Spinach Biomass Research Articles

Interactive effect of cadmium and zinc on chromium uptake in spinach grown in Vertisol of Central India

A pot culture experiment was conducted to study impact and interaction of multi-metals on growth, yield and metals uptake by spinach (variety All Green). Three levels of each chromium (0, 50 and 100 mg/kg), cadmium (0, 1 and 2 mg/kg) and zinc (0, 10 and 20 mg/kg) in combinations (total treatments 3 × 3 × 3 = 27) were applied in a Vertisol (5 kg). The results showed that increasing the concentration of chromium, cadmium and zinc in soil enhanced the respective metal concentrations in spinach root and shoot. When cadmium at 2 mg/kg along with chromium at 100 mg/kg soil was applied, chromium concentration and uptake were decreased in root and shoot. Meanwhile, zinc application had no significant effect on chromium uptake and concentration in spinach biomass. From the results, it was concluded that cadmium at higher dose had an antagonistic effect over chromium. On the other hand, in chromium, cadmium and zinc combinations particularly at their higher levels, a competition among each other was found. Therefore, the findings could be used as guidelines for controlling and management of heavy metals pollution in farmland.

Spinach biomass yield and physiological response to interactive salinity and water stress

Critical shortages of fresh water throughout arid regions are forcing growers to decide among the following options, applying insufficient fresh water, causing water stress, applying saline water causing salt stress or applying some combination minimizing saline water application, causing combined water and salt stress. A comprehensive approach to manage drought and salinity is to evaluate the impact of water stress and salt stress individually and then examine their interactions on plant production. To analyze salinity and water stress responses and their interaction together on spinach growth, an experiment was conducted from April 1 to May 21, 2013, using 6 different irrigation waters at electrical conductivity (EC): 0.85, 4, 7, 9, 12, 15dSm−1. Soil moisture was recorded by sensors and stress treatments had the following soil water matric pressure control (−45kPa), −200 to −300kPa, and −400 to −500kPa. We evaluated three replicates per treatment for yield, vegetative parameters, ion composition, and physiological parameters. The results showed that the spinach yield response to salt and water stress was very different. Spinach yield initially increased with salinity and subsequently decreased only when the irrigation water was EC 9dSm−1and above (osmotic pressure of −310kPa). In contrast, yield decreased at the first water stress level (−230kPa) relative to control. The additional presence of salinity stress decreased the relative yield response due to water stress. Similarly under water stress the relative yield response to increasing salinity was reduced. Although no model provided good prediction of stress response, the best predictive model (relative error) was one that considered the response to multiple stresses as the product of the response to the individual stresses.

Limestone-Mediated Suppression of Fusarium Wilt in Spinach Seed Crops.

Fusarium wilt of spinach is caused by the soilborne fungus Fusarium oxysporum f. sp. spinaciae and occurs in most regions of spinach production. The disease is favored by acid soils and warm temperatures, and the fungus can survive extended periods as chlamydospores or by asymptomatic colonization of the roots of nonhost plant species. The 10- to 15-year rotation required to minimize losses to Fusarium wilt is the primary constraint on spinach seed production in the maritime Pacific Northwest, the only region of the United States suitable for this cool-season, daylength-sensitive crop. Raising soil pH with agricultural limestone (97% CaCO3) results in a transitory, partially suppressive effect on spinach Fusarium wilt. A field trial was completed from 2009 to 2012 to assess the potential for annual applications of agricultural limestone at 0, 2.24, and 4.48 tons/ha for 3 years prior to a spinach seed crop to improve Fusarium wilt suppression compared with the level of suppression attained from a single limestone amendment at 4.48 tons/ha. Three proprietary female spinach lines were planted that ranged from highly susceptible to partially resistant to Fusarium wilt. Three successive annual applications of limestone at 4.48 tons/ha reduced midseason wilt incidence by an average of 20%, increased spinach biomass by 33%, and increased marketable spinach seed yield by 45% compared with plots amended once with the same rate of limestone in the spring of planting. The suppressive effect increased with increasing rate of limestone amendment, with the greatest difference observed when limestone was applied at between 0 and 2.24 tons/ha annually for 3 years. The effects on seed yield were greatest for the partially resistant female line, followed by the moderately susceptible and highly susceptible female lines. Overall, the results demonstrate that annual applications of agricultural limestone on acid soils of the maritime Pacific Northwest of the United States can enhance suppression of spinach Fusarium wilt, potentially reducing the required rotation interval by as much as 50%, thereby doubling the capacity for spinach seed production in the United States.

Contrasting plant–microbe interrelations on soil Di-(2-ethylhexyl) phthalate and pyrene degradation by three dicotyledonous plant species

ABSTRACTPlants and associated microbial communities can actively participate in the biodegradation of organic pollution. Potexperiments were conducted to explore the plant–microbe interrelations on Di-(2-ethylhexyl) phthalate (DEHP) and pyrene degradation in a soil culture system. Three dicotyledonous plant species, Ceylon spinach (Gynuracusimbua (D. Don) S. Moore), sunflower (Helianthus annuus L.), and Shuidong mustard (Brassica juncea (L.) Coss.var. foliosa Bailey), were cultivated for 45 days in DEHP and pyrene co-contaminated soils using three initial content levels: 0 (T0), 20 (T20) and 50 mg kg−1 (T50) with no plants (NP) as control. The results demonstrated that Shuidong mustard biomass and sunflower biomass had significantly positive correlations with the removal rate of DEHP (P < .05), respectively, while Ceylon spinach biomass has no significant correlation with the removal rate of DEHP. Shuidong mustard–actinomycetes and Ceylon spinach–actinomycetes accelerated the removal rate of pyrene, and sunflower–gram-positive bacteria could also enhance the removal rate of pyrene. Our results suggest that a better understanding of plant–microbe interrelations could be exploited to enhance the phytoremediation of organic co-contaminated soils.

Utilization of biochar and activated carbon to reduce Cd, Pb and Zn phytoavailability and phytotoxicity for plants

In the present study, the content of risk elements and content of free amino acids were studied in spinach (Spinacia oleracea L.) and mustard (Sinapis alba L.) subsequently grown on uncontaminated and contaminated soils (5 mg Cd/kg, 1000 mg Pb/kg and 400 mg Zn/kg) with the addition of activated carbon (from coconut shells) or biochar (derived from local wood residues planted for phytoextaction) in different seasons (spring, summer and autumn). The results showed that activated carbon and biochar increased biomass production on contaminated site. Application of amendments decreased Cd and Zn uptake by spinach plants. Mustard significantly increased Pb accumulation in the biomass as well in subsequently grown autumn spinach. Glutamic acid and glutamine were major free amino acids in leaves of all plants (15–34% and 3–45%) from total content. Application of activated carbon and biochar increased content of glutamic acid in all plants on uncontaminated and contaminated soils. Activated carbon and biochar treatments also induced an increase of aspartic acid in spinach plants. Biochar produced from biomass originated from phytoextraction technologies promoted higher spinach biomass yield comparing unamended control and showed a tendency to reduce accumulation of cadmium and zinc and thus it is promising soil amendment.

The role of exogenous humic and fulvic acids in iodine biofortification in spinach (Spinacia oleracea L.)

The strong sorption of iodine in soils is a major factor that limits its uptake by plants. The aim of this study was to evaluate the influence of Humistar (a concentrate of exogenous humic acids 12 % w/w and fulvic acids 3 % w/w; abbreviated: HU) applied with KI or KIO3 on the efficiency of iodine biofortification, yield and the accumulation of undesirable compounds in spinach. Methods of iodine application with or without HU were tested in two pot experiments and a hydroponic study with spinach cultivation. The spinach biomass and the content of iodine, soluble oxalates, Cd and Pb in leaves were determined. The physicochemical properties and chemical composition of the soil and media were analysed. No negative influence of iodine and HU on spinach yield was observed. Fertigation with iodine resulted in a higher efficiency of iodine biofortification than its application pre-sowing (particularly for KIO3), with no increase in the Cd and Pb content in spinach plants compared to the control. The improvement of iodine uptake and root-to-leaf transfer (represented by higher transfer factor values) in spinach can be obtained by the application of HU via plant fertigation with IO3 −. The level of soluble oxalates in spinach grown in the pot experiments was not affected.

Effects of Nitrogen and Calcium Nutrition Withdrawal Before Harvesting on Biomass and Nutritive and Safety Quality in Spinach (Spinacia Oleracea L.)

A hydroponic culture was used to study different nitrogen and calcium supply patterns on biomass, nutritive, and safety quality of spinach seven days before harvesting. The results showed that the complete or partial withdrawal of nitrogen (N) and calcium (Ca) nutrient decreased spinach biomass compared to control (CK). At the same time, the withdrawal of N and Ca supply before harvesting increased vitamin C contents and decreased nitrate and oxalate content in edible parts of spinach. The decrease in spinach biomass could be partially compensated by the increase of the nutritive and safety quality of spinach and the reduced use of N and Ca nutrients.

A Study of Nitrogen Cycle in an Integrated Aquaponic System with Different Plant Densities

Introduction: There is no doubt that a fundamental element like nitrogen is one of the most important components in both animal and plants cells. Within an integrated aquaponic system, nitrogen cycle has highest priority because it converts fish wastes into nutrients for plants. Aims: The main goal of this study is to quantify the nitrogen budget for an integrated rainbow trout - spinach aquaponic system, where three plants densities were used. The second objective is to determine a balanced plant density for optimal nitrogen removal rate and hydroponic vegetable production. Materials and methods: The experimental design consist in a recirculating aquaculture system with 12 growing units, mechanical and biological water treatment units and four aquaponic units. Three plants densities were used (V1 - 59plants/m 2 , V2 - 48plants/m 2 and V3 - 39plants/m 2 and a control variant V4). Fish were fed with two types of feed (41% and 50% protein), using 3 different feeding regimes. Water samples were taken and analysed by using Merck kits so that nitrate, ammonium and TAN retention rates will be observed. Water oxygen, pH and conductivity levels were also monitored. The meat, plants and faeces nitrogen content was determined by Kjeldahl method. The feed protein content was verified using the same method. Results: The amount of nitrogen removed from integrated aquaponic system through biological filtration and also by each of the three tested spinach biomass densities was determined apart. The nitrate, ammonium and TAN retention rates, as water passes through mechanical filter, were found to be insignificant (p>0,05), compared to ones from the biological filter that were higher. Differences between the retention rates for each of the three variants of tested plants densities were significant higher (p<0,05) at V1 compared to V3 and also higher at all three variants comparing them to the control variant. Also differences between plants nitrogen composition from V3 compared to V1 were found significant higher (p<0,05). The content of nitrogen from fish meat and fish faeces was found to be according to literature. Conclusion: In the present study, nitrate, ammonium and TAN retention rates were found to be related in a certain way with plants density and total nitrogen input in the aquaponic system, facts that also influence the plants nitrogen content. It is recommended higher plants densities to be used and also a better light intensity can be also used.

Development and Evaluation of a TaqMan Real-Time PCR Assay for Fusarium oxysporum f. sp. spinaciae.

Fusarium oxysporum f. sp. spinaciae, causal agent of spinach Fusarium wilt, is an important soilborne pathogen in many areas of the world where spinach is grown. The pathogen is persistent in acid soils of maritime western Oregon and Washington, the only region of the United States suitable for commercial spinach seed production. A TaqMan real-time polymerase chain reaction (PCR) assay was developed for rapid identification and quantification of the pathogen, based on sequencing the intergenic spacer (IGS) region of rDNA of isolates of the pathogen. A guanine single-nucleotide polymorphism (G SNP) was detected in the IGS sequences of 36 geographically diverse isolates of F. oxysporum f. sp. spinaciae but not in the sequences of 64 isolates representing other formae speciales and 33 isolates representing other fungal species or genera. The SNP was used to develop a probe for a real-time PCR assay. The real-time PCR assay detected F. oxysporum f. sp. spinaciae at 3-14,056 CFU/g of soil in 82 soil samples collected over 3 years from naturally infested spinach seed production sites in western Washington, although a reliable detection limit of the assay was determined to be 11 CFU/g of soil. A significant (P < 0.05), positive correlation between enumeration of F. oxysporum on Komada's agar and quantification of the pathogen using the TaqMan assay was observed in a comparison of 82 soil samples. Correlations between pathogen DNA levels, Fusarium wilt severity ratings, and spinach biomass were significantly positive for one set of naturally infested soils but not between pathogen DNA levels, wilt incidence ratings, and spinach biomass for other soil samples, suggesting that soilborne pathogen population is not the sole determinant of spinach Fusarium wilt incidence or severity. The presence of the G SNP detected in one isolate of each of F. oxysporum ff. spp. lageneriae, lilii, melongenae, and raphani and reaction of the real-time PCR assay with 16 of 22 nonpathogenic isolates of F. oxysporum associated with spinach plants or soil in which spinach had been grown potentially limits the application of this assay. Nonetheless, because all isolates of F. oxysporum f. sp. spinaciae tested positive with the real-time PCR assay, the assay may provide a valuable means of screening for resistance to Fusarium wilt by quantifying development of the pathogen in spinach plants inoculated with the pathogen.

Effects of NH4+-N/NO3--N ratios on growth, nitrate uptake and organic acid levels of spinach (Spinacia oleracea L.).

The objective of this investigation was to study the effects of NH 4 + -N/ NO 3 - -N ratios on the growth of spinach, the nitrate and organic acids contents of spinach fresh shoot. A completely randomized design was established as 5 treatments, that is, NH 4 + -N/ NO 3 - -N ratio of 100/075/25, 50/50, 25/75 and 0/100, the total N concentration was 12 mmol l -1 . Each treatment had 3 replications, results showed that the spinach biomass significantly (P = 0.05) decreased as the NH 4 + -N/ NO 3 - -N ratio was above 50:50 in nutrient solution. Spinach supplied with NO 3 - -N as its sole nitrogen source had the highest biomass, but there was no notable difference (P = 0.05) in dry matter weight between 25: 75 and 0:100 of NH 4 + -N/ NO 3 - - N ratio. A strongly (r = 0.9826) positively linear relationship was found between the nitrate content of spinach fresh shoots and the proportion of NO 3 - -N in total nitrogen. When the NH 4 + -N/ NO 3 - -N ratios was decreased from 100:0 to 0:100, the pyruvate, citrate, succinate, fumarate contents were all increased gradually and the malate content was highest at NH 4 + -N/ NO 3 - -N ratio of 25:75. The water soluble oxalate content of the spinach fresh shoot at either NH 4 + -N or NO 3 - -N as sole nitrogen resource, was higher than other combinations of NO 3 - -N and NH 4 + -N and, for example, the soluble oxalate content was significantly (p = 0.05) decreased by 8% when 25% of NO 3 - -N was replaced by NH 4 + -N. In conclusion, some replacement of NO 3 - -N by NH 4 + -N could improve the spinach quality while the dry biomass was not significantly affected.

Development of a procedure for the sequential extraction of substances binding trace elements in plant biomass

This work investigates how the amounts of some important substances in a plant, and their behaviour inside the plant, depend on the levels of stress placed on the plant. To this end, model plant spinach (Spinacia oleracea L.) was cultivated on soil treated with sewage sludge. The sewage sludge contained various trace elements (As, Cd, Cu, Zn), and the uptake of these trace elements placed the plant under stress. Following this, a sequential extraction procedure was employed to determine the levels and distributions of trace elements within the most important groups of compounds present in the spinach plants. Since the usual five-step sequential extraction procedure provides only general information on the distributions of elements within individual groups of organic compounds, due to the wide range of organic compounds within the individual fractions, this scheme was extended and improved through the addition of two solvent extraction steps-a butanol step (between the ethyl acetate and methanol solvent steps) and an H(2)O step (after the methanol+H(2)O solvent step). The distributions and levels of the trace elements within the main groups of compounds in spinach biomass was investigated using this new seven step sequential extraction (water free solvents: petroleum ether (A) --> ethyl acetate (B) --> butanol (C) --> methanol (D) --> water solvents: methanol+H(2)O (1+1; v/v) (E) --> H(2)O (F) --> methanol+H(2)O+HCl (49.3+49.3+1.4; v/v/v) (G)). The isolated fractions were characterized using IR spectroscopy and the trace element contents were determined in the individual fractions. Lipophilic compounds with low contents of Cd, Cu and Zn were separated in the first two fractions (A, B). Compounds with higher As contents (11.5-12.8% of total content) were also extracted in the second fraction, B. These two fractions formed the smallest portion of the isolated fractions. Low molecular compounds from secondary metabolism and polar lipids were separated in the third (C) and fourth (D) fractions, and high molecular compounds (mainly polypeptides and proteins) separated in the fifth and sixth fractions (E, F). The addition of the H(2)O solvent step was particularly useful for separating compounds that have a significant impact on trace element bounds. The methanol fraction was dominant for all treatments, and a significant decrease in the spinach biomass separated in this fraction was observed when the soil was treated with sewage sludge. Most of the As (35.5-38.8% of total content), Cu (45.0-51.6%) and Zn (39.8-47.2%) was also determined in this fraction. The G fraction (obtained after acid hydrolysis) contained polar compounds. Most of the Cd was also found in this fraction, as was a significant amount of Zn. Non-extractable residues formed the last fraction (polysaccharides, proteins).

The effect of Cd and Zn contents in plants on Fe binding into organic substances of spinach biomass

Partial characterization of iron binding compounds in spinach above ground biomass and differences between binding of Cd, Zn and Fe in spinach biomass were investigated on two soils treated by sewage sludge in model pot experiment. After application of sludge to both soils, Cd and Zn accumulation in spinach biomass was increased in sludge treatments. Total Fe content in biomass showed opposite trend with these treatments and was decreased 2.5&amp;ndash;2.7 fold. Results of sequential analysis of spinach biomass showed lower portions of iron in all individual fractions of both sewage sludge treatments compared to control treatments. The largest differences in iron content between control and sludge treatments were determined in ethyl acetate fraction. While majorities of Cd and Zn were found in fractions methanol + H2O and H&lt;sub&gt;2&lt;/sub&gt;O and methanol + H&lt;sub&gt;2&lt;/sub&gt;O + HCl, iron content determined in these two fractions was only 7&amp;ndash;8% in control treatments and 15&amp;ndash;20% in sludge treatments of total iron. In fraction, Fe portion was 87.7&amp;ndash;90.7% in treatments without sludge and 76.1&amp;ndash;83.5% in sludge treatments in spinach biomass. Results showed tighter iron binding to plant cell membranes in contrast to cadmium and zinc.

The effect of soil properties on cadmium bonds to organic substances of spinach biomass

AbstractThe main objective of this study was focused on sequential fractionation of spinach biomass, partial characterization of cadmium‐binding compounds and determination of the cadmium concentration in these fractions. Spinach was cultivated after application of sewage sludge on two soils of different properties and total cadmium content in a model pot experiment. Two non‐polar solvents (light petroleum and ethyl acetate), a polar solvent (methanol) and two solvent mixtures (methanol + H2O &amp; H2O and methanol + H2O + HCl) were used in the extraction series. Isolated fractions were characterized by IR spectroscopy. The lower weight of light petroleum (aliphatic hydrocarbons), ethyl acetate (fatty acids), and methanol (carboxylic acids, mainly acids of citric cycle, pyrrole substances) fractions in sludge treatments compared with the controls showed that the metabolism of plant natural products was inhibited by toxins from sludge. The weight of methanol fraction was dominant for all treatments. The cadmium determined in these fractions was low. The majority of cadmium was found in the methanol + H2O &amp; H2O (oligopeptides, mainly phytochelatins, extractable polypeptides, proteins) and methanol + H2O + HCl (compounds isolated from cell walls and cytoskeleton after hydrolysis) fractions. The effect of toxin stress only appears to be on the quantity of substances, as there is no qualitative change observed in the isolated fractions (measured values of IR spectra bands did not differ for treatments tested). The application of sequential analysis for spinach biomass extraction makes it possible to investigate the complex effects of cadmium and other toxins on plant metabolism. Copyright © 2002 John Wiley &amp; Sons, Ltd.