the external factors; accordance with the finding of scientist who sunlight, wind, rain, hail storm were not stated that plants that are grown in soil tended much adversely effective.
Table 1. Average number of leaves per with T3 9. Effect of various treatments on number of leaves per plant Treatments Number of Leaves per Plant T1 Static pipe with 7. Leaf Leaf length Table 3 of lettuce in all length in treatment T5 7. Leaf length in 7. Optimum leaf length 8. Leaf geoponics which is in accordance with the Length in treatment T2 8.
Table 3. Leaf breadth in treatment T2 Leaf breadth Table 4 of lettuce was 4. Leaf breadth in treatment T5 respectively. The greater leaf breadth 4. Table 4. Yield measured in all treatments of static reduction in geoponic is due to positive and hydroponic system and in geoponics at the negative ions of silt and clay particles of soil. Yield per plant in Nutrient react with these positive and treatments T1, T2, T3, T4, T5, T5 was observed negative ions of soil and forms chemical The greater yield per plant plants and restrict proper growth.
While in Yield in treatment T2 Another probability. Yield per plant in treatment T5 scientist also reported that is more production T3 and T4 Table 5. Effect of various treatments on yield per plant Treatments Yield per plant g T1 Static pipe with 7.
Average production in static pipe with 7. Minimum lettuce production was 1. For vegetable production: An overview. J Soil greenhouse lettuce production, it is therefore Water Conserv 17 4 : Kruchkin A Hydroponic crop hydroponic system was a better option as farming.
Research on OD Retrieved March 9, Production of should be carried out to develop indigenously lettuce in different growing media in cold automation model for maintaining oxygen glasshouse in Turkish. Application of composition A to both used and new rockwool and perlite at a dilution of eliminated all fungal and bacterial populations. Reference should now be made to Table 1. Growing and phytotoxicity trials were carried out to identify the level of phytotoxicity of composition A when used as a pre-planting drench to once-used hydroponic substrates.
Phytotoxicity was tested using rapid bioassay techniques. The use of treated material for the production of salad crops was then investigated. In order to determine the presence or absence of any phytotoxic residues in hydroponic substrates previously treated with composition A, a rapid assay method based on standard procedures was adopted. Rockwool and perlite samples were treated with composition A at a dilution of or , or with clean water. Test solutions were applied to approximately 0. Samples of a similar volume of used perlite Tilcon Ltd were also used.
Assessment of phytotoxicity was carried out by treating substrate samples with composition A and subsequently flushing twice, to run off, with clean water prior to bioassay.
Substrate samples were treated with composition A solutions or water controls and allowed to soak for one hour. Germination and subsequent growth were assessed on a subjective scale of 0 to 5. The samples were kept moist with nutrient solution as required. The results obtained showed that germination was good in all cases.
On the basis of results from rapid bioassay of compound A residues and efficacy data indicating activity of product against natural populations of bacteria and fungi, compound A was tested on crop plants.
Tomatoes were grown in treated and untreated perlite and cucumbers grown in treated and untreated rockwool and maintained under standard commercial conditions prior to assessment of plant establishment and growth. Propagation: New perlite in 13 cm mesh based pots Plantpak Ltd. Growing on: Once-used perlite Tilcon Ltd 25 dm 3 growing modules. Each 25 dm 3 perlite growing module was planted with three tomato plants. The modules were positioned end to end in rows within a glasshouse.
Each rockwool slab was planted with two cucumber plants. The modules were positioned end-to-end in rows within a glasshouse. Both species were trained up vertical strings and side shoots removed at an early stage to maintain a single plant stem in each case.
Irrigation water and nutrients were applied manually on a twice-daily basis, or more frequently as required under bright conditions.
Nutrition was supplied according to current recommendations. Environmental control was provided by a Van Vliet CR environmental computer. The plants were destructively harvested five weeks after planting and assessed for establishment and growth in the various treated substrates. The plants were visually assessed for plant establishment and root and shoot development after 5 weeks growth under standard commercial conditions. Within the course of the trial, plant growth was sufficiently good to ensure flower set and fruit development in all treatments.
This formed the basis of records of plant productivity in view of the commercial relevance of fruit, rather than foliage, production. All tomato and cucumber plants established well both in untreated perlite and rockwool and in material previously treated with compound A and flushed out with water prior to planting.
No evidence of root death or scorching of foliage was noted for any treatment. Differences between treated plots and untreated controls Tables 3 and 4 were slight in all cases. No evidence of phytotoxic residues in either rockwool or perlite was detected. Composition A at a dilution of or may also be used to prepare the liquid-supply troughs of a no-substrate hydroponics system for a fresh crop production cycle.
The composition can be supplied through the irrigation system normally used for the nutrient liquid, the irrigation system and liquid supply troughs being thoroughly flushed afterwards with clean water.
Laboratory scale investigations were performed to investigate the effect of sample preparation on recovery of micro-organisms from treated and untreated perlite and the influence of organic matter on the effectiveness of composition A as a sterilant.
Six or eight flasks were inoculated with g perlite to which 3 or 4 had 66 cm 3 water added and 3 or 4 had 66 cm 3 of composition A. The samples were then removed, the composition A inactivated, by either filter washing or sodium thiosulphate, and microbial counts performed.
Two procedures for inactivating composition A were tested. The first was the filter wash where composition B was diluted and then removed by washing the perlite with water, trapping bacteria in the wash water on a membrane filter, followed by homogenisation of both the perlite and the filters.
The other procedure was chemical inactivation with sodium thiosulphate. There was no significant differences between the counts obtained using either method and it was concluded that sodium thiosulphate is a satisfactory inactivator to use in this application. The first laboratory scale test using perlite taken from recently used bags in-situ in the greenhouse gave a 2.
There was some peaty organic matter in the perlite and laboratory trails were carried out to determine the impact of this organic material on the effectiveness of composition A. Two samples of perlite were compared. A stored used perlite, low in organic matter provided the low organic matter samples. High organic matter perlite was prepared by the addition of the peaty residues of propagation pot compost, which were obtained from used perlite bags.
In the low organic matter perlite the bacterial counts were reduced by 4. The presence of the peaty material almost completely inactivated composition A. This was carried out according to the following schedule. Each perlite bag contained 3 inlets for composition A, which were sampled. The samples were removed from the whole depth of each inlet using a scoop sterilised with alcohol between samples. Samples remote from the inlet were taken by cutting the plastic bag and sampling to approximately 10 cm depth.
Once sampled, the hole left by sampling was caved in using adjacent perlite. Samples were put into stomacher bags and transferred to the lab for testing. The method of sampling was randomised using 10 petri dishes with 3 labels in each, i. A label was chosen from each dish in turn, so as to create a sampling plan. No attempt was made to remove any peat, algae, roots etc, which were present in the samples.
In test series 1, the perlite around the inlets was contaminated with peaty material derived, presumably, from the rooting compost in which the plants were grown before planting out.
The perlite in test series 2 was free from such extraneous material. Perlite bags were tested in the glass house before and directly after treatment with composition A.
The composition A reduced the bacterial count by 2. Immediately after treatment yeast numbers were only reduced by 1. Numbers of yeasts recovered to their original level after 1 week but mould numbers did not increase.
There was roughly a 3 log reduction in bacterial counts. The bacterial spore count was reduced by only 1. The bacterial counts recovered after 1 week while the small increases in spore and mould numbers were not statistically significant. There is a greater reduction in microbial counts in series 2 compared to series 1.
This confirms the laboratory scale findings that composition A is more effective in disinfecting perlite containing no peat compost around the planting sites. Tomato seed, cv. Shirley, was sown into fine grade perlite, and propagated under standard commercial conditions. Seedlings were pricked out into horticultural grade perlite in 13 cm mesh-based pots.
These were maintained in a heated glasshouse until the first flower on the majority of plants was open, at which point they were planted by plunging the pots into the perlite contained in bags, arranged as previously described.
Planting was carried out after 45 days. On the basis of previous trials results application of composition A was at a dilution rate of with mains water. This was applied by commercially available irrigation harness as previously described. Experimental design was modified because of the complexity of the experimental procedure adopted for microbiological assay and the need for re-installation of treated and untreated substrates for the procedures described previously. Plots were of previously used perlite only for crop trials.
Yield was only recorded in terms of gross marketable class I yield irrespective of colour. No evidence of phytotoxic residues were detected in crops grown in perlite previously treated with composition A and subsequently flushed with water.
No scorching of leaf margins, as noted in some previous, preliminary trials work occurred, nor were any chlorotic symptoms, typical of low dose phytotoxicity, observed. All foliage was of a uniform dark green colour typically associated with healthyplants. Early yield of fruit from plots previously treated with product was greater than that from untreated substrates, Table 9.
This trend continued at the second pick but the situation was subsequently reversed. In each case differences between treatments were small. In economic terms early plant establishment and yield is more important than development later in the cropping sequence. These results support the view that composition A can have a beneficial effect on plant establishment in comparison to untreated plots, even in the absence of specific disease organisms.
Chitted seeds were transferred to horticultural grade perlite contained in 13 cm mesh-based pots and propagated under standard commercial conditions. Planting, after 45 days, was by plunging the pots directly into planting holes of the previous crop in perlite.
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