Investigations on the growth and metabolism of cultured explants of Daucus carota

Summary Earlier papers of this series relate to different growth-promoting substances and systems which, singly and in combination, have interacted with trace elements (Mn and Mo) and Fe to induce growth and to affect the metabolism of aseptic cultures of carrot. The solutes of cultured carrot cells (K⁺, Na⁺, Cl^–, total solutes) are also affected. Two clones were grown in 9 combinations of growth factors and under 4 trace-element regimes (a complete complement including Fe, and this complement lacking either Mn or Mo, or both Mn and Mo), a total of 36 treatments under otherwise standardized experimental conditions. Under the treatments applied the number of cells varied over a 35fold range and their average size over a 7fold range; the concomitant effects on their solutes are expressed in terms of concentrations and of total content per cell. Both growth and the solutes accumulated were variously affected by carrot growth-promoting system I (mediated by inositol), by system II (mediated by IAA), and by coconut milk in the presence of Fe, with and without Mn, Mo, or Mn and Mo.The greatest concentrations of total solutes occurred in tissue cultured in nutrient solutions which lacked the stimuli to rapid cell multiplication and were also limited by the trace elements Mn and Mo. Moreover, specific regulatory effects of the trace elements on solute content, not solely attributable to their effects on cell growth, have been noted. An imbalanced growth-factor regime (zeatin acting alone, i.e. without IAA) shifted the normal preference for K⁺ over Na⁺ strongly toward Na⁺, a trend which could also be induced by certain trace elements and more balanced growth-factor regimes, e.g. in a basal coconut milk medium lacking only Mn.The data are interpreted in the context of views on the de-novo uptake of salts and solutes in cultured cells as they grow. These cells respond to a network, or matrix, of interacting factors by distinctive effects that are attributable to the component parts of the culture medium acting singly and in various combinations. These interactions (involving trace elements and exogenous growth factors) control growth (fresh weight, number and size of cells) and regulate the solutes (organic and inorganic; K⁺ vs. Na⁺; organic anions vs. Cl^–) which the cells acquire as they grow and develop. The intensity of the response of the cultures to balanced, or imbalanced, growth factors creates the internal spaces accessible to solutes; and the metabolism, as it is also affected by growth factors and trace elements, determines how these spaces are to be filled at a given osmotic value. The evidence shows the range of factors that affect the accumulation of solutes in cells as they grow and is to be contrasted with conventional observations on mature cells held in steady states under conditions that preclude all growth and when only a single ionic species is followed over a very short interval of time.     

Regulation of Mineral Redistribution in Pod-Bearing Soybean Explants

On the way from the roots to the seeds during reproductive developmentin soybean (Glycine max), a large proportion of the mineralspass through the leaves rather than travelling directly viathe xylem. This direct and indirect movement of mineral nutrientshas important implications for mineral redistribution, seeddevelopment and leaf senescence. Therefore, we have studiedthe role of cytokinin and mineral flux from the roots in regulatingmineral redistribution from the leaves to the seeds using explants,i.e. a leaf, a pod and a subtending stem segment, with theirbases immersed in treatment solutions. Thus, defined solutionscontaining cytokinin and/or minerals can be substituted forthe roots. When explants (excised at early-mid podfill) aresupplied H₂O only, leaf N, P, K, Mo, Mg, Zn, Fe, B, Cu, Ca,and Mn decline, ranging from 93% for Mo to 38% for Fe. In explantson H₂O, N, P, K, Mo, Mg, Zn, and Fe appear to be redistributedfrom the leaves to the seeds, while the B, Cu, Ca, and Mn lostfrom the leaves do not seem to move to the seeds. Although amixture of minerals resembling xylem sap can delay net lossof these elements from the leaves, it does not prevent the decreases.The cytokinin zeatin (4.6 µM) inhibits the loss of N,IC, Mo, Mg, Zn, Fe, B, Cu, Ca, and Mn from the leaves, but notthat of P. When combined with minerals, zeatin not only preventsthe loss of the minerals from the leaves but may even greatlyincrease them with the possible exception of Zn, Fe, and Cu.Supplying the mineral nutrient mixture increases the quantitiesof N, P, K, Mg, Cu, and B in the seeds but not Zn, Fe, Mn, Ca,and Mo. For those minerals, especially N, where zeatin inhibitsefflux from the leaves, it may reduce the amounts in the seeds,but it does not change P, K, Mg, and Ca. The accumulation andredistribution patterns of the different mineral nutrients showmany dissimilarities thereby suggesting differences in the controlof their distribution. Key words: Cytokinin, mineral transport, seed development, senescence     

Comparison of the nutrient ecology of coastal Banksia grandis elfinwood (windswept shrub‐like form) and low trees,Cape Leeuwin‐Naturaliste National Park,Western Australia

Abstract Trees growing along windy coasts often have canopies that are greatly reduced in size by the sculpting effects of wind and salt spray. Trees with environmentally reduced stature are called elfinwood (windswept shrub‐form or krummholz) and are ecologically important because they represent outposts growing at the limit of tree success. The purpose of this study was to assess if Banksia grandis elfinwood growing at Cape Leeuwin had a different nutrient status than normal low‐form (LF) trees growing nearby, and if nutrient deficiencies, toxicities and/or imbalances were among the limiting factors imposed on elfinwood. The concentrations of N, P, K, Ca, Mg, Na, Cl^–, Fe, Mn, Zn, Cu, Mo and B were analysed for mature green foliage, immature foliage, foliage litter, flowers and soil. When the elfinwood and LF trees were compared, the foliar nutrient status was generally similar, except that elfinwood foliage had significantly higher mean concentrations of N, Zn and Cu, while LF trees had higher Fe and Mn contents. Many nutrients were conserved before leaves were shed in both elfinwood and LF trees, including N, P, K, Na, Cl^–, Mn and Cu (LF trees also conserved Ca and Mg). However, elfinwood and LF tree‐litter contained significantly higher Fe concentrations than green foliage (elfinwood litter also had higher levels of Mg and B). It is tempting to suggest that the translocation of Fe into leaves before they were shed is a regulation mechanism to prevent Fe toxicity, or imbalance in the Fe : Mn ratio. Proteoid roots strongly acidify the soil to mobilize P, which also chemically reduces Fe⁺³ to plant‐available Fe⁺². The increased supply of Fe⁺² in the rhizosphere, caused by the action of proteoid roots, might tend to defeat self‐regulation of Fe uptake. It is possible that excess Fe accumulation in the plant might be regulated, in part, by exporting Fe into the leaves before they are shed. The nutrient status of B. grandis elfinwood is compared with mountain elfinwood of North America. The extreme habitat of coastal elfinwood provides many theoretical pathways for nutrient limitation, but B. grandis elfinwood at Cape Leeuwin does not appear to be nutrient deficient.     

Glucose tolerance factor potentiation of insulin action in adipocytes from rats raised on a torula yeast diet cannot be attributed to a deficiency of chromium or glucose tolerance factor activity in the diet

The nature of the dietary component responsible for adipocytes having the ability to respond to Glucose Tolerance Factor (GTF) was investigated. Rats were raised on either a control diet or one of three diets differing only in the protein source (torula yeast, brewer's yeast, or casein). Only in adipocytes from rats fed the torula yeast diet did a GTF fraction prepared from brewer's yeast potentiate the action of suboptimal concentrations of insulin in the incorporation of label fromd-[1-¹⁴C]-glucose andd-[U-¹⁴C]-glucose into CO₂ and fatty acids. It was concluded that this potentiation was not the result of a deficiency of GTF activity in torula yeast, because a GTF fraction prepared from torula yeast had similar insulin potentiating activity. Differences in response among diets were not owing to differences in levels of amino acids or owing to concentrations of 22 (Al, As, B, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mo, Na, Ni, P, Pb S, Se, Si, Sn, Sr, Zn) of the 23 trace elements investigated. The level of Mn, was low in all diets, but particularly low in the torula yeast diet. Mn deficiencies have previously been implicated in perturbations of glucose metabolism, so that it is possible that this deficiency may be responsible for the effects attributed to the torula yeast diet.     

Influence of organic matter on the availability of certain elements to barley seedlings grown by a modified neubauer method

Summary The influence of organic matter on the availability of 17 elements (Na, K, Cs¹³⁷, Mg, Ca, Sr, Ba, N, P, B, Cu, Zn, Fe, Mn, Mo, Al, and Si) to barley seedlings grown by a modified Neubauer technique was determined. Three different soils that were treated with dry ground mustard spinach leaves (1 g/100 g soil) and incubated for various lengths of time (0, 1, 2, 5, 9, 13, and 17 weeks) in moist condition before cropping were used for this study.The addition of organic matter to the soils increased the plant yields. The average N and K concentrations were consistently increased in the plants grown in soils with added organic matter. The average concentration of B, P, Na, Mg, Sr, Ba, and Si were almost consistently decreased in the plants. The average contents of Cu, Zn, Fe, Mn, Mo, Ca, and Al varied with the soil types and precropping incubation time. The average Cs¹³⁷ contents of the plants were reduced considerably by the addition of organic matter to the soils. The reduction of Cs¹³⁷ contents ranged from 29 to 75 per cent, depending on the pre-cropping incubation time and soil type. The main factors causing this reduction were considered to be microbial immobilization, ion antagonism by K, carbohydrate dilution, and the state of decomposition and the kind of organic matter added to the soils.     

Accumulation of metals and metalloids in radish (Raphanus sativus L.) and spinach (Spinacea oleracea L.) irrigated with domestic wastewater in the peri-urban areas of Khushab City,Pakistan

Accumulation of different metals and metalloids was assessed in two vegetables radish (Raphanus sativus L.) and spinach (Spinacea oleracea L.) irrigated with domestic wastewater in the peri-urban areas of Khushab City, Pakistan. In general, the metal and metalloid concentrations in radish and spinach were higher at site-II treated with sewage water than those found at site-I treated with canal water. In case of radish at both sites the levels of metals (Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Mo, Cd, and Pb) were below the permissible level except those of Mn, Ni, Mo, Cd, and Pb. At both sites, the transfer factor ranged from 0.047–228.3 mg kg^?1 with Cr having the highest transfer factor. The metal pollution index in soil was in the following order: As > Fe > Ni > Zn > Cd > Mo > Se > Co > Pb > Mn > Cr > Cu, respectively. While in case of spinach at both sites, the concentrations of metals and metalloids in vegetable samples irrigated with canal and sewage water were observed below the permissible level except Mn, Ni, Zn, Mo, and Pb. At both sites, the transfer factor ranged from 0.038–245.4 mg kg^?1 with Cr having the highest transfer factor. The metal pollution index in soil was in the following order: Cd > Ni > Co > Se > Mn > Zn > Mo > Pb > Fe > Cr > As > Cu, respectively.     

Investigations on the growth and metabolism of cultured explants of Daucus carota

Summary The responses of carrot explants to various growth-promoting agents and to certain trace elements with which they interact have been investigated. A great range in the metabolic behavior of the tissue may be brought about in this way. The responses to the exogenously applied substances are described in terms of the growth of the carrot explants in fresh weight and number of cells and also in terms of their metabolism, as shown by the final content and composition of the non-protein N compounds, by the relations between protein and non-protein (alcohol-soluble) N and by the content of nucleic acid in the cultured tissue.The growth-promoting agents employed consisted of (1) the balanced complex of factors found in coconut milk, (2) an active isolate from Aesculus (AF_aesc), which is one of a class of growth factors (AF₁) that interact with inositol (AF₁+inositol) and which in this sense comprise growth-promoting System I, (3) the substance zeatin (Zeat) which is typical of a class of active factors (AF₂) that interact with indoleacetic acid (AF₂+IAA) and which, therefore, function as a growth promoting complex termed System II in the culture of carrot tissue.The carrot explants stimulated by coconut milk grew better than those stimulated by the other combinations of growth factors and they converted their soluble N more effectively to protein. The growth, whether it was induced by coconut milk or by System I or II, and other specific effects attributable to the growth factors employed were markedly affected also by the elements iron and molybdenum.The carrot explants that had responded to coconut milk emphasized alanine in their soluble, non-protein, nitrogenous pool, whereas those subjected to the active components of System I or of System II as clearly emphasized glutamine as the prominent non-protein, nitrogen-rich compound.The partial effects due to the component parts of System I (AF_aesc or inositol) and to the component parts of System II (Zeat. or IAA), as these interacted also with iron and molybdenum in an otherwise trace element free basal medium (B ^**), revealed a pattern of interlocking effects, due to trace elements and to growth factors, upon the metabolism (especially the nitrogen metabolism) of the aseptically cultured carrot explants. These effects show that the individual growth factors do not act alone and that their implications are far reaching. The interactions between growth promoting Systems I and II and their component parts, with each other, with various environmental factors, and especially with trace elements constitute a network, or a matrix, of parameters that will merit further investigation to reveal all that is required to control the growth and metabolism of carrot cells.This investigation was supported by PHS Research Grant No. GM 09609 to one of us (F.C.S.) from the National Institutes of Health.The collaboration with Dr. K. V. N. Rao, later made possible by this grant, was first arranged under the terms of a Fulbright travel grant and the award of a Smith-Mundt stipend.     

Treatment of swine manure effluent using freshwater algae: Production, nutrient recovery, and elemental composition of algal biomass at four effluent loading rates

Cultivating algae on nitrogen (N) and phosphorus (P) in animal manure effluents presents an alternative to the current practice of land application. The objective of this study was to determine how algal productivity, nutrient removal efficiency, and elemental composition of turf algae change in response to different loading rates of raw swine manure effluent. Algal biomass was harvested weekly from laboratory scale algal turf scrubber units using four manure effluent loading rates (0.24, 0.40, 0.62 and 1.2 L m⁻² d⁻¹) corresponding to daily loading rates of 0.3–1.4 g total N and 0.08–0.42 g total P. Mean algal productivity values increased from 7.1 g DW m⁻² d⁻¹ at the lowest loading rate (0.24 L m⁻² d⁻¹) to 9.4 g DW m⁻² d⁻¹ at the second loading rate (0.40 L m⁻² d⁻¹). At these loading rates, algal N and P accounted for> 90% of input N and 68–76% of input P, respectively. However, at higher loading rates algal productivity did not increase and was unstable at the highest loading rate. Mean N and P contents in the dried biomass increased 1.5 to 2.0-fold with increasing loading rate up to maximums of 5.7% N and 1.8% P at 1.2 L m⁻² d⁻¹. Biomass concentrations of Al, Ca, Cd, Fe, K, Mg, Mn, Mo, Si, and Zn increased 1.2 to 2.6-fold over the 5-fold range of loading rate. Biomass concentrations of Cd, K, Pb, and Si did not increase significantly with loading rate. At the loading rate of 0.40 L m⁻² d⁻¹ (corresponding to peak productivity) the mean concentrations of individual components in the algal biomass were (in mg kg⁻¹): 250 (Al), 4900 (Ca), 0.30 (Cd), 1050 (Fe), 3.4 (Pb), 2500 (Mg), 105 (Mn), 6.0 (Mo), 7,500 (K), and 510 (Zn). At these concentrations, heavy metals in the algal biomass would not be expected to reduce its value as a soil or feed amendment.     

Control of stem-gall of coriander by fungicides

Summary The stem-gall caused byProtomyces macrosporus Ung. is a common disease of coriander which is an important spice crop of India and other countries. For the first time, it has been possible to obtain at least a partial field control of this disease, through seed treatment with thiram at the dose of 0.25 kg per 100 kg of seed. There are indications that better control is possible by combining seed and soil treatments with thiram. Seed treatment with TCNA — an experimental fungicide — may prove to be effective at a dose of 0.5 kg per 100 kg of seed.The authors are grateful to Dr.N. K. A. Rao, Dean, College of Agriculture and Dr.R. L. Paliwal, Director of Experiment Station, for their help. The Junior authors thank U. S. Agency for International Development (University of Illinois) for the award of graduate traineeships.     

Nitrogen-molybdenum-manganese co-fertilization reduces nitrate accumulation and enhances spinach (Spinacia oleracea L.) yield and its quality

Spinach (Spinacia oleracea L.) is considered a nitrogen (N) intensive plant with high nitrate (NO₃^?) accumulation in its leaves. The current study via a two-year field trial introduced an approach by combining N fertilization from different sources (e.g., ammonium nitrate; 33.5 % N, and urea; 48 % N) at different rates (180, and 360 kg N ha^?1) with the foliar spraying of molybdenum (Mo) as sodium molybdate, and/or manganese (Mn) as manganese sulphate at rates of 50 and 100 mgL^?1 of each or with a mixture of Mo and Mn at rates of 50 and 50 mg L^?1, respectively on growth, chemical constituents, and NO₃^? accumulation in spinach leaves. Our findings revealed that the highest rate of N fertilization (360 kg N ha^?1) significantly increased most of the measured parameters e.g., plant length, fresh and dry weight plant^?1, number of leaves plant^?1, leaf area plant^?1, leaf pigments (chlorophyll a, b and carotenoids), nutrients (N, P, K, Fe, Mn, Zn), total soluble carbohydrates, protein content, net assimilation rate, and NO₃^? accumulation, but decreased leaf area ratio and relative growth rate. Moreover, plants received urea-N fertilizer gave the highest values of all previous attributes when compared with ammonium nitrate –N fertilizers, and the lowest values of NO₃^? accumulation. The co-fertilization of N-Mo-Mn gave the highest values in all studied attributes and the lowest NO₃^? accumulation. The best treatment was recorded under the treatment of 360 kg N-urea ha^?1 in parallel with the combined foliar application of Mo and Mn (50 + 50 mg L^?1). Our findings proposed that the co-fertilization of N-Mo-Mn could enhance spinach yield and its quality, while reducing NO₃^? accumulation in leaves, resulting agronomical, environmental and economic benefits.     

Biomass and nutrient concentrations of sporocarps produced by mycorrhizal and decomposer fungi in Abies amabilis stands

Summary Sporocarps and sclerotia were collected for a one-year period in 23- and 180-year-old Abies amabilis stands in western Washington. All sporocarps were classified and chemically analyzed for N, P, K, Ca, Mg, Na and Fe. Lactarius sp. and Cortinarius sp. contributed the largest proportion of the total annual epigeous sporocarp production in both stands. Annual epigeous production was 34 kg/ha in the young stand and 27 kg/ha in the mature stand. Hypogeous sporocarp production increased from 1 kg ha^-1 yr^-1 to 380 kg ha^-1 yr^-1 with increasing stand age. High sclerotia biomass occurred in the young (2,300 kg/ha) and mature (3,000 kg/ha) stands. Peak sclerotia and epigeous sporocarp biomass in the young stand and epigeous and hypogeous sporocarp biomass in the mature stand coincided with the fall peak of mycorrhizal root biomass.In the young stand, sporocarps produced by decomposer fungi concentrated higher levels of Ca and Mn than those produced by mycorrhizal fungi. In the mature stand, sporocarps of decomposer fungi concentrated higher levels of N, P, Mn, Ca and Fe than sporocarps of mycorrhizal fungi. Epigeous and hypogeous sporocarps concentrated higher levels of N, P, and K than sclerotia or mycelium. The highest concentration of N (4.36%), P (0.76%), K (3.22%) and Na (1,678 ppm) occurred in epigeous sporocarps. Highest Mn (740 ppm) and Ca (20,600 ppm) concentrations occurred in mycelium, while highest Mg (1,929 ppm) concentrations were in hypogeous sporocarps and highest Fe (4,153 ppm) concentrations were in sclerotia.     

Crop residue application increases nitrogen fixation and dry matter production in groundnut (Arachis hypogaea L.) grown on an acid sandy soil in Niger,West Africa

Field experiments were conducted during the rainy reasons of 1989, 1990 and 1991 on an acid sandy soil in Niger, West Africa, to assess the effect of millet straw application (+CR) on growth and N₂ fixation of groundnut (Arachis hypogaea L.).Three years of +CR (4 t ha^–1 yr^–1) increased symbiotic N₂ fixation, total dry matter production (haulm plus pods) by 83% and total nitrogen (N) accumulation by 100%. Concentration of N in the shoot dry matter and total N in the soil were only slightly affected by the +CR treatment.Crop residue application increased the concentration of potassium (K) and molybdenum (Mo) and decreased the concentrations of aluminium (Al) and manganese (Mn) distinctly, both in the plant (shoot and nodule dry matter) and in the soil.The increase in dry matter production and N uptake was mainly due to improved N₂ fixation reflected by enhanced formation and growth of nodules as well as nitrogenase activity. This was attributed to improved chemical soil conditions, particularly to the higher availability of Mo and the lowered content of available Al and Mn.Although with the application of 4 t CR ha^–1, 60 kg K were supplied, increased growth could not be attributed to the additional supply of K.ICRISAT Journal Article No. 1229.ICRISAT Journal Article No. 1229.     

Decomposition of duckweed (Lemna gibba) under axenic and microbial [-2pt] conditions: flux of nutrients between litter water and sediment, the impact of leaching and microbial degradation

The decomposition of axenic Lemna gibba has been studied over a 200 day period under laboratory conditions in the presence and absence of wastewater micro-organisms. The residual mass of plant litter in the decomposition vessels decreased three times more rapidly under biotic than abiotic conditions. The organic matter in the duckweed litter lost about half its weight within 67.9 days in the presence of micro-organisms while more than 200 days were required in axenic vessels. In the former case, AFDW loss followed an exponential pattern of decay. The rate constant was 0.0102 day ^–1 and the decay was virtually complete after 200 days. The C and K concentration of the remaining duckweed litter decreased; the N, Ca, Fe and B concentration increased in both treatments. The concentration of total N, P, K, Mg, and Mo increased in the receiving water in both treatments but was much higher under biotic than abiotic conditions. Mass balances of nutrients in the vessels and flux of these nutrients between compartments in the vessels (duckweed litter, water and sediment) have been determined. Under axenic conditions the release of elements was very slow. Only notably potassium leaching had occurred. Leaching of potassium, magnesium and organic carbon took place mainly during the first term of incubation and then slowed down. Under biotic decomposition the elemental content of the litter decreased by more than 50% over 43 days for K, 53 days for Mo, 64 days for C, 81 days for Mg, 101 days for S, 104 days for P, 108 days for Na, 111 days for N, 140 days for B. Calcium and iron immobilised in the litter. Most of the released N, S, P, K, Mg and Mo remained in the water, but B and Mn settled into the sediment. The result of the investigation demonstrated that the nutrient flux from decomposing duckweed litter is mainly a microbially mediated process.     

Seasonal fluctuations of the mineral concentration of alder (Alnus glutinosa (L.) Gaertn.) from the field

Summary The seasonal fluctuation of N, P, K, Ca, Mg, Fe, Mn, Mo, and Co, in leaves, roots and nodules of 40–50 year oldAlnus glutinosa trees growing at four different locations along the banks of the Tormes river, in the province of Salamanca, was studied. Also, the evolution of the soil organic matter under the trees sampled was evaluated. The data obtained for the various nutrient elements in the three plant parts are statistically treated at the significance levels of 99–95 per cent, and some remarks as to the nutritional status of the European alder in respect to the nutrients and its contribution to soil nutrient-cycling are provided. A positive correlation was found between N–P, N–K, N–Mg, and N–Mo, in leaves, and between N–P, N–K, N–Fe, N–Mn, and N–Mo in root nodules. In roots only, no significance at any level was obtained between N and any of the elements analyzed.     

Variations in essential and non-essential element composition and yield of silage corn fertilized with sulfur

Abstract

The effect of sulfur fertilization on the silage yield and essential and non-essential element composition of silage corn was investigated at the Experimental Field of Research and Experiment Station of the Ankara University during the years 2002 and 2003. The experimental design was a randomized complete block with five replications. Sulfur was applied at 1000 (S₁) and 1500 (S₂) kg ha^?1 as gypsum. Element concentration of the plants was measured by polarized energy dispersive X-ray fluorescence (PEDXRF). Sulfur fertilization increased S concentrations and improved silage corn yield for both years. Applied S reduced P and Mo concentrations, increased Fe and Mn concentrations, and had no significant effect on the K, Ca, Mg, Zn and Cl concentrations of silage corn. Non-essential element composition of silage corn was also influenced by S fertilization. Applied S significantly increased Sr and Pb, reduced Si, Ba and U, while had no effect on Na, Ti, Ni, Br and Rb concentrations of silage corn. In the current work, essential and non-essential element concentrations of silage corn in 2002 and 2003 years under our experimental conditions were as follows; 1.58–1.89 S, 1.07–1.046 P, 14.3–15.9 K, 8.35–9.20 Ca, 3.34–4.28 Mg, 0.26–0.53 Na, 1.36–2.46 Cl, 38.4–42.1 Si as g kg^?1, and 2.06–3.13 Mo, 140–144 Fe, 6.08–17.69 Zn, 104–116 Mn, 9.37–12.2 Cu, 23.9–22.6 Ti, 2.10–2.31 Ni, 6.54–6.71 Br, 7.04–8.74 Rb, 94.8–118.8 Sr, 24.0–31.51 Ba, 1.20–2.22 Pb and 3.17–4.07 U as mg kg^?1.     

Effect of mercury vapour on the non-protein thiol content and respiration rate of eggs of the cattle tickBoophilus microplus (Acari: Ixodiae)

With continuous and ultimately lethal exposure of eggs ofboophilus microplus to mercury vapour, respiration and non-protein thiol decreased to low levels. With sub-lethal exposure, respiration decreased initially and then increased, whereas non-protein thiol (largely glutathione) increased initially and then decreased. This initial increase in glutathione (GSH) which probably resulted from an attempt by the organism to control or reverse the biochemical lesion, did not arise from the oxidized form (gssg) through a shift in the equilibrium from right to left thus: 2gshgssg+2H⁺+2e^–.The significance of the results are discussed in relation to theories ofgsh function and of Hg toxicity. The possible application of mercurials in tick control is discussed.     

Interaction between VA-mycorrhizal fungus and Azotobacter and their combined effects on growth of tall fescue

Amounts of N, P, K, Ca, Mg, Zn, Fe, and Mn absorbed by a nodulating and a non-nodulating (Non-nod) peanut genotype at two nitrogen fertilizer levels (nil and 200 kg N ha^–1) were determined in a field experiment. The amounts of nutrient elements in the plant parts were greatest for N, followed by K, Ca, Mg, P, Fe, Mn, and Zn in descending order. Although there were differences in the uptake of other nutrients, the major difference between Non-nod and nodulating genotypes was in nitrogen indicating the poor yield of the Non-nod line due to its inability to acquire N.Submitted as Journal Article No: 677 by International Crops Research Institute for the Semi-Arid Tropics (ICRISAT).     

Seasonal and annual variations in biological regime of lakes in an ultracontinental climate (Trans-Baikal Region of U.S.S.R)

Summary The lakes are covered 7 months with ice, but under the transparent ice (up to 180 cm thickness) a rich vegetation of phytoplankton, phytomicrobenthos and macrophyta develop and activate the bacterial and animal population. Winter production of the phytoplankton reaches 36 g/m² C and that of the phytomicrobenthos 70 g/m² C.The water levels of the lakes show fluctuations with an amplitude of 2–4 m, affecting the whole trophic system inclusive species composition, proportion and abundance of individual aquatic organisms as well as related abiotic conditions.Co-authors: E. I. Bondereva, T. N. Morozova, (primary production), A. A. Topolov, K. A. Shishkina (microbiology), V. P. Gorlachov (zooplankton), I. M. Shapovalova (zoobenthos), N. M. Pronin (fish and their parasites), V. N. Kuzmich (nutrition of fish).Co-authors: E. I. Bondereva, T. N. Morozova, (primary production), A. A. Topolov, K. A. Shishkina (microbiology), V. P. Gorlachov (zooplankton), I. M. Shapovalova (zoobenthos), N. M. Pronin (fish and their parasites), V. N. Kuzmich (nutrition of fish).     

Analysis of nutrient deficiencies affecting in vitro growth and development of <Emphasis Type="Italic">Eucalyptus dunnii</Emphasis> Maiden

Although basal medium optimization is a key factor in the success of tissue culture, its mineral composition is frequently disregarded when optimizing in vitro propagation protocols. A previous work on Eucalyptus dunnii micropropagation suggests that excessive callus formation and leaf chlorosis are related to specific nutritional conditions of the basal media. Recently, a novel basal medium based on the mineral nutrient analysis of E. dunnii young stump shoots was developed and successfully tested in plant regeneration and micropropagation of E. dunnii, avoiding all these issues. Considering this basal medium as an ideal growth condition, a mild deprivation of each macro and micronutrient and of the total organic fraction was imposed to E. dunnii in vitro cultures for 30 d. As a result, K, Mg, Mn, Cl, Zn, Mo, Ni or Co deprivation quantitatively affected growth and development of axillary shoots. Moreover, leaf chlorosis and the development of organogenic callus under Fe deficiency, and leaf drop along with shoot tip necrosis under N deficiency were observed. These symptoms suggest that nutrient content in E. dunnii tissues needs to be above 420.3 mg kg^?1 for Fe and 27.7 g kg^?1 for N to avoid the symptoms of leaf chlorosis and shoot tip necrosis. Additionally, the main role of Mn in quantitative responses and the antagonism between ions, especially for Mg/K and Mg/Zn, were denoted by the multivariate analysis. Overall, these results make a relevant contribution to the optimization of in vitro propagation of E. dunnii and other hard-to-propagate related species.     

Nutrient Accumulation in the Fruits of Two Species of Seagrass, Posidonia australis and Posidonia sinuosa

The accumulation is described of N, P, K, S, Ca, Mg, Na, Fe,Zn, Mn and Cu in the developing pericarp and seed of two speciesof seagrass. Both species showed essentially the same patterns,which resemble those of herbaceous terrestrial plants. Therewas a close relation between dry matter and nutrient accumulation.N, P, K, Fe, Zn, Mn and Cu accumulated in the fruit againstlarge concentration gradients, with discrimination against Na.Seeds accumulated N, P and trace elements to a greater extentthan pericarps and other plant parts; P was apparently retrievedfrom pericarps to a greater extent than other elements. Calculationswere made of the losses of these elements from seagrass meadowsin shed fruits. Posidonia spp., seagrass, nutrient accumulation in fruits