Showing papers in "Plant and Soil in 1967"

The sulphur requirements of plants as evidenced by the sulphur - nitrogen ratio in the organic matter : a review of published data

Abstract: From a review of published data on S- and N-fractions it has been shown that on a gram atom basis these elements occur in organic forms in a ratio ranging from 0.025 (legumes) to 0.032 (gramineous plants) and that this is the same as the S : N ratio in the proteins which constitute about 80 per cent of the organic S and N present. In plants deficient in sulphur, the ratio organic-S : organic-N becomes less than normal due to an increase in the proportion of non-protein organic-N compounds low in sulphur. With sulphur deficiency the cytoplasmic proteins decrease out of proportion to the chloroplast proteins of a higher S content so that the ratio of protein-S to protein-N tends to increase. A similar change may occur during the fall in tissue protein content with increasing plant age. Sulphur-deficient plants show a subnormal ratio of organic-S to organic-N in the absence of sulphate in the tissues. Plants in which the protein content is decreased by proteolysis may have subnormal organic-S : organic-S ratios in the presence of sulphate in the tissues,i.e. without S shortage. This may occur during dark starvation or in seedlings drawing upon reserve proteins in the seeds. The S-requirements for growth are reflected in the normal ratio of organic-S to organic-N. In most species investigated, organic-S occurs mainly as cystine and methionine and is directly related to protein metabolism. Because of the presence of other forms of organic-S, the organic-S : organic-N ratio in the Brassica species is higher.

A survey of urease activity in soils of Northern New South Wales

Abstract: The hydrolysis of urea to ammonia is an important pathway of conversion of organic nitrogen to inorganic nitrogen in solls receiving applications of urea 9 and excretions of urine from stock 6. C o n r a d 8 4 hypSthesised that urea hydrolysis could be catalysed by extracelhflar urease adsorbed in soils, a process quite independent of the catalytic action initiated by viable urease-containing soil micro-organisms. Since then the activity of this enzyme in soils has been examined both as a separate enzyme system 2 14 15 23 and as orte of a number of enzymes in broader studies of the total enzyme activity s 12 la It would appear that urease in soil is found within the eells of metabolizing ureolytic micro-organisms and plant organs, and as an extracellular portion derived from ruptured, moribund cells. Since extracellular urease is adsorbed on clay particles and humified organic marter 4 iß 19 23, soils exhibit levels of urease activity which are not necessarily directly related to the numbers, weights or activity of the viable ureolytic organisms at the time of determination of the urease activity la. Nevertheless, factors influencing the ureolytic population and the production of urease from this source, as well as factors influencing the aetivity and preservation of the enzyme itself, taust together determine the urease activity of a soil. I t should be noted that in conformity with other workers 12 la 14 23 the term urease activity as used herein without qualification refers principally to the activity of extracellular urease in the soil, and excludes the urease activity of metabolizing ureolytic micro-organisms. This definition accepts the premises that in the method

Interactions between aluminium and phosphorus on root surfaces and cell wall material

Abstract: The incorporation of aluminium into barley roots followed similar kinetics over a 24-hour incubation at either 23°C or 3°C. At either temperature most of the aluminium was recovered in the cell wall fraction of the roots. Aluminium is adsorbed by preparations of cell wall material, and once bound is not appreciably exchangeable with calcium or sodium ions. Cell wall material pretreated with aluminium is able to adsorb appreciable amounts of phosphorus. In experiments with root segments the phosphorus associated with aluminium was found to be almost completely exchangeable. A mechanism for the interaction of aluminium and phosphorus on the root surface is proposed.

Phosphate diffusion in soil and uptake by plants

Abstract: The changes in solid-phase P31 concentration with radial distance from the surface of actively absorbing cylindrical roots have been calculated from data previously obtained for the apparent self-diffusion coefficients (D) of P32 in Seddon soil over a range of P31-additions. Values were computed for hourly time intervals to at least 5 days for soils of different initial P31-status and for two root radii corresponding to the measured dimensions of the main root and root hairs of wheat plants.

A comparison of autoclaved and gamma-irradiated soils as media for microbial colonization experiments

Abstract: The effects on various properties of Lincoln Clay of a sterilizing dose of gamma radiation (3.0 megarads) were compared to the effects resulting from autoclaving the soil (121°C) for 1 hour. Effects of both treatments were much more drastic when moist, rather than air-dry soil was treated but, in general, radiation had less effect on soluble organic matter and on total water-extractable electrolyte than did autoclaving. Radiation caused a greater release of NH4-N from soil treated moist than did autoclaving but the reverse was true in dry soil. Alcohol-soluble ninhydrin-positive material was increased by both sterilization procedures with irradiation having the greater effect. The aggregate stability of Lincoln clay was decreased by irradiation and increased by autoclaving. Pure cultures of bothArthrobacter sp. andPseudomonas sp. grew better, on the basis of cell yields, in irradiated than in autoclaved soil. Respiration of mixed soil organisms in an artificial soil amended with an extract of irradiated soil was almost identical with that in an extract of air-dried soil but auto-claved soil extract was only metabolized after a prolonged lag period.

Manganese and silicon interaction in the gramineae

Abstract: Silicon is generally not considered to be an essential element for higher plants. It has been assumed to perform one or more vital functions in grasses and it has been reported, first by S 0 m m e r 5 for rice and later by L i p m a n 2 for barley and sunflower, that silicon meets the criteria for essentiality. One function assigned to silicon in grasses relates to resistance against disease 1 10 A significant response to silicon was obtained by W a g n e r 6 for a wide variety of plants but these results are vitiated by the excessive amounts of copper used in the solutions. Deficiency symptoms for silicon also are described by R a l e i g h 4 for beets. W o o l l e y 9 conducted a very careful investigation of the essentiality of silicon for tomato plants but his results were negative. In barley, silicon has been shown to undergo an interesting interaction with manganese. When barley is grown in standard nutrient solutions which do not include silicon, a necrotic spotting pattern develops. This necrosis increases in severity if the manganese concentration is raised and decreases if it is lowered. Another way of overcoming the symptoms is by the addition of silicon. Using Mn54 it was found that silicon did not appreciably alter the uptake of manganese, but rather affected the microdistribution of manganese in the leaves s. Barley has been found to be more sensitive to Mn-toxicity in Hoagland's solution than lettuce and tomato 7. This phenomenon suggested the present investigation to compare the response of other members of the grass family to a range of Mn concentrations in culture solutions and the interaction between Mn and Si.

Some factors affecting the mineralization of organic sulphur in soils

Abstract: Factors affecting the release of sulphate from a number of eastern Australian soils were studied.

The effect of nutrients on the salt tolerance of crops

Abstract: Under the climatic conditions of Israel, characterized by a short, rainy winter and a long, dry summer, modern farming is based mainly on irrigated crops. Initially non-saline soils gradually became salinized to varying degrees with the development of intensive irrigated rotations 5 9 10 11 12. The extent and rate of salt aceumulation in the soil is a function of irrigation water quality, irrigation methods and amounts, soil properties, and of annual precipitation. In the dry regions of Israel, where intensive irrigated agriculture is now being developed, the low annual precipitation is insufficient for leaching out of salts accumulated in the soil during a single irrigation season. Research carried out in one of the semi-arid regions of Israel 12, with an annual precipitation of about 300 mm, showed that the winter rains suIficed to leach the salts out of the upper soil layers only. In yet drier regions the leaching effectiveness of the rains will of course be even lower. The problem of these regions is aggravated by the fact that many of the water sources available there are of poor quality. The tendency to intensify land use by increasing the number of crops per year also increase the amount of irrigation water applied annnally, thus fnrther accelerating salt accumulation in the soil even when watet quality is good to medium.

Utilization of phosphorus sources of different availability by mycorrhizal and non-mycorrhizal maize*

Abstract: In experiments with phosphorus sources of different availability mycorrhizal and non-mycorrhizal maize grew equally well when the phosphorus source was readily available. When the phosphorus source was slowly available, however, mycorrhizal maize had a much higher phosphorus content and grew much better than non-mycorrhizal maize.

Comparative effects of varying levels of chlorides and sulphates of sodium, potassium, calcium, and magnesium on ammonification and nitrification during incubation of soil

Abstract: The effect of chlorides and sulphates of sodium, potassium, calcium, and magnesium, added at 01.% to 2.0% sodium chloride-equivalent (soil basis), on nitrogen mineralization and nitrification during incubation (3 weeks, 30°C) of soil was studied. For the chloride series the critical level for virtually complete suppression of nitrification was between 0.5% and 1.0% of the added salts. Nitrogen mineralization was reduced only where 1–2% of salts were added. In the sulphate series nitrogen mineralization and nitrification were reduced to a fair extent only by the 2% level of sodium sulphate, the other sulphates having little or no effect on these processes. At some levels the sulphates and chlorides of all cations, except sodium, resulted in a small but significant increase in nitrogen mineralization.

The effect of intermittent drying and wetting of a calcareous soil on carbon and nitrogen mineralization

Abstract: The mineralization of carbon and nitrogen in a calcareous sandy loam soil with and without the addition of lucerne meal and incubated continuously for 12 weeks, was compared with the mineralization of carbon and nitrogen in similar soils dried and rewetted every two weeks. The amount of carbon and nitrogen mineralized and the total number of micro-organisms were determined periodically.

Uptake and translocation of zinc by intact plants

Abstract: Certain cations were added to nutrient solution cultures, in which intact bean plants were being grown, in an attempt to establish whether they influenced either entry of radiozinc (Zn*) into these plants or translocation of this element from the roots to the tops, or both. The Zn*-level in the culture solution was maintained at 5µM and the concentrations of the added cations were varied from zero through 60µM in the highest treatments. When copper was present as the added cation at the Zn*-level (5µM), Zn*-uptake was severely reduced but internal translocation was not especially altered. When zinc was present as the added cation it exerted the expected competition on Zn*-uptake and in addition exerted an unexpected, suppressing effect on Zn* being translocated to the tops. Manganese, as an added cation, has an effect on Zn*-uptake only at high concentrations (30µM or more) but it did not alter the internal Zn* distribution. Cadmium behaved similarly to copper in its influence on Zn*-uptake and translocation. It is concluded that the general effect of added cations on Zn*-uptake and translocation in intact bean plants is predominantly to inhibit uptake, not internal distribution.

Root-zone temperature effects on the early development of maize

Abstract: Maize plants were grown in sand culture under greenhouse conditions from emergence to the 4-leaf stage at root-zone temperature of 12.5°, 15° and 17.5°C in one experiment, and grown to the 6-leaf stage at root zone temperatures of 15°, 20°, and 25°C in a second experiment. Attention was given to plant part differentiation as determined by leaf appearance, and to growth as determined by dry tissue accumulation, at specified growth stages.

Nodulation and nitrogen-fixation byHippophaë rhamnoides L. in the field

Abstract: 1. The extent of nodulation and nitrogen fixation by a population ofHippophae rhamnoides bushes occurring on a sand dune system on the east coast of England has been studied.

Effect of associating anions on phosphorus retention in soil II. Under variable anion concentration

Abstract: The results of the present investigation reveal that the presence of anions in the reacting medium greatly modify the reactions between soil and solution P. Associating anions reduce considerably the retention of phosphate in soils. Citrate, tartrate, and silicate are found to be superior to arsenate, oxalate, and fluoride in reducing phosphate retention in soil. The performance of associating anions depends on the pH and P concentration of the reacting medium. The nature and properties of soil also play a highly significant role on the effectiveness of associating anions.

Immobilization and mineralization of tracer nitrogen in forest raw humus: I. Effect of temperature on the interchange of nitrogen after addition of urea-, ammonium-, and nitrate-N15

Abstract: SummaryA series of laboratory incubation experiments was conducted to provide information about the effects of soil temperature on the nitrogen interchange in forest raw humus after addition of different forms of nitrogen fertilizers enriched with the N15-isotope.A positive correlation between temperature and immobilization of nitrogen (non-extractable inN KCl) added as urea-N15, was found at temperatures of 4°, 12°, and 20°C. When ammonium was added as the source of nitrogen the data indicated a gradual and continual immobilization of tracer nitrogen throughout the entire 90 days experimental period at temperatures of 4° and 12°C. At an incubation temperature of 20°C the amount of immobilized tracer nitrogen reached a relatively low but almost constant level within 10 days.A positive correlation between incubation temperature and the overall nitrogen turnover was found in the raw humus after the nitrate application. Within 3 days of incubation significant net re-mineralization of added tracer nitrate nitrogen took place at the highest temperature (20°C) used. The data show a negative correlation between incubation temperature and net accumulated nitrite-nitrate nitrogen after addition of urea, while no significant amount of nitrite-nitrate was detected in the humus after the ammonium application.At temperatures of 4° and 12°C the nitrogen added as ammonium as compared with nitrate was more rapidly used in supplying the needs of the micro-organisms decomposing forest raw humus. However, the results reveal that in spite of the presence of ammonium in the system, nitrate nitrogen is included in the pathway of the internal nitrogen cycle. Compared with the ammonium and the nitrate treatment the preferential utilization of nitrogen added as urea generally increased with increasing incubation time and temperature.

Isolation of protein from humic acid extracted from soil

Abstract: Chromatography of humic acid in a phenol containing solvent system reveals, in the case of the three types of soil analyzed, the presence of humoprotein containing 11 per cent of nitrogen. Isolation of a humoprotein complex from humic acid, according to the method used by Kirby, followed by paper chromatography allowed the isolation of a protein fraction containing 14.8 per cent nitrogen. This fraction is not dialysable; it has a maximum absorption in ultraviolet light between 260–280 mµ, a small electronegative charge and gives rise to twenty different amino acids. This is the first time that a protein has been separated from humus. Thereby demonstrating that part of the nitrogen contained in humic acid is in the form of protein protected from decomposition.

Effect of associating anions on phosphorus retention in soil

Abstract: The results of the present investigation reveal that the presence of anions in the reacting medium greatly modify the reactions between soil and solution P. Associating anions reduce considerably the retention of phosphate in soils. Citrate, tartrate, and silicate are found to be superior to arsenate, oxalate, and fluoride in reducing phosphate retention in soil. The performance of associating anions depends on the pH and P concentration of the reacting medium. The nature and properties of soil also play a highly significant role on the effectiveness of associating anions.

Boron adsorption by plant roots

Abstract: The adsorption capacity of boron by roots of several monocotyledonous and dicotyledonous farm crops was determined. The monocots exhibited a lower capacity for boron adsorption in comparison with dicots.

A method for studying spatial relationships between the root systems of two neighbouring plants

Abstract: A description is given of a method for the quantitative assessment of intermixing between the root systems of two neighbouring plants (A and B). This is based on the counting of the number of ‘nearest neighbour’ pairs of root segments in each of the four possible classes (AA, AB, BA, BB), each root segment being identifiable by means of previous C14 labelling of one of the two plants.

The production of a phytotoxin, nectrolide, by some root-surface isolates ofCylindrocarpon radicicola, Wr.

Abstract: A phytotoxic compound, for which the name nectrolide has been proposed, was isolated fromCylindrocarpon radicicola. Analysis of nectrolide and its physical and chemical properties show that the compound is identical with brefeldin A, an antibiotic produced byPenicillium brefeldianum.

Methods of detection and estimation of rhizobia in soil

Abstract: The plant-infection technique for the estimation of rhizobia, in which small-seeded hosts are grown on agar within test-tubes, is applicable to soils with a moderate rhizobial population (in the order of at least 100/g). Account might have to be taken of “skips” (less diluted: negative, when more diluted are positive) likely to result, at least in part, from unfavourable conditions for rhizobial survival, multiplication or nodulation. Because of such effects, a sparse population (in the order of (10/g) may not be detected even without dilution (1 g soil per plant tube). Localisation of rhizobia in the soil is likely to be important in determining contact with the plant roots in the dilution count and in sampling from the field. Difficulties with sparsely populated soils can be partly overcome by carefully conducted direct sowings of sterilised seed, preferably in the confines of cores, either left in the field or brought back to the glasshouse.

Contamination of urban garden soils with copper, boron, and lead

Abstract: Spectrochemical analysis of representative samples of topsoil from urban gardens and from individual fields in rural areas indicates that the levels of total copper, EDTA-extractable copper, water-soluble boron, and acetic-acid extractable lead are markedly enhanced in urban areas. No significant differences were discovered between levels of these elements in soils from built-up areas in small towns and large conurbations. These results suggest the possibility of general enhancement of the trace element content of plants grown in private gardens in built-up areas.

Phosphate diffusion in soil and uptake by plants: I. Self-diffusion of phosphate in soils

Abstract: SummaryThe self diffusion of P32 has been determined by transient-state methods in four different soils over a wide range of P31 additions. All soils were moistened to a water content approximating field capacity and packed into the diffusion cells to a bulk density such that during the experimental period all pores were filled with liquid.During any single experiment, the apparent diffusion coefficient (De) showed a strong dependence on level of P31 addition for all soils. However, the absolute values were influenced by the period of moist storage prior to assembly into the diffusion cells and thus are of limited value unless they can be related definitely to the conditions existing in the soil during the diffusion period.The concentration of phosphate in the soil solution also varied with the level of P31 addition made to the soil but no uniform relationship could be found betweenDe and phosphate concentration for the four soils.For an inert medium, such as glass beads, in which adsorption of phosphate onto the solid phase does not occur, there was very little change inDe with change in solution concentration from 1 to 200µgP perml. In soils, adsorption occurs to varying extents, and it is suggested that the diffusion coefficient (Dp) in an inert medium can be related to diffusion in soil by considering the proportion of the available pool which is present in the solution phase. $$i.e. D_p .\\frac{{solution - phase P}}{{total P}}$$ This relation was developed from extensive data on one soil, but appears to be valid for the other soils tested. The apparent diffusion coefficientDe is shown to be related to both the capacity and intensity factors often used to characterise soil phosphate availability.

The influence of molybdenum on iron nutrition of tomato

Abstract: Both beneficial and antagonist ic influences of Mo on the Fe nutrit ion of plants have been reported, M i l l i k a n 21 22 observed an allev ia t ion by added Mo of Fe-deficieney symptoms induced by excessive levels of heavy metals. This was interpreted as a direct beneficial influence of Mo upon Fe-nuti t ion. I n contrast , G e r l o f f et al. s noted an increase in the severi ty of Fe-chlorosis and a decrease in the yield of tomatoes grown in solution culture as a result of increased molybda te additions. K i t s c h ef a117, present da ta in which two effects of Mo are suggested, one beneficial and one detrimental . The na ture and mechanisms of these effects are not understood. Accordingly experiment s were conducted in which the influence of plant Mo s ta tus on Fe absorpt ion and related processes in tomato were evaluated.

Sulfur content of alfalfa in relation to growth in filtered and unfiltered air

Abstract: The effects of sulfur on plant growth have been studied intensively by many w o r k e r s a 5 6 7 9 1 4 1 5 ~ 1 2 4 2 5 2 6 272s Roots normally absorb sulfur from the soil as sulfate, although other forms of sulfur can be absorbed and utilized by plants 2 21 2~ ~s. Sulfur in the air, from natural or industrial sources, can supply some sulfur for growth to aerial portions of plants directly as SO2 8 22 23, sulfite 24 or sul, fate 26. Appreciable, but highly variable, quantities of sulfur compounds are carried by rainfall to the soil 1 4 12 16. Minor additions of sulfate to the nutrient medium increase primarily the organic-S content of the plant but with major sulfate additions sulfate-S increases much more rapidly in the plant than organic-S iv 19 2a. I t is the purpose of the present s tudy to examine these plant-sulfur interrelationships relative to growth and sulfate supply for alfalfa grown in culture solution 10 under two environmental conditions; in an unshaded greenhouse with smogfree, carbon-filtered air and in full sunlight outdoors with unfiltered air.

The localization of zinc-65 in germinating corn tissues

Abstract: The distribution of zinc in the different solubility groups of proteins and cell wall constituents was studied, using Zn-65 in small maize plants.