The Effect of the Ionic Strength of Nutrient Solution on Gas Exchange,Ionic Concentration and Leaf Biomass of Annona emarginata (Schltdl.) H. Rainer Variety ‘Terra-Fria’ Seedlings

The present study aimed to test the hypothesis that different levels of the availability of mineral nutrients from Hoagland and Arnon's nutrient solution no. 2 affect the photosynthesis, ionic concentration and biomass production in seedlings of Annona emarginata (Schltdl.) H. Rainer variety ‘terra-fria’. Seedlings were grown in a hydroponic setting with 100% ionic strength and with ionic strength reduced to 75%, 50%, and 25%. Ionic strengths intermediate resulted in higher rates of carbon net assimilation and plants grown under these conditions increased biomass as well ionic concentrations of calcium, magnesium and sulfur. The ‘terra-fria’ plants with nutrient solutions of 50% and 75% ionic strength exhibited higher ionic concentrations, instantaneous carboxylation efficiency and biomass production. It can be concluded that the ‘terra-fria’ does not require the maximum mineral nutrients availability from Hoagland and Arnon's nutrient solution to achieve high primary productivity and intermediate ionic strengths can even reduce the time required for rootstock formation.     

Nutrient disorders of Dianthus ‘Bouquet Purple’

‘Bouquet Purple’ pinks (Dianthus sp.) were grown in silica-sand culture to induce and photograph symptoms of nutritional disorders. Plants received a complete modified Hoagland's all-nitrate (NO₃) solution. Nutrient-deficient treatments were induced with a complete nutrient formula minus one of the nutrients, and a boron (B)-toxicity treatment was induced by increasing B 10-fold in the complete nutrient formula. Plants were monitored daily to document sequential series of symptoms as they developed. Typical symptomology of nutrient disorders and corresponding tissue concentrations were determined. All treatments exhibited deficiency symptomology. Disorders for nitrogen (N), iron (Fe), calcium (Ca), and sulfur (S) were the first to manifest in pinks. Unique symptomology was observed for plants grown under potassium- (K), B-, copper- (Cu), and molybdenum- (Mo) deficient conditions, which supported the need for a species-specific approach when characterizing nutrient disorders of floriculture crops.     

Changes in Anthocyanin Content as Indicator of Maize Sensitivity to Selenium

The aim of this experiment was to examine the effect of exogenous selenium (Se) on anthocyanin and chlorophyll accumulation, Se content, as well as the growth of maize (Zea mays var. ‘saccharata Kcke’) cv. ‘Zlota Karlowa’ seedlings. Plants were grown hydroponically in Hoagland's nutrient solution at different pH values: 4.5, 6.2, and 7.5. Selenium was added to the solution as either selenate (Na₂SeO₄) or selenomethionine (C₅H₁₁NO₂Se) to a final concentration of: 0 (control), 5, 25, 50, and 100 μ M Se. Generally, the presence of Se in the medium caused an increase in the anthocyanin content and a simultaneous decrease of the total chlorophyll concentration depending on the Se form and dosage. Higher concentrations of anthocyanin were detected in the presence of selenomethionine than selenate, notably at pH 4.5. The effect of individual Se forms on maize seedlings, expressed on the basis of the fresh weight, indicate that selenomethionine was more phytotoxic than selenate. Selenium content both in roots and shoots increased linearly with increasing Se concentration in solution culture. However, a much higher Se level was found in the maize organs when plants were supplied with selenomethionine than selenate. Experimental evidence shows that the changes in anthocyanin content can be used as a test parameter reflecting the degree of Se toxicity in maize plants, and may be potential useful for bioindication of Se phytotoxicity in other higher plants.     

Capacity for biocompatibility assessment in tissue culture and hydroponic systems

In vitro and hydroponic intercropping systems were compared to examine the biocompatibility responses between ‘Fiona F₁’ tomato (Lycopersicon esculentum Mill.) and ‘Spunta’ potato (Solanum tuberosum). The biological response of monocultures (with four plantlets per vessel) of each species (including change in medium electrical conductivity (EC), osmotic potential (OS), and tissue mineral element content) were directly compared to intercropped cultures of the following tomato:potato; 1:1, 2:1, 3:1, 1:2, 1:3, and 2:2 plantlets per vessel. The in vitro intercropping systems were performed using a Murashige and Skoog (MS) shoot proliferation medium (5.0 μM BA and 0.5 μM IBA). The parallel hydroponic intercropping system was performed using a Hoagland's solution. Monoculture of both species grows better in both systems than intercropped species. In the intercropped vessels, tissue mineral content decreased, medium pH became more acidic, OS decreased and EC increased as compared to monocultures in parallel vessels. A lettuce seedling bioassay did not indicate evidence of allelopathic compound accumulation in either hydroponic or in vitro intercropped systems.     

EFFECT OF CADMIUM ON PHYSIOLOGICAL RESPONSES OF WHEAT AND CORN TO IRON DEFICIENCY

This work evaluated the effect of cadmium (Cd) on the physiological responses of corn (Zea Mays L.) and wheat (Triticum aestivum L.) to iron (Fe) deficiency. For this purpose, seedlings of corn and wheat were cultivated under controlled conditions, plants were grown in different strength Hoagland's solutions for one month. In the fifth week, some seedlings were still in full strength Hoagland's solution (+Fe) and others were in full strength Hoagland's solutions without iron (?Fe). The plants were exposed to different cadmium (Cd) concentrations for four days. The plant chlorophyll content of young leaves, Fe and Cd content in shoots and roots, biomass production, and phytosiderophores (PS) release by roots were assessed. Results showed that Cd decreased the chlorophyll content of young leaves, accompanied by a significant shoot and root biomass reduction for Fe-deficient and Fe-sufficient wheat and corn across all Cd treatments. However, chlorophyll content and shoot and root biomass of Fe-deficient wheat and corn were lower than Fe-sufficient plants at different Cd concentrations. Iron-deficiency induced Cd accumulation compared to Fe-sufficient in wheat and corn; however, a depressive effect of Cd on iron acquisition in shoots and roots of Fe-deficient and Fe-sufficient wheat and corn across all Cd treatments was observed. Cadmium also inhibited PS release in Fe-deficient and Fe-sufficient wheat and corn. Iron-deficient PS release was higher than Fe-sufficient corn and wheat across all Cd treatments. These results suggested that Cd might reduce capacity of plants to acquire iron from solution by inhibiting PS release.     

Growth and nitrate consumption of sunflowers in the rhizostat,a device for continuous nutrient supply to plants

A hydroponic system was designed in which the replenishment of nutrients is proportional to the consumption of nitrate or ammonium by higher plants. Further characteristics of this ‘rhizostat’ are on‐line measurement of nitrate or ammonium, bubble‐free aeration of the culture solution with pure oxygen, and auxostatic pH control at 6.00±0.1. Young sunflowers were grown in the rhizostat for up to 16 days. Leaf area, total fresh weight, root fresh weight, and nutrient demand per day increased exponentially. The rate of nitrate consumption per plant followed a characteristic diurnal pattern with maximal values at the end of the 12‐h photoperiod. After two weeks of growth, about 95% of the inorganic bound nitrogen removed from the nutrient solution was recovered in the biomass of the plants. Growth of sunflower seedlings over two weeks led only to slight but tolerable deviations of macronutrient and trace element concentrations from the formula of the nutrient solution. As expected, nitrate‐grown plants lowered potassium concentration, whereas growth with ammonium resulted in an accumulation of this ion. Other plants successfully grown in the rhizostat have been corn, soybean, sugarcane, tobacco, and spinach.     

Relationship between Phosphorus in Organic Growing Media and Its Uptake by Ryegrass

The supply of nutrients to plants from organic growing media depends on mineralization as the addition of inorganic nutrients is forbidden in certified organic systems. The objective of this study was to determine the relationship between total phosphorus (P), extractable (Olsen's) P, organic P, and biomass P in growing media and uptake of P by ryegrass. Three proprietary products were used alone and combined in 1:2 and 2:1 proportions to give nine growing media. Perennial ryegrass (Lolium perenne L. cv. ‘Choice’) was irrigated with a modified Hoagland's solution minus P, and the shoots were harvested after 28, 56, and 84 days. There was no significant correlation between the amounts of the different forms of P in the growing media and ryegrass dry weight or P concentration in harvested grass. However, total ryegrass P uptake was significantly positively correlated with initial total P and organic P in the growing media.     

Interactive effects of aluminum and chromium stresses on the uptake of nutrients and the metals in barley

Aluminum (Al) and chromium (Cr) stresses often occur simultaneously in agricultural soils, and pose a great damage to crop growth, yield formation and product safety. In the current study, the influence of combined Al and Cr stresses on plant biomass, metal and nutrient contents was determined in comparison with that of Al or Cr stress alone. A hydroponic experiment was conducted to investigate the effect of pH, Al and Cr in the medium solution on the uptake of mineral elements as well as Al and Cr in the two barley genotypes differing in Al tolerance. Aluminum sensitive genotype Shang 70-119 had significantly higher Cr and Al contents in plants than Al-tolerant genotype Gebeina. Barley roots had much higher Al and Cr contents than above-ground plant parts. Chromium contents were much higher in the solution with pH 4.0 than in that with pH 6.5. Aluminum stress reduced phosphorus (P), calcium (Ca), magnesium (Mg), sulfur (S), copper (Cu), manganese (Mn), zinc (Zn) and boron (B) contents in roots and restrained potassium (K) and iron (Fe) from being translocated into shoots and leaves. Chromium stress resulted in reduced P, K, Mg, S, Fe, Zn and Mn contents in roots at pH 6.5 and P, K, Ca, Mg, S, Zn and Mn contents at pH 4.0. Translocation of all nutrients from roots to upper parts of plants was inhibited except Ca in pH 6.5 with Cr addition. Lower contents of all nutrients were observed at pH 4.0 as compared to pH 6.5. Combined stress of Cr and Al, on the whole, caused further reduction in mineral content in all plant parts of the two barley genotypes as compared to Al or Cr stress alone. Moreover, the reduction was more pronounced in Al sensitive genotype Shang 70-119.     

NUTRIENT DISORDER SYMPTOMOLOGY AND FOLIAR CONCENTRATIONS OF CLERODENDRUM THOMSONIAE

Clerodendrum thomsoniae plants were grown in silica sand culture to induce and photograph nutritional disorder symptoms. Plants were grown with a complete modified Hoagland's all nitrate solution. The nutrient deficiency treatments were induced with a complete nutrient formula minus one of the nutrients. Boron toxicity was also induced by increasing the element ten times higher than the complete nutrient formula. Reagent grade chemicals and deionized water of 18-mega ohms purity were used to formulate treatment solutions. The plants were automatically irrigated and the solution drained from the bottom of the pot and captured for reuse. The nutrient solutions were completely replaced weekly. Plants were monitored daily to document and photograph sequential series of symptoms as they developed. Typical symptomology of nutrient disorders and critical tissue concentrations are presented. Plants were harvested for nutrient analysis when initial symptoms were expressed. Nutrient deficiency symptoms were described and foliar nutrient concentrations provided.     

Effects of Nickel on Growth and Composition of Metal Micronutrients in Barley Plants Grown in Nutrient Solution

Abstract

A hydroponic experiment was conducted in a phytotron at pH 5.5 to study the effects of nickel (Ni) on the growth and composition of metal micronutrients, such as copper (Cu), iron (Fe), manganese (Mn), and zinc (Zn), of barley (Hordeum vulgare L. cv. Minorimugi). Four Ni treatments were conducted (0, 1.0, 10, and 100 μM) for 14 d. Plants grown in 100 μM Ni showed typical visual symptoms of Ni toxicity such as chlorosis, necrosis of leaves, and browning of the root system, while other plants were free from any symptoms. Dry weights were the highest in plants grown in 1.0 μM Ni, with a corresponding increase in the chlorophyll index of the plants, suggesting that 1.0～10 μM Ni needs to be added to the nutrient solution for optimum growth of barley plants. The increase of Ni in the nutrient solutions increased the concentrations of Cu and Fe in roots, while a decrease was observed in shoots. The concentrations of Mn and Zn in shoots and roots of plants decreased with increasing Ni supply in the nutrient solution. Shoot concentrations of Cu, Fe, Mn, and Zn in plants grown at 100 μ M Ni were below the critical levels for deficiency. Plants grown at 1.0 μ M Ni accumulated higher amounts of Cu, Fe, Mn and Zn, indicating that nutrient accumulation in plants was more influenced by dry weights than by nutrient concentrations. The translocation of Cu and Fe from roots to shoots was repressed, while that of Mn and Zn was not repressed with increasing Ni concentration in the nutrient solution.     

Effect of B,Mn and Zn on nodulation and N2‐fixation in southernpeas

Abstract

Two greenhouse studies were conducted to evaluate the effect of B, Mn and Zn on nodulation and N₂‐fixation of southernpea (Vigna unguiculata (L.) Halp.) cultivars ‘Freezegreen’, ‘Mississippi Silver’ and ‘Pinkeye Purple Hull’. The cultivars were grown in plastic pots with a Norfolk sandy loam (fine, loamy siliceous thermic, Typic Paleudult) soil treated with B, Mn and Zn at rates of 0, 5, 10 and 20 kg/ha each at pH levels 5.5, 6.0 and 6.5. At pH 6.5 all micronutrient treatments significantly increased nodulation and N₂‐fixation over the control (no micronutrient applied). The effects of B, Mn and Zn on nodulation and N₂‐fixation depended on the cultivar and soil pH. For plants given the 5 kg/ha B and Mn treatments, ‘Mississippi Silver’ produced the highest number of nodules and ‘Pinkeye Purple Hull’ the least. At 20 kg/ha Zn, nodulation of ‘Freezegreen’ was highest and ‘Pinkeye Purple Hull’ the lowest. As a whole, maximum nodulation was at 5 kg/ha B and Mn and 20 kg/ha for Zn. Nitrogen fixation rates responded similarly except that the optimum rate for Zn was 10 kg/ha. Seed yield of plants peaked at 5 kg/ha for B and 10 kg/ha for Zn, indicating a possible relation of N₂‐fixation to seed yield.     

Mineral nutrient concentration and uptake by tomato irrigated with recirculating aquaculture water as influenced by quantity of fish waste products supplied

Fish and tomato (Lycopersicon esculentum Mill.) production were linked in a recirculaing water system. Fish (tilapia) were fed a commercial diet with 32% protein. Tomato cultivars ‘Laura’ and ‘Kewalo’ were grown during summer 1988 and spring 1989, respectively, in a Raleigh, NC greenhouse. Plants were grown in biofilters at 4 plants/m² and surface irrigated 8 times daily with water pumped from an associated fish tank. Four tank‐to‐biofllter ratios were established by varying the filter size. Each system received identical nutrient inputs and an equal quantity of water was applied per plant. Biofilter drainage returned to the tanks. Biological filtration, aeration, and mineral assimilation by plants maintained water quality within limits for tilapia. All nutrients were assimilated above deficiency levels. Tissue concentrations of N, P, K and Mg were not limiting. Calcium was low and S high when their sole nutrient source was fish waste. Micronutrients were assimilated in excess of sufficiency, but toxicity was not seen. Irrespective of fruit yield, metabolic products of each kilogram increase in fish biomass provided sufficient nutrient for two tomato plants for a period of three months. Under reduced growth rates of mature fish, K became limiting. Alterations in fish feed mineral nutrient content are suggested which better meet plant requirements and still remain within the range of fish needs.     

Soil fertilization and pH effects on meadowfoam growth and flowering 1

Meadowfoam (Limnanthes alba Hartweg ex. Bentham) is a new oilseed crop. Published information on nutritional requirements and optimum soil pH for growing meadowfoam in controlled environments is currently lacking. This study evaluated the effects of application rates and timing of a modified Hoagland's solution and a range in initial potting medium pH on meadowfoam (L. alba subsp. alba, cv Mermaid) growth and development under controlled environment conditions. Weekly application of 50 mL of nutrient solution at a nitrogen (N) concentration of 840 mg/L (four times higher than the concentration in modified Hoagland's solution) resulted in good Mermaid growth and flower production. Optimum fertilizer application timing is apparently from one week after transplanting (38 days after seeding) until the flowering stems begin to elongate above the rosette leaves. Optimum soil pH seemed to be between 5 and 6, although Mermaid grew relatively well under initial soil pH ranging from 3.8 to 7.3.     

Differential tolerance of canola to arsenic when grown hydroponically or in soil 1

Separate studies found canola tolerant to arsenic (As) when grown in hydroponic solutions and generally sensitive to As when grown in soil. Fourteen‐day‐old canola was transferred to pots containing either soil or nutrient solution and then grown for an additional 14 days in a growth chamber at different times for the two different media. Plants were grown in 0.25‐strength Hoagland's solution containing either 0, 0.27, 6.67, or 13.3μM As or in three soils with As added at rates of 0,5, and 10 mg.kg^‐1. Soil‐solution As concentrations were determined via column displacement and were the same or less (0.147 to 4.27μM) than the hydroponic As concentrations. Soil‐solution phosphorus (P) concentrations were determined in the same manner and averaged 9.28μM P compared to 500μM P from the hydroponic solutions. Chlorosis, wilting, and stunted growth—symptoms of As toxicity—occurred in canola at the highest As rate in two of the three soils used. Dry‐matter yields from the third soil were low from all treatments and a lack of response to As additions was probably due to injury from other soil‐related factors. Shoot As concentrations were generally similar from both experiments. Canola did not suffer a yield loss or exhibit As toxicity symptoms when grown in the hydroponic solutions. Leaf P was 8,000 mg.kg^‐1 in the hydroponically‐grown canola and 100 mg.kg^‐1 for the soil‐grown canola. These values are greater than (hydroponic) and lower than (soil media) sufficiency levels for plants similar to canola. High solution P concentrations in the hydroponic solution may have detoxified As by competing with As for uptake in the solution and during metabolism. Phosphate should be added to hydroponic solutions in As studies at levels close to normal soil P levels and added daily to replenish plant uptake.     

Response of foliar-applied nutrient solution with and without soil-applied fertilizers on growth and yield of mung bean

Hoagland's nutrient solution of 0, 25, 50, or 75% strength with or without soil-applied nitrogen, phosphorus, and potassium (NPK) fertilizers were sprayed at 7, 14, and 21 days after emergence on two cultivars (AZRI-2006 and NIAB-2011) of mung bean (Vigna radiata (L.) Wilczek). Hoagland's nutrient solution of 75% strength with soil-applied NPK fertilizers markedly increased the growth and yield of mung bean cultivars if applied at 21 days after crop emergence. However, 75% strength Hoagland's nutrient solution without soil-applied NPK fertilizers was comparable to 0, 25, and 50% strengths without NPK fertilizers. Foliar application of 75% strength of Hoagland's nutrient solution with soil-applied NPK fertilizers might enhance the yield of mung bean in low fertile areas. Performance of NIAB-2011 was superior to the other cultivar. It is concluded that Hoagland's nutrient solution of 75% strength can be sprayed at 21 days after emergence to get better yield of mung bean.     

INVESTIGATION OF SALINITY STRESS AND POTASSIUM LEVELS ON MORPHOPHYSIOLOGICAL CHARACTERISTICS OF SAFFRON

A greenhouse research experiment was conducted to investigate the effect of salinity stress and potassium (K) fertilization on biomass accumulation of roots and shoot of saffron plants. Treatments were four levels salinity in the form of sodium chloride (NaCl; 3.4, 6.4, 9.4 and 12.4 dS m^?1) and three levels of potassium (50, 100, and 150 % of Hoagland's nutrition solution base). Results indicated that higher levels of potassium significantly controlled the negative effects of NaCl on length and number of roots as well as fresh weight and number of leaves per plant. Increase in salinity and potassium levels caused a reduction in leaf water content, and enhancement in electrolyte leakage. It seems that in the presence of salinity increasing 50% extra potassium (Based on Hoagland's nutrient solution) in the rhizosphere of saffron can improve damaging effects of NaCl up to 9.4 dS m^?1 of soil solution.     

Influence of Aluminum on the Growth and Organic Acid Exudation in Alfalfa Cultivars Grown in Nutrient Solution

A study was conducted to evaluate the effects of aluminum (Al) in nutrient solutions on the dry weight (DW) yield, Al and phosphorus (P) contents, and organic acid exudation in alfalfa (Medicago sativa L.). Four alfalfa cultivars (‘Robust’, ‘Sceptre’, ‘Aquarius’, and ‘California-55’) were grown in nutrient solution at pH 4.5 and 6.0, with (50 and 100 μM) and without Al. The results revealed that Al caused a significant reduction in DW, especially in pH 4.5 treatment. Organic acid exudation was affected by pH and Al treatments. Citrate and succinate exudation increased with the high Al treatment at pH 4.5. However, no relationship between pH and carboxylate exudation was observed at pH 6.0. Accumulation of P and Al in roots suggests the existence of an exclusion mechanism for Al in alfalfa. Selection of cultivars with enhanced organic exudation capacity in response to Al might be useful for alfalfa production in moderately acidic soils.     

Mitigation of alkaline stress by arbuscular mycorrhiza in zucchini plants grown under mineral and organic fertilization

A greenhouse experiment was carried out during the spring–summer 2009 to test the hypotheses that: (1) arbuscular‐mycorrhizal (AM) inoculation with a biofertilizer containing Glomus intraradices gives an advantage to overcome alkalinity problems, (2) mineral fertilization is more detrimental to AM development than organic fertilization on an equivalent nutrient basis. Arbuscular mycorrhizal (AM) and non‐AM of zucchini (Cucurbita pepo L.) plants were grown in sand culture with two pH levels in the nutrient solution (6.0 or 8.1) and two fertilization regimes (organic or mineral). The high‐pH nutrient solution had the same basic composition as the low‐pH solution, plus an additional 10 mM NaHCO₃ and 0.5 g L^–1 CaCO₃. Increasing the concentration of NaHCO₃ from 0 to 10 mM in the nutrient solution significantly decreased yield, plant growth, SPAD index, net assimilation of CO₂ (A_CO2), N, P, Ca, Mg, Fe, Mn, and Zn concentration in leaf tissue. The +AM plants under alkaline conditions had higher total, marketable yield and total biomass compared to –AM plants. The higher yield and biomass production in +AM plants seems to be related to the capacity of maintaining higher SPAD index, net A_CO2, and to a better nutritional status (high P, K, Fe, Mn, and Zn and low Na accumulation) in response to bicarbonate stress with respect to –AM plants. The percentage root colonization was significantly higher in organic‐fertilized (35.7%) than in mineral‐fertilized plants (11.7%). Even though the AM root colonization was higher in organic‐fertilized plants, the highest yield and biomass production were observed in mineral‐fertilized plants due to the better nutritional status (higher N, P, Ca, and Mg), higher leaf area, SPAD index, and A_CO2.     

Symptomatology and analyses of nutrient deficiencies produced on flowering annual plants

Abstract

Deficiency symptoms were produced on 11 different flowering annual plants grown in sand cultures containing Hoagland's complete and nutrient deficient solutions. Visual observations were recorded and leaf analyses run to establish standard and threshold levels of important macro‐and micro‐elements.     

Growth and cadmium accumulation in two durum wheat cultivars

Abstract

A solution culture study was conducted to determine the effects of cadmium (Cd) application on Cd accumulation and growth of two durum wheat (Triticum turgidum L. var durum) cultivars. Arcola and DT618 were grown in nutrient solution for 13 days. Cadmium application to nutrient solution significantly (P ≤ 0.05) decreased root and shoot biomass, leaf area, leaf mass, total root length, and chlorophyll a and b concentration of the first leaf. The deleterious effects of Cd on plant growth were explained by a modified version of Weibull distribution function of the form, y = a.exp(b.√Cd), where ‘y’ is the growth parameter, ‘a’ is plant growth in the absence of Cd, and ‘b’ is reduction in growth with per unit increase in solution Cd. Total root length was decreased the most (80%) and chlorophyll b concentration of the first leaf decreased the least (9%) with per unit increase in solution Cd. Although the two cultivars were significantly different in some growth characteristics, both responded similarly to increase of Cd concentration in solution. Cadmium concentration in roots and shoots increased significantly (P ≤ 0.05) with Cd application, but due to concomitant decrease in growth the Cd content of plants remained constant at solution Cd concentrations of 5 μm or above. We concluded that seedlings of durum cultivars with different growth potential responded similarly to Cd application in nutrient solution.