Showing papers in "Plant and Soil in 1978"
TL;DR: In this article, the anion exchange resin method for soil-phosphate extraction was investigated on four different soils under varying experimental conditions, and the variables were: (a) the type of anion-exchange resin, (b) the anionic form of the resins, (c) the ratio between the amounts of resin, soil, and water, and (d) the time of shaking.
Abstract: The anion-exchange resin method for soil-phosphate extraction was investigated on 4 different soils under varying experimental conditions. The variables were: (a) the type of anion-exchange resin, (b) the anionic form of the resin, (c) the ratio between the amounts of resin, soil, and water, and (d) the time of shaking.
244 citations
TL;DR: The effect of silicon on manganese tolerance of bean plants (Phaseolus vulgaris L var ‘Red Kidney’) grown in water culture was studied at different levels of manganous supply.
Abstract: The effect of silicon on manganese tolerance of bean plants (Phaseolus vulgaris L var ‘Red Kidney’) grown in water culture was studied at different levels of manganese supply Without silicon, growth depression and toxicity symptoms occurred already at 5 × 10−4 mM Mn in the nutrient solution After addition of Aerosil (075 ppm Si), the plants tolerated 5 × 10−3 mM Mn and, at a higher silicon supply of 40 ppm, as much as 10−2 mM Mn in the nutrient solution without any growth depression This increase in manganese tolerance was not caused by a depressing effect of silicon on uptake or translocation of manganese but rather by an increase in the manganese tolerance of the leaf tissue In absence of silicon, 100 ppm Mn was already toxic for the leaf tissue, whereas with a supply of 40 ppm Si, this ‘critical level’ in the leaves was increased to more than 1000 ppm Mn At lower manganese levels in the leaf tissue, a molar ratio Si/Mn of 6 within the tissue was sufficient to prevent manganese toxicity Above 1000 ppm Mn, however, even a much wider Si/Mn ratio (> 20) could not prevent growth depression by manganese toxicity With54Mn and autoradiographic studies, it could be demonstrated that, in absence of silicon, even at optimal manganese supply (10−4 mM), the distribution of manganese within the leaf blades was inhomogeneous and characterized by spot-like accumulations In presence of silicon, however, the manganese distribution was homogeneous in the lower concentration range of manganese and still fairly homogeneous in the high concentration range This effect of silicon on manganese distribution on the tissue level was also reflected on the cellular level In the presence of silicon, a higher proportion of the leaf manganese could be found in the press sap,ie, had been transported into the vacuoles, than in the absence of silicon The increase in manganese tolerance of bean leaves by silicon therefore seems to be primarily caused by the prevention of local manganese accumulation within the leaf tissue which leads to local disorders of the metabolism and, correspondingly, growth depression
216 citations
TL;DR: There was little uptake of Bi, Sb and Te even from solutions that reduced the yield of young barley, and it is believed that these elements may have reduced the availability or translocation of other nutrient elements.
Abstract: Theupper critical level of a potentially toxic element is its minimum concentration in actively growing tissues of a plant at which yield is reduced.
200 citations
TL;DR: In this paper, Trifolium subterraneum and Ornithopus compressus were grown in soil and solution culture at varying P concentrations and the efficiency of P utilization was determined using the following criteria: (1) The ability to produce top dry matter with a given amount of applied P, (2) Tops dry matter produced per unit of P taken up, (3) TOPS dry matter generated at a constant plant P level and (4) Phosphorus uptake per unit root weight.
Abstract: Trifolium subterraneum, Trifolium glomeratum andOrnithopus compressus were grown in soil and solution culture at varying P concentrations. Efficiency of P utilization was determined using the following criteria: (1) The ability to produce tops dry matter with a given amount of applied P, (2) Tops dry matter produced per unit of P taken up, (3) Tops dry matter produced at a constant plant P level and (4) Phosphorus uptake per unit root weight. The order of efficiency varied according to the crieteria used. Using the agronomic definition (1), Serradella was the most efficient species at 70 days.
75 citations
TL;DR: A mathematical model is described which enables the flow of water, the water content and the matric potential to be calculated for any depth in an uncropped soil.
Abstract: A previous model for simulation of the vertical distribution of water in a fallow soil has been developed to include water extraction by plant roots. Results from the model agreed well with field measurements, the main differences being caused by horizontal variations in root density, hysteresis in the soil hydraulic properties and by the apparently anomalous infiltration behaviour of the field soil. The model demonstrated the simulated effects on water extraction of root hydraulic resistance, of non-polar flow in the roots, and the capacity of the plant to store water.
65 citations
TL;DR: Nitrification occurred at both levels of H-ion concentration but at the higher pH the rate of nitrification was greater and the population estimates of nitrifying bacteria were correspondingly greater at the high pH.
Abstract: The rate of nitrification by soil aggregates at pH 5.5 and 7.5 was examined by a perfusion technique. Nitrification occurred at both levels of H-ion concentration but at the higher pH the rate of nitrification was greater. The population estimates of nitrifying bacteria were correspondingly greater at the high pH. Once the pH was lowered from 7.5 to 5.5, the nitrification rate decreased slowly with a corresponding decrease in the numbers of nitrifying bacteria. The distribution of nitrifying bacteria throughout soil aggregates was homogenous. The lower limit of pH for nitrification was 4.3.
64 citations
TL;DR: It is concluded that nodulated specimens of Ulmaceae all belong to Parasponia, and the taxonomic position of nodulate specimens which previously have been identified as Trema cannabina has been re-investigated.
Abstract: A description was given of the nodulation and N2-fixing activity ofParasponia parviflora Miq. (Ulmaceae) in Indonesia. In addition, the taxonomic position of nodulated specimens which previously have been identified asTrema cannabina has been re-investigated. It is concluded that nodulated specimens of Ulmaceae all belong to Parasponia. A review was given of neglected literature on the occurrence of root nodules in Ulmaceae in Indonesia.
59 citations
TL;DR: In this article, the authors used a 1∶1 mixture of ammonium and nitrate, combined factorially with pH values of 4.6, 5.3 and 6.0 giving a total of nine treatments.
Abstract: Lodgepole pine (Pinus contorta Dougl.), Engelmann spruce (Picea engelmanni Parry), and Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) seedlings were grown in open-ended tube cultures of sand and perlite, irrigated with nitrate, ammonium, and a 1∶1 mixture of ammonium and nitrate, combined factorially with pH values of 4.6, 5.3 and 6.0 giving a total of nine treatments. Douglas-fir showed intolerance to ammonium which was especially marked in root weight. Lodgepole pine and Engelmann spruce made poor growth with nitrate, but showed little difference between ammonium and mixed sources. Only Douglas-fir showed a significant response to pH treatments with pH 5.3 plants being largest. Contamination of the sand with carbonate-bicarbonate, apparently caused seedlings grown in ammonium solutions to be larger in sand than in perlite.
57 citations
TL;DR: Maize and wheat crops grown for 60 days and maturity respectively in soils with a range of available zinc indicated 7 ppm Zn in soil and 60 ppm in plant being toxic for wheat.
Abstract: Maize and wheat crops grown for 60 days and maturity respectively in soils with a range of available zinc (0.4 to 109 ppm DTPA extractable) indicated 7 ppm Zn in soil and 60 ppm in plant being toxic for wheat. These limits for maize were 11 ppm Zn in soil and 81 ppm Zn in plant. Wheat crop is more susceptible to Zn toxicity as compared to maize.
57 citations
TL;DR: In this paper, it is indicated that organic macro molecules in the soil are aggregated due to bonds, presumably hydrogen bonds, formed in the presence of water and when the soil is dried, this structure is broken and the stability of the organic matter decreases.
Abstract: It is indicated here that organic macro molecules in the soil are aggregated due to bonds, presumably hydrogen bonds, formed in the presence of water. When the soil is dried, this structure is broken and the stability of the organic matter decreases. This process is not an instantaneous process and apparently some relaxation period is needed for a complete dispersion of the organic matrix. An appreciable fraction of the organic molecules is hindered, even from contact with the solution in the aggregated structure, as indicated by the lower acidity in the wet soil. This steric hinderence seems to be one of the important factors contributing to the stability of humic compounds.
56 citations
TL;DR: The influence of soil moisture content and soil water potential on plant water potential, transpiration and net-photosynthesis of potted larch (Larix decidua), spruce (Picea abies) and pine (Pinus cembra) was studied under constant and close to optimum conditions in a laboratory as discussed by the authors.
Abstract: The influence of soil moisture content and soil water potential on plant water potential, transpiration and net-photosynthesis of potted larch (Larix decidua), spruce (Picea abies) and pine (Pinus cembra) was studied under constant and close to optimum conditions in a laboratory.
TL;DR: In this paper, the effects of atmospheric carbon dioxide enrichment on nitrogen fixation by white clover and pea, and on stomatal aperture, transpiration loss and nitrate reductase activity were discussed.
Abstract: The effects of atmospheric carbon dioxide enrichment on nitrogen fixation by white clover and pea, and on stomatal aperture, transpiration loss and nitrate reductase activity in white clover, are described and the implications discussed.
TL;DR: In this article, Douglas fir seedlings were grown for two to three months in sand and soil cultures in a greenhouse to examine their growth response to nitrogen (N) source at different levels of pH and iron (Fe) supply.
Abstract: Douglas fir seedlings were grown for two to three months in sand and soil cultures in a greenhouse to examine their growth response to nitrogen (N) source at different levels of pH and iron (Fe) supply. In the first two experiments nutrient solutions of known pH were automatically applied to the top of the sand cultures and allowed to run to waste from the bottom. Under these conditions seedlings made most growth on nitrate (NO3−N) under acid (pH4) conditions, but most growth on ammonium (NH4−N) under neutral (pH7) conditions. Calcium carbonate (CaCO3) was used to create a range of pH conditions (from 4.0 to 7.2) in a peat and sand artificial soil. Over the pH range 4 to 6 NH4−N or NO3+NH4−N produced larger seedlings than NO3−N alone, but above pH6 growth on all N sources was depressed. Chemical analysis showed that seedling Ca concentration had increased and Fe concentration had decreased with increase in CaCO3 application. Both Ca and Fe concentrations were higher in seedlings receiving NO3−N than in those receiving NH4 or NO3+NH4. In sub-irrigated sand cultures, Doughlas fir seedlings receiving NO3−N were shown to respond to additions of Fe chelate, but seedlings receiving NH4−N responded little to Fe chelate. At pH5 seedlings receiving NO3−N did not grow as big as seedlings receiving NH4−N in the absence of Fe chelate, but addition of Fe chelate resulted in NO3-fed seedlings growing larger than NH4-fed seedlings. The relationship between seedling Fe concentration and N nutrition is discussed. The relatively larger root dry weight and surface area of seedlings grown on NO3−N, as compared to NH4−N, in sand culture, was noted.
TL;DR: In this paper, distribution and localization of cadmium and zinc at plant and cellular levels were studied at both cellular and plant levels, showing that the relative distributions of Cd and Zn present at the same concentration in the growing medium are quite identical.
Abstract: Rice plants are grown in nutrient solutions (Hoagland-Arnon 1) containing different concentrations of cadmium (0.005; 0.010 and 0.100 ppm) and one concentration of zinc (0.070 ppm) traced respectively with109Cd and65Zn. Distribution and localization of both elements are studied at plant and cellular levels. Contrary to zinc, cadmium remains fixed by radicular sites and its translocation index is very low. Centrifugation of roots homogenates showed that % Cd recovered in the residue increases with Cd concentration and emphasize the high capacity of Cd fixation by walls when Cd external concentration is high. The relative distributions of Cd and Zn present at the same concentration in the growing medium are quite identical. In the 100,000×g supernatant fraction of roots, both elements are associated with compounds of low molecular weight, Cd being bound to higher MW ligands than zinc (1000 to 3000 for zinc). The fact that Cd was recovered in fractions in which most of35S-cysteine was present suggests that in plants, like in animals, peptides rich in — SH residues may play a role in the fixation of heavy metals.
TL;DR: In this paper, the authors found that exposure of tomato roots to different concentrations of phenyl acetic, benzoic, phenyl butyric and cinnamic acids imparted some resistance to invasion by the nematode.
Abstract: Amendment of soil with margosa cake or sawdust supplemented with NPK fertilizers increased its phenolic content. The concentration of total phenols was related to the amount of amendment used and varied with the length of decomposition period. Total phenols estimated in ether extract were more in margosa cake amended soil than in sawdust amended soil. Roots of tomato plants grown in amended soil showed presence of higher quantity of total phenols than those grown in non-amended soil. Exposure of females ofMeloidogyne javanica to benzoic, phenyl butyric, phenyl acetic and cinnamic acids significantly reduced their egg laying capacity. Suppression of larval motility was one of the main direct effects of these acids on the nematode. Exposure of tomato roots to different concentrations of phenyl acetic, benzoic, phenyl butyric and cinnamic acids imparted some resistance to invasion by the nematode. In such treated plants fewer larvae could penetrate the roots and develop into mature females and fewer eggs were produced.
TL;DR: In this paper, a series of nutrient solutions in which 0, 60, 90, 95, 98 and 99 percent of the K was replaced by Na were used to grow tomato leaves.
Abstract: Tomato plants (Lycopersicon esculentum cv. Amberley Cross) were grown in a series of nutrient solutions in which 0, 60, 90, 95, 98 and 99 per cent of the K was replaced by Na. The plants selectively absorbed K relative to Na from the nutrient solutions and transported K to the shoots in preference to Na. In the nutrient solution having the highest K/Na ration most of the Na taken up by the plants accumulated in the roots, but as the K was progressively replaced by Na an increasing proportion of the total Na absorbed was transported to the leaves. Sodium was present at up to 2.4 per cent of the dry wt of whole, fully-expanded leaves without there being any apparent visual signs of damage or reduction in the rate of growth of the plants. On closer examination it was found that most of the Na transported to the leaves was excluded from the laminar tissue and accumulated in the adjacent petioles. The ability of the roots and petioles to retain large amounts of Na depended on an adequate supply of K to the plants.
TL;DR: In this article, a solution containing a mixture of phenolic compounds which have previously been reported to be produced by these shrubs was added to soil taken from an area dominated by Adenostoma fasciculatum H & A, (chamise), and Arctostaphylos glandulosa Eastw sppmollis (Adams) Wells, (manzanita).
Abstract: To soil taken from an area dominated byAdenostoma fasciculatum H & A, (chamise), andArctostaphylos glandulosa Eastw sppmollis (Adams) Wells, (manzanita), was added a solution containing a mixture of phenolic compounds which have previously been reported to be produced by these shrubs The soil was then subjected to an alkaline soil-extraction technique similar to those commonly employed for the determination of soil phenolics in various allelopathic studies Gas-chromatographic analysis revealed the compounds yielded in this extraction to be of three sources: 1) those compounds extracted from the soil prior to the addition of the phenolic compounds, 2) those phenolic compounds which were added to the soil, and 3) compounds which probably owe their origin to the action of the alkaline extractant upon the added phenolic compounds The likelihood of the introduction of phenolic artifacts, the result of alkaline degradation of soil organic matter, into soil extraction results is discussed It is concluded that the use of alkaline soil extraction techniques is inappropriate for the purpose of allelophathic studies
TL;DR: It is inferred that soil organic matter was important in the efficiency of nitrogen fertilizer on pearl millet because more than half of the plant nitrogen was nevertheless provided by the soil when the yield expressed in a fertilizer nitrogen unit basis was the highest.
Abstract: In a lysimetric experiment conducted in a sandy soil of Senegal, nitrogen fertilization (15N) and straw incorporation, were combined factorially, the soil being left bare or cropped with millet. On the one hand, yields were estimated, and on the other hand nitrogen absorption, immobilization, and losses were estimated in the soil-plant system.
TL;DR: Observations of a selected area in the forest zone of south western Nigeria indicate that the distribution of Macrotermes bellicosus and Macrotermes subhyalinus mounds are mainly affected by the drainage conditions of the soils along a toposequence.
Abstract: SummaryObservations of a selected area in the forest zone of south western Nigeria indicate that the distribution ofMacrotermes bellicosus (Smeathman) andMacrotermes subhyalinus (Rambur) mounds are mainly affected by the drainage conditions of the soils along a toposequence. Higher number of mounds are observed on the better drained soils, ranging from 35.4 to 17.2 mounds/ha covering an area of respectively 0.84 and 0.10 per cent. The shallow and poorly drained soils show lower mound density (<1 mound/ha).The mound soil bears close resemblance to the subsoil, has higher clay content, lower pH, organic C, CEC and extractable P, but higher P retentio than the adjacent surface soil.Growth of maize (Zea mays L.) and soybean (Glycine max. (L.) Merrill) was poorer in the mound soil than in the surface soil. The problem of increased soil variability when large number of mounds are encountered in the field is discussed.
TL;DR: Cobalt levels for most species of Aeolanthus were considerably above typical values for phanerogams and indicate the favorable potential of the genus for further study.
Abstract: Hyperaccumulators (here defined as species containing at least 500 μg/g dryweight of either copper or cobalt in leaves), are of interest for the fields of mineral exploration and phytochemistry. Reported hyperaccumulation of copper inAeolanthus biformifolius and the presence of two other species on copper/cobalt mineralization in Shaba (Zaire) led to a survey of these elements in 49 species of the African genusAeolanthus Mart.A. biformifolius appears to be also a hyperaccumulator of Co (2520 μg/g in leaves, 4300 μg/g in corms). Cobalt levels for most species ofAeolanthus were considerably above typical values for phanerogams and indicate the favorable potential of the genus for further study.
TL;DR: In a micro-plot experiment 1.5 ppm boron in the irrigation water was toxic for wheat and pea plants, Nitrogen in both species increased significantly and calcium decreased with the increase in B in irrigation water.
Abstract: In a micro-plot experiment 1.5 ppm boron in the irrigation water was toxic for wheat. Its concentration in the soil solution increased to 1.53 ppm and in the plant tissue to 58 ppm. In pea plants 4 ppm B in the irrigation water was toxic with 2.00 ppm soil solution B and 213 ppm tissue B. Nitrogen in both species increased significantly and calcium decreased with the increase in B in irrigation water. The yield of wheat grain declined by 13, 20 and 32 per cent at the 4.0, 6.0 and 8.0 ppm B respectively. The yield of straw and grains of pea declined by 31, 56 and 41, 56 per cent at 6.0 and 8.0 ppm B levels respectively. Thus tolerance to B in irrigation water was between 3.0 and 4.0 ppm for wheat and 4.0 and 6.0 ppm for pea.
TL;DR: In this paper, the peroxidase/catalase ratio varied with iron supply and showed a minimum value of about 39 at 15 and 30 days growth, at adequate iron supplies.
Abstract: Pea plants (Pisum sativum L., var. Lincoln) were grown in nutrient cultures at 4 levels of iron, 0.60 ppm (low), 0.96 ppm (low), 3.0 ppm (normal) and 30 ppm (excess) for 45 days. Leaf extracts were assayed for chlorophyll, proteins, catalase and peroxidase activities. Catalase and chlorophyll were closely related to iron supply. An inverse relationship was observed between peroxidase and catalase activities. Peroxidase was increased both at dificiency and excess iron levels, but was depressed at normal iron supply. The peroxidase/catalase ratio varied with iron supply and showed a minimum value of about 39 at 15 and 30 days growth, at adequate iron supplies. Measurement of catalase activity and the use of peroxidase/catalase ratios appear to be helpful in identifying iron deficiencies in peas.
TL;DR: In this article, the uptake of Mn from manganous ions and pyrolusite (MnO2) by three week-old oat plants (Avena sativa L.) grown in nutrient solutions controlled at pH values between 6 and 8, was almost completely inhibited by suspensions of Mn oxidizing bacteria over a three day uptake period.
Abstract: The uptake of Mn from manganous ions (Mn-ions) and pyrolusite (MnO2) by three week-old oat plants (Avena sativa L.) grown in nutrient solutions controlled at pH values between 6 and 8, was almost completely inhibited by suspensions of Mn- oxidizing bacteria over a three day uptake period.
TL;DR: The organism exhibited maximum positive chemotactic response to histidine and negative response to alanine among the amino acids and to glucose and gluconic acid among the sugars and sugar acids.
Abstract: Root exudate from seedlings ofCicer arietinum L. was collected in a chamber under aseptic conditions. The exudate was fractionated into anion, cation and neutral fractions. The anionic fraction was made up of galacturonic acid, gluconic acid, mannuronic acid and two unidentified compounds withR
f
values 0.56 and 0.62. The cationic fraction contained alanine, arginine, aspartic acid, cystine, glycine, histidine, isoleucine, leucine, lysine and serine. The neutral fraction was made up of arabinose, galactose, glucose, ribose and xylose. The amino acids contributed to the bulk of the root exudate. The ratio of anionic, cationic and neutral fraction was 1∶7∶2. The crude root exudate was tested for its chemotactic ability using the capillary tube method. It was highly chemotactic for theRhizobium sp. The individual fractions and their various combinations were tested for chemotaxis. The chemotactic response of the Cicer strain of Rhizobium was least with anionic fraction most with cationic fraction and intermediate with neutral fraction. Maximum chemotactic response among the fractional combinations was obtained with all the three fractions and least with cationic plus neutral factions. Individual compounds constituting the various fractions were also tried for their ability to elicit chemotactic response. The organism exhibited maximum positive chemotactic response to histidine and negative response to alanine among the amino acids and to glucose and gluconic acid among the sugars and sugar acids.
TL;DR: In this article, the significance of the term "ecological climax" is explained in relation to the productivity and fertiliser requirement of a pastoral ecosystem, and a model has been constructed for drawing up nutrient balance sheets where a climax had been reached in a typical case.
Abstract: The significance of the term ‘ecological climax’ is explained in relation to the productivity and fertiliser requirement of a pastoral ecosystem. A model has been constructed for drawing up nutrient balance sheets where a climax had been reached in a typical case. The balance sheets have been used to study the phosphate problem over a range of inputs and outputs for fertiliser elements likely to apply in practice. Results indicate that in a stable high-producing system phosphorus is not abnormal in comparison with other fertiliser elements. This conclusion is at odds with the theory of phosphate fixation.
TL;DR: Perennial ryegrass was sown in flowing solution culture at 7, 6, 5 and 4 weeks before the addition of cadmium to the nutrient solution.
Abstract: Perennial ryegrass was sown in flowing solution culture at 7, 6, 5 and 4 weeks before the addition of cadmium to the nutrient solution The concentration of cadmium in solution was held constant at 001 ppm for the following 15 days during which period uptake by the 4 sets of plants of different ages was followed by plant analysis at 3-day intervals During the 15-day period the total uptake per g (dry weight) root remained nearly constant The cadmium content of the roots was much greater than that of the corresponding shoots and, although older plants contained more cadmium than younger plants, the proportion of the total content retained by roots was much the same in the 4 sets of plants,ie >90 per cent It is concluded that the roots of ryegrass restrict the transport of cadmium to the shoots The concentration in the shoots increased only slightly during the 15-day period but to a different extent amongst the 4 sets of plants These differences reflect differences in growth rate; thus the shoots of the younger sets of plants had lower growth rates and contained correspondingly higher concentrations of cadmium
TL;DR: Root length and number of roots can be reliably used for screening triticales for Al tolerance within 12 days of exposure to Al, and Root length, Al concentration, and dry weight after 22 days of Al treatment were also reliable criteria for evaluating differential Al tolerances amongtriticale cultivars.
Abstract: Screening large populations of plant species for Al tolerance requires simple and rapid tests. In this study, root characteristics of 12 cultivars of triticale (X Triticosecale, Witt Mack), wheat (Triticum aestivum L.), and rye (Secale cereale L.) were measured in nutrient solution with 0 or 6 ppm Al added. Aluminum injury to roots of triticale and wheat was characterized by decreases in root length, increases in the number of roots, and in Al-sensitive Redcoat and Arthur wheats by decrease in root weight. Root length and number of roots were correlated in triticale (r=−0.73*) and in wheat (r=−0.85*). Root length was also correlated with root weight in wheat (r=0.65*); there was no relationship between the number of roots and weight. Differences in Al tolerance of cultivars of the three species were greater when the solution was adjusted to pH 4.8 only on the first day of the experiment than when pH was maintained at pH 4.8 throughout the growing period. Triticale and rye cultivars low in ability to increase solution pH gradually overcame Al toxicity by increasing the nutrient solution pH between 12 and 22 days. Aluminum sensitive triticale and wheat accumulated more Al in roots than tolerant cultivars when the solution pH was not adjusted daily; but no differences in Al accumulation were obtained between wheat cultivars at constant pH value. This study indicated that root length and number of roots can be reliably used for screening triticales for Al tolerance within 12 days of exposure to Al. Root length, Al concentration, and dry weight after 22 days of Al treatment were also reliable criteria for evaluating differential Al tolerances among triticale cultivars.
TL;DR: Air-borne Mg and Ca show a similar, but much reduced, trend to Na but still have a major rôle in nutrient cycling systems and may be expected to influence tree growth and development and possibly soil formation.
Abstract: The distribution of air-borne salt within a forest was investigated. Na deposition decreased rapidly for three canopy heights' from the windward edge of the forest. Deposition was constant throughout the remainder of the forest. Levels of deposition experienced near the edge of the forest may be expected to influence tree growth and development and possibly soil formation. Air-borne Mg and Ca show a similar, but much reduced, trend to Na but still have a major role in nutrient cycling systems.
TL;DR: Experimental findings depict that staling growth substances diffused in the agar created the change in the pattern of colony interaction.
Abstract: Effect of staling growth substances on the colony interaction in between some dominant rhizosphere fungi andSclerotium rolfsii Sacc. a root pathogen ofLens esculantum Moench. was examinedin vitro. Experimental findings depict that staling growth substances diffused in the agar created the change in the pattern of colony interaction. Measurement of growth inhibition of colony interaction was assessed with the help of a proposed model.
TL;DR: In this paper, the behavior of ferric EDTA and ferric citrate in nutrient solution and their interaction with humic acid was investigated at various hydrogen ion concentrations using the technique of membrane ultra-filtration to separate small iron species from high molecular weight products of hydrolysis and to estimate the binding of iron by Humic acid.
Abstract: The behaviour of ferric EDTA and ferric citrate in nutrient solution and their interaction with humic acid was investigated at various hydrogen ion concentrations using the technique of membrane ultrafiltration to separate small iron species from high molecular weight products of hydrolysis and to estimate the binding of iron by humic acid. Ferric EDTA was found to be of small molecular size at all pH values between 5.0 and 7.0 whilst ferric citrate solutions contained an increasing proportion of high molecular weight material as pH was increased from 5.0 to 7.0. Some iron present in solutions of both ferric EDTA and ferric citrate was bound by humic acid at all pH values from 5.0 to 7.0. Studies were also made of the uptake of iron by wheat roots from nutrient solutions containing either ferric EDTA or ferric citrate and of the effect of humic acid on uptake. More iron was absorbed from ferric EDTA than from ferric citrate at all pH values. Increasing pH between 5.0 and 7.0 resulted in a progressive decrease in the uptake of iron in both cases. The presence of humic acid depressed iron absorption from both solutions at all pH values.