Background In soils with a low phosphorus (P) supply, sugar beet is known to intake more P than other species such as maize, wheat, or groundnut. We hypothesized that organic compounds exuded by ...sugar beet roots solubilize soil P and that this exudation is stimulated by P starvation. Results Root exudates were collected from plants grown in hydroponics under low- and high-P availability. Exudate components were separated by HPLC, ionized by electrospray, and detected by mass spectrometry in the range of mass-to-charge ratio (m/z) from 100 to 1000. Eight mass spectrometric signals were enhanced at least 5-fold by low P availability at all harvest times. Among these signals, negative ions with an m/z of 137 and 147 were shown to originate from salicylic acid and citramalic acid. The ability of both compounds to mobilize soil P was demonstrated by incubation of pure substances with Oxisol soil fertilized with calcium phosphate. Conclusions Root exudates of sugar beet contain salicylic acid and citramalic acid, the latter of which has rarely been detected in plants so far. Both metabolites solubilize soil P and their exudation by roots is stimulated by P deficiency. These results provide the first assignment of a biological function to citramalic acid of plant origin.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Background and aims
The effects of root glutathione (GSH) supplementation on leaf chlorophyll, Fe concentrations and contents in leaves, stems and roots, and traits associated to Fe deficiency were ...studied in
Medicago scutellata
plants grown in rock sand under conditions of Fe deficiency, in the presence of different concentrations of bicarbonate.
Methods
Plants were grown in acid-washed rock sand irrigated with a zero Fe solution (pH 7.8 with 0.5 g L
−1
CaCO
3
) or a 45 μM Fe(III)-EDDHA solution (5 mM MES, pH 5.5), with 0, 5 or 15 mM NaHCO
3
, and 250 mL of 1 mM GSH was added daily to half of the pots.
Results
Iron deficiency caused characteristic symptoms in plants, with GSH supplementation relieving them. Glutathione supplementation led to increases in total Fe, chlorophyll and leaf total and extractable Fe, whereas root Fe concentrations decreased. Traits associated to Fe deficiency, including changes in biomass, root morphology, carboxylate contents and antioxidant parameters became less intense with GSH supplementation.
Conclusions
Glutathione supplementation allowed plants to take up Fe from the rock sand via a reductive solubilization mechanism. Also, the distribution of Fe within the plant changed, with more Fe being allocated to the shoot tissues and less to the roots.
This study investigated the impact of monovalent cations on clay dispersion, aggregate stability, soil pore size distribution, and saturated hydraulic conductivity on agricultural soil in Iran. The ...soil was incubated with treatment solutions containing different concentrations (0-54.4 mmol l
) of potassium and sodium cations. The treatment solutions included two levels of electrical conductivity (EC=3 or 6 dS m
) and six K:Na ratios per electrical conductivity level. At both electrical conductivity levels, spontaneously dispersible clay increased with increasing K concentration, and with increasing K:Na ratio. A negative linear relationship between percentage of water-stable aggregates and spontaneously dispersible clay was observed. Clay dispersion generally reduced the mean pore size, presumably due to clogging of pores, resulting in increased water retention. At both electrical conductivity levels, hydraulic conductivity increased with increasing exchangeable potassium percentage at low exchangeable potassium percentage values, but decreased with further increases in exchangeable potassium percentage at higher exchangeable potassium percentage. This is in agreement with earlier studies, but seems in conflict with our data showing increasing spontaneously dispersible clay with increasing exchangeable potassium percentage. Our findings show that clay dispersion increased with increasing K concentration and increasing K:Na ratio, demonstrating that K can have negative impacts on soil structure.
Filter cake is a valuable by-product generated during the process of making sugar from sugarcane in factories. The purpose of this experiment was to study the effect of different basic solutions on ...humic acid extraction rate. Chemical and spectroscopic characterization of humic acids extracted from filter cake has also been investigated. In this research, extraction and chemistry of humic acid have been studied in two separate experiments. In the first experiment, humic acid was taken from filter cake using the IHSS reference method in three concentrations (0.5 M, 1 M and 2 M) of KOH and two preparation liquids (water and vinasses) in the laboratory of the School of Environmental Sciences at the University of Guelph. Changes in the extraction rate of humic acid with type and concentration of base solution also were studied. In the second experiment, Fourier transform infrared (FTIR) and
13
C NMR were used to examine the chemistry of humic acid extracted from filter cake by 0.5 M KOH solutions (prepared using distilled water and vinasse). The results indicate that the highest extraction rate of humic acid was obtained when the 2 M KOH made from vinasse solution was used. Elemental analysis results, FTIR and NMR analyses as well as the E4/E6 ratio showed that all samples of extracted humic acid had similar chemical characteristics compared to the reference humic acid.
Purpose
The aim of this work was to test the hypothesis that Fe mining sub-products and thiols can alleviate a moderate Fe-deficiency in the Strategy I species soybean (
Glycine max
) grown in a ...calcareous soil in greenhouse conditions.
Methods
Combinations of three Fe sources Fe(III)-EDDHA and two Fe mining sub-products, one containing Fe oxides and FeS
2
and the other Fe oxides, and three thiols (glutathione, dithiothreitol and thiophenol) were applied in solution to the soil, three times in a 55 day period, and different parameters related to Fe deficiency were measured. The thiol-mediated solubilization of Fe from the Fe mining sub-products was assessed by measuring in the solution total Fe and the reducible Fe pool using an Fe(II) chelator.
Results
Application of Fe-EDDHA, the two Fe mining sub-products and the three thiols relieved the Fe deficiency symptoms to different extents, increased the Fe concentrations and contents throughout the plant and changed the redox state of leaves and roots, as judged from the changes in reduced and oxidized glutathione, ascorbate and antioxidant enzymes. When using Fe(III)-EDDHA, the addition of thiols led to a better leaf regreening. However, the addition of thiols did not cause further regreening in the case of the Fe mining sub-products, in spite of being able to solubilize Fe from them.
Conclusion
Application of Fe-mining sub-products, thiols and the combination of Fe(III)-EDDHA and thiols could be used to alleviate moderate Fe deficiency in
G. max
grown in a calcareous soil.
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•Plant-based hydrogels are inexpensive eco-friendly alternative to synthetics due to their biodegradable nature.•Lignin-based hydrogel synthesized from plant materials improves maize ...growth and alleviates water stress.•Application of lignin-based hydrogel in soil causes less leaf electrolyte leakage and proline accumulation in maize.•Plant leaf relative water content, biomass and total phosphorus content are higher in pots with lignin-based hydrogel.
Global water shortage is a crisis for all living systems, including agricultural cropping systems. Water absorbent hydrogels from synthetic polymers can retain moisture from irrigation or rainfall and release it in response to crop water demands, but have a limited functional lifespan and may release byproducts that are harmful to plants or pollute the soil environment. Hydrogels fabricated from plant-based polymers are more suitable for agricultural cropping systems because they could improve the soil water availability to the crop and gradually biodegrade to harmless carbon dioxide and water. The objective of this work was to determine how biodegradable lignin hydrogel affected the soil water availability to maize grown under drought conditions. The lignin hydrogel was applied at 0.3 % and 0.6 % (by weight) in pots subjected to water deficit or sufficiency, and compared to sodium polyacrylate hydrogel that was applied at the same rates. Maize plants were taller, had greater phosphorus content and more biomass when grown in soil with lignin hydrogel and sodium polyacrylate hydrogel than without hydrogel. Furthermore, soil receiving 0.6 % lignin hydrogel produced significantly (P < 0.05) greater maize biomass and relative leaf water content, with an 86 % reduction in leaf proline content and 10 % less electrolyte leakage under severe drought conditions than without hydrogel. There was more soil soluble Na and Na uptake by maize in the sodium polyacrylate-amended soil due to solubilization of the Na+ ions from the sodium polyacrylate. We recommend lignin hydrogel as a soil additive to increase water availability to crops experiencing drought stress that will not release undesirable byproducts into the cropping system.
There is a gap of knowledge for the fate, effects and bioavailability of coated and uncoated ZnO nanoparticles (NPs) in soil. Moreover, little is known about the effects of soil properties on effects ...of NPs on plants. In this study, the availability ZnO NPs in two soils with different organic matter content (one treated with cow manure (CM) and the other as untreated) was compared with their bulk particles. Results showed that coated and uncoated ZnO NPs can be more bioaccessible than their bulk counterpart and despite their more positive effects at low concentration (< 100mgkg−1), they were more phytotoxic for plants compared to the bulk ZnO particles at high concentration (1000mgkg−1) in the soil untreated with CM. The concentration of 1000mgkg−1 of ZnO NPs, decreased shoot dry biomass (52%) in the soil untreated with CM but increased shoot dry biomass (35%) in CM-treated soil compared to their bulk counterpart. In general, plants in the CM-treated soil showed higher Zn concentration in their tissues compared with those in untreated soil. The difference in shoot Zn concentration between CM-treated and untreated soil for NPs treatments was more than bulk particles treatment. This different percentage at 100mgkg−1 of bulk particles was 20.6% and for coated and uncoated NPs were 37% and 32%, respectively. Generally, the distribution of ZnO among Zn fractions in soil (exchangeable, the metal bound to carbonates, Fe-Mn oxides, organic matter and silicate minerals and the residual fraction) changed based on applied Zn concentration, Zn source and soil organic matter content. The root tip deformation under high concentration of NPs (1000mgkg−1 treatment) was observed by light microscopy in plants at the soil untreated with CM. It seems that root tip deformation is one of the specific effects of NPs which in turn inhibits plant growth and nutrients uptake by root. The transmission electron microcopy image showed the aggregation of NPs inside the plant cytoplasm and their accumulation adjacent to the cell membrane.
•ZnO NPs are more bioaccessible than bulk NPs.•Phytotoxicy of ZnO NPs are higher than bulk one.•ZnO NPs fraction in soil were influenced by Zn size and organic matter content.
•Application of treatments included different K:Na ratios created clay dispersion.•Pore size decreased due to migration of dispersed clay particles toward the pores.•Increase in plant available water ...because of increase in small pores.
The effect of K:Na ratio on plant available water (PAW), least limiting water range (LLWR), integral water capacity (IWC), penetration resistance and plant growth was assessed in this study. Treatment solutions including different K:Na ratios at two electrical conductivity levels (EC = 3 and 6dSm−1) were applied into an agricultural loamy soil in pots using capillary rise from the bottom, and the soil in the pots were kept at a water content close to field capacity for one month. In addition, maize was planted into the treated soils in three replicates. PAW, LLWR and IWC were calculated by soil available water calculator (SAWCal) software based on measurements of soil water retention and penetration resistance. In our study, LLWR was limited by PAW. The results showed that PAW of the treated soils increased significantly with increasing K:Na ratio in comparison with the control soil at both EC levels, due to increasing clay dispersion with increasing K:Na ratio. A reduction in the soil pore size due to migration of dispersed clay particles into soil pores could be a possible reason for the increase in PAW. Positive relations were found between PAW and meso-porosity and micro-porosity at both EC. Maize growth significantly increased with increasing PAW at EC = 6dSm−1. It can be concluded that the application of different K:Na ratios induced different degrees of dispersion of clay particles, which presumably migrated into soil pores, changing the soil pore size distribution towards smaller pores. This increased PAW in our studied soil, with positive effects on plant growth.
The application of permanent salt stress during fruit production has been suggested to restrict vegetative growth and improvement of fruit quality, especially sweetness. The present study was carried ...out due to the lack of application of increasing the electrical conductivity of a nutrition solution in a specific period in order to enhance the quality of strawberries grown in a soilless culture system. The investigated cultivars differed in their sensitivity to increasing nutrient solution concentration. Camarosa and Gaviota Cultivars in 120% temporary increasing the concentration of nutrient solution produced about 45.7% and 8.24% reducing yield, respectively, than the control. The highest SSC/TA (soluble solid content/titrable acidity) was observed in 80% (15.6%) and 120% (22.15%) of temporary increasing the concentration of nutrient solution treatments, compared to control. Also, the maximum of total anthocyanin content (33.38%) was observed in 120% of temporary increasing the concentration of nutrient solution treatment - Gaviota, compared to control. The finding of the present study showed that cultivar Camarosa and 120% of temporary increasing the concentration of nutrient solution treatment could improve strawberry fruit quality in soilless culture. Although, according yield in temporary increasing the concentration of nutrient solution condition, cultivar Gaviota tolerant was higher than cultivar Camarosa.
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•Few studies have examined the effects of Ca nano-fertilizers on pomegranate fruit yield and quality.•Fruit yield and quality of pomegranate trees have been assessed after two sprays ...with different Ca formulations, including a nano-fertilizer and CaCl2.•Ca foliar fertilization had no effects on pomegranate yield and only small effects on fruit quality.•A positive effect of Ca fertilizers in decrease pomegranate fruit cracking was found.•Low doses of a Ca nano-fertilizer were better than high doses of CaCl2 in reducing pomegranate fruit cracking.
An experiment was conducted to assess the effects of foliar sprays of a calcium fertilizer containing nanoparticles (nano-Ca) and calcium chloride (CaCl2.2H2O) on the yield and quality of pomegranate fruits cv. Ardestani, during two consecutive years, 2014 and 2015. The nano-Ca fertilizer was sprayed at concentrations of 0.25 and 0.50g Ca L−1, and CaCl2.2H2O was used at concentrations of 1 and 2% (2.73 and 5.45g Ca L−1), with treatments being applied twice, first at full blooming and then one month later. Calcium foliar fertilization did not have significant effects on yield, number of fruits per tree and average fruit weight, whereas it increased fruit length only in the case of the CaCl2 1% treatment in the first season. The untreated trees in the orchard were moderately affected by fruit cracking, with 6–7% of the fruits being affected. Calcium foliar treatment with the nano-Ca fertilizer at 0.50g Ca L−1 and 1% CaCl2 (in the both seasons) and also 2% CaCl2 (only in the second season) decreased significantly fruit cracking when compared with the control treatment, resulting in increases in marketable fruit yield. Foliar sprays with CaCl2 1% increased TSS by 7.6% only in the second season. Moreover, foliar nano-Ca fertilization at 0.50g Ca L−1 led to minor decreases (approximately 1%) in total phenolics only in the first season. Other chemical properties, including titratable acidity, fruit maturity, total sugar, antioxidant activity and total anthocyanin contents were not affected by Ca foliar fertilization. Leaf analyses show that Ca foliar treatments increased leaf Ca concentrations in the first season, with the exception of the low dose of nano-fertilizer, whereas the leaf concentrations of N, P, K, Fe, Zn and Mn were unaffected. In summary, fertilization with a low (0.50g Ca L−1) Ca concentration in the form of a nano-Ca formulation resulted in similar decreases in pomegranate fruit cracking than those obtained with higher doses of CaCl2 (2.73 and 5.45g Ca L−1).
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