Organic Nutrient Solutions Research Articles

Comparisons of nutrient solutions from organic and chemical fertilizer sources on herbage yield and quality of hydroponically produced maize fodder

We investigated the use of four nutrient solutions (organic, organo-mineral, inorganic, and a commercial hydroponics solution that served as a control) on the yield and quality of hydroponically produced maize fodder. The organic, organo-mineral, and inorganic nutrient solutions were formulated from poultry manure, Aleshinloye organo-mineral fertilizer, and NPK 20:10:10, respectively. The nutrient solutions were used to irrigate “Swan-1” maize seeds for 16 days after which herbage yield, water use efficiency, chemical composition, and in vitro variables were determined. Formulated nutrient solutions had no significant (p > 0.05) effect on recorded fodder yield values (0.96 − 1.05 kg/tray). Water use efficiency values ranged from 0.23 to 0.26 kg DM/m3 with no significant (p > 0.05) treatment effect. The organo-mineral nutrient solution decreased crude protein content but increased ash content in the plants. The other treatments had statistically similar (p > 0.05) crude protein and ash values with the control. Recorded crude protein and ash values were 8.88%−13.69% and 5.43%−8.25%, respectively. Plants irrigated with the organo-mineral nutrient solution had consistently higher (p < 0.05) mineral concentration values (3.68, 2.13, 63.60, 13.70, and 5.29 g/kg for Ca, P, K, Mg, and Na); although, P concentration was similar with the control. In vitro gas volumes and dry matter digestibility were not significantly (p > 0.05) affected by the treatments. In conclusion, the formulated organic and organo-mineral nutrient solutions produced plants with similar yield and quality as the inorganic and standard nutrient solutions.

Effects of different organic nutrient solution formulations and supplementation on tomato fruit quality and aromatic volatiles

ABSTRACT In order to improve the quality of life, people are paying more attention to food safety and flavor quality. As a new type of organic fertilizer, organic nutrient solution (ONS) is easily absorbed by plants and can improve fruit quality. However, if and how ONS affects tomato aromatic volatiles remains elusive. In order to explore the role of ONS in the biosynthesis of tomato aromatic volatiles, we set an inorganic nutrient solution and two ONS formula treatments in experiment 1 and five ONS supplementation treatments (0, 6, 12, 18 and 24 L plant−1) in experiment 2. Compared to inorganic nutrient solution, ONS significantly increased the content of soluble sugar, organic acid, lycopene, ascorbic acid, soluble protein and characteristic aromas in tomato fruit, with treatment of pig, cow and sheep manure nutrient solution equal to 4:1:1 being the most effective. With increased ONS supplementation, the nutrients and characteristic aromas content first increased and then decreased. The most effective amount was 12 L plant−1, which markedly increased the nutrients and characteristic aromas. Correlation analysis revealed a high correlation between nutrients and aromatic volatiles content in tomato fruit, suggesting that ONS potentially affects aromatic volatile emissions via the regulation of substrate content.

Influence of Potassium Nutrition and Exogenous Organic Acids on Iron Uptake by Monocot and Dicot Plants

Iron (Fe) is a vital element for the survival and proliferation of all plants; therefore, Fe-biofortification by the application of chemical and organic fertilizers is being as an effective approach to fight hidden hunger retards the growth and development of crop plants. Two experiments were carried out to investigate the effect of potassium and exogenous organic acids on iron uptake by two different plants: one is monocotyledon, maize (Zea mays L.) and the second is dicotolydon pea (Pisum sativum L.) grown under controlled conditions. The seedlings were grown in sand culture in a greenhouse experiment and irrigated with one-tenth strength modified nutrient solution of Hoagland and Arnon as a base solution (pH 7.5), containing different iron treatments (0, 1, and 5 ppm as FeSO4·7H2O) combined with potassium nutrition (0, 5, 10, and 50 ppm as K2SO4). After 30 days, the best interaction treatment was selected for further experiment including 5.0 ppm Fe as FeSO4.7H2O and 50 ppm K as K2SO4 in combination with 1 × 10-5 mole/liter of one of the following organic acids: Citric acid, Oxalic acid, Formic acid, Acetic acid, Propionic acid, Tartaric acid, Succinic acid, Fumaric acid, Malic acid, Glutamic acid, besides the free organic acid nutrient solution as a control. Results revealed that the interaction between 5.0 ppm Fe and 50 ppm K was the best interaction treatment for increasing biomass production and iron uptake of maize and pea seedlings under applied condition. Furthermore, exogenous application of organic acids improves uptake and translocation of nutrient such as iron, potassium and phosphorus by the maize and pea plants. In conclusion, potassium nutrition and exogenous organic acids have the potential to stimulate Fe-uptake of monocot and dicot plants and mediate iron-biofortified crops.

Comparative evaluation of productivity of ryegrass and ryegrass-goatling grass stands affected by different mineral and organomineral nutrition

Production volumes must be increased not by any means, but only by those of them that are economically sound and justify the labor of present-day agricultural workers and funds spent on solution of its problems. The number of such priorities undoubtedly includes realization of the complex program of developing biotechnologies, approved by the President of the Russian Federation, V.V. Putin, on April 24, 2012. It is aimed at the reduction of expenditures on the production of competitive, environmentally safe foodstuff based on widespread use of modern fertilizing and stimulating compositions, organic and mineral nutrient solutions and biological preparations. In this connection, the questions of foliar dressing, discussed in this work, using various nutrient solutions, containing highly digestible amino acids and chelate forms of microfertilizers of poorly explored in Middle Volga region ryegrass agrocoenoses, are not only relevant, but are also significant from the theoretical and practical viewpoints.

Comparisons of commercial organic and chemical fertilizer solutions on growth and composition of lettuce

The objective of this experiment was to assess the effects of organic or chemical nutrient solutions on the growth and composition of lettuce (Lactuca sativa L.) in greenhouse production. Hoagland and Arnon nutrient solution, an organic hydroponics solution, and no fertilization were factored with lettuce cultivars of different phenotypes, iceberg, romaine, loose head, and loose leaf. Lettuce growth was higher with Hoagland and Arnon solution than with the organic fertilizer or with no fertilization. The organic fertilizer increased growth above no fertilizer applied. Hoagland and Arnon solution gave the highest concentration of nitrogen, potassium, magnesium, and iron in the lettuce whereas lettuce grown with the organic fertilizer had the highest phosphorus. Plant nutrient accumulation differed slightly among the cultivars. Hoagland and Arnon solution produced high nitrate in leaves. Nitrate concentrations with organic or no fertilization were low. Loose head or loose leaf cultivars had higher nitrate than romaine or iceberg.

Effects of irrigation frequency of organic nutrient solution and irrigation amount on yield, quality, fertilizer and water use efficiency of melon in facility

To investigate the organic cultivation mode for high-yield and high-quality melon, we measured the growth of melon that grown in pots with different conditions of organic nutrient solution and irrigation. There were three irrigation frequencies of organic nutrient solution (8-time application, each time 750 mL per plant, F1; 12-time application, each time 500 mL per plant, F2; 16-time application, each time 375 mL per plant, F3) and two different irrigation amount per single plant (irrigating by 120% daily evapotranspiration (ET) before fruit enlargement, by 140%ET after fruit enlargement, W1; irrigating by 140%ET before fruit enlargement, by 160%ET after fruit enlargement, W2), following a randomized block trial design. The effects of those treatments on photosynthetic characteristics, yield, quality, fertilizer and water use efficiency of melon were investigated. The results showed that photosynthetic rate of melon leaves was significantly increased by more frequent and less amount of organic nutrient solution application. Fruit yield and water use efficiency were significantly improved under low irrigation condition. Fertilizer utilization was optimal under the treatments of high irrigation and medium organic nutrient solution frequency. Fruit quality was improved under less organic nutrient solution and relatively suitable water supply. A mathematical model of exponential function y=0.214e0.18x (R2=0.851) could be used to quantify the relationship between the vitamin C content of melon fruit and frequency of organic nutrient solution application. Considering the variables, such as yield, quality and water use efficiency, F3W1 treatment was recommended with the aim to improve fruit quality and optimal water use efficiency under promising yield, which could achieve high-yield and high-quality cultivation of organic melon in facilities.

Effectiveness of Organic Fertigation and Moringa Leaf Extract Spray as an Alternative to Chemical Fertigation for Improving Yield and Quality of Lettuce under Soilless Condition

TWO experiments were conducted at Sakha Agricultural Research Station, Bacteriology Lab greenhouse for studying the effect of fertigation with fish extract organic solution as an alternative to mineral nutrient solution as well as foliar spray with moringa leaf extract on morphological, chemical, microbial characteristics and yield of lettuce plant grown under soilless system during winter seasons of 2014 and 2015. In general, the results indicated that fertigation with the fish extract organic nutrient solution increase all the studied characteristics compared to fertigation with the mineral nutrient solution, except for NO3 content which sharply decreased due to organic nutrition treatment which attained 157.52 and 175.24 (mg plant-1) compared to 497.14 and 476.8 (mg plant-1) for mineral nutrition treatment at 2014 and 2015 seasons, respectively. Similarly, foliar spray with moringa extract with mineral nutrition decreased nitrate content (463.46 and 450.16 mg plant-1) lower than mineral nutrition without spray (497.14 and 476.8 mg plant-1) at 2014 and 2015 seasons, respectively. Therefore, positive results on vegetative growth, chemical characteristics and yield of lettuce plant grown under soilless system by using of fertigation with fish extract organic solution and foliar spray with moringa leaf extract to decrease the nutritive gap and vegetables nitrate pollution problems as well as partially avoid the problem of irrigation water shortage.

Photosynthetic Response and Antioxidant Content of Hydroponic Bitter Gourd as Influenced by Organic Substrates and Nutrient Solution

Crop-specific nutrient solution and suitable growing media mixtures are necessary in hydroponic system to improve the yield of vegetables. Therefore, an experiment was conducted to specify the required amount of nutrient solution and ecofriendly mixtures of growing substrates of a hydroponic bitter gourd. Treatments consisted two factors, viz., four different types of growing substrate (M1 = 60% rice husk + 30% coconut coir + 10% vermicompost, M2 = 60% coconut coir + 30% khoa + 10% vermicompost, M3 = 60% sawdust + 30% khoa + 10% vermicompost, and M4 = 60% ash + 30% khoa + 10% vermicompost) and three different composition of nutrient solutions [N1 = full strength Rahman and Inden (2012), N2 = full strength Hoagland and Arnon (1940), and N3 = ½ strength Rahman and Inden (2012)]. Photosynthetic responses and its related parameters, namely, stomatal conductance (gs), transpiration (E), and photosynthetic rate (PN) were significantly affected by nutrient solution composition and growing substrate mixtures. Results revealed that the leaf gas exchange parameters, yield contributing characters, and biochemical parameters showed that full strength of Rahman and Inden (2012) nutrient solution application was better in a growing mixture of 60% rice husk + 30% coconut coir + 10% vermicompost in soilless culture for obtaining high yield and high quality of bitter gourd.

Animal-based organic nutrition induces comparable fruit quality to that of inorganic fertigation in soilless-grown grape tomato

ABSTRACTThe aim of the present study was to determine the effect of animal-based organic nutrition and environmental parameters on tomato fruit quality, as well as to establish relations among colour and morphological values performed by the Tomato Analyzer (TA) software application. Organic tomato fruits produced by three organic nutrient solutions, which consisted of different mixtures of several OMRI certified nitrogen fertilizers and one inorganic nutrient solution (Steiner’s solution) as the control, were evaluated for their polyphenol and carotenoid content. We used Tomato Analyzer (TA) to evaluate fruit size and shape. Moreover, we implemented a digital image analysis tool, Color Test (CT), as part of the TA software application to collect and analyse fruit colour parameters. The application of organic fertilizers positively affected the total hydrolysable and condensed polyphenols of tomato fruits compared to the control. The high air temperature (>30°C) and sub-optimal light intensity negatively affected the carotene content of tomato fruits, as well as their morphological and colour attributes. Plants fed with organic solutions containing ASA + ASB + NK2SO4 showed comparable morphology and fruit colour attributes to those of the control plants that received Steiner’s nutrient solution. The results indicated that the application of organic fertilizers positively affected the total hydrolysable and condensed polyphenols of tomato fruits compared to the control. Plants fed with the Steiner’s nutrient solution exhibited the highest carotenoid content in tomato fruits. Organically produced tomatoes through animal-based fertilizer application displayed similar fruit morphology and colour attributes compared to conventionally produced tomatoes.

English

The influence of organic hydroponic nutrient solution on tomato growth and yield was studied using a randomized complete block design (RCBD) with three treatments (organic nutrient solution, conventional hydroponic fertiliser (as positive control) and plain tap water (as negative control)) replicated three times. Determinate tomato seeds were germinated and transplanted into the 3 treatments. Twenty days after transplanting, vegetative response variables were recorded at fifteen days intervals from each treatment. Vegetative response variables included plant height, number of leaves and stem diameter. The reproductive parameters included number of flowers per plant, number of fruits per plant, average fruit weight (g), yield (kg) per plant and yield (kg) per treatment. Furthermore, the organic nutrient solution formulated from goat manure positively improved plant growth and yield performance of a tomato crop, and provided a technique feasible and alternative to conventional hydroponics. These results open further possibilities for other crops currently grown in hydroponics using conventional fertilisers. Key words: Organic nutrient solution, growth, yield, goat manure, tomato.

Seedling Production of Pak Choy (Brassica rapa L. var chinensis) using Organic and Inorganic Nutrients

&lt;p&gt;Pak Choy or Bok Choy (&lt;em&gt;Brassica rapa &lt;/em&gt;L. var. chinensis) is one of favorite Chinese leafy vegetable for various dishes in Indonesia. In this study, it was used as a plant model to identify the appropriate organic hydroponic nutrient solution for leafy vegetable seedling production. The seed was sown on rock wool slabs submerged with 200 ml of a nutrient solution containing biofertilizer of &lt;em&gt;Beyonic StarTmik@Lob&lt;/em&gt; (0, 25, 50, 75, and 100%). commercial hydroponic solution (0, 25, 50, 75, and 100%) and its combination (25, 50, and 75%). The experiments were arranged in a CRD. Meanwhile, the obtained data was analyzed using ANOVA followed by DMRT. The relationship among growth parameters was observed using Pearson correlation analysis. The result of the study showed that the combination of organic and inorganic nutrient (25% &lt;em&gt;Beyonic StarTmik@Lob&lt;/em&gt; and 75% commercial hydroponic solution) resulted in the highest seedling growth parameters and leaf indices as well as the perfectly positive correlations among growth parameters. This result indicated that the use of organic nutrient alone was not appropriate for hydroponic seedling production of Pak Choy. Therefore, further study needs to be done to identify the hydroponic solution without inorganic nutrients towards the organic vegetable production.&lt;/p&gt;

YIELD AND NUTRACEUTICAL QUALITY OF TOMATO FRUIT PRODUCED WITH NUTRIENT SOLUTIONS PREPARED USING ORGANIC MATERIALS

Increasing public concern about negative environmental effects of agricultural practices like conventional chemical fertilization has promoted the evaluation of alternatives like the use of organic nutrient solutions. This study evaluated the effect on fruit yield and commercial and nutraceutical qualities of fresh tomato (Solanum lycopersicum L.) fruits grown under greenhouse conditions fertilized with nutrient solutions prepared from organic materials. Treatments were: a) Inorganic nutritive solution (Steiner); b) Compost tea; c) Vermicompost tea; and d) Vermicompost leachate. Highest fruit yield derived from fertilization with inorganic solution. However, highest antioxidant capacity, soluble solids content and phenolic content were obtained with organic nutrient solutions. Fresh tomatoes obtained with vermicompost leachate had the best nutraceutical quality, higher phenolic content and higher antioxidant capacity, than the inorganically fertilized fruits. Vermicompost leachate is a feasible fertilization alternative for tomato production under greenhouse conditions.

ORGANIC NUTRIENT SOLUTIONS IN PRODUCTION AND ANTIOXIDANT CAPACITY OF CUCUMBER FRUITS

The aim of the current study was to evaluate the effect of organic nutrient solutions over yield, quality and antioxidant capacity of hydroponic cucumber (Cucumis sativus L.) fruits produced under greenhouse conditions. The organic solutions used were compost and vermicompost teas, and the Steiner nutrient solution was used as control. Evaluated variables were: yield, quality, and antioxidant capacity of cucumber fruits. Nutritive solutions affected yield and antioxidant capacity of the produce. Steiner solution obtained a higher yield (41.8 - 44.4%) than organic nutritive solutions; however organic cucumber samples had higher antioxidant capacity. Compost tea treatment obtained the highest antioxidant capacity among all treatments, resulting 42% higher than inorganically fertilized produce. Compost tea is a viable alternative as a nutrient source in the production of hydroponic cucumber under greenhouse conditions with an improved nutraceutical quality.

Nutraceutical quality of cantaloupe melon fruits produced under fertilization with organic nutrient solutions

Consumption of fruits and vegetables provides natural antioxidants in the human diet that are capable of preventing diseases resulting from the action of free radicals. The aim of the current study was to evaluate the effect of organic nutrient solutions on the nutraceutical quality of hydroponic cantaloupe melon ( Cucumis melo L.) produced under greenhouse conditions. The applied organic solutions consisted of compost and vermicompost teas and vermicompost leachate, while Steiner nutrient solution was used as a control. Analytical tests were run to determine the antioxidant capacity and total phenolic content of the melon fruits. The nutraceutical quality (antioxidant capacity and phenolic content) of the fruits fertilized with the organic solutions was higher than that of melons fertilized using Steiner solution. Treatment with vermicompost leachate led to the highest antioxidant capacity and phenolic content among all of the treatments, resulting a 46.1% higher in antioxidant capacity (DPPH + method) and a 29.3% higher phenolic content compared with inorganically fertilized fruits. Vermicompost solutions (leachate and tea) are viable alternatives for use as a nutrient source in the production of hydroponic cantaloupe melon with improved nutraceutical quality under greenhouse conditions. El consumo de frutas y vegetales incluye antioxidantes naturales a la dieta humana, los cuales son capaces de prevenir enfermedades derivadas de la accion de radicales libres. El objetivo del presente estudio fue evaluar el efecto de soluciones nutritivas organicas sobre la calidad nutraceutica de melon Cantaloupe ( Cucumis melo L.) producido bajo condiciones de invernadero. Las soluciones organicas usadas fueron tes de compost y de vermicompost, lixiviado de vermicompost, y solucion nutritiva Steiner como control. Las pruebas analiticas realizadas fueron: capacidad antioxidante y contenido fenolico total del fruto de melon. La calidad nutraceutica (capacidad antioxidante y contenido fenolico) de los frutos fertilizados con las soluciones organicas fue mayor que en los melones fertilizados con la solucion Steiner. El tratamiento con lixiviado de vermicompost obtuvo los mayores valores de capacidad antioxidante y contenido fenolico de todos los tratamientos, resultando un 46,1% mayor en capacidad antioxidante (metodo DPPH + ), y 29,3% mayor en contenido fenolico que los frutos fertilizados inorganicamente. Las soluciones obtenidas a partir de vermicompost (lixiviado y te) son alternativas viables de fuentes nutricionales para la produccion de melon Cantaloupe hidroponico bajo condiciones de invernadero, el cual tendra una calidad nutraceutica mejorada.

SEEDLINGS PRODUCTION OF OCIMUM BASILICUM IN TWO SYSTEMS (FLOAT AND SEEDBED) WITH ORGANIC AND INORGANIC FERTILIZATION

Ocimum basilicum (sweet basil) is an aromatic plant with a highly commercial interest because of its multiple uses (ornamental and seasoning) and its properties (extract of essential oils). Float system gives the opportunity to produce a large number of seedlings within a short period with good quality characteristics. The possibility of developing Ocimum basilicum seedlings in Float system and nursery as well as the effect of organic and inorganic fertilization on quality characteristics were examined. For both systems polystyrene pallets of multiple seats (176) were used in which the seeds were placed in a mixture of peat-perlite 1:1 v/v. Treatments included two organic nutrient solutions formulated with a) Fishfert (FF) and b) Codaphos and Codasting (C&C) and an inorganic nutrient solution formulated with soluble fertilizer (11-11-23). Growth characteristics (shoot and root fresh and dry weight) and leaf area per plant, was determined. Significant differences in germination and T50 were not detected between the two methods. The organic fertilization C&C gave the best results in both methods for all basil characteristics. Therefore, the production of Ocimum basilicum seedlings in float system using the organic nutrient solution C&C is recommended. This combination can produce seedlings with high quality characteristics, while the method is environmentally friendly.

Biogas slurry added amino acids decreased nitrate concentrations of lettuce in sand culture

Human health worldwide is being threatened by excessive nitrate intake through the dietary pathway, i.e. vegetables and drinking water, and the former is the primary source (about 80%) for large quantitative ingestion and the biological characteristics of nitrate accumulation, especially for leafy vegetables. In this paper, four kinds of organic nutrient solutions (biogas slurry dilution or biogas slurry dilution with added glycine) were developed to culture lettuce in order to lower the nitrate concentrations in leafy tissue. The results showed that all organic nutrient solutions significantly decreased nitrate concentrations of lettuce shoot, and simultaneously had an increased or unbiased yield compared with inorganic nutrient solution (containing NO3 −-N solely) in sand culture with high-level nitrogen supply (8.69–15 mmol/L). In addition, glycine addition only slightly decreased nitrate concentrations in lettuce shoot both at 1:4 and 1:5 dilution rates of biogas slurry. Leafy SPAD values indicated that there were differences in lettuce N nutrition of new and old leaves responding to various N-form supplies, and no correlations between nitrate concentration and SPAD values were found. It was concluded that application of organic nutrient solutions formulated from biogas slurry dilution and amino acid in soilless cultivation is an effective means for reduction nitrate concentrations in leafy vegetables.

Life detection experiments of the Viking Mission on Mars can be best interpreted with a Fenton oxidation reaction composed of H2O2 and Fe2+ and iron-catalysed decomposition of H2O2

AbstractThe findings of the life detection experiments carried out during the Viking mission to Mars were reinterpreted with a chemical hypothesis. The labelled release (LR), pyrolytic release (PR) and gas exchange (GEx) experiments were interpreted with Fenton chemistry. Oxygen and carbon dioxide evolution from Martian soil upon wetting and nutrient addition could be attributed to competition reactions between the Fenton-type oxidation of organic nutrients with the aqueous (hydrogen peroxide+Fe(II)) combination and the iron-catalysed decomposition of hydrogen peroxide. A substantial evolution of radioactive gas upon addition of labelled organic nutrient solution to soil, whereas the ceasing of this gas with a heat treated sample in the LR experiments, was attributed to Fenton oxidation and hydrogen peroxide thermal decomposition, respectively. The peculiar kinetics of LR and PR experiments – that cannot be fully explained by other chemical or biochemical scenarios – were easily explained with this new hypothesis, i.e. limitation of the Fenton reaction may arise from the depletion of reactants, the build-up of ferric hydroxide on soil and excessive scavenging by the organic nutrients of the generated hydroxyl radicals. Reabsorption or adsorption of evolved or introduced CO2 may involve the formation of carbonate compounds (e.g., magnesium carbonate and bicarbonate) on the surface of alkalinized soil as a result of the Fenton reaction.A critical evaluation of the recent biological hypothesis assuming the utilization of a hydrogen peroxide–water intracellular fluid by putative organisms (Houtkooper &amp; Schulze-Makuch 2007) is also made.

Effect of nutrient sources on cucumber production in different substrates

The research was conducted in two successive seasons to compare the effect of nutrient sources, organic manure and inorganic conventional nutrient solution, in cucumber production performed with different local substrates. In fall, the experiment was designed to test three factors, namely cultivar [(a) Armada, (b) Gordion], nutrient source [(a) inorganic nutrient solution, (b) solid organic manure] and substrate [(a) 3 + 1 perlite + clinoptilolite, (b) 1 + 1 perlite + clinoptilolite, (c) 3 + 1 tuff + clinoptilolite, (d) 1 + 1 tuff + clinoptilolite, v/v]. Results showed that organic manuring decrease the total yield by 22.4% in comparison to inorganic nutrient solution. In organic manure treatment, vigorous variety (Armada) gave higher yield than less vigorous variety (Gordion). In the spring season, the tested factors were decreased to two and tested as nutrient source [(a) inorganic nutrient solution, (b) solid organic manure, (c) organic nutrient solution] and substrate. Armada was the only cultivar. Compared to that of the inorganic nutrient solution, total yield was reduced by 10.9% in the organic nutrient solution system and 31.3% in solid organic manure treatment.

(303) Challenges of Organic Hydroponic Production of Strawberries (Fragaria ×ananassa)

Feasible protocols for organic hydroponic production of strawberry are necessary and this study compares the yield and fruit quality of organic and conventional inorganic hydroponic production. Some issues identified with organic hydroponic strawberry production are: 1) dominant ammonium nitrogen form; 2) solution alkalinity; and 3) dissolved oxygen level of nutrient solution. Eighty bare-rooted `Diamante' plantlets were planted in coconut fiber pots with a mixture of coconut coir (30%) and perlite (70%) and grown in a modified nutrient film technique system inside a polycarbonate greenhouse. The organic nutrient solution contains mostly ammonium nitrogen and little nitrate nitrogen. To enhance colonization and activities of nitrifying bacteria, coconut fiber mats were placed in the organic nutrient solution reservoir. A similar system was also introduced for stock solution pre-conditioning where nitrification and pH stabilization were achieved before application to the strawberry plantlets. The organic nutrient solution prior to pre-conditioning had only 1.53 mg·L-1 nitrate nitrogen, although the nitrate nitrogen level increased to 63.2 mg·L-1 after pre-conditioning. The organic nutrient solution pH was 4.5 initially, 8.5 after 24 hours of pre-conditioning, and finally, shifted to and stabilized at 5.7–5.9 after 3 days. Dissolved oxygen level is critical for both nitrifying bacteria activities and plantlet root growth; therefore, oxygen enrichment was achieved by constantly aerating the nutrient solution in the reservoir, which raised the oxygen level from 2.5 to 7.4 mg·L-1. Comparisons of yield and quality of strawberry fruits between organic and inorganic nutrient solutions will be presented and further improvements of hydroponic systems will be discussed.

Effects of exogenous organic chelators on phytochelatins production and its relationship with cadmium toxicity in wheat ( Triticum aestivum L.) under cadmium stress

Phytochelatins (PCs) have been proposed as a potential biomarker for metal toxicity. In this study, cadmium (Cd) toxicity, PCs production and their relationship in wheat under Cd stress were examined using various exogenous organic chelator-buffered nutrient solutions. Single Cd stress produced strong toxic effects, as indicated by decreases of growth parameters, high level of lipid peroxidation in leaf and overproduction of PCs in root. Exogenous organic chelators with proper dose more or less reduced Cd toxicity by increasing growth parameters and decreasing lipid peroxidation in leaves. Of organic chelators (EDTA, DTPA, citric acid, malic acid and oxalic acid), EDTA was the most effective in decreasing Cd toxicity in plants, followed by DTPA and citric acid. Simultaneously, the concentrations of Cd-induced PCs in roots decreased, and the greatest decrease was caused by application of EDTA and DTPA. Linearly positive relationships were observed between Cd toxicity and root PCs concentrations under the influences of organic chelators, particularly EDTA, DTPA and citric acid. Furthermore, present results provide stronger evidence that PCs synthesis in plant cells was related to free Cd ion concentrations, not total Cd, and demonstrate that the levels of PCs production in plants correlated well with toxic effects caused by the bioavailable Cd levels.