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1.
为了减少营养液排放对环境造成的污染，世界范围内的无土栽培系统正逐步由开放式向封闭式转变。封闭式无土栽培系统中根系病害的传播危险急剧增加，因此营养液消毒技术的研究和应用发展迅速。该文综述了国内外营养液消毒方法、原理、成本及应用效果，重点介绍了营养液消毒新技术－慢砂过滤。  相似文献   

2.
无土栽培营养液消毒技术研究与应用   总被引：1，自引：0，他引：1  
为了减少营养液排放对环境造成的污染,世界范围内的无土栽培系统正逐步由开放式向封闭式转变.封闭式无土栽培系统中根系病害的传播危险急剧增加,因此营养液消毒技术的研究和应用发展迅速.该文综述了国内外营养液消毒方法、原理、成本及应用效果,重点介绍了营养液消毒新技术-慢砂过滤.  相似文献   

3.
Studies were carried out in the years 2005–2007 with greenhouse tomato (Lycopersicon esculentum Mill.) cv. ‘Emotion F1’ grown in rockwool with the recirculating and non-recirculating nutrient solution systems. No significant differences were found in yields of fruits in both systems. In the recirculating system there was more intensive accumulation of sodium (Na), calcium (Ca), chloride (Cl), and zinc (Zn) in the root environment. Leaves of tomato grown in the recirculating nutrient solution system showed a higher content of Ca, magnesium (Mg), and Zn. There were no differences in the contents of nitrates and nitrites in fruits. In the recirculating system, the following savings were recorded: 42.5% of water and (in%): 42.1 nitrogen (N)- ammonium (NH4), 56.0 N- nitrate (NO3), 31.4 phosphorus (P), 52.1 potassium (K), 63.5 Ca, 47.9 magnesium (Mg), 49.4 sulfur (S)- sulfate (SO4), 51.9 Cl, 50.9 iron (Fe), 47.9 Zn, 24.6 manganese (Mn), 53.3 copper (Cu) and 47.2 boron (B). A high effectiveness in decreasing of bacteria number in drain water by UV irradiation was found.  相似文献   

4.
Abstract

This paper presents a simple model for the changes in ion concentration and electrical conductivity (EC) of the recirculating nutrient solution in a closed-loop soilless culture of tomato (Lycopersicon esculentum Mill.). The model was designed on the basis of a balanced equation for plant nutrient uptake: for macrocations (K+, Mg2+ and Ca2+), a linear dependence of concentration on crop water uptake was assumed, while for non-essential ions, such as sodium (Na+), a non-linear function was used. The model was developed for closed-loop hydroponic systems in which crop water uptake (namely, transpiration) is compensated by refilling the mixing tank with complete nutrient solution. In these systems, EC gradually increases as a result of the accumulation of macro-elements and, principally, of non-essential ions, like Na+, for which the apparent uptake concentration (i.e., the ratio between nutrient and water uptake) is lower than their concentration in the irrigation water. For model calibration, data from both the literature and a previous work were used, while validation was performed with data from original experiments conducted with tomato plants in different seasons and using water with different sodium chloride (NaCl) concentrations (10 and 20 meq/L). The results of validation indicate that the model may be a useful tool for the management of closed-loop hydroponics, because it simulates rather well the salt accumulation that occurs in the recirculating nutrient solution when it is prepared with irrigation water of poor quality. Furthermore, the model is able to estimate the amount of crop evapotranspiration that leads to a value of EC at which flushing is necessary, thus enabling one to predict the water and nitrogen runoff of the semi-closed soilless culture.  相似文献   

5.
This study was conducted to investigate the effect of Trichoderma harzianum (T22) on the growth and development of maize (Zea mays) plants. T. harzianum was applied to the grains in two different treatments, either by inoculating the soil with air-dried mycelia of T. harzianum or by treating the seeds with different concentrations of the metabolic solution (as the culture supernatant of T. harzianum) before sowing. Comparisons were made between the two treatments to determine if any beneficial effects for improving the growth of maize plants occurred. Results revealed that application of the highest concentration of air-dried mycelia and all concentrations of the metabolic solution of T. harzianum caused increases in all measured parameters which include growth parameters, chlorophyll content, starch content, nucleic acids content, total protein content and phytohormone content of maize plants but the magnitude of these increases was much more pronounced in case of treating the seeds with the metabolic solution of T. harzianum.  相似文献   

6.
紫外线－臭氧组合式营养液消毒机的设计及灭菌性能试验   总被引：1，自引：1，他引：0  
为了充分利用紫外线、臭氧在封闭式无土栽培系统营养液消毒上的优势,设计、试制并检测了一种紫外线－臭氧组合式营养液消毒机。样机主要包括紫外线消毒器、4个文丘里射流器、臭氧发生器、自吸泵、ABS管路及自动控制设备等。工作时,灌溉后回收的营养液首先由自吸泵提高压力后以一定流量和速度通过文丘里射流器的喉管,在此由臭氧发生器产生的臭氧由于负压作用吸入并与营养液充分混合,从而杀灭营养液中的病原微生物;然后营养液再经过紫外线消毒器,在紫外线的照射下进一步杀灭病原微生物。对所研制的消毒机,用经过了180 d番茄栽培试验的营养液进行了UV、O3、UV+O3 3种方法的灭菌性能测试,结果表明：主要微生物（细菌、真菌、放线菌）总的消毒效果分别达到70.6%、15.9%和89.9%。可以看出,紫外线－臭氧组合式消毒,达到了比单一灭菌方法更好的灭菌效果,显现出了协同效应,可以较大幅度地提高消毒效率。  相似文献   

7.
An experiment was conducted to determine the effects of chloride (Cl) and reduced forms of nitrogen (N) on the nitrate (NO3), total N, and Cl concentrations in onion (Allium cepa L.) plants using a non‐recirculating nutrient film growing system. The reference treatment was a nutrient solution containing 19 mM NO3 and 1.25 mM ammonium (NH4). The results from this treatment were compared with that obtained using mixed amino acid, urea, and glycine treatments with or without additional Cl (10 mM) in which 20% of the NO3 in the reference treatment was substituted with one of these reduced forms of N. Fresh and dry weights of the onion plants were not affected by the treatments. The NO3 content was considerably lower in the mixed amino acid treatment, being 4236 mg NO3/kg FW as compared to either the reference, urea, or glycine treatments. The NO3 contents of the plants in these treatments were 5393, 5339, and 5261 mg NO3/kg FW, respectively. The presence of Cl in the nutrient solution also reduced the NO3 content of the plants from 5816 to 4299 mg NO3/kg FW. The reduced‐N treatments increased the total N contents of the plants. The Cl content of the plants was increased by the Cl supplied and by the reduced forms of N in the nutrient solution.  相似文献   

8.
Nutrients play an important role in improving productivity and quality of banana. It has been observed that the nutrient applied alone was less effective in improving banana production as compared to nutrients applied in combination with organic manures and biofertilizers. Keeping in view the conservation of soil health and quality production on a long-term basis, a field experiment was conducted during 2009–2011 to find out the influence of Integrated Nutrient Management of banana on leaf characteristics, growth and nutrient status of tissue cultured banana cv. ‘Grand Naine’. The study indicates that combination of inorganic fertilizers with organic manures, biofertilizers and bioagents significantly increased growth parameters, leaf characteristics, and leaf nutrient status of banana. The leaf characteristics in terms of functional leaves, total number of leaves, phyllochron, leaf area, and leaf area index were significantly influenced by the combination of inorganic fertilizers with different biofertilizers and organic manures. Similarly, leaf nutrient status like nitrogen, phosphorus pentoxide, (P2O5), potassium dioxide (K2O), and leaf relative water content were also influenced greatly by different nutrients. Treatment involving combination of 100% recommended dose of fertilizer (RDF) + arbuscular mycorrhizal fungi (AMF) + Azospirillum+ Trichoderma harzianum showed overall superiority in most of the parameters.  相似文献   

9.
Abstract

Cucumbers were grown in nutrient film systems with (A) recirculation of solution and (B) membrane filtration and recirculation of solution. Samples of the nutrient solutions were taken during May-August. Nutrient solution in circulation without membrane filtration contained on average 23 ppm TOC (total organic carbon), while the filtered nutrient solution contained 15 ppm TOC. Spectrophotometric analysis of the samples showed a clear correlation of absorbance at 295 nm with TOC. The spectrometric data are compatible with tannin- and lignin-like material as the main organic residues in the nutrient solution. Membrane-filtered nutrient solutions were rapidly reinfected with bacteria, and filtered and non-filtered nutrient solutions flowing to the plants did not differ with regard to the number of bacteria.  相似文献   

10.
The knowledge about element leaching and biogeochemical cycles during initial stages of soil development is very limited. Therefore, we studied the effects of parent material characteristics and plant litter addition on element leaching from young sandy soils in a microcosm experiment. Our objective was to evaluate the function of young soils as a source and/or sink for nutrients during initial pedogenesis and to identify main processes which are involved in the initial development of biogeochemical cycles. The main research questions were: (1) How do differences in parent material characteristics affect nutrient leaching?; and (2) How is nutrient leaching of young soils influenced by litter addition of different plant functional groups (e.g., legume and grass species)? Combined treatments of two minimally weathered parent materials (pure sand and loamy sand) with plant litter of two plant species (Lotus corniculatus L. and Calamagrostis epigejos L.) were investigated in a soil column experiment. In addition, control columns with parent material or plant litter only were included. Carbonate weathering as a main source for calcium leaching was induced by the moderately acidic irrigation solution used in the experiment. It was 7.5 fold greater for the loamy sand parent material compared to the pure sand despite lower carbonate contents in the loamy sand. Leaching of K was very low for both parent materials but greater for the loamy sand parent material, likely due to transfer processes from fixed to exchangeable potassium forms in the clay minerals of the loamy sand. Plant litter addition generally increased leaching losses. Carbonate dissolution was intensified by both plant litter types, especially by L. corniculatus, very likely due to H+ released during nitrification of N released from plant litter and an increase in partial pressure of CO2 from microbial respiration. In contrast, K was largely retained in the soils, probably due to fixation by clay minerals and microbial immobilization. Only the pure sand treated with L. corniculatus litter leached K, resulting in 4–6 fold greater leaching losses compared to all other treatments. Nitrogen released from L. corniculatus litter was almost completely nitrified and was nearly doubled as compared to that from C. epigejos, resulting in greater N leaching. The results of our study allow identifying the general function and processes of vegetation patches in young ecosystems formed as a result of initial parent material characteristics and invading vegetation with respect to litter decomposition, soil solution composition, nutrient retention and leaching, and effects on the soil mineral phase. These patterns are not mere additive effects of parent materials plus plant litter, but reflect differences in biogeochemical process intensities and could result in an increasing heterogeneity of soil properties, nutrient availability, and element leaching fluxes with time.  相似文献   

11.
Microcystins (MCs) are endotoxins produced by cyanobacteria in freshwaters globally. With known potential for human health risks, rapid and effective treatment methods are needed for MCs. Previous studies have shown photocatalysis can achieve rapid half-lives with UV lamps and slurries of TiO2. In this experiment, rates and extents of solar photocatalysis of MCs were measured using bench-scale reactors with fixed films of TiO2 for solutions with a range of cellular:aqueous MC ratios. Since cellular MCs can be removed physically, photocatalysis rates were measured following sand filtration to discern the extent of MC removal post-filtration. Since UV energy drives photocatalysis using TiO2, rates of removal were calculated as a function of cumulative UV insolation and time. For water containing < 10% aqueous MC, filtration removed 90% of total MC, and the subsequent photocatalysis half-life was 0.37 MJ/m2 (or 111 min). For water with ~?50% aqueous MCs, filtration removed 52% of the total MCs, and the average half-life for photocatalysis was 0.38 MJ/m2 (or 138 min). For the >?90% aqueous MC treatment, filtration removed 0% MCs, and the photocatalysis half-life for MCs was 0.37 MJ/m2 (or 135 min). Previous studies have used clarified waters; however, results from this study are likely representative of scenarios with waters containing confounding water characteristics and use of solar light for UV, as anticipated in developing countries with less advanced water treatment methods. Photocatalysis is a rapid and effective process for decreasing concentrations of MCs and could be useful for mitigating risks from MC exposures in drinking water.  相似文献   

12.
Apple seedling (Malus domestica Borkh.) growth and nutrition were compared over a range of nutrient level treatments using A different experimental nutritional methods: nutrient‐film, soil, sand, and solution culture. A 2‐ to 10‐fold difference in nutrient level caused significant differences between experimental methods on seedling growth. Higher nutrient levels resulted in reduced growth in the nutrient‐film and soil cultures, increased growth in sand cultures and little effect on growth in solution cultures. Tissue Ca, of the nutrients studied, was significantly different depending upon the experimental method. Alternating the nutrient level either by elevating K or reducing Ca/Mg resulted in significant interactions on tissue Ca depending upon the experimental method used. The results showed that under similar environmental and treatment conditions, data on growth and nutrition of apple seedlings can vary significantly depending on the type of experimental method employed.  相似文献   

13.
Abstract

Three greenhouse experiments were conducted to compare the response of five tobacco (Nicotiana tabacum L.) cultivars to different levels of NaH2PO4 and ammonium polyphosphate (APP) in nutrient media by measuring tissue content of selected nutrient elements (P, Na, K, Ca and Mg). Plants were grown in sand cultures fertilized with nutrient solutions in two experiments and a soil‐sand mix fertilized with solid materials in a third experiment. Plant P and Na content increased as the concentrations of these elements increased in nutrient solution. Plant K content was not generally affected by treatments. Magnesium was reduced in flue‐cured and cigar‐filler tobaccos but was not changed in cigar‐wrapper and Turkish types by increasing amounts of NaH2PO4. All of the cultivars responded similarly to NaH2PO4 with respect to plant Ca. High levels of P in the nutrient media were consistently related to low levels of Ca in plant tissue.  相似文献   

14.
We assessed the effects of organic fertilization on the response of biochemical and physiological indicators and the yield of saladette-type tomato (Solanum lycopersicum L.) grown under greenhouse conditions. Five fertilization forms [sand + inorganic nutrient solution (F1); sand + vermicompost tea (F2); a mixture of sand, compost, + vermicompost tea (F3); a mixture of sand, vermicompost, + vermicompost tea (F4); and a mixture of sand, compost, vermicompost, + vermicompost (F5)] and two genotypes (Cuauhtémoc and El Cid) were evaluated. The parameters analyzed were leaf pigments, enzymatic activity of nitrate reductase (NR) in vivo, and yield. A fertilizer source of sand + vermicompost tea resulted in the best assimilation of nitrate (NO3-), the greatest NR endogenous activity, the second highest foliar concentration of organic nitrogen (N), and the second best yield. In conclusion, for improved tomato cultivation during organic production, treatment F2 produced the maximum organic yield and resulted in more efficient N utilization.  相似文献   

15.
The relative effectiveness of Amberlite IRC‐50 resin, in a recirculating ion exchange column, and several concentrations of MES [2(N‐mor‐pholino)ethanesulfonic acid] were evaluated for control of nutrient solution pH of hydroponically cultured soybean (Glycine max [L.] Merr. cv Williams). A low buffering capacity, urea‐based nutrient solution was used. MES buffer, at the concentrations evaluated (1,2, 4, and 10 mM), was less effective at maintaining desired pH than the IRC‐50 resin system. The pH of the 4.0 mM MES buffered nutrient solution decreased from 6.5 to below 4.0 in five days with 25 to 30 day old plants. By comparison, the pH of the IRC‐50 resin buffered nutrient solution dropped from 6.5 to 5.9 during the same period. Nitrate uptake by 27 to 29 day‐old plants was significantly slower when solutions were buffered with MES than with IRC‐50 resin. Rate of nitrate uptake decreased with increasing MES buffer concentrations and decreasing pH in short‐term studies on plants previously grown on IRC‐50 resin buffered nutrient solution. Mass of the plants grown on IRC‐50 resin buffered nutrient solution equaled or exceeded that of plants grown on 1, 2, or 4 mM MES. Total elemental uptake (mg/plant) by plants grown on nutrient solution buffered by IRC‐50 resin, for the ten elements tested, was equal to or greater than uptake by plants grown on nutrient solution buffered by 1, 2, or 4 mM MES. It is concluded that IRC‐50 resin in recirculating columns provides better pH control than does MES buffer for hydroponically grown soybean.  相似文献   

16.
Abstract

A greenhouse experiment was conducted at the University of lbadan, Nigeria to determine the optimum sulphur (S) rate for Celosia (Celosia argentia L. CV. TLV 8) production under hydroponic growing conditions. Average temperature and light intensity in the greenhouse was 27.7°C and 1.32 x 103 μEinstein M‐2 S‐1 (PAR), respectively. Five rates of S(0, 13.5, 27, 40.5, and 54 ug g?1 of sand) in a series of nutrient solutions were imposed in a completely randomized design. Application of S significantly increased leaf number, plant height, leaf area, weights of leaf, stem, root, and raised contents of leaf sulphate (SO4)‐S, chlorophyll, vitamins A and C, and crude protein. The optimum S rate for leaf formation, plant height at harvest (seven weeks after transplanting‐WAT), shoot production, SO4‐S, vitamin A, and crude protein synthesis was 40.5 μg S g?1 of sand in the applied nutrient solution, while that for maximum leaf production, chlorophyll, and vitamin C synthesis was 54 ug S g?1 of sand. These results indicate that S nutrition is necessary for the optimum growth, yield, and yield attributes of Celosia.  相似文献   

17.
In tomato (Lycopersicon esculentum L. cv Trust Fl), effects of various nutrient treatments on growth, fruit yield and quality, nutrient uptake and accumulation were studied in a hydroponic system. Reductions of macronutrient concentrations to 50% (0.5 × C) or 25% (0.25 × C) of the control (C) levels as well as cessation of replenishment of the feed solution for the last 16 days after 7 months growth at control levels, had no adverse effect on growth, fruit yield and fruit quality. However, reduction of macronutrient concentration to 10% of control (0.1 × C) reduced fruit yield by ‐30%. Steady‐state influx and net flux of NO3 ‐ into the roots of 4–6 week‐old seedlings had not acclimated and showed concentration dependence from 1.1 mM (0.1 × C) to 11 mM (C). Whereas, Pi and K+ fluxes were similar at 0.5 × C and C levels, at 0.1 × C they were significantly lower than the fluxes at higher concentrations, showing lack of acclimation at this concentration. This lack of flux acclimation may account for the adverse effects of low concentration (0.1 × C) on yield. The results have been discussed in the context of eutrophication and it is suggested that in a non‐recirculating hydroponic system, NO3 ‐, Pi, and K+ levels can be reduced to 25% of the concentrations currently being used in commercial greenhouses (C). In a recirculating system, the crop may be grown at control levels and used to deplete the feed solution for ～3 weeks prior to release of the solution to the drain.  相似文献   

18.
Fertigation with KNO3 as a means of reducing salinity hazards was tested with peanut (Arachis hypogaea) plants grown on dune sand, resulting in a reduction of plant growth and yield. The objective of this work was to study the interactions between N, K+ and NaCl as well as the effects of the NH4 +/NO3 ‐ ratio on vegetative and reproductive growth. Wheat (Triticum aestivum L.) plants were grown in polyethylene pots with fine calcareous dune sand with different proportions of NH4 + and NO3 ‐, under saline (60 mM NaCl) and non‐saline conditions. Three replicates were harvested at the beginning of flowering, and one was grown to grain maturity. NaCl reduced shoot dry weight in all the treatments. Increasing the NH4 + proportion in the total of 6 mM N in the nutrient solution, increased shoot dry weight, did not change nitrogen concentration in the dry mass but increased P percentage, either with or without 60 mM NaCl. The number of tillers produced in each treatment was correlated with dry matter yield. The effect of the NH4 +/NO3 ‐ ratio may be explained by alteration of the cation‐anion balance on the nutrient uptake by roots, which lowered pH of the nutrient solution with increasing NH4 + concentration, by alteration of the cation‐anion balance on the nutrient uptake by roots, which lowered pH of the nutrient solution with increasing NH4 + concentration.  相似文献   

19.
The objective of this study is to examine the reuse of wastewaterfor beneficial purposes. To accomplish this objective, the efficiency of slow sand filters in removing total coliforms (TC) was studied using a probabilistic method. Three pilot scale slowsand filters were constructed at Alkhobar wastewater treatment plant, Dhahran, Saudi Arabia. The removal efficiency of filters was estimated under different operating control parameters, which included filtration rate (q), sand bed depth (d) and sand grain size (c). The Type III extreme value distribution best fitted theremoval efficiency data. A multiple linear regression analysis was performed to develop a relationship for mean removal efficiency as a function of control parameters. The predicted mean response and experimental results of previous studies werecompared to validate the empirical regression model. The controlparameters and influent concentrations of total coliform were used in Monte Carlo (MC) simulations for calculating the reliability index (β). The reliability index and corresponding risk were calculated for lognormally distributedsafety margins (SM). An effluent standard of 100 total coliform/100 mL was defined as capacity of the filter to ascertainthe risks of exceedence, which was approximately less than 50 for95% of the time. Pre and/or post disinfection would be necessaryto meet the stipulated effluent standards for unrestricted agriculture use.  相似文献   

20.
The aim of this study was to assess differences in rhizodeposition quantity and composition from maize cropped on soil or on 1:1 (w/w) soil–sand mixture and distribution of recently assimilated C between roots, shoots, soil, soil solution, and CO2 from root respiration. Maize was labeled in 14CO2 atmosphere followed by subsequent simultaneous leaching and air flushing from soil. 14C was traced after 7.5 h in roots and shoots, soil, soil solution, and soil‐borne CO2. Rhizodeposits in the leachate of the first 2 h after labeling were identified by high‐pressure liquid chromatography (HPLC) and pyrolysis–field ionization mass spectrometry (Py‐FIMS). Leachate from soil–sand contained more 14C than from soil (0.6% vs. 0.4%) and more HPLC‐detectable carboxylates (4.36 vs. 2.69 μM), especially acetate and lactate. This is either because of root response to lower nutrient concentrations in the soil–sand mixture or decreasing structural integrity of the root cells during the leaching process, or because carboxylates were more strongly sorbed to the soil compared to carbohydrates and amino acids. In contrast, Py‐FIMS total ion intensity was more than 2 times higher in leachate from soil than from soil–sand, mainly due to signals from lignin monomers. HPLC‐measured concentrations of total amino acids (1.33 μM [soil] vs. 1.03 μM [soil–sand]) and total carbohydrates (0.73 vs. 0.34 μM) and 14CO2 from soil agreed with this pattern. Higher leachate concentrations from soil than from soil–sand for HPLC‐measured carbohydrates and amino acids and for the sum of substances detected by Py‐FIMS overcompensated the higher sorption in soil than in sand‐soil. A parallel treatment with blow‐out of the soil air but without leaching indicated that nearly all of the rhizodeposits in the treatment with leaching face decomposition to CO2. Simultaneous application of three methods—14C‐labeling and tracing, HPLC, and Py‐FIMS—enabled us to present the budget of rhizodeposition (14C) and to analyze individual carbohydrates, carboxylates, and amino acids (HPLC) and to scan all dissolved organic substances in soil solution (Py‐FIMS) as dependent on nutrient status.  相似文献   

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