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1.
Abstract

Although the application of manure to upland fields is believed to induce changes in the quality of humic substances in soil as well as the quantity, the direction and extent of these changes have not been elucidated. To understand temporal variations in humic acids, periodically collected soil samples from two fields, a Typic Hapludult (Togo) and a Pachic Melanudand (Kuriyagawa), with cattle manure and chemical fertilizer (CF) were examined. The content and degree of humification (darkening) of the humic acids were distinctly greater in Kuriyagawa than in Togo soil. Corresponding to the difference in the degree of humification, molecular size distribution, elemental composition, infrared (IR) spectra, and 13C cross polarization/magic angle spinning nuclear magnetic resonance (CPMAS NMR) spectra of humic acids differed between the two soils. Manure application at 40 Mg ha?1 year?1 for 16 years (Togo) and at 80 or 160 Mg ha?1 year?1 for 19 years (Kuriyagawa) resulted in greater humic acid content compared with plots with CF only because of its increase in the manured plots and/or decrease in the CF plots. Manure application at an extremely high rate (160 Mg ha?1 year?1) resulted in higher H content and greater signal intensities of alkyl C, O-alkyl C and amide C=O in the 13C CPMAS NMR and/or IR spectra. Although humic acids with larger molecule sizes increased in all the manured plots, differences between the humic acids from the plots with and without manure applied at practical levels in the elemental and spectroscopic analyses were small or scarce. These results were considered to be because of the similarity between the indigenous soil humic acids and the manure-derived ones in Togo soil (a low degree of humification) and because of the abundance of highly-humified humic acids in Kuriyagawa soil.  相似文献   

2.
Abstract

The humic substances contained in an animal organic waste were extracted and the total extract separated into three humic fractions with different molecular weights (low, F1 <103; medium, F2, with molecular weights ranging from 103 to 104; and high, F3 >104). The C content was highest in F2, the same fraction also showing the lowest N content. The molecular weight of the humic fractions influenced the electrical conductivity, the highest molecular weight resulting in the lowest degree of electrical conductivity. Membrane-controlled ultrafiltra-tion (the method used to separate the various fractions from the whole extract) was also suitable for purifying such enzymes as phosphatase and β-glucosidase: the total activity obtained from the three fractions was considerably greater than that determined in the whole extract, Pyrolysis-gas chromatography (Py-GC) applied to the whole extract and humic fractions showed that in the F3 fraction (highest molecular weight) benzene was the major fragment while furfural was the major fragment of F1 (lowest molecular weight). For this reason, the humification index benzene/toluene indicates that the fraction with the highest molecular weight was the most humified while the furfural/pyrrole ratio indicates that the fraction with the lowest molecular weight was the most degradable. The whole extract and the fraction F1 had a negative effect on seed germination when the concentration was equivalent to 100 mg kg?1 of C, while the germination index was higher than that of the control when only 10 mg kg?1 were used. The F2 fraction had a positive effect on germination regardless of the concentration used. When 10 mg kg?1 of C of the humic substances studied were added to the nutrient solution for growth experiments with maize plants, F3 led to increases in root weight and F2 led to increases in shoot weight. An inhibitor effect was observed for fraction F1.  相似文献   

3.
ABSTRACT

To examine the effects of uniconazole (UCZ) on the distribution and transport of photosynthate in sweetpotatoes, three spraying levels of UCZ, 0 (control), 50 and 100 mg L?1, were exposed to an experimental field cultivated with Jishu26 (‘J26?) and Xushu32 (‘X32?) varieties. Compared to control, the distribution of carbon-13 (13C) was significantly higher in the tuberous roots of both varieties treated with UCZ. In addition, UCZ treatments promoted a desirable top-to-base sucrose gradient and significant greater declines in the top-to-bottom amino acid and potassium ion (K+) gradients along the stem. Higher tuberous root yields were found in the UCZ-treated ‘J26? and ‘X32?. In comparison to 50 mg L?1 UCZ, ‘J26? treated with 100 mg L?1 UCZ exhibited significantly higher distribution ratio of 13C in tuberous root, and reductions in the top-to-bottom amino acid and K+ gradients along the stems at 105 and 150 days after planting. Furthermore, 100 mg L?1 of UCZ application exhibited a significantly higher tuberous root yield. For ‘X32?, the two concentrations of UCZ demonstrated no significant differences in these parameters. A reasonable distribution structure of photosynthates that responsible for high yields is associated with the desirable sucrose, ammonia nitrogen (N) or K+ gradient along the stems caused by UCZ application.  相似文献   

4.
The goal of this experiment was to investigate the effect of aeration quantity (0, 11, 33, 55, and 77 L·min?1) on the growth of aerated compost extracts from a pig manure–straw compost. When the aeration quantity was 11 L·min?1, lettuce root growth enhancement of normalized compost extracts was at a maximum. As the aeration quantity increased, the total water-soluble organic carbon (TWSOC), total nitrogen (TN), total phosphorus (TP), humic carbon (humic C) content, and humification degree of compost extracts improved gradually. No differences in functional group structure were found among the aerated compost extracts. The positive root growth could be attributed to physicochemical and spectral characteristics, such as TN content, humic substances content, humification, aromaticity, and the low content of carboxyl groups. In conclusion, the aeration quantity of 11 L·min?1 was suitable for the production of aerated compost extracts, which obtained much greater promotion growth.  相似文献   

5.
Flower quality loss, especially short postharvest life, is a major problem in gerbera production. An experiment was conducted to determine how different combinations of humic substances (HS) affect gerbera. Humic acid (HA) and fulvic acid (FA) applied to nutrient solutions in six combinations including control (nutrient solution only), 80 mg L?1 HA + 20 mg L?1 FA, 60 mg L?1 HA + 40 mg L?1 FA, 40 mg L?1 HA + 60 mg L?1 FA, 100 mg L?1 FA, and 50 mg L?1 FA. The HS application enhanced root architecture, nutrient content, number of harvested flowers, and vase life. Fifty (50) mg L?1 FA extended vase life by 8 days and increased flower number (72.9%). Results suggest that HA and FA (especially 50 mg L?1 FA) can improve quality and quantity of gerbera through improving root architecture, leading to enhanced nutrient uptake and possibly affecting hormone-like activities. It seems that using low concentrations of FA may be part of a solution in improving gerbera flower quality.  相似文献   

6.
The morphology and length of roots and shoots of tomato (Lycopersicon esculentum Mill.) seedlings grown on a nutrient medium for fourteen days in a controlled environment chamber were apparently not affected, whereas the dry matter content of roots was significantly enhanced when 200 mg L?1 of humic acid (HA) isolated from either a non-amended soil or a sewage-sludge-amended soil was present in the nutrient medium. In contrast, the HA-like fraction isolated directly from the sewage sludge caused, under the same conditions, extensive alterations of tomato morphology and a significant reduction of the length and dry weight of both shoots and roots. The presence in the nutrient medium of the herbicides alachlor or imazethapyr at concentrations of 1 and 0.01 mg L?1, respectively, caused a marked decrease of tomato root and shoot length and dry weight. Differently, the herbicide rimsulfuron at a concentration of 0.01 mg L?1 produced a slight decrease in shoot and root length and a slight increase in their dry weight. A combination of 200 mg L?1 soil HA and each of the herbicides alachlor, rimsulfuron and imazethapyr at concentrations of 1, 0.01 and 0.01 mg L?1, respectively, in the nutrient medium attenuated the growth depression of tomato shoots and roots observed in the presence of the herbicide alone. However, the simultaneous presence of sewage sludge HA and any herbicide in the nutrient solution caused negative synergistic effects on tomato growth. The volume of nutrient solution and the amount of electrolytes taken up by tomato plants during the growth experiments correlated highly significantly with the total plant dry weight. Tomato seedlings induced a pH decrease in the nutrient medium in all treatments except in those where sludge-HA was present, either alone or in combination with any herbicide.  相似文献   

7.
To determine whether there is a relationship between the composition of soil organic matter and the activity of the soil microbial biomass, the composition of the organic matter in 12 typical arable soils in Northwest Germany was investigated by wet chemical analysis and CPMAS cross polarization magic angle spinning 13C-NMR spectroscopy. The data were correlated with the microbial biomass as estimated by substrate-induced respiration. A strong correlation between the microbial biomass and alkylic C compounds was observed (r=-0.960***). Recalcitrant substances were enriched in this fraction, which were classified as humic acids according to the wet chemical procedure. The microbial decomposition of these humic acids is probably retarded, due to their chemical structure and/or physical bonding, when the soil microbial biomass activity is limited.  相似文献   

8.
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9.
Abstract

Can humic acid (HA) and glutamic acid (GA), when added to tomato (Lycopersicon esculentum Mill. cv. ‘Hongyangli’) nutrient solution in a hydroponic system, improve growth? Tomato seedlings were grown in six nutrient solutions: (1) control (C), (2) C + 25 mg L?1 HA (HA1); (3) C + 50 mg L?1 HA (HA2); (4) C + 100 mg L?1 GA; (5) HA1 + GA; (6) HA2 + GA. Various biochemical and physiological parameters were measured. HA increased photosynthesis rate and mesophyll conductance. HA did not significantly affect transpiration, stomatal conductance, titratable acidity, or antioxidant activity. In addition, GA improved protein and sugar content, mesophyll conductance and yield. The combination of HA and GA was more effective, especially with 50 mg L?1 HA. The activity of superoxide dismutase (SOD) and peroxidases (POD) did not change in the presence of HA or GA. Malondialdehyde (MDA) content increased by 30% in HA2 together with GA. HA has a positive effect on tomato hydroponic growth when applied with GA. This expands the use of HA and GA for horticultural commodities in hydroponic systems.  相似文献   

10.
The influence of Hg on soybean plants under different pH conditions and Hg concentrations was studied. Growth inhibition by Hg was higher in roots than the upper part of the plant, but was highly dependant on pH condition. Growth inhibition of roots was observed when Hg concentration was higher than 1 mg Hg L?1 for pH 4.0 and 5 mg Hg L?1 for pH 6.0. Using 203Hg as a radioactive tracer, the amount of Hg (1 mg Hg L?1) uptake in root was found to be about 1.5 times higher at pH 4.0 than that at pH 6.0; suggesting that Hg when highly accumulated at the lower pH induced inhibition of root growth. Decreased amounts of Hg due to evaporation during the plant growth were very low, but were higher at pH 6.0 than that at pH 4.0. There was hardly any translocation of Hg from roots to the upper parts through the stem within 24 h.  相似文献   

11.
Purpose: The purposes of this study were to determine the effect of matrine on the migration and the colonization dynamics of the two fluorescent-tagged rhizobia in Gannong No.5 alfalfa (Medicago sativa L. Gannong No. 5) tissues, and also to determine the effect of the combination treatments on alfalfa seedlings’ growth.

Materials and methods: 0, 100, 200, 300 and 400 mg L?1 matrine levels were added into two cyan fluorescent protein (CFP)-tagged rhizobia; Ensifer meliloti LZgn5f (gn5f) and Ensifer meliloti 12531f (12531f), respectively; and drenched the alfalfa root with the inoculants. Then the migration and colonization of the two rhizobia in alfalfa on D7, D14, D21 and D28, and subsequently seedling growth were investigated.

Results: The results showed that the optimum matrine level enhanced the colonization of both fluorescent-tagged rhizobia in alfalfa roots and the highest colonization densities of log 6.31 cfu g?1 and log 5.87 cfu g?1 were achieved by adding 300 mg L?1 matrine into 12531f and adding 100 mg L?1 matrine into gn5f, respectively. They could migrate to the aerial tissues and most colonize stems through the application of adding 300 mg L?1 matrine into 12531f and 100 mg L?1 matrine into gn5f, respectively. No fluorescent-tagged rhizobia were detected in the control treatment. Alfalfa seedling growth parameters like leaf chlorophyll content, seedling growth rate, root length, seedling biomass and total N percentage also increased the most when 300 mg L?1 matrine was added into 12531f and 100 mg L?1 matrine added into gn5f treatments.

Conclusions: Our results suggest that 300 mg L?1 matrine added into 12531f and 100 mg L?1 matrine added into gn5f might be exploited to promote the colonization of rhizobia in alfalfa tissue and positively impact growth and yield, indicating possible benefits for plant cultivation.  相似文献   

12.
ABSTRACT

The effects of three sodium chloride (NaCl) levels (0, 1200, and 2400 mg kg? 1 soil) and three irrigation intervals (3, 7, and 14 d) on the growth and chemical composition of two Pistacia vera rootstocks (‘Sarakhs’ and ‘Qazvini’) were investigated under greenhouse conditions. Eight-week-old pistachio seedlings were gradually exposed to salt stress which afterward, water stress was initiated. At any irrigation interval, plant height and shoot and root dry weights of both rootstocks were reduced with increasing salinity. However, increasing irrigation intervals alleviated the adverse effects of soil salinity. A negative relationship observed between relative shoot growth and electrical conductivity of soil saturation extract (ECe) confirmed the above findings. Under 3-d irrigation interval, the ECe required to cause a 50% growth reduction was lower than those under 7- and/or 14-d irrigation intervals. Shoot and root chemical analyses indicated that the salinity as well as irrigation regime affected the concentration and distribution of sodium (Na+), potassium (K+), and chloride (Cl?) in pistachio. The concentration of Na+, K+ and C1? ions increased with a rise in NaCl level, and was generally declined with increasing irrigation interval. Based on plant height, shoot and root dry weights and the concentrations of Na+, K+, and C1? in the plant tissues, at lowest irrigation intervals ‘Sarakhs’ shows a higher sensitivity to soil salinity than ‘Qazvini’, but with increasing irrigation interval, ‘Sarakhs’ and ‘Qazvini’ can be classified as resistant and sensitive to salinity, respectively.  相似文献   

13.
Abstract

Aluminum (Al)–humus complexes are abundant in the A horizons of non-allophanic Andosols and contribute to the unique properties of volcanic ash soils, such as high reactivity with phosphate ions and a low bulk density. Natural non-allophanic Andosols commonly show Al toxicity to plant roots. There have been very few studies examining the contribution of Al–humus complexes to the Al toxicity of plant roots, although the complexes are the probable source of the toxic Al. We extracted humic substances from the A horizon of a non-allophanic Andosol using NaOH solution and reacted the humic substances and partially neutralized the AlCl3 solution at three pH conditions (pH 4.0, 4.5 and 5.5) to prepare pure Al–humic substance complexes. The Al solubility study (equilibrium study in 10?2 mol L?1 CaCl2) and the Al release study (a stirred-flow method using 10?3 mol L?1 acetate buffer solution adjusted to pH 3.5) indicated that all the synthetic complexes easily and rapidly release monomeric Al into the liquid phase with slight changes in pH and ion strength, although the Al contents and their extent of polymerization are considerably different among the complexes. A plant growth test was conducted using a medium containing the Al–humic substance complexes and perlite mixture. Root growth in burdock (Arctium lappa) and barley (Hordeum vulgare L.) was reduced equally by all three complex media, and the roots showed the typical injury symptoms of Al toxicity. These results indicate that in soils dominated by Al–humus complexes the Al released from the Al–humus complexes, as well as the exchangeable Al adsorbed by soil minerals, is definitely toxic to plant roots.  相似文献   

14.
Low molecular weight (LMW) organic compounds in soil solution are easily biodegradable and could fuel respiration by soil microorganisms. Our main aim was to study the mineralization kinetics of monosaccharides using 14C-radiolabelled glucose. Based on these data and the soil solution concentrations of monosaccharides, we evaluated the contribution of monosaccharides to basal respiration for a variety of tropical forest soils. Further, the factors controlling the mineralization kinetics of monosaccharides were examined by comparing tropical and temperate forest soils. Monosaccharides comprised on average 5.2 to 47.7% of dissolved organic carbon in soil solution. Their kinetic parameters (V max and KM ), which were described by a single Michaelis-Menten equation, varied widely from 11 to 152?nmol?g?1?h?1 and 198 to 1294?µmol?L?1 for tropical soils, and from 182 to 400?nmol?g?1?h?1 and 1277 to 3150?µmol?L?1 for temperate soils, respectively. The values of V max increased with increasing microbial biomass-C in tropical and temperate soils, while the KM values had no correlations with soil biological or physicochemical properties. The positive correlation between V max values and microbial biomass-C indicates that microbial biomass-C is an essential factor to regulate the V max values in tropical and temperate forest soils. The biodegradation kinetics of monosaccharides indicate that the microbial capacity of monosaccharide mineralization far exceeds its rate at soil solution concentration. Monosaccharides in soil solution are rapidly mineralized, and their mean residence times in this study were very short (0.4–1.9?h) in tropical forests. The rates of monosaccharide mineralization at actual soil solution concentrations made up 22–118% of basal respiration. Probably because of the rapid and continuous production and consumption of monosaccharides, monosaccharide mineralization is shown to be a dominant fraction of basal respiration in tropical forest soils, as well as in temperate and boreal forest soils.  相似文献   

15.
The effects of calcium and humic acid on seed germination, growth and macro- and micro-nutrient contents of tomato (Lycopersicon esculentum L.) seedlings in saline soil conditions were evaluated. Different levels of humic acid (0, 500, 1000 and 2000 mg kg?1) and calcium (0, 100, 200 and 400 mg kg?1) were applied to growth media treated with 50 mg NaCl kg?1 before sowing seeds. Seed germination, hypocotyl length, cotyledon width and length, root size, shoot length, leaf number, shoot and root fresh weights, and shoot and root dry weights of the plant seedlings were determined. Macro- and micro-nutrient (N, P, K, Ca, Mg, S, Cu, Fe, Mn and Zn) contents of shoot and root of seedlings were also measured. Humic acid applied to the plant growth medium at 1000 mg kg?1 concentration increased seedling growth and nutrient contents of plants. Humic acid not only increased macro-nutrient contents, but also enhanced micro-nutrient contents of plant organs. However, high levels of humic acid arrested plant growth or decreased nutrient contents. Levels of 100 and 200 mg kg?1 Ca2+ application significantly increased N, Ca and S contents of shoot, and N and K contents of root.  相似文献   

16.
In recent years, applying humic acid (HA) has been common in turfgrass management. A series of experiments were conducted to evaluate the effect of HA on qualitative and quantitative characteristics of “Speedygreen” perennial ryegrass (Lolium perenne L.). Different concentrations of HA (0, 100, 400, and 1000 mg L?1) were applied monthly as foliar application. Results showed that leaf phosphorus (P), potassium (K), and zinc (Zn) content, fresh and dry weight, chlorophyll content, and root fresh weights were not affected by HA. Meanwhile, HA improved the root and shoot development, except for root fresh weight. While just 100 mg L?1 improved height, visual quality, nitrogen (N) content, roots length, and surface of roots, all of HA concentrations were effective on iron content. These results suggest that HA foliar application might be of benefit to enhance some nutrients uptake and root development of ryegrass possibly leading to improved drought resistance.  相似文献   

17.
Abstract

Se is beneficial to plants’ growth and it is an essential mineral for animals and humans. However, relatively little is known about the relationship between nano-Se concentrations and plant antioxidant activity. In this work, a pot experiment was carried out using two cultivars of tobacco and increasing nano-Se concentrations. The changes of plant biomass, root growth, chlorophyll content, nutrient accumulation and reactive oxygen species (ROS) content in tobacco leaves after being sprayed with nano-Se were studied. The results indicated that the growth of tobacco can be promoted by applying nano-Se in an appropriate concentration. In addition, our research proves that there is cultivars variation in the response of tobacco to increased concentrations of nano-Se. The biomass, root growth characteristics, chlorophyll content and N accumulation of E'yan 1 were increased significantly and were the highest at 5.0?mg L?1 of nano-Se. On the other hand, the above mentioned indicators for K326 reached the maximum value at 2.5?mg L?1 and decreased at 5.0?mg L?1 of nano-Se. The antioxidant enzymes activity were increased by the application of nano-Se, however cultivars variation was detected. The application of nano-Se reduced the amount of thiobarbituric acid reactive substances (TBARS) and ROS at 5.0?mg L?1 for both cultivars. This study confirms that nano-Se affects positively the growth and oxidative status of tobacco plants. However, this study points out that more research is needed to understand the interaction phenomena observed here between tobacco cultivars and concentrations specifically for the anti-oxidant status of the plant.  相似文献   

18.
ABSTRACT

Vaccinium corymbosum L. (Ericaceae) is a highly valued fruit crop and the most common type of blueberry grown in Chile. Plant growth and yield crop production are affected by agricultural practices and different soil parameters including chemical and biological properties. We performed a field assay to assess the effect of the inoculation with a mixture of 10 microorganisms and the addition of humic substances on the growth of blueberry, quality of fruit and soil chemical and biological properties. Two years after planting, the microbial consortium was more effective than the addition of humic substances recording a 35% increase in shoot dry weight, 70% increase in root dry weight and 104% on total fruits yield compared to the control plants. Total polyphenols and ferric reducing antioxidant power (FRAP) in fruit were increased on humic substance treatment. The combination of both factors increased by 18% organic matter and 60% cation exchange capacity. Soil respiration, microbial biomass C and enzyme activities (dehydrogenase, phosphatase, β-glucosidase, urease, and protease) to a greater extent than individual application. The combined treatment, involving microbial inoculant and humic substances, had an additive effect on improving the biochemical and microbiological quality of the soil.  相似文献   

19.
《Journal of plant nutrition》2013,36(10):2315-2331
ABSTRACT

Split root solution culture experiments were conducted to study the effects of the rare earth element lanthanum (La) on rice (Oryza sativa) growth, nutrient uptake and distribution. Results showed that low concentrations of La could promote rice growth including yield (0.05 mg L?1 to 1.5 mg L?1), dry root weight (0.05 mg L?1 to 0.75 mg L?1) and grain numbers (0.05 mg L?1 to 6 mg L?1). High concentrations depressed grain formation (9 mg L?1 to 30 mg L?1) and root elongation (1.5 mg L?1 to 30 mg L?1). No significant influence on straw dry weight was found over the whole concentration range except for the 0.05 mg L?1 treatment. In the pot and field experiments, the addition of La had no significant influence on rice growth.Lanthanum had variable influence on nutrient uptake in different parts of rice. Low concentrations (0.05 mg L?1 to 0.75 mg L?1) increased the root copper (Cu), iron (Fe), and magnesium (Mg), and grain Cu, calcium (Ca), phosphorus (P), manganese (Mn), and Mg uptake. High concentrations (9 to 30 mg L?1) decreased the grain Ca, zinc (Zn), P, Mn, Fe and Mg, and straw Ca, Mn, and Mg uptake. With increasing La concentration, root Zn, P, Mn, Cu, and Ca concentrations increased, and grain Ca and Fe, and straw Mn, Mg, and Ca concentrations decreased. Possible reasons are discussed for the differences between the effects of La in nutrient solutions and in pot and field experiments.  相似文献   

20.
Abstract

The objective of this study was to determine the effect of phosphorus applied through fertigation on growth and root yield of cassava. This was achieved through a greenhouse pot-experiment consisting of 1, 4, 7, 10, 20 and 30?mg?P?L?1. Increasing P from 1 to 30?mg?P?L?1 realized a 57.1 and 150.0% increase in leaf blade P in 2014 and 2015, respectively. Similarly, chlorophyll content and shoot growth increased as P concentration in solution increased. However, leaf stomatal conductance and net photosynthesis reached a maximum in 7 and 20?mg?P?L?1 in 2014 and 2015, respectively. This trend of stomatal conductance and net photosynthesis was consistent with that of dry root yield and storage roots numbers. Regressing dry root yield against storage root numbers showed that R2 = 0.80. Phosphorus encourages formation of storage roots and the duration of cassava’s growth affects the amount of P required for maximum root yield.  相似文献   

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