The uptake of phosphate by barley plants from soil under aseptic and non-sterile conditions

The uptake of phosphorus by barley plants growing in soil has been compared in the presence and absence of microorganisms. The soil chosen for study was basaltic loam which earlier investigations had shown required the addition of supplementary phosphate to obtain successful growth of plants.Despite a rapid turnover of the phosphorus in microorganisms as a result of death and lysis, less was absorbed by plants grown under non-sterile conditions causing a considerable reduction in the yield of dry matter. These microbial effects were obviated by the addition of a small quantity of KH₂PO₄ (0.15 m-equiv/500 g soil). In this soil therefore, competition appears to exist between microorganisms and plants similar to that demonstrated previously in water culture.     

The uptake of strontium and cesium by plants from soil with special reference to the unusual cesium uptake by lowland rice and its mechanism

In the previous experiments using strontium-90 and cesium-134, the authors found some differences between lowland and upland rice with respect to their uptake from soil, particularly the unusual high absorption of cesium by lowland rice.     

溶磷真菌液体培养条件下对磷矿粉的溶解效果

Rock phosphate （RP） is a low efficiency P fertilizer that is directly applied to the soil and can be solubilized by phosphate-solubilizing microorganisms （PSMs） in fermentation or soil conditions. This study investigated dynamic solubilization of 2 concentrations of rock phosphate in a liquid culture with different dosages of glucose by two fungal isolates,Aspergillus niger P39 and Penicillium oxalicum P66, from soybean and wheat rhizosphere soil. Although during the 20 day culture period A. niger P39 had a stronger ability to acidify the culture media than P. ozalicum P66, soluble P concentrations at glucose dosages of 30 and 50 g L^-1 with RP of 15 g L^-1 in the culture solution were much higher by P. oxalicum P66. The greater effectiveness of P. oxalicum P66 compared to A. niger P39 in the solubilization of RP was strongly associated with the production of organic acids. This study suggested that for RP solubilization the type rather than the concentration of PSM-produced organic acids was more important.     

Noticeable increase in cadmium absorption by zinc deficient rice plants

The uptake and transport of cadmium were studied using zinc deficient rice plants. As a result, these plants absorbed and transported cadmium more rapidly than normal rice plants. A zinc deficiency might bring about physiological changes which significantly increase the cadmium accumulation in the roots and its transport into the shoots.     

A method for determining Michaelis-Menten kinetic parameters of nutrient uptake for plants growing in soil

The relationship between nutrient influx (I_n) and solution concentration at the root surface (C_lo) has not yet been determined for roots growing in soil because of difficulties in measuring C_lo. Corn was grown on two soils with 12 and 21% clay. Each soil had five K levels ranging from low to very high. Potassium influx (I_n) was determined from K uptake between two harvests and root length. C_lo was then calculated from the average soil solution concentration and I_n by assuming that diffusion is the main transport mechanism for K to the root. Potassium influx plotted against C_lo showed a saturation curve, typical of a Michaelis-Menten kinetic relationship. The Michaelis-Menten uptake parameters, maximum influx (I_max) and Michaelis constant (K_m), were obtained by the “Hanes” plot. There was close agreement, without lack of fit, between calculated and observed data. The proposed procedure therefore appears to be suitable for estimating the uptake kinetics of roots growing in soil. Requirements for applications of the method are discussed.     

Factors affecting the amount of phosphate extracted from soil by anion exchange resin

In resin—solution systems at equilibrium, solution concentration of phosphate was proportional to the square of the phosphorus sorbed, and inversely proportional to the weight of resin and the volume of solution. The rate of approach to equilibrium was decreased by: enclosing the resin in mesh bags, by increasing the volume of solution, and by decreasing the vigour of shaking.In resin-solution-soil systems, the concentration of phosphate in the solution was important in determining the amount of phosphate extracted from the soil. Consequently, phosphorus extracted increased as volume of water and weight of resin increased, and decreased when the resin was enclosed in mesh bags. Even after long periods of shaking, when the concentration of phosphate in solution had reached low values, appreciable phosphate remained on the soil in equilibrium with this solution phosphate. Equations suggested that, if the solution concentration could be reduced to zero, phosphate sorbed by the resin would be proportional to the phosphorus added to the soil. However, at finite levels of addition of resin, the proportion of added phosphate sorbed by the resin increased as the level of addition of phosphate increased.     

Cadmium contamination of soils and rice plants caused by zinc mining IV. Use of soil amendment materials for the control of Cd uptake by plants

In view of the difficulty in practicing water management as a measure to prevent the production of high Cd rice, alkaline or calcareous soil amendment materials were examined, concerning their pH effect on the availability of soil heavy metals.

1. In the experiment conducted on the contaminated paddy field, the essential Cd uptake by the plant occurred after the ear-forming stage and was reduced remarkably by a basal application of the amendment materials followed by top application, depending on the activity of raising the soil pH. Combined use of calcium silicate and fused magnesium phosphate for a basal dressing was most effective on Cd uptake, producing rice of the lowest Cd content, one fifth of the control.

2. The content of Cu in rice also decreased with the treatment to an extent second to Cd, while that of Zn and Pb decreased in straw but hardly changed in rice. Cu seemed fastest in the straw-to-grain movement which was also promoted by the treatments.

3. Soil Cd and Cu were less soluble in 0.1 N HCl solutions than were Zn and Pb, with the application of fused phosphate. Soil Cd became more insoluble in the incubated soil in a submerged condition and its solubility appeared to be depressed by the addition of ammonium sulfate.

4. Based on the good results for the control of high Cd rice obtained through three years' survey in the problem area, it was recommended that these materials be used in sufficient quantity to raise soil pH, taking care not to cause delay in the first growth.     

增氧型复混肥提高土壤氧化还原电位促进水稻养分吸收

  【目的】   稻田长期淹水所导致的土壤通气性差妨碍水稻的生长。探索增氧型复混肥对改善土壤通气状况的作用,为水稻专用肥研发提供理论依据。   【方法】   在复混肥制造过程中,添加特制的粘结剂和3.6%、4.8%、6.1%的过氧化钙制成具有增氧功能的复混肥OCF1、OCF2、OCF3。以Q681 (全两优681) 和EK1 (鄂科1号) 两种常规中稻品种为试材进行盆栽试验。设淹水 (WL)、增氧灌溉 (MBWI) 和分次增施过氧化钙 (FCP) 为对照,一次性基施OCF1、OCF2、OCF3 3个处理,在水稻主要生育期,测定土壤氧化还原电位、无机氮含量和pH,测定水稻叶片光合作用、水稻产量及氮磷钾养分含量。   【结果】   增氧措施OCF2和OCF3处理均能不同程度地提高移栽期、分蘖期、齐穗期和乳熟期土壤的氧化还原电位。与WL、MBWI和FCP处理相比,OCF1、OCF2和OCF3处理的土壤在分蘖期和齐穗期保持较高的氧化还原电位,其中以OCF2和OCF3的作用最明显;整个生育期,对照和各处理的土壤pH没有显著差异,与WL处理相比增氧型复混肥还可提高齐穗期土壤过氧化氢酶的活性。所有增氧处理均能够保持或显著提高耕层土壤铵态氮含量,其中OCF2和OCF3表现最明显。与WL处理相比,各增氧处理均不同程度地提高水稻叶片的光合速率,其中OCF3处理增幅最大,提高了11%以上,高于或显著高于增氧灌溉和分次增施过氧化钙处理 (MBWI和FCP)。OCF3处理的有效穗数、千粒重和产量比淹水灌溉WL处理分别提高25%、38%和107%,比MBWI和FCP处理提高29%～58%。   【结论】   增氧型复混肥能较长时间提高土壤通气性和土壤的氧化还原电位,有利于水稻对土壤养分的吸收利用。与分次追施过氧化钙和增氧灌溉相比,肥料制作过程中添加过氧化钙制备增氧型复混肥提高水稻土通气性的效果更好,操作更加方便,是提高水稻专用肥效益的有效途径。     

Solubilization of zinc phosphate by a strain of Pseudomonas fluorescens isolated from a forest soil

 A strain of Pseudomonas fluorescens, able to solubilize zinc phosphate, was isolated from a forest soil. Colonies of the microorganism produced clear haloes on solid medium incorporating zinc phosphate, but only when glucose was provided as the carbon source. Solubilization of zinc phosphate occurred by both an increase in the H⁺ concentration of the medium, probably a consequence of ammonia assimilation, and the production of gluconic acid. High concentrations of gluconic acid were produced when P. fluorescens 3a was cultured in the presence of zinc phosphate. Although under some conditions gluconic acid is purportedly able to solubilize metals by the formation of chelates, no evidence of zinc chelation was obtained in our experiments. Furthermore, the increased Zn²⁺ concentration caused by the solubilization process resulted in the manifestation of toxic effects on the culture. A sample of the culture, sonicated to disrupt cells, still possessed the ability to produce gluconic acid from glucose, in the presence and absence of zinc phosphate. The lack of gluconic acid overproduction in cultures of P. fluorescens 3a which were not amended with zinc phosphate suggests that at least some of the glucose oxidation required for the zinc solubilization occurred as a result of the toxic stress caused by the high Zn²⁺ concentration. Received: 16 December 1997     

Dissolution of slag fertilizers in a paddy soil and Si uptake by rice plant

Abstract

Maize (Zea mays L.) cv. Ganga 2 was grown in refined sand at three levels of copper: deficient (0.00065 mg L^-1), adequate (0.065 mg L^-1), and excess (6.5 mg L^-1), each at three levels, deficient (0.00065 mg L^-1), adequate (0.065 mg L^-1), and excess (6.5 mg L^-1) of zinc. Excess Cu magnified the zinc deficiency effects in maize by lowering further the biomass, the concentration of leaf Zn, activities of carbonic anhydrase, aldolase, and ribonuclease and intensified the visible foliar symptoms of Zn deficiency. The effects of Cu deficiency, low dry weight, the concentration of leaf Cu and activities of cytochrome oxidase and polyphenol oxidase were enhanced by excess Zn. Synergism was observed between combined deficiency of Cu and Zn and Cu or Zn deficiency, because the depression in the parameters characteristic of Cu or Zn deficiency was more pronounced when both Cu and Zn were deficient than when Cu or Zn was deficient. Antagonism was observed in some parameters between combined excess of Cu and Zn and Cu or Zn excess. Dry weight was decreased further when both Cu and Zn were in excess than when either Cu or Zn was in excess. After the infiltration of Cu and Zn together to the leaf discs from deficient Cu-deficient Zn treatment, the increase in the concentration of leaf Zn and the activities of aldolase, carbonic anhydrase, polyphenol oxidase, and cytochrome oxidase was more pronounced than after the infiltration of Cu or Zn singly. Discontinuance of excess Zn supply from the excess Zn-deficient Cu treatment increased the concentration of leaf Cu and activities of polyphenol oxidase and cytochrome oxidase and lowered the concentration of Zn. Similarly the discontinuance of excess Cu supply from the leaf discs in the “excess Cu-deficient Zn” treatment increased the leaf Zn concentration and the activities of carbonic anhydrase and aldolase.     

Arsenic speciation in xylem exudates of rice growing in arsenic-contaminated soil

Rice has a much enhanced arsenic (As) accumulation compared with other cereal crops. How As is transported in xylem exudates of rice growing in soil remains unknown. We quantified the chemical species of As in xylem exudates of rice growing in arsenic-contaminated soil (62.5 mg As per kg soil) under flooded and aerobic conditions. In the aerobic treatment, the predominant species of As in the xylem sap was arsenate [As(V)], accounting for 64–88%, and the remainder was arsenite [As(III)]. In the flooded treatment, dimethylarsinic acid (DMA) was detected in the xylem sap besides As(III) and As(V), and the percentages of the three species As was 11–20%, 26–77%, and 12–54%, respectively. As speciation in the soil solution was dominated by As(V) under aerobic conditions, and dominated by As(III) under flooded conditions. DMA was detected at low concentrations in some of the flooded solution samples. Our results show that As speciation in the xylem sap differs in different water management regimes and correlate with As speciation in the soil solution strongly.     

Effects of root morphology and Hg concentration in the soil on uptake by terrestrial vascular plants

Vascular plant tissues of various species growing on flood plain soils along the South River at Waynesboro, VA. have previously been shown to contain Hg. These soils characteristically contain 10–20μg Hg g^?1. In the field, root/rhizome Hg content inAsclepias syriaca andSolidago sp. ranged from undetectable amounts at low Hg control sites to 1.96μg Hg gdw^?1 at contaminated sites, with the association being inversely related to subterranean organ size. Within each size class, tissue Hg was directly related to soil Hg concentration. The relationship of subterranean organ size and enhanced Hg association was further substantiated by high levels of Hg in the fibrous root systems of grasses grown under greenhouse conditions.     

Yield and uptake of fertilizer nitrogen by direct-drilled winter barley growing on a chalk soil

Abstract. This paper reports the growth and yield of grain and the utilization of fertilizer nitrogen applied on either one or two occasions in spring to a crop of winter barley established by direct drilling on a chalk soil in southern England. Nitrogen, as ammonium nitrate, was applied at rates of 0 to 140 kg N ha⁻¹ in a range of proportions on two occasions (March and April 1981); nitrogen-15 was used to facilitate study of the nitrogen utilization by the crop.
When sampled before the second top-dressing in April, the greatest number of tillers were found on plants treated with 70 and 100 kg N ha⁻¹ in March. The total above ground dry matter production at harvest was greatest when the split nitrogen dressing totalled more than 100 kg N ha⁻¹, although the apparent efficiency of nitrogen usage (kg DM per kg N applied) was greatest when 60 kg N ha⁻¹ was divided equally between the two application dates. Grain yield was heaviest (6.471 ha⁻¹) at the largest rate of nitrogen applied (140 kg N ha⁻¹); the lightest yield from the nitrogen treated crops was recorded from 100 kg N ha⁻¹ applied as a single dressing in April that stimulated shoot production and decreased individual grain weight. The recovery in grain and straw of labelled fertilizer nitrogen applied only in March averaged 42.2% and was 49.8% when the nitrogen was applied only in April. The recovery of nitrogen applied in both March and April at the total rate of 100 kg N ha⁻¹ but split 30/70 or 70/30 was 44.5% and 42.5% respectively. Non-fertilizer sources of nitrogen contributed 60.7–71.7% of the total nitrogen uptake by the crop at harvest.     

The relationship between boron soil test results and boron uptake by bean plants

Abstract

Boron sensitive crops, kidney beans and soybeans, were grown in pots containing soil collected from a beet field and a nearby pasture. Two soil extraction procedures were used to measure boron concentrations in the soils. Dilute acid was used to extract what is believed to be readily available boron. A modified‐Soxhlet apparatus, which employed continuous leaching with hot water, measured what is believed to be slowly available boron. Plant boron status was determined by analyzing the above ground portion of the plants grown in two soils. The amount of boron in the plant tops provides an indication of biologically available boron or that boron actually available to plants. Although kidney beans and soybeans extracted more boron from the beet soil, both soil extraction procedures indicated that the concentration of boron was higher in the pasture soil. Neither extraction procedure proved reliable in predicting plant response.     

Role of soil redox in growth and fertilizer nitrogen uptake by rice in Thailand paddy soils

Abstract. In a laboratory study, ¹⁵N ammonium fertilizer uptake and rice growth was determined in a non-acid sulphate marine soil (Typic Tropaquept) and an acid sulphate soil (Sulfic Tropaquept). Acid sulphate sensitive (IR 26) and acid sulphate tolerant (IR 46) rice varieties were grown in soil suspensions incubated at four Eh levels (+500, +250, +50, and -150 mV) in microcosms for three weeks. The results showed that rice grown in non-acid sulphate marine soils gave slightly better dry matter weight of 1.8g/pot, greater ¹⁵N uptake of 12.8 mg N/pot, and higher total N uptake of 38.4 mg N/pot than under acid sulphate soil conditions indicating the non-acid marine soil is more favourable to rice culture. Growth as measured by weight of dry matter was significantly reduced from 2.1g/pot under oxidized condition (+500 mV) to 0.8g/pot under highly reduced condition (-150 mV). N uptake by rice was significantly reduced from 16.9 mg/pot at + 500 mV to 4.5 mg N/pot at -150 mV Total N uptake also decreased with decreasing Eh. Growth, ¹⁵N uptake and total N uptake by acid sulphate tolerant rice, IR 46 were significantly higher than the acid sulphate sensitive rice variety, IR 26. Under highly reduced soil conditions (-150 mV), growing rice in acid sulphate soil would require additions of lime, intermittent irrigation and/or mid season drainage in order to increase soil redox potential and remove toxic substances.     

Applications of fertilizer cations affect cadmium and zinc concentrations in soil solutions and uptake by plants

A pot experiment was conducted to study changes over time of Cd and Zn in soil solution and in plants. Radish was grown in a soil which had been contaminated with heavy metals prior to 1961. Constant amounts of a fertilizer solution (NH₄NO₃, KNO₃) were added daily. Soil solution was obtained at intervals by displacement with water. The cumulative additions of small amounts of fertilizers were made equal to the plants' requirements at the final harvest but were found to exceed them during most of the experiment. Excess fertilizers caused substantial increases of major (K, Ca, Mg) and heavy-metal (Cd, Zn) ions in soil solutions and a decrease in soil pH, probably due to ion-exchange mechanisms and the dissolution of carbonates. Uptake of Cd and Zn into leaves was correlated with the mass flow of Cd (adjusted r²= 0.798) and Zn (adjusted r²= 0.859). Uptake of K, Ca and Mg by the plants was independent of their concentrations in solution. It is concluded that, in order to study effects of plants on heavy-metal availability and obtain soil solution that has not been altered by fertilizer ions, nutrients must be added according to the needs and growth of the plants. This could be achieved by linking fertilizer additions to the rate of transpiration, as nutrient uptake and transpiration were closely correlated in this experiment.     

The influence of pH,soil type and time on adsorbtion and uptake by plants of Cd added to the soil

Adsorption of Cd by two soils and its uptake by perennial ryegrass (Lolium perenne) and winter rape (Brassica napus) as a function of pH (pH 4 to 7) and the amount of Cd added to the soil (0 to 5 mg kg^?1 soil) were studied in a 2-yr pot experiment. In the soils, the more soluble fractions of Cd increased as the pH was lowered. Increasing the pH from 5 to 7 by adding CaO invariably reduced the Cd-content of ryegrass plants, but this decrease was less consistent where the pH had only been increased to 6. In some cases, acidifying the soil with S to reach a pH of 4 also led to a decrease in plant Cd-content. The Cd-content of rapeseed plants was markedly higher at pH 4 than at pH 5. Plant damage at low pH was observed in this crop. Water-leachable and CaCl₂-extractable soil Cd levels as well as plant uptake were higher in the sand soil than in the clay soil, whereas 1M NH₄AcO (buffered at pH 4.8 and 7) extracted roughly equal amounts from both soils. Adding more Cd to the soil did not change the relation between Cd levels in soil and those in plants; instead the amounts of Cd in both increased in direct proportion to the amounts added. Fixation of added Cd apparently did not occur continuously at any pH or Cd-level during the 2-yr period, but seasonal variations in solubility and uptake were observed.     

Trace elements accumulation in soil and rice plants irrigated with the contaminated water

We carried out a study to see the effect of contaminated water of Nullah Dek on fine rice paddy and straw yields and trace elements accumulation in different parts of rice plants and soil. A site was selected near the bank of Nullah Dek at Kot Pindi Das in the District of Sheikhupura, Pakistan. The water of this nullah is contaminated by industrial effluents carrying different micronutrients. This water was employed to grow rice crop. Water samples were collected before transplanting and during the season with 15 days interval for analysis from 20 July to 1 November 2002 from a spot near village Shamke. Three fine rice varieties, viz. Super Basmati, Shaheen Basmati and Basmati 2000 were transplanted. These rice varieties were grown up to maturity. Paddy and straw yields data were recorded. Six composite soil samples from three random spots were collected from the experimental site before the start of the study to see the status of trace elements in soil. After the harvest of rice crop, soil, paddy and straw samples were analysed for Zn, Cu, Fe and Mn. The chemical analysis of Nullah Dek water showed that total salts concentration was greater than the safe limit, i.e. electric conductance (EC) > 1.0 dS m⁻¹. Even sodium adsorption ratio (SAR) was very high, but there was no problem of high residual sodium carbonate (RSC). Zn, Cu, Fe and Mn were present but within safe limits. The water of Nullah Dek remained within permissible limits of irrigation from onset of rainy season till 15 October. There was an increase in EC, SAR and trace elements concentrations after 15 October but within safe limits. Soil analysis revealed its saline nature, devoid of sodicity. Among trace elements, the zinc ranged between deficiency (<0.5 mg kg⁻¹) and adequate limits (>1.0 mg kg⁻¹). Copper, Mn and Fe were present in adequate amounts. After the harvest of rice crop there was a slight decrease in pH, EC_e and SAR at both the depths, while the concentrations of all trace elements were slightly increased with more in upper layer than the lower layer. Shaheen Basmati produced the maximum paddy yield followed by Basmati 2000 and then Super Basmati. The chemical analysis of paddy samples indicated a sufficient accumulation of zinc (1.68–1.78 mg kg⁻¹), copper (1.38–1.45 mg kg⁻¹), iron (6.12–6.37 mg kg⁻¹) and manganese (2.22–2.42 mg kg⁻¹). Analysis of rice straw also showed sufficient accumulation of zinc (27.50–28.50 mg kg⁻¹), copper (20.0–20.50 mg kg⁻¹), iron (270–280 mg kg⁻¹) and manganese (2.38–2.41 mg kg⁻¹).