Showing papers in "Plant and Soil in 1974"

Evaluation of a rapid test for the hidden hunger of zinc in plants

Abstract: Fresh leaf discs/pieces of wheat, gram, maize and mustard were incubated in a substrate consisting of 4 ml 0.2M phosphate buffer (pH 6.8), 4 ml 0.2M NaHCO3 and 0.2 ml 0.002% bromthymol blue at 0 to 4°C for 120–240 seconds. The conversion of light blue colour due to the activity of zinc dependent carbonic anhydrase into yellowish green and greenish yellow was used as an index for zinc deficiency and sufficiency, respectively, in the plant tissues. A correlation coefficient value of r=>+0.9 between the different parameters of rapid tissue test and standard enzyme extraction method, indicated the feasibility of using the present method. re]19730724

Heavy metal pollution and soil enzymatic activity

Abstract: The activity of hydrolytic soil enzymes was studied on spruce mor, polluted with Cu and Zn from a brass foundry in Sweden. Approximately straight regression lines were obtained between enzymatic activity or respiration rate and log Cu+Zn concentration, with highly significant negative regression coefficients for urease and acid phosphatase activity as well as respiration rate, whereas β-glucosidase activity was not measurably lower at high concentrations of Cu+Zn.

Soil temperature, soil moisture and maize yield from mulched and unmulched tropical soils

Abstract: The effect of mulching on maize yield was investigated for luvisol and cambisol tropical soils during 1970–72. The increase in grain yield by mulching was 46, 52 and 22 per cent respectively, for 1970, 1971 and 1972. Mulched plants had higher growth rate and vigour and chlorotic symptoms of nutritional disorders were observed only for unmulched plants. Mulching significantly decreased the maximum soil temperature measured at 5, 10 and 20 cm depths. In the initial stages of crop growth, temperature differences of as much as 8°C were observed between mulched and unmulched plots at a 5-cm depth. Mulched plots also had a higher soil moisture content. Increase in grain yield by mulching was attributed primarily to a decrease in soil temperature and partly to improved soil moisture regime.

Effects of neutral salts on carbon and nitrogen mineralisation of organic matter in soil

Abstract: In an incubation experiment the mineralisation of gulmohur (Delonix regia L.) leaves added to soil was studied at increased salt concentrations. CO2 evolution and total carbon mineralisation decreased with increased concentrations of salt mixture (NaCl+CaCl2) from 0.1 to 5.1 per cent, and the process of nitrification was completely inhibited between 0.6–0.9 per cent salt. The loss of nitrogen was about 10.4 per cent from control up to 0.6 per cent salt and about 17.8 per cent from 0.9 to 5.1 per cent salt. The formation of ammonium was of the same order of magnitude under all treatments. Extractable carbon varied between 27–32 per cent of the total carbon in the soil and humic/fulvic acid carbon ratio varied between narrow limits of 0.41–0.58 in saline and non-saline soils.

Ethylene in relation to the response of roots to physical impedance

Abstract: When the axial growth of bean roots (Vicia faba, L., variety Broad Windsor) was impeded by a barrier, the rate of ethylene evolution increased by as much as six times that of unimpeded controls. This high rate was maintained for at least 30 hours. When the barrier was removed, the rate of ethylene evolution decreased to near the rate of control roots. Exogenous applications of very low concentrations were inhibitory. Exogenous ethylene also resulted in an increase in radial diameter. These results indicate that ethylene evolved by bean roots in response to high mechanical resistance may act as an endogenous growth regulator.

No-tillage effects on soil properties and maize (Zea mays L.) production in Western Nigeria

Abstract: The grain yields in the no-tillage plots were equivalent to those of conventionally plowed treatments. No-tillage treatments had higher organic matter content and, by controlling soil erosion, the silt and clay content than the plowed plots. The water holding capacity and moisture release characteristics of the surface soil horizon were significantly different for the two tillage treatments. A decrase in the maximum soil temperature and favourable moisture regime in the no-tillage plots stimulated biological activity e.g. earthworms. While the fertilizer had no response on the plowed plots, irrigation had a negative effect due probably to severe leaching losses. No-tillage techniques have a potential in achieving continuous cultivation on otherwise highly erodible and shallow tropical soils.

The influence of phosphate deficiency on nitrification

Abstract: Ammonium sulphate applied to savanna grassland stimulated nitriteoxidizers in some plots but not in others. Extracts from the contrasting soils differed in suitability as growth media for nitrite-oxidizers. This difference could be eliminated by adding KH2PO4 or Na2HPO4 to the extracts. The concentration of available P was highest in soils where nitrite-oxidizers had responded to (NH4)2SO4.

Zinc uptake by rice, as affected by metabolic inhibitors and competing cations

Abstract: Absorption of Zn by 14-day-old intact rice seedlings was studied in short-term uptake experiments. Severe retardation of Zn absorption by various metabolic inhibitors indicated that an active process prevails at Zn concentrations often found in soil solutions. Several cultivars all showed similar sensitivity to the metabolic inhibitor 2,4-dinitrophenol (DPN). At concentrations of 10−4 M, both FeCl2 and MnCl2 depressed Zn uptake in roots and translocation to shoots; uptake was depressed to a lesser extent with Ca. Although Mg reduced uptake by the roots, translocation to the shoots was enhanced. These results suggest that high solution concentrations of reduced Fe and Mn which develop in paddy culture may be related to Zn nutrition. This information could assist in predicting Zn deficiency and may explain correction of Zn deficiency by draining flooded rice fields.

Insoluble phosphorus usage by Eucalyptus

Abstract: Eucalyptus gummifera shows a marked growth response to insoluble phosphates (AlPO4, FePO4). An hypothesis of the mechanism of phosphorus nutrition involving the interaction of root exudates, micro-organisms, aluminium ions and uptake mechanisms is presented. The hypothesis is suggested as an adaptive mechanism of E. gummifera for survival in its habitats on very impoverished soils which commonly have phosphorus content as the chief factor limiting growth. E. gummifera (Gaertn.), Hochr. is commonly found in ridge-top habitats which contain very impoverished soils. The most deficient nutrient element in these habitats is phosphorus 3. In an attempt to determine the form of phosphorus used by E. gummifera, the following experiment was carried out.

Volatile selenium in higher plants the production of dimethyl selenide in cabbage leaves by enzymatic cleavage of Se-methyl selenomethionine selenonium salt

Abstract: The volatile selenium compound produced by cabbage (Brassica oleracea var. Capitata) when cultured on media containing either selenite or selenate is dimethyl selenide, (CH3)2 Se. The dimethyl selenide arises from enzymatic cleavage of a Se-methyl selenomethionine selenonium compound. re]19730424

Diffusion of phosphate to plant roots in soil: II. Uptake along the roots at different times and the effect of different levels of phosphorus

Abstract: SummaryAutoradiographs of rape (Brassica napus L.) seedlings growing in a Begbroke Sandy Loam treated to different P levels showed P accumulations near root apices of primary and lateral roots, without corresponding depletion from the adjacent soil, indicating marked translocation.Laterals less than 2 days old did not deplete the soil despite considerable P accumulations in them. Their growth and P uptake were enhanced when the growth of the primary root was checked. The length of root hairs decreased markedly with increasing P supply.The P depletion zones developed in the same way at all points along the primary axis (except for a short length behind the apex). At the highest P level the concentration of exchangeable P at the root surface was lowered by about 30% on day 2, by about 40% on day 4 and rose slowly after day 8.Whereas in P treated soils the depletion from within the root hair cylinder was fairly uniform, in the low P soil there was a continuous decrease in P concentrations toward the root surface, within the root hair zone.

Movement and retention of Klebsiella aerogenes in soil columns

Abstract: The movement and retention of two strains of Klebsiella aerogenes into saturated soil columns was found to depend on soil type, pH, and bacterial size. The movement of the cells was considered as a specific case of gel permeantion chromatography. The infiltration of the bacterial cells into dry soil columns was affected by soil type, and their upward movement was stopped when the water content of the soil was at or below field capacity level. re]19730907

Root hair infection and nodulation in lucerne (Medicago sativa L.) as influenced by salinity and alkalinity

Abstract: Experiments with lucerne (Medicago sativa L.) under bacteriologically controlled conditions on the effects of chloride, carbonate and bicarbonate of sodium, alkaline pH levels and saline/alkaline soil extracts demonstrated that increasing levels of salinity/alkalinity of the root medium resulted in a root system devoid of root hairs, mucilaginous layer and infection thread formation in spite of the optimum growth of Rhizobium under such conditions. The results point out the existence of ‘alkali sensitive steps’ in the early phases of nodulation which lead to an elimination of legume ‘rhizosphere’ as postulated by earlier workers.

The effects of shading and defoliation on nodulation and nitrogen fixation by white clover

Abstract: In a glasshouse experiment, single plants of ten-weeks old white clover (Trifolium repens L.) were subjected to two levels of shading and two levels of defoliation. Nodulation and nitrogen fixation parameters were measured at six sequential harvest over four weeks. Changes in nodule number and hence nodule dry weight per plant were due to nodule decay, sloughing off and non-production and were closely related to losses in root dry weight. Severe defoliation caused degradation of leghaemoglobin, an effect which was seen in less than three days from treatment. It led also to a temporary but marked decrease in the nitrogen fixation capacity of the nodules as measured by the acetylene reduction assay. Recovery of normal activity by the nitrogenase system took about ten days. The effects of shading and defoliation on the pattern of nodulation have been described briefly.

Diffusion of phosphate to plant roots in soil: III. Depletion around onion roots without root hairs

Abstract: SummaryThe P depletion zones around onion roots (without mycorrhizas) were narrower than those around rape roots at all P levels. At a high level of soil P, the fractional depletion of exchangeable P at the surface of the onion root was similar to that from the entire root hair zone of rape.The rate of P uptake by onion roots was much lower than that by rape roots. The onion roots had a constant uptake rate until 11 days as against the drop in uptake rate observed after 8 days in the case of rape. There was a much closer agreement between the uptake observed in the experiment and that predicted from diffusion theory in the case of onion than in the case of rape.The differences between the two species are associated with the presence of dense root hairs in rape and their complete absence in onion.

Evaluation of the claim that grass root exudates inhibit nitrification

Abstract: Washings from living or decaying grass roots did not inhibit nitrification when applied to soil daily. In liquid cultures of nitrite-oxidizers the washings from live roots slightly prolonged the lag period and washings from decaying roots were inhibitory only if collected during initial stages of decay. Macerated roots mixed with soil did not inhibit nitrification in the soil during perfusion with (NH4)2SO4 solution. When Hyparrhenia roots were incubated in soil with added (NH4)2SO4 they caused considerable immobilisation of mineral nitrogen with consequential depression of nitrate accumulation but did not prevent nitrification of surplus ammonia. In Hyparrhenia grasslands paucity of nitrifying bacteria was not confined to root zones, and the bacteria multiplied when ammonia availability was artificially increased. It is concluded that nitrification in Hyparrhenia grasslands is restricted by limited availability of ammonia and that there is no convincing evidence for toxic inhibition by root secretions.

Influences of high acidity and aluminum on the growth of lowland rice

Abstract: Lowland rice was grown on nutrient solutions in a continuous-flow system, with pH levels varying from 3.5 to 6.0. The chemical compositions of all nutrient solutions were alike, except for small amounts of HCl or KOH, needed for pH adjustments, and for variations in the Al supply.

Effect of fertilization on biomass and nutrient content of fine roots in a beech-birch-maple stand

Abstract: Quantitative samples of fine roots (d≤3 mm) were extracted from the soil of a 90-year-old beech-birch-maple stand that had been previously treated with lime (1120 kg/ha) or lime plus 15-10-10 NPK fertilizer (6720 kg/ha). Estimates of fine root biomass were: 1246±94 g/m2, control; 1229±194 g/m2, lime only; and 2711±423 g/m2, lime+NPK. Increased root concentration in the fertilized plot was greatest in upper soil horizons, but extended through the profile to all but the C horizon. Concentrations of N, P, Ca, and Mg in the roots were increased significantly by fertilizer treatment; K concentration was unaffected. Elements not added in the fertilizer or lime-Al, Fe, Mn, Zn, and Cu-also increased in concentration in roots from the fertilized plot. Increased root biomass, nutrient content, and rooting depth resulting from fertilization should lead to: (1) a higher organic matter and nutrient content of the deeper soil horizons, (2) availability of a larger volume of soil —with its moisture and nutrients—to the vegetation, and (3) increased wind-firmness in addition to the more direct effects of fertilization upon growth, vigor, and soil properties. re]19730806

Free proline accumulation in drought-stressed plants under laboratory conditions

Abstract: Free proline accumulation was measured in leaves of intact sorghum (Sorghum bicolor L. cv. Pioneer 846) and soybean (Glycine max. L. cv. Calland) grown in growth chambers and subjected to ‘normal’ drought stress. Stomatal diffusive resistance and leaf water potential were used to determine the degree of stress at the time of proline analysis. Free proline did not accumulate markedly in either species until each was severely stressed, indicating that proline is not a sensitive indicator of drought stress. Free proline accumulated under less stress in soybean than in sorghum. Since soybean is less drought resistant than sorghum, proline accumulation may be an indicator of drought resistance or susceptibility. re]19731003

Effect of P fertilizer on root morphology and P uptake ofCarex coriacea

Abstract: Carex coriacea was grown under high light intensity in sterilized silt loam (Olsen P 5.9 μg/ml) with six levels of P fertilizer. Plant D.M. yield rose exponentially and was limited solely by P uptake at all fertilizer levels.

The interaction of nitrogen and phosphorus on the growth, nutrient status and nodulation of Stylosanthes humilis H.B.K. (townsville stylo)

Abstract: The growth response of S. humilis to six levels of phosphorus × five levels of nitrogen × three levels of potassium in association with Rhizobium CB103 is described for plants growing in a nitrogen deficient, light textured, solodic soil. Phosphorus greatly stimulated growth and nodulation at all levels of nitrogen addition. The effect of nitrogen interacted strongly with level of phosphorus application, with response in yield of tops to nitrogen increasing with phosphorus level up to P500 (kg superphosphate/ha). The addition of nitrogen depressed nodulation at P0–P125 but was beneficial at P250–P1000. Visual observations suggested that high nitrogen checked growth initially but despite this the high nitrogen-high phosphorus combination produced the largest and best nodulated plants. There were only minor responses to potassium in this trial. Particular balanced combinations of nitrogen and phosphorus stimulated successful nodulation of S. humulis, enabling it to achieve higher yield and nitrogen content than from symbiotic nitrogen alone.

The content of scandium, thorium, silver, and other trace elements in different plant species

Abstract: Thirty five plant species apartaining to 16 divisions, representing the main plant kingdom, as well as some soil samples collected under these plants, were analysed for Sc, Th, Cr, Co, Rb, Cs, Fe, Zn, and Ag. Higher amounts of scandium and thorium as well as of other elements were found in some fungi (Basidiomycetes) and bryophytes, whereas a lower content was found in angiosperms and gymnosperms. A higher silver content was found in some plant species.

The significance of solution flow rate in flowing culture experiments

Abstract: Solution flow rate is an important factor to be considered when designing or operating flowing culture equipment. A theoretical model is developed showing that the actual flow rate required for a particular experiment will depend upon many factors, important among which are the nature and concentration of the ion under consideration, the quantity of roots per pot, and the efficiency of these roots in absorbing the test ion under the conditions of the experiment. The results of experiments conducted at low concentrations of ammonium and nitrate nitrogen clearly demonstrate that flow rates of the order of 1 litre per pot per minute or greater may be required to prevent excessive depletion of the nutrient solution. At lower flow rates, solution depletion resulted in substantial reductions in growth and nitrogen uptake. Quantities of nutrient solution required for experiments at very high flow rates can be reduced to practical levels by the use of recirculating flowing culture systems, even in installations containing large numbers of pots.

Internal root control of iron uptake and utilization in maize genotypes

Abstract: Studies were conducted to determine whether Fe uptake and transport in maize (Zea mays L.) is controlled inside or outside the root. Two maize genotypes exhibiting wide differences in Fe uptake and utilization were used. They were the Fe-efficient genotype WF9 and the Fe-inefficient genotype ys1/ys1. Iron-stressed WF9 produced higher amounts of H-ions and ‘reductant’ in nutrient solutions and reduced more Fe at the root surface than ys1/ys1. These properties were measured outside the root and they were associated with increased Fe uptake by WF9. When WF9 and ys1/ys1 were grown together in the same container, these properties did not benefit Fe uptake and utilization in ys1/ys1. Thus, we conclude, Fe-efficiency in WF9 and ys1/ys1 is controlled inside the root. re]19731029

The development of manganese toxicity in pasture legumes under extreme climatic conditions

Abstract: Manganese levels and pH in soil were measured on limed and unlimed plots at bi-monthly intervals for two years at five field sites with lucerne (Medicago sativa) and subterranean clover (Trifolium subterraneum) and related to rainfall and temperature. Pot experiments with lucerne, subterranean clover and rape (Brassica campestris) were used to confirm the results of the field experiments. Manganese toxicity developed in lucerne and subterranean clover under waterlogged conditions after heavy rain on the slightly acid soils (pH 4.7–5.5). Lucerne also showed manganese toxicity on the same soils in summer after extended hot, dry conditions. The maximum available manganese was 210 μg/g in the waterlogged soil (0–15 cm) and 128 μg/g in the heat affected soil. Lime treatment of 2240 kg/ha reduced the maximum available manganese to 148 μg/g in waterlogged plots and to 47 μg/g in the heat affected plots but failed to correct manganese toxicity. However, lime corrected toxicity symptoms under less severe conditions. In the pot experiments, available manganese reached 270 μg/g after 2 weeks artificial waterlogging and 68 μg/g after 2 weeks dry heat exposure.

Calcium-transport in Wurzeln von Mais- und Bohnenkeimpflanzen

Abstract: Zur Untersuchung des Ca-Transportes in Wurzeln intakter Pflanzen wurde Wurzeln von 9 Tage alten Pflanzen von Mais (Zea mays L., Velox) und Bohnen (Phaseolus vulgaris L., Saxa) an einer 3 cm langen Zone Ca45-markierte Nahrlosung angeboten. Die ubrigen Zonen der Wurzeln (Gesamtlange der Primarwurzel 25–30 cm) befanden sich in nichtmarkierter Nahrlosung. Nach einer Versuchsdauer von 1–7 Tagen wurde die Verteilung von Ca45 in den einzelnen Wurzelzonen und im Spros ermittelt. Wachsende Wurzelspitzen mussen somit ihren gesamten Ca-Bedarf direkt durch Aufnahme aus der Ausenlosung decken, eine Durchwurzelung Ca-armer Bodenhorizonte ist deshalb erschwert oder nicht moglich. re]19730417

Mycorrhiza in plants of the 'cerrado'

Abstract: The object of the present paper is to give an account of the mycotrophic species of the ‘cerrado’, studied in Brazil. Also, this work is a contribution to the anatomical and morphological study of mycorrhizas.

The distribution of chromium-51 in lowland rice in relation to the chemical form and to the amount of stable chromium in the nutrient solution

Abstract: Distribution of radiochromium at the plant and cellular levels varies with the chemical form added to the nutrient medium. Cr EDTA is less absorbed and metabolized by the roots than Cr+++ and CrO4−− but its translocation rate is clearly higher.

The effect of nitrogen sources and iron levels on the growth and composition of Sitka spruce and Scots pine

Abstract: Nitrate-N was an inferior source of N for both Sitka spruce and Scots pine, resulting in lower dry weights and moderate chlorosis of newly developing needles. The NO3-N source resulted in a greater cation concentration in the tissues and a greater organic anion content as measured by the difference in inorganic cations and inorganic anions. Chlorosis was partially alleviated when additional Fe was supplied as FeEDDHA and there was a slight decrease in organic anions (C-A). It is suggested that the chlorosis might be explained by the competitive chelation hypothesis which states that the activity of the Fe is reduced by metals or various ligands, in this case by the excess organic anions produced by NO3-N nutrition.

Effects of cadmium, lead, and sodium salts on nitrification in a mull soil

Abstract: Increasing amounts of Cd, Pb, and Na salts were added to a fresh mull soil and the NO3 and NH4 concentrations measured after 2–8 weeks of incubation. The highest amounts used (CdCl2 9–18 μmol/g dry weight, CdAc2 9–22 μmol/g, PbAc2 121 μmol/g and NaAc 250 μmol/g) significantly increased NO3 accumulation. Lower concentrations had either no effect or caused a slight decrease. re]19730529