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1.
Fedoseeva Elena Stepanov Andrey Yakimenko Olga Patsaeva Svetlana Freidkin Mikhail Khundzhua Daria Terekhova Vera 《Journal of Soils and Sediments》2019,19(6):2676-2687
Purpose
The study of interactions between humic substances (HSs) and soil filamentous fungi is the key to understanding the sustainable soil functioning. The present work aims to examine the decomposition of HSs by filamentous dark-pigmented fungus Alternaria alternatа under the laboratory conditions and to determine the effect of easily assimilable organic carbon on this process. Analyzing such polydisperse substances like HSs by a complex integrated methodology makes it possible to explore the data on their decomposition by microorganisms.
Materials and methodsTo achieve the aforementioned goals, we used chromatographic and spectroscopic approaches: low-pressure size-exclusion and hydrophobic interaction chromatography accompanied by absorption and fluorescence spectroscopy. To determine the effect cometabolism conditions produced on HS decomposition, two types of carbon substrates were added to the nutrient media: easily assimilable organic carbon (standard 0.3% or reduced 0.03% sucrose content) and hardly assimilable organic carbon (HSs), as well as their combinations. Five HS samples of different organic matter origin have been inspected: potassium humates (HPs) and humic acids (HAs) from coal, peat, and lignosulfonate. Correlation matrix and principal component analysis (PCA) were calculated for comprehensive data analysis.
Results and discussionTransformations of the investigated HSs under fungal cultivation lead to the increase in the low molecular weight fraction, rise of hydrophilic fraction, enlargement of absorbance ratio A250/A365, shortening of the emission wavelength of the humic-type fluorescence, and growth in the fluorescence quantum yield measured with excitation at 355 nm. A positive correlation was observed between the accumulation of fungal biomass and the degree of HS decomposition. PCA analysis confirms that the difference in the results of HS decomposition largely depends on the sucrose content and the nature of HSs. We divided all the HS samples into four groups according to the degree of HS decomposition: original HS solutions, HPs altered using fungal cultivation at 0.03% sucrose, HAs after fungal cultivation at 0.03% sucrose, and finally, HSs (both HPs and HAs) after fungal cultivation at 0.3% sucrose.
ConclusionsIn the laboratory experiments, we showed that (1) the isolated HAs were more effectively degraded than the parent HPs, and this process was more pronounced at a reduced sucrose content, and (2) the decomposition of stable organic compounds (HSs) was activated by the easily assimilable carbon sources (especially 0.3% sucrose) being present. We assume that it is the easily assimilable organic carbon that most likely triggers the HS degradation working as the priming effect in natural environments.
相似文献2.
《Communications in Soil Science and Plant Analysis》2012,43(9-10):1529-1545
Mechanisms of macroaggregation, carbon dynamics, and carbon sequestration were investigated in degraded mine tailings. Humic substances (HSs), wheat straw, lime, and their various combinations were added to the mine tailings and then incubated at 20 °C for 24 weeks. A significant increase (up to 79%) of water‐stable macroaggregates was observed in the HS‐amended tailings after the incubation. During the macroaggregation, 20–33% sand of the mine tailings was bound by HS‐derived active carbon pool. The organic carbon concentration of the macroaggregates significantly increased in the HS‐amended mine tailings compared to the control. Mineral‐associated organic matter carbon derived from the HSs was mainly responsible for the increased concentration of macroaggregate carbon and the increased amount of macroaggregates as well. This active pool of added organic matter was sequestered in aggregates during the process of macroaggregation and thus improved the structure of the mine tailings. 相似文献
3.
Scope and Goal Humic substances (HSs) are the product of microbial degradation, chemical polymerisation and oxidation of organic matter.
HSs can be divided into different fractions: humic acid (HA), hymatomelanic acid (HMA), fulvic acid (FA) and humin. HSs play
a fundamental role in accumulation and exchange processes of chemical compounds (metals and organic pollutants) in the environment.
HSs can form soluble complexes that migrate long distances or precipitate, carrying bound cations with them. The migration/precipitation
abilities depend on the metal ion, the ion charge, the degree of ionisation of the organic molecule, the ionic strength of
the media, and the location of the metal ion.
Objective Estonia is rich in the Baltic Sea and lake sediments. Historically, mud has been used in human treatment as a curative mud.
High-molecular HSs are an important part of curative mud and they have a strong effect on its properties. The curative mud
which is used in human therapy may not be polluted with different organic and inorganic contaminants. The aim of this work
is to characterise and compare HSs isolated from the Baltic Sea mud (Haapsalu Bay) and from the sediments of Lake Ermistu
(Estonia).
Results and Conclusions We determined the yield of basic extraction of different HSs components from mud in the course of separation. We found that
acid pre-treatment of mud increased the amount of extracted HSs more in the sea mud than in the lake mud. These results show
that HSs are bound to the inorganic/organic structure of mud and are released during prolonged treatment with an acid.
We performed elemental analysis of the different fractions of HS extracts. HMA fractions had the highest carbon content and
the lowest nitrogen content. HMA contains more polysaccharides than amino acid residues. These subunits may cause a better
solubility of HMA in water as compared to HA. Acid pre-treatment of the natural sea and the lake mud diminished the content
of carbon in most of the HS fractions. The content of nitrogen in the sea and in lake FA diminished by about two times.
We determined the metal content in the mud and its HS fractions. We found that the concentration of heavy metals Pb and Cr
is lower than <0.08 mg/kg. As expected, the total metal concentration is considerably lower in the lake than in the sea mud.
Acid pre-treatment of mud shows that the sea HA forms more stable Fe and Mg complexes, while the sea HMA contains more stable
Zn and Cu complexes. The lake HSs result in more stable Mg complexes with HA and HMA fractions. Sea FA binds Cu and Mg better,
but lake FA is more effective in binding Zn. To compare the amount of metals extracted from HA, HMA, FA (with that, remains
in HS fractions), the metal concentration in the alkaline full extract of the sea mud was determined. Alkaline treatment removed
0.8% Mg, 7.9% Cu, 5.2% Zn and 3.8% Fe together with HSs from the sea mud, the rest remained in humin and in the mineral part
of the mud. The following work-up was additionally carried out for most of the metals. So, we found that there was only 1.7%
of Fe, 2.1 % of Mg, 23.2% of Zn and 45.2% of Cu left in HA, HMA and the FA fraction (as a sum) from the total amount of those
metals in HSs. This means that Cu is the metal most strongly bound to HSs. On the bases of HS separation data we found that
the order of stability of the metal-humate complexes is Cu>Zn>Mg>Fe.
The ultraviolet spectra of HA, HMA and FA revealed that HMA had the biggest molar absorption and calculated aromaticity. Recommendations
and Outlook. The characteristics of HSs, isolated from the Baltic Sea and Lake Ermistu mud reveal the difference of HSs from
the sea and the lake mud. Also, different properties of HS fractions are observed. Metals are concentrated variously in different
HS fractions. In all cases the content of Pb and Cr was low, meaning that the mud preparations are nontoxic in respect to
these metals. The order of stability of metal-humate complexes is Cu>Zn>Mg>Fe. The order of affinity of metals to HS fractions
obtained have to be extended to other metals of environmental interest. The ability of HSs to bind metals may make them a
candidate for natural, environmentally safe substances to concentrate hazardous metals and to remove them from natural water
reservoirs. 相似文献
4.
Lignite‐derived humic substances modulate pepper and soil‐biota growth under water deficit stress
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下载免费PDF全文 Organic matter‐derived soil amendments containing humic substances (HS) have a functional role to improve plant growth and soil quality, but their response to water deficit stress is less reported, particularly in vegetable crops. This study assessed the impact of lignite‐derived HS on biota growth and evaluated their potential mitigative effects under water deficit stress in growth chamber and greenhouse environments. Bell pepper (Capsicum annuum L. cv. Revolution) plants were grown in sandy and clay soil previously mixed with lignite‐derived HS and subjected to four irrigation levels (20%, 40%, 60%, and 80%) based on soil water‐holding capacity. Plant growth traits, soil chemical properties, and microbial populations were measured and analyzed. HS increased plant root development and soil bacteria population in moderate and no stress conditions (60%, 80%). Physiologically, HS rapidly decreased leaf stomatal conductance and transpiration after imposing severe or mild stress (20%, 40%). The results indicate that HS transiently ameliorated plants exposed to water stress by reducing moisture loss. In addition, due to their capacity to improve plant root growth, soil nutrient cycling and microbial activity, application of HS might have long‐term benefits in agricultural systems. 相似文献
5.
Functional groups and molecular fragments of humic substances (HSs) from cryohydromorphic peat gley tundra and surface-gley tundra soils have been identified by 13C-NMR spectroscopy. The analysis of HS preparations has shown that the molecules of humic acids (HAs) are enriched with aromatic fragments compared to fulvic acids (FAs). Aliphatic chains, carbohydrate- and amino acid-type structures prevail in the carbon skeleton of the FAs. An integrated parameter of the HS hydrophobicity has been proposed. The parameter represents the total portion of unoxidized carbon atoms and allows indirectly assessing the amphiphilic properties of HSs. 相似文献
6.
In the current approach to the study of humic substances (HSs), they are usually considered as complex chemical polymeric compounds with a specific combination of properties. This concept of HSs cannot explain their role in soils as a depot of nutrients for microorganisms and some experimental data. The main problem is related to the low energy efficiency of this depot of nutrients, because microorganisms have to consume energy for synthesizing enzymes that destroy HS polymers (macromolecules). At the same time, the recently proposed consideration of HSs as a system of supramolecular compounds completely eliminates this contradiction. In this work, an attempt has been made to consider HSs from other positions based on their possible functional role in soils and entire ecosystems. A scheme has been proposed for the transformation of the litterfall that is based on the supramolecular nature of the HSs and confirmed by reported experimental results. 相似文献
7.
The increasing global demand for food production, often causing excessive use of chemical fertilizers, has led to the deterioration of soil health. Immediate action is required to restore soil health in a sustainable manner. This review advocates switching to use of organic matter(manure and compost) that contains vital nutrients for plant growth and helps restore soil health. Humic substances(HSs), derived from degraded plant remains and found ubiquitously in nature,are an important source of o... 相似文献
8.
调亏灌溉和施氮对玉米叶片保护系统的影响 总被引：2，自引：0，他引：2
通过盆栽试验,研究了不同生育期亏水和氮肥处理对春玉米叶片丙二醛(MDA)含量、可溶性糖(SS)含量、过氧化物酶(POD)和超氧化物歧化酶(SOD)活性的影响.结果表明,调亏灌溉可使玉米叶片MDA和SS含量明显升高,而使POD和SOD活性有所降低.施氮处理能保证叶片在抽雄期前SS含量、SOD和POD活性处于较高水平.MDA含量与灌水和施氮水平呈负相关,拔节后期达最大值,之后减小.从苗期到拔节后期,调亏灌溉施氮处理的可溶性糖含量较高,而高氮持续亏水处理可导致可溶性糖含量降低.POD活性到拔节后期达到最大,抽雄期有所降低.亏水处理明显降低了叶片POD活性,复水后补偿效应明显.施氮可适当提高POD活性,但抽穗亏水和全生育期亏水高氮处理在抽雄期的酶活性降低.SOD活性的变化趋势和POD相似.苗期亏水处理在复水后各生理生化指标补偿效果较好,拔节期亏水处理次之.高氮处理不宜在抽雄期调亏灌溉.调亏灌溉和施氮的最佳处理组合为苗期调亏低氮处理. 相似文献
9.
Marcelo Ribeiro Vilela Prado Oscarlina Lúcia dos Santos Weber Milton Ferreira de Moraes Carlos Leandro Rodrigues dos Santos Morgana Santos Tunes Fabricio Tomaz Ramos 《Communications in Soil Science and Plant Analysis》2016,47(21):2405-2413
Hypothetically, humic substances (HSs) can improve the response of plants in sandy soils. The objective was to assess the effect of applying an organomineral fertilizer enriched with HSs on soybean plants grown with and without water stress. The experimental design was entirely randomized, in a greenhouse, in a 2 × 5 factorial setup (two moisture levels and five fertilizer doses: 0, 1, 2, 4, and 8 mL dm?3), for a total of 10 treatments, with eight repetitions, using as substrate a Psamment. The organomineral fertilizer was applied in the soil 21 days after plant emergence, and the water regimes were established 1 week thereafter. Plant height, shoot and root dry mass, mineral nutrition, and grain yield were evaluated. There was a positive response to the doses, with the most efficient one under water stress being 6.5 mL dm?3 and HSs favored the uptake of micronutrients. 相似文献
10.
Hamzeh Amiri Ahmad Ismaili Saeed Reza Hosseinzadeh 《Compost science & utilization》2017,25(3):152-165
One goal in the face of deficit water conditions is to increase growth and yield. Agro-industrial production frequently causes environmental pollution by using chemical fertilizers. In recent decades, bio-fertilizers such as vermicompost have been used as a safe alternative to chemical fertilizer. The present study considered the response of the chickpea to different combinations of vermicompost and water deficit stress in a greenhouse environment. Plant response was determined by measuring a range of morpho-physiologic parameters. The treatments were addition of 0%, 10%, 20%, and 30% of vermicompost to soil, and water deficit stress at the following levels: non-stress (100% of field capacity), moderate water stress (75% of field capacity), and severe water stress (25% of field capacity). The results showed that vermicompost had a significant effect on all traits under stress and non-stress conditions. The vermicompost treatments under non-stress conditions significantly increased plant height, number of pods, leaf area, stem and leaf dry weight, pod dry weight, chlorophyll a, carotenoid, total chlorophyll content, CO2 assimilation rate, internal CO2 concentration, and water-use efficiency over that of the control condition. The addition of 30% vermicompost under moderate and severe water stress conditions significantly increased plant height, number of pods, leaf area, leaf dry weight, carotenoids, and water-use efficiency over that of the control level. This study confirmed that vermicompost improved the morphological features, soil biological activity, and quality of the chickpea, but did not positively influence the physiological features under moderate and severe water deficit stress. 相似文献
11.
Maria G. Chernysheva Ivan Yu. Myasnikov Gennadii A. Badun Dmitry N. Matorin Dilara T. Gabbasova Andrey I. Konstantinov Viktor I. Korobkov Natalia A. Kulikova 《Journal of Soils and Sediments》2018,18(4):1335-1346
Purpose
Detonation synthesis nanodiamonds (ND) are among the most widely applied nanoparticles due to their low cost of production and broad scope of applications. However, the fate and behavior of NDs in the environment are largely unknown. The behavior of NDs is greatly affected by humic substances (HSs), which comprise 50 to 80 % of natural organic matter in water and soil ecosystems. The uptake of detonation NDs by wheat seedlings and its toxicity were evaluated in the presence of seven HSs of different origins, including humic acids (HA, HS fraction soluble in alkali and insoluble in acid) and fulvic acids (FA, soluble in both alkali and acid).Materials and methods
To monitor the uptake of NDs by plants, tritium-labeled NDs were produced. Liquid scintillation spectrometry and autoradiography were used to determine the amount of NDs absorbed by plants. The photosynthetic activity of the plants was measured using light response curves.Results and discussion
After a 24-h exposure period, the ND content in the plant roots was 1720 μg g?1. The introduction of HSs decreased the ND contents in the plant roots to 680–1570 μg g?1 (except for peat FA, for which the ND content did not differ from the blank value). The observed phenomenon was probably related mainly to the influence of HSs on the zeta potential of the NDs, which shifted from positive to negative. Based on chlorophyll fluorescence evaluation, the toxicity of NDs did not inhibit photosynthesis during illumination in the physiological range. However, NDs were slightly toxic to wheat plants under excessive light, likely due to the inhibition of electron transport between Q A and Q B and the disruption of the formation of a thylakoid transmembrane potential.Conclusions
The introduction of HA in a suspension of NDs obviously reduced the inhibiting effect of the NDs; however, the mitigating activities of FA were not so apparent. Our results demonstrate the urgent need for further studies of the influences of NDs on plant growth and development.12.
It was shown that self-organization with the development of nano- and microstructures is typical for soil gels. Humic substances (HSs), which form the basis of soil gels, have a multilevel structural organization. They appear due to weak interactions during the aggregation of low-molecular-weight organic substances, which results in the formation of HS supermolecules several nanometers in size. The obtained results indicated that the aggregation of HS supermolecules produces fractal clusters of many tens to several hundreds of nanometers in size. These fractal clusters of HS supermolecules are the main elements forming soil gels. The resulting soil gels are suprapolymer systems. On the basis of the generalized experimental data, a conclusion was drawn that self-organization involving microsegregation with the formation of different-type structures is typical for the suprapolymer matrix of soil gels. A mechanism was proposed for the self-organization of the suprapolymer humic matrix with the formation of various nano- and microstructures in soil gels. 相似文献
13.
土壤干旱对冬小麦功能叶过氧化物酶同工酶及抗旱性的影响 总被引：2，自引：0，他引：2
以６个抗旱性不同的冬小麦品种为试验材料，研究了土壤干旱对拨节期冬小麦功能叶片过氧化物酶同工酶、生物产量及某些经济性状的影响。结果表明：一定程度的土壤干旱可导致小麦功能叶片过氧化物酶同工酶发生相应的变化，抗旱性不同的小麦品种其同工酶酶谱不同，其酶谱变化与抗旱性间存在着一定的相关性。 相似文献
14.
水分条件对豌豆保护酶活性及膜脂过氧化的影响 总被引：3，自引：0，他引：3
为探讨不同水分条件对豌豆保护酶系统和膜脂过氧化的影响,采用盆栽人工控水试验方法,模拟干旱胁迫及复水条件,研究了不同水分处理对花荚期豌豆叶片超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)活性以及过氧化产物丙二醛(MDA)含量和脂膜相对透性(RC)的影响,并对花荚期豌豆抗氧化能力进行了综合评价.结果表明:不同程度干旱胁迫历时5 d时并未影响豌豆叶片SOD、CAT活性,但有明显的滞后效应.重度干旱胁迫历时10 d可显著降低豌豆叶片SOD、CAT活性,显著提高MDA含量.不同程度的干旱胁迫均导致豌豆叶片POD活性提高,膜脂相对透性加大.复水可对干旱胁迫所造成的CAT、POD活性变化产生显著补偿作用,对SOD活性变化产生超补偿作用.同时,可显著降低MDA含量和脂膜相对透性;干旱胁迫历时10 d内和复水历时10 d内,豌豆有较强的抗氧化能力,仅在重度胁迫10 d后复水历时达到10 d时抗氧化能力趋弱. 相似文献
15.
It has been shown that the distribution features of the hydrophilic and hydrophobic fractions of humic substances (HSs) in the upper genetic horizons of undisturbed podzolic soils and litho-barrier podzols are similar. The concentrations of the separate HS fractions in the mineral horizons are largely determined by the soil mineralogy. In forest litters of secondary phytocenoses developed after the cutting of spruce forests, an increase in the content of hydrophilic compounds has been observed on loamy deposits at a decrease in the portion of lignin-like organic compounds. An increase in the portion of Al-Fe-humus compounds has been revealed in the mineral soil horizons of secondary phytocenoses. It has been proposed to use the degree of hydrophilicity (D H ) for characterizing the features of the organic matter in taiga soils. An increase in the content of the fractions of occluded organic matter and that bound to minerals (density of 1.6–2.2 g/cm3) has been observed in the eluvial horizons of a young cutover area. 相似文献
16.
以辣椒为研究对象,研究了不同光照强度和土壤水分对辣椒叶片相对含水率（RWC）、叶绿素（Chl）含量、保护酶活性以及游离脯氨酸和丙二醛（MDA）含量的影响。结果表明：1）随着遮阴程度和土壤水分的增加,叶片RWC,叶绿素含量均呈上升趋势,土壤水分增加主要有利于叶绿素a含量的增加,遮阴主要有利于叶绿素b含量的增加。类胡萝卜素含量随遮阴程度的增加和土壤水分的降低而下降。MDA含量在干旱胁迫条件下升高,随着遮阴程度的增加呈先降后升的趋势。光照相同,在干旱和高水条件下,保护酶活性和脯氨酸含量均表现出不同程度的上升;水分条件相同,保护酶活性和脯氨酸含量均随遮阴程度的增加而下降,且保护酶对光照强度的敏感性为SOD＞CAT＞POD。2）保护类物质（脯氨酸与保护酶）与伤害类物质（MDA）均达到了极显著正相关,膜保护酶与叶绿素含量达到了极显著负相关。综合以上认为,将遮阴30%和土壤相对含水率为70%～85%作为适宜的遮阴和灌溉指标是科学合理的。 相似文献
17.
Tara Ali Dan Bylund Sofia A. Essén Ulla S. Lundström 《Soil biology & biochemistry》2011,43(12):2417-2422
Low molecular mass organic acids (LMMOAs) and hydroxamate siderophores (HS) are molecules secreted by microbes and have previously been found in soil solution and in cultures. Mycorrhizal fungi are suggested to be involved in the nutrient uptake processes of trees and weathering of minerals. In this study soil samples taken from the O and E horizons of a podzol were extracted with 10 mM potassium phosphate buffer at pH 7.2. Variable parameters included addition of methanol to the extraction buffer and the use of ultrasonication or rotary shaking during extraction. LMMOAs and HS content of the soil extracts were determined. Analysis of soil extracts were carried out by liquid chromatography mass spectrometry (LC–MS) and the extraction results compared to results for soil solution samples obtained by centrifugation of the soils sampled. The extraction yields were significantly increased by addition of methanol to the extraction buffer, especially for the O horizon samples. Rotary shaking of the samples for 90 min gave slightly higher yields than ultrasonication for 15 min but the reduction in extraction time makes ultrasonication an attractive option. Of the HSs determined, ferricrocin was found in all samples. Optimal extraction conditions showed citric acid and isocitric acid to be the most abundant organic acids in the O and E horizons, respectively. 相似文献
18.
《Soil biology & biochemistry》2012,44(12):2417-2422
Low molecular mass organic acids (LMMOAs) and hydroxamate siderophores (HS) are molecules secreted by microbes and have previously been found in soil solution and in cultures. Mycorrhizal fungi are suggested to be involved in the nutrient uptake processes of trees and weathering of minerals. In this study soil samples taken from the O and E horizons of a podzol were extracted with 10 mM potassium phosphate buffer at pH 7.2. Variable parameters included addition of methanol to the extraction buffer and the use of ultrasonication or rotary shaking during extraction. LMMOAs and HS content of the soil extracts were determined. Analysis of soil extracts were carried out by liquid chromatography mass spectrometry (LC–MS) and the extraction results compared to results for soil solution samples obtained by centrifugation of the soils sampled. The extraction yields were significantly increased by addition of methanol to the extraction buffer, especially for the O horizon samples. Rotary shaking of the samples for 90 min gave slightly higher yields than ultrasonication for 15 min but the reduction in extraction time makes ultrasonication an attractive option. Of the HSs determined, ferricrocin was found in all samples. Optimal extraction conditions showed citric acid and isocitric acid to be the most abundant organic acids in the O and E horizons, respectively. 相似文献
19.
Chang-Quan Wang 《Journal of plant nutrition》2013,36(12):1874-1885
This study was designed to examine whether external calcium (Ca2+) would improve the tolerance of Trifolium repens L to polyethylene glycol (PEG)-induced water deficit, and to determine the physiological mechanisms of Ca2+ effect on plant tolerance to water deficit. T. repens seedlings were subjected to PEG-induced water deficit alone or combined with 5 mM calcium chloride (CaCl2) for 72 h. During PEG-induced water deficit period, leaf relative water content (RWC) decreased gradually, and chlorophyll content increased after 24 and 48 h of water deficit but decreased below the control level after 72 h. The Ca2+-treated plants had higher RWC and chlorophyll content than untreated plants. Smaller amounts of thiobarbituric acid reactive substances (TBARS) and hydrogen peroxide (H2O2) accumulated in Ca2+-treated plants than in untreated plants during the period of water deficit. The activity of superoxide dismutase (SOD) increased gradually during the experimental period, and external Ca2+ treatment further promoted SOD activity under water deficit. The activity of the catalase (CAT) was not influenced after 24 and 48 h of water deficit and insignificantly increased after 72 h, whereas the activity of ascorbate peroxidase (APOX) increased linearly and glutathione reductase (GR) activity slightly increased over the course of treatment. Seedlings treated with Ca2+ had higher CAT, GR, and APOX activities than untreated plants under water deficit. These results suggested that exogenous Ca2+ application enhanced T. repens tolerance to PEG-induced water deficit, and this enhancement was related to alleviation of lipid peroxidation and maintenance of antioxidant activities. 相似文献
20.
Influence of sodium polyacrylate on the water-holding capacity of three different soils and effects on growth of wheat 总被引：1，自引：0，他引：1
Abstract. The effectiveness of sodium polyacrylate to increase soil water retention and to enhance growth of wheat under water deficit was evaluated. Water-holding capacity of the soils was considerably increased only when the soil was amended with the polymer at a rate 3 g L−1 . The effect on plant-available water was greater at soil matric potentials up to −1000 hPa. The biomass and grain yield of plants without water deficit were increased by the polymer amendment, but decreased under severe water deficit stress. The polymer had no significant affect on plant N, grain N or grain Na content. 相似文献