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1.
The different responses of two populations of Suaeda salsa (Linn.) Pall. (saline seepweed) from an intertidal zone and a saline inland zone to salinity [1 or 500 mM sodium chloride (NaCl)] and nitrogen [N; 0.05, 1, or 10 mM nitrate (NO3 ?)‐N] were investigated. Greater NO3 ?‐N supply (10 mM) increased shoot dry weight for the two populations of S. salsa, especially for S. salsa from the saline inland zone. Greater NO3 ?‐N supply (10 mM) increased the concentrations of chlorophyll and carotenoid in leaves and the NO3 ? and potassium (K+) concentrations in shoots for both populations. Greater NO3 ?‐N supply (10 mM) increased shoot Na+ in S. salsa from the intertidal zone. In conclusion, S. salsa from the saline inland zone is more responsive to NO3 ?‐N supply than the intertidal population. Greater NO3 ?‐N supply can help the species, especially the intertidal population, to grow and to mediate ion homeostasis under high salinity.  相似文献   

2.
This trial was carried out to study the evolution of the nutrient parameters of the nutrient solution applied to tomato plants (Lycopersicum sculentum Mill. Forteza) cultivated in Mediterranean greenhouse conditions under different fertigation management models. The dynamic model is based on soil water content, which was measured by tensiometers, and on soil solutions obtained with suction cups (porous ceramic cup water samplers). The local traditional method consists of following technical recommendations, and the classical model requires the estimation of Crop Factor (Kc) and knowing the nutrient extraction. Nutrient solution and water applied are functions of the fertigation management criteria. The water used for fertigation was classified as C4-S3 according to the Riverside classification system. The cultivation period lasted from 15 August to 20 April. The nutrient parameters studied in nutrient and soil solution were pH, electrical conductivity (EC), nitrate (NO3 ?), phosphate (H2PO4 ?), potassium (K+), calcium (Ca2+), magnesium (Mg2+), sodium (Na+), and chloride (Cl?). The pH shows similar trends under the different treatments. Electrical conductivity is in the range of 2.8–4.5 dS m?1. Chloride, sodium, magnesium, and sulfate are exclusively modified by the salt concentration in the irrigation water, so it can be assumed that the three treatments vary equally. Nitrate, potassium, phosphate, and calcium are modified depending on each fertigation management method. Soil solution is modified by the nutrient solution applied. Dynamic management allows low nutrient concentration in the nutrient solution to be maintained and keeps soil nutrient concentration low, reducing fertilizer losses and therefore aquifer contamination.  相似文献   

3.
Predicting nitrogen (N) mineralization has been one of the greatest challenges to improving N management in agriculture. A laboratory incubation experiment was conducted to study the N mineralization of soil amended with rock phosphate (RP)-enriched composts. The RP-enriched rice straw compost amended soil mineralized highest N as compared to compost prepared from mustard stover and tree leaves. The first-order model was found to be the most suitable for N because it provided the best fit to the experimental data and for its simplicity. The model predicted that potentially mineralized N (N0) was varied from 4.0 to 52.1 mg kg?1 and the mineralization rate k varied from 0.015 to 0.066 day?1. The rice straw compost amended soil had higher N0 value than mustard stover and tree leaves compost amended soil. This study demonstrated the importance of application of rock phosphate-enriched composts in improving N supplying capacity of soil.  相似文献   

4.
Nitrogen (N) metabolism is of great economic importance because it provides proteins and nucleic acids which in turn control many cellular activities in plants. Salinity affects different steps of N metabolism including N uptake, NO3? reduction, and NH4+ assimilation, leading to a severe decline in crop yield. Major mechanisms of salinity effects on N metabolism are salinity-induced reductions in water availability and absorption, disruption of root membrane integrity, an inhibition of NO3? uptake by Cl?, low NO3? loading into root xylem, alteration in the activities of N assimilating enzymes, decrease in transpiration, and reduction in relative growth rate which results in a lower N demand. However, the effects of salinity on N metabolism are multifaceted and may vary depending on many plant and soil factors. The present review deals with salinity effects on N metabolism in plants, emphasizing on the activities of N metabolizing enzymes in a saline environment.  相似文献   

5.
The worldwide production of rice husk, a by‐product and agrowaste that causes serious environmental problems, may reach 116 million t y?1. The objectives of this study were (i) to determine the physicochemical changes of rice husk and its structural chemistry during composting using 13carbon nuclear magnetic resonance (13C NMR) and (ii) to determine the effect of the composted rice husk (CRH) on the properties of Oxisol and cocoa (Theobroma cacao L.) growth under glasshouse conditions. Results showed an active composting phase occurred at the first 53 days as revealed by high carbon dioxide (CO2)‐C (40–71 µg g?1 h?1) production, followed by a matured composting phase occurring at 54–116 days as revealed by decreasing in CO2‐C production (10 µg g?1 h?1). The active composting was accompanied by increases in electrical conductivity (EC), pH, ammonium (NH4 +), and nitrate (NO3), whereas during the matured composting phase, the EC and cation exchange capacity increased but pH, NH4 +, and NO3 ?1 decreased. The ash of the produced compost contains mainly calcium (Ca), potassium (K), sulfur (S), magnesium (Mg), and phosphorus (P) as essential nutrients. The CP/MAS 13C NMR spectra before and after various composting times indicated the dominance of sharp and well‐resolved signal peaks at O‐alkyl C and di‐O‐alkyl C regions (67–73%), which are characteristic of cellulose. The percentage of N‐alky/methoxyl was 23–26% whereas phenolic, carboxyl, and alkyl C types were less than 3% each. The application of the CRH to an Oxisol significantly increased soil pH and Ca, Mg, K, sodium (Na), and silicon (Si) ions of in situ soil solution but decreased the amounts of toxic ions [aluminum (Al), manganese (Mn), and iron (Fe)]. The CRH was found to increase cocoa growth up to 37%.  相似文献   

6.
Ammonium and nitrate are the major forms of nitrogen (N) present in tropical soils. An experiment was conducted to assess the influence of nitrate and ammonium forms (NO3?, NH4+, and mix of NO3? + NH4+), and levels (1.5–12.0 mM) of N on the growth and nutrition of cacao (Theobroma cacao L). Growth parameters were significantly influenced by N forms, and nitrogen supplied as NH4+ proved better for the growth of cacao compared with NO3? form and mixtures of these two forms. Irrespective of the forms of N, levels of N had no significant effect on plant growth parameters. Nutrient efficiency ratios (NERs) (shoot dry matter produced per unit of nutrient uptake) for macronutrients were sulfur>phosphorus>calcium>magnesium>nitrogen>potassium (S>P>Ca>Mg>N>K) and for micronutrients NERs were in the order of copper>boron>zinc>iron>manganese (Cu>B>Zn>Fe>Mn).  相似文献   

7.
A field experiment was conducted at the Arkansas Valley Research Center in 2005 through 2007 to study the effects of manure and nitrogen fertilizer on corn yield, nutrient uptake, N and P soil tests, and soil salinity under furrow and drip irrigation. Manure or inorganic N was applied in 2005 and 2006 only. There were no significant differences in corn yield between drip and furrow irrigation even though, on average, 42% less water was applied with drip irrigation. Inorganic N or manure application generally increased grain yield, kernel weight, grain and stover N uptake, and grain P uptake. Nitrogen rates above 67 kg ha?1 did not increase grain yield significantly in 2005 or 2006, nor did manure rates in excess of 22 Mg ha?1. High manure rates increased soil salinity early in the season, depressing corn yields in 2005 and 2006, particularly with drip irrigation. Salts tended to accumulate in the lower half of the root zone under drip irrigation. Residual nitrate nitrogen from manure and inorganic N application sustained corn yields above 12.0 Mg ha?1 in 2007. More research is needed to develop best manure and drip irrigation management for corn production in the Arkansas Valley.  相似文献   

8.
ABSTRACT

A study was carried out to determine the influence of nitrogen (N) sources on the growth, nitrate (NO3 ?) accumulation, and macronutrient concentrations of pakchoi (Brassica chinensis L.) in hydroponics. Plants were supplied with NO3 ? and two amino acids (AA), glutamic acid (Glu), and glutamine (Gln), at six NO3 ?-N/AA-N molar ratios: (1) 100:0, (2) 80:20, (3) 60:40, (4) 40:60, (5) 20:80, (6) 0:100. The total N concentration was 12.5 mmol/L for all treatments in nutrient solutions. Both AAs reduced plant growth with decreasing NO3 ?-N/AA-N ratios, but the reduction was for Gln than for Glu. At 80:20 NO3 ?-N: Gln-N ratio, the Gln had no significant effect on pakchoi fresh weights. Decreasing NO3 ?-N/AA-N ratios reduced NO3 ? concentrations in the plant, regardless of AA sources. Adding an appropriate portion of AA-N to nutrient solutions for hydroponic culture increased concentrations of N, phosphorus (P), and potassium (K) in pakchoi shoots. Substituting 20% or less of NO3 ?-N with Gln-N in hydroponic culture will increase the pakchoi quality by reducing NO3 ? concentration and increasing mineral nutrient concentrations in shoots without significant reduction of crop yields.  相似文献   

9.
Co-composting of chicken slurry and rice straw with clinoptilolite zeolite and urea as additives was conducted to determine the characteristics of a compost and their effects on controlling ammonium (NH4+) and nitrate (NO3?) losses from urea. Quality of the compost was assessed based on temperature, moisture content, ash, pH, electrical conductivity, carbon/nitrogen (C/N) ratio, NH4+, NO3?, macronutrients, heavy metals, humic acid, microbial population, germination index, and phytotoxicity test. Moisture content and C/N ratio of the compost were 43.83% and 15, respectively. Total N, humic acid, ash, NH4+, NO3?, phosphorus (P), calcium (Ca), magnesium (Mg), potassium (K), and sodium (Na) increased after co-composting rice straw and chicken slurry. Copper, iron (Fe), manganese (Mn), zinc (Zn), and microbial biomass of the compost were low. The germination rate of Zea mays on distilled water and Spinacia oleracea growth on peat-based growing medium (PBGM) and compost were not significantly different. Urea amended with compost reduced N loss by retaining NH4+ and NO3? in the soil.  相似文献   

10.
Two municipal solid waste composts were added to three agricultural soils developed over different parent material (schist, gabbro and granite) and incubated in two laboratory studies, in order to assess the effect of compost addition in the dynamics of soil Ca, Mg, K and P. Soils and mixtures of soil and compost (2.5% dry weight, roughly equivalent to 60 t ha?1) were incubated at 25°C for three months in a first experiment, and for five months in a second experiment. The concentrations of available Ca, Mg, K and P were determined throughout both experiments. The soils amended with compost always had higher available Ca, Mg and K concentrations than the soils without amendment. The increases were approximately 800 mg kg?1 for Ca, 30 mg kg?1 for Mg, and 150 mg kg?1 for K. Nevertheless, the concentrations of these elements did not increase with time. The available P concentrations were not increased by the addition of compost, an effect which is attributed both to microbial immobilization and to the P-fixation capacity of the soils. Therefore, the expected release of these elements in parallel to compost mineralization was not observed during the experiments, and the only fertilizing effect of the compost was that of their initial input in available forms.  相似文献   

11.
The importance of using low-quality water, such as saline waters, for food production has been increased in the recent decades. An experiment was conducted to evaluate the effect of diluted seawater (electrical conductivity (EC) of 6 dS m?1) on growth and nutrient uptake of tomato. We examined if surfactant (0, 1, 2, 4 mg L?1) and biological fertilizer (compost tea + arbuscular mycorrhizal fungi propagules) have potential to alleviate the adverse effects of salinity on tomato plant. Salinity stress significantly reduced all plant growth parameters. Under salinity stress, nitrogen (N) and potassium (K) contents in tomato shoot were lower, while phosphorus (P), sodium (Na), and calcium (Ca) contents were higher than non-salinized plants; showing ionic imbalance in this condition. Biological fertilizer improved root weight in saline condition. Under salinity stress surfactant application at the rate of 1 mg L?1 helped tomato plants to maintain their ionic balance, especially declining Na uptake, and improved plant growth.  相似文献   

12.
Evaluation of nutrient status in soil is important for nutritional, environmental, and economical aspects. The objective of this work was to find out the most suitable universal extractant for determination of available phosphorus (P) and nitrate (NO3-) and exchangeable potassium (K), calcium (Ca), and magnesium (Mg) from soils using 0.01 M calcium chloride (CaCl2), 0.01 M barium chloride (BaCl2), 0.1 M BaCl2, 0.02 M strontium chloride (SrCl2), Mehlich 3, and ammonium bicarbonate diethylene triamine penta acetic acid (AB-DTPA) extractants. Composite surface soil samples (0–20 cm) were collected from the Eastern Harage Zone (Babile and Haramaya Districts), Wolaita Zone (Damot Sore, Boloso Bombe, Damot Pulasa, and Humbo Districts), and Dire Dawa Administrative Council by purposive sampling. The experiment was carried out in a completely randomized design (CRD) with three replications. Results indicated that the greatest correlations were found between Mehlich 3 and Olsen method and also between 0.02 M SrCl2 and Olsen method for available P. The amount of NO3– extracted by 0.02 M SrCl2 was significantly correlated to the amount determined by 0.5 M potassium sulfate (K2SO4). The amounts of exchangeable K, Ca, and Mg determined by ammonium acetate (NH4OAc) method were significantly correlated to the amount determined by universal extractants tested. In general, both 0.02 M SrCl2 and Mehlich 3 can serve as universal extractants for the macronutrients considered in this study with the former being more economical when NO3– is included.  相似文献   

13.
Abstract

The root parasitic plants Orobanche spp. (broomrapes) seriously affect agricultural production. A visualization and quantitative analytical method for the interception of nutrients was established using a positron-emitting tracer imaging system and 13NO? 3. By using this analytical method that involves volume normalization with 18F? images, the nitrogen nutrient interception ratio of the Orobanche spp. was calculated to be 73.6 ± 3.9% in a host–parasite system of red clover (Trifolium pratense L.).  相似文献   

14.
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   

15.
Sludge derived from cow manure anaerobically digested to produce biogas (methane; CH4) was applied to maize (Zea mays L.) cultivated in a nutrient-low, alkaline, saline soil with electrolytic conductivity 9.4 dS m?1 and pH 9.3. Carbon dioxide (CO2) emission increased 3.1 times when sludge was applied to soil, 1.6 times when cultivated with maize and 3.5 times in sludge-amended maize cultivated soil compared to the unamended uncultivated soil (1.51 mg C kg?1 soil day?1). Nitrous oxide (N2O) emission from unamended soil was -0.0004 μg nitrogen (N) kg?1 soil day?1 and similar from soil cultivated with maize (0.27 μg N kg?1 soil day?1). Application of sludge increased the N2O emission to 4.59 μg N kg?1 soil day?1, but cultivating this soil reduced it to 2.42 μg N kg?1 soil day?1. It was found that application of anaerobic digested cow manure stimulated maize development in an alkaline saline soil and increased emissions of CO2 and N2O.  相似文献   

16.
Abstract

Soybean [Glycine max(L.) Merrill] is moderately salt tolerant, but the method of irrigation used for crop production under saline conditions may influence the uptake and distribution of potentially toxic salts. This field study was conducted to determine the effects of application of saline waters by different methods, namely, drip and above‐canopy sprinkler irrigation, on the ion relations of soybean cultivar “Manokin”. Salinity was imposed by adding NaCl and CaCl2 (1:1 by weight) to nonsaline irrigation waters. Saline treatments with electrical conductivity (EC i ) of 4 dS m?1 were compared with nonsaline controls (EC i  = 0.5 dS m?1). Ion concentrations in leaves, stems, roots, and when present, pods were determined at four stages of growth: vegetative, flowering, podding, and grain filling. Both Na+ and Cl? were excluded from the Manokin leaves and stems when plants were drip‐irrigated and the uptake of these ions occurred solely via the root pathway. However, when saline water was applied by sprinkling, the ions entered leaves by both foliar absorption and root uptake and their concentrations in the leaves were about 9‐fold higher than in those under saline drip irrigation. Regardless of treatment, leaf‐K was highest during the vegetative stage, then decreased with plant age as K+ was mobilized to meet nutrient demands of the developing reproductive structures.  相似文献   

17.
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18.
Abstract

In a lysimeter study it was found that moderate rates of ammonium nitrate increased utilization percentages in spring wheat, and the leaching was 10% or less of added N. Over-optimal rates reduced utilization percentages and increased leaching to almost 50% of the highest doses. Late split application of calcium nitrate increased the percentage of N in grain. Furthermore, leaching of N was not reduced, but occurred somewhat later in the fall and winter seasons. Leaching of Cl? was more rapid and that of SO4 2- was delayed relative to the leaching of NO3 ?. Rather large negative N balances were obtained, also after over-optimal application rates, and total N content of the soil was reduced. Compared with the N0 treatment, differences in soil N residues amounted to 15–25% of added N in seven years. Gaseous losses had apparently taken place both from the added N and from soil N according to the total-N analysis.  相似文献   

19.
The potential of Nostoc 9v for improving the nitrogen (N)2–fixing capacity and nutrient status of semi‐arid soils from Tanzania, Zimbabwe, and South Africa was studied in a laboratory experiment. Nostoc 9v was inoculated on nonsterilized and sterilized soils. Inoculum rates were 2.5 mg dry biomass g?1 soil and 5 mg dry biomass g?1 soil. The soils were incubated for 3 months at 27 °C under 22 W m2 illumination with a photoperiod of 16 h light and 8 h dark. The moisture was maintained at 60% of field capacity. In all soils, Nostoc 9v proliferated and colonized the soil surfaces very quickly and was tolerant to acidity and low nutrient availability. Cyanobacteria promoted soil N2 fixation and had a pronounced effect on total soil organic carbon (SOC), which increased by 30–100%. Total N also increased, but the enrichment was, in most soils, comparatively lower than for carbon (C). Nitrate and ammonium concentrations, in contrast, decreased in all the soils studied. Increases in the concentration of available macronutrients were produced in most soils and treatments, ranging from 3 to 20 mg phosphorus (P) kg?1 soil, from 5 to 58 mg potassium (K) kg?1 soil, from 4 to 285 mg calcium (Ca) kg?1, and from 12 to 90 mg magnesium (Mg) kg?1 soil. Positive effects on the levels of available manganese (Mn) and zinc (Zn) were also observed.  相似文献   

20.
ABSTRACT

Roots of young ‘Golden Delicious’ apple on M9 rootstock were inoculated with four strains of Azotobacter chroococcum, which were isolated from various soils. Effects of these strains in combination with different levels of nitrogen (N) fertilizer and compost on plant growth and nutrient uptake were studied over two seasons. Therefore, a factorial arrangement included four strains of A. chroococcum, two levels of N-fertilizer (0 and 35 mg N kg?1soil of ammonium nitrate) and two levels of compost (0 and 12 g kg?1 soil of air-dried vermicompost). Among the four strains, AFA146 was the most beneficial strain, as it increased leaf area, leaf potassium (K), magnesium (Mg), iron (Fe), manganese (Mn), zinc (Zn), and boron (B) uptake and root N, phosphorus (P), potassium (K), Mn, and Zn. The combination of AFA146 strain, compost and N fertilizer increased leaf uptake of Ca, Mg, Fe, Mn, Zn, and B, and root uptake of P, K, Ca, Mg, Mn, and copper (Cu), and root dry weight.  相似文献   

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