Partitioning of Dry Matter and Mineral Nutrients During a Reproductive Cycle of the Mistletoe Amyema linophyllum (Fenzl.) Tieghem Parasitizing Casuarina obesa Miq.

Budgets for utilization of dry matter, nitrogen and a rangeof mineral elements were constructed for the reproductive season(September 1988–May 1989) of plants of the mistletoe Amyemalinophyllum (Loranthaceae) parasitizing the swamp she oak (Casuarinaobesa Miq.) at Gingin, W. Australia. Shed buds comprised 55%of the allotment of dry matter to reproduction, shed flowers7%, abscised perianths and styles 15%, prematurely shed fruits15%, and successfully ripened fruits a mere 12%. Commitmentto reproductive biomass peaked sharply in October, while thegenerally higher rate of allocation to vegetative biomass declinedfrom beginning to end of the 9-5 month reproductive cycle. Investmentsof dry matter in new leaves and secondary thickening of previousseason's stems were several-fold greater budget items than productionof new stems and shedding of leaves. There was no evidence ofpre-senescence retrieval of N, P, and K from leaves, and concentrationsof Ca, Mg, Na, and Cl increased steadily in dry matter withleaf age. Values for reproductive effort (RE) for dry matterand specific mineral elements were calculated as commitmentto reproduction divided by commitment to reproduction plus vegetativebiomass (? 100). Due to highly differential partitioning ofcertain elements between reproductive and vegetative parts,RE values for minerals for the reproductive season ranged widely,viz. 7% for Ca, 10% for Mn, 15% for Mg, 17% for N, 25% for Kand Zn, 26% for Cu, and 35% for P. The comparable RE for drymatter was 29%. The weight ratio for net intake of nutrientelements from the host by A. linophyllum for the reproductiveseason was 21?5:20?2:6?6:1?6:1 (N:K:Ca:Mg:P), while the meanweight ratio for the concentrations of these elements in xylem(tracheal) sap of the Casuarina host was 13?9:15?6:4?1:30:1,respectively. The data are discussed in relation to the demonstrationof a direct lumen-to-lumen tracheary continuity between hostand mistletoe in mature regions of the haustorial interface. Key words: Mistletoe, resource allocation, mineral nutrition, reproductive effort, host:parasite relationships     

Seasonal Dynamics of the Accumulation, Distribution and Redistribution of Dry Matter and Mineral Nutrients in a Weedy Species of Gladiolus (Gladiolus caryophyllaceus)

The seasonal dynamics of the accumulation, distribution andredistribution of dry matter and 12 mineral nutrients by a weedyspecies of gladiolus (Gladiolus caryophyllaceus) were studiedat Perth, Western Australia, where it has colonized the nutrient-poorsandy soils. Parent corms sprouted in autumn, and the plantshad completed their growth cycle by early summer. The maturereplacement corm had 15-25% of the plant's P, Ca, Na, Zn andCu, 5-15% of its K, N, Cl, Mg, S and dry matter, and < 5%of its Fe and Mn. Seeds had 26% of the plant's dry matter, 60%of its N and P, 21-33% of its S, Mg, Cu and K, 5-20% of itsFe, Mn and Zn, and < 5% of its Ca and Na. The mature vegetativeshoot had 47% of the plant's dry matter and over 40% of eachnutrient, except for N, P and Cu. Phosphorus, K and N were redistributedfrom the parent corm with over 85% efficiency, S, Mg, Zn andCu with 60-70% efficiency, but there was < 10% redistributionof Ca, Na, Cl, Fe and Mn. The efficiency of redistribution fromthe leafy shoot was over 70% for N and P, 29-52% for K, Mg andCu, 16-20% for S, Zn and Cl, but negligible for Ca, Na, Fe andMn. Redistribution from the shoot could have provided the replacementcorm and seeds with 53-98% of their Cu, Mg, N, P and K, and29-38% of their S, Zn and dry matter. Seeds contained over 60%of each nutrient in a capsule, except for Ca, Na and Fe. Redistributionfrom the capsule walls could have provided 13-19% of the P,Cu and Zn, and 3-7% of the N, K, Mg and dry matter accumulatedby seeds. Each plant produced an average of 520 seeds. Removalof flowers and buds at first anthesis resulted in a larger replacementcorm containing a greater quantity of most nutrients, indicatingcompetition between the replacement corm and seeds for nutrients.Redistribution from parent to replacement cormlets in the absenceof shoot and root development was high, with over 50% of thedry matter and each nutrient, except for Ca, being transferred.Concentration of nutrients were low in all organs of G. caryophyllaceus,especially the replacement corm. It was concluded that the effectiveredistribution of key nutrients, such as N and P, to reproductivestructures and tolerance of low internal concentrations of nutrientscontribute to the capacity of G. caryophyllaceus to colonizeand persist on infertile soils.Copyright 1993, 1999 AcademicPress Gladiolus caryophyllaceus, corm, distribution, dry matter, gladiolus, mineral nutrients, nutrient accumulation, nutrient redistribution, seasonal growth, weed     

Abscisic Acid and the Regulation of Water Loss in Plantlets of Brassica oleracea L. var. botrytisRegenerated Through Apical Meristem Culture

Water loss was studied in regenerated plantlets of Brassicaoleracea var. botrytis cv. Currawong derived through apicalmeristem culture. Hardening of plantlets was eliminated by asingle application of a polyvinyl resin (S600) sprayed immediatelyafter transplanting. Plantlets sprayed with S600 had highercuticular resistances than unsprayed plantlets; this treatmenthad no effect on stomatal resistance. Leaves formed during theculture period showed very little wax formation and using markedleaves it was found that only reduced levels of wax formed onthese leaves even after transplanting. New leaves formed aftertransplanting, showed typical wax formation compared to seedgrown plants. Abscisic acid (ABA) at 10^–4 M applied as a leaf sprayto transplants did not cause a substantial increase in stomatalresistance in leaves which had been initiated during the cultureperiod. Leaves of seed-grown plants as well as leaves of plantletsformed after transplanting did respond to a leaf spray of ABAat 10^–4 M by a large increase in stomatal resistance. Relative concentrations of K, Na, Ca, P, S and Mg in guard cellswere calculated for each leaf type by X-ray micro-probe analysis.K/Na values decreased in the order: seedling > leaves formedafter transplanting > leaves intiated during culture. A highpositive correlation was also found between K/Na and K/P forthe three leaf types. K:Mg and K:Ca ratios for leaves formedduring culture were low in comparison to the values obtainedfor leaves formed after transplanting and seedlings for whichthe values were similar. Brassica oleracea var. botrytis, cauliflower, regenerated plantlets, meristem culture, stomatal resistance, water loss, abscisic acid, X-ray micro-probe analysis     

The Locations and Amounts of Endogenous lons and Elements in the Cap and Elongating Zone of Horizontally Oriented Roots of Zea mays L: An Electron-probe EDS Study

We used quantitative electron-probe energy-dispersive x-raymicroanalysis to localize endogenous Na, Cl, K, P, S, Mg andCa in cryofixed and freeze-dried cryosections of the cap (i.e.the putative site of graviperception) and elongating zone (i.e.site of gravicurvature) of horizontally oriented roots of Zeamays. Ca, Na, Cl, K and Mg accumulate along the lower side ofcaps of horizontally oriented roots. The most dramatic asymmetriesof these ions occur in the apoplast, especially the mucilage.We could not detect any significant differences in the concentrationsof these ions in the central cytoplasm of columella cells alongthe upper and lower sides of caps of horizontally-oriented roots.However, the increased amounts of Na, Cl, K and Mg in the longitudinalwalls of columella cells along the lower side of the cap suggestthat these ions may move down through the columella tissue ofhorizontally-oriented roots. Ca also accumulates (largely inthe mucilage) along the lower side of the elongating zone ofhorizontally-oriented roots, while Na, P, Cl and K tend to accumulatealong the upper side of the elongating zone. Of these ions,only K increases in concentration in the cytoplasm and longitudinalwalls of cortical cells in the upper vs lower sides of the elongatingzone. These results indicate that (1) gravity-induced asymmetriesof ions differ significantly in the cap and elongating zoneof graviresponding roots, (2) Ca accumulates along the lowerside of the cap and elongating zone of graviresponding roots,(3) increased growth of the upper side of the elongating zoneof horizontally-oriented roots correlates positively with increasedamounts of K in the cytoplasm and longitudinal walls of corticalcells, and (4) the apoplast (especially the mucilage) may bean important component of the pathway via which ions move ingraviresponding rots of Zea mays. These results are discussedrelative to mechanisms for graviperception and gravicurvatureof roots. Corn, gravitropism (root), ions, x-ray microanalysis, Zea mays     

Mobilization of Minerals to Developing Seeds of Legumes

The mineral nutrition of fruiting plants of Pisum sativum L.,Lupinus albus L. and Lupinus angustifolius L. is examined insand cultures supplying adequate and balanced amounts of essentialnutrients. Changes in content of specific minerals in leaves,pods, seed coat, and embryo are described. P, N and Zn tendto increase precociously in an organ relative to dry matteraccumulation, other elements more or less parallel with (K,Mn, Cu, Mg and Fe) or significantly behind (Ca and Na) dry weightincrease. Some 60–90 per cent of the N, P and K is lostfrom the leaf, pod and seed coat during senescence, versus 20–60per cent of the Mg, Zn, Mn, Fe and Cu and less than 20 per centof the Na and Ca. Mobilization returns from pods are estimatedto provide 4–39 per cent of the seeds' accumulations ofspecific minerals, compared with 4–27 per cent for testatransfer to the embryo. Endosperm minerals are of only minorsignificance in embryo nutrition. Comparisons of the mineral balance of plant parts of Lupinusspp. with that of stem xylem sap and fruit tip phloem sap supportthe view that leaves and pod are principal recipients of xylem-borneminerals and that export from these organs via phloem is themajor source of minerals to the seeds. Endosperm and embryodiffer substantially in mineral compostition from phloem sap,suggesting that selective uptake occurs from the translocationstream during seed development. Considerable differences are observed between species in mineralcomposition of plant organs and in the effectiveness of transferof specific minerals to the seeds Differences between speciesrelate principally to Ca, Na and certain trace elements.     

Accumulation, Partitioning and Redistribution of Dry Matter and Mineral Nutrients in Ixia flexuosa L., with Special Reference to its Cormaceous Habit

The seasonal dynamics of uptake, partitioning and redistributionof dry matter, N, P, K, S, Ca, Mg, Na, Cl, Fe, Zn, Mn and Cuby the cormaceous plant Ixia flexuosa were studied in pot cultureat Perth, Western Australia. Dry matter and P, N, K, Zn andCu were redistributed from the mother corm with about 90 percent net efficiency: there was no net redistribution of Ca,Na, Fe or Mn. The efficiency of redistribution from the leafyshoot to fruits and the new season's corm was 80 per cent forN and P, 24–49 per cent for K, Cu and Zn, and 0–15per cent for Na, Fe, Ca, Mn, Cl, Mg, S and dry matter. Redistributionfrom the mother corm and vegetative organs could have suppliedthe replacement corm, cormlets and fruits with 32–53 percent of their S, K, P, N, Cu and Zn, and 11–25 per centof their Ca, Cl, Mn, Mg and dry matter. The mature replacementcorm had over 60 per cent of the plant's N and P, 25–50per cent of its dry matter, Zn, Cu, Mg, K and Cl, but less than20 per cent of its Ca, Na, Fe and Mn. Each plant produced anaverage of 12 cormlets; these had 35 per cent of the dry matterand 23–47 per cent of the amount of a particular nutrientin the new season's corms. Fruits had less than 16 per centof the dry matter and each mineral in the mature plant. Ratesof mineral intake by Ixia were much lower than reported forcrop plants, and may be related to the long growing season ofthe species. Ixia polystachya L., corm, nutrition, mineral nutrients, nutrient redistribution     

Seasonal variation in nutrient concentration in leaves and branches of Quercus pyrenaica

Abstract. Seasonal variation in nutrient concentration in leaves and branches of Quercus pyrenaica was studied in natural Q. pyrenaica forest in the Sierra de Gata (Salamanca Province, Spain). Two permanent plots were established at the two extremes of a rainfall gradient in this area: annual mean precipitation from 720 mm at Fuenteguinaldo (granite bedrock) to 1580 mm at Navasfrias (schists and graywackes). Leaf and branch samples were collected every three weeks during the growing season from May to October, at three height levels of the tree canopy. Seasonal changes and internal nutrient dynamics were investigated for N, Ca, Mg, K, Na, Mn, Fe and P during a two-year period. The concentrations of all nutrients varied among the seasons; these variations were related to nutrient mobility and the annual physiological cycle. Nutrient concentrations decrease in the case of K and P, while the sparse mobile nutrients Ca, Mg, Mn and Fe gradually accumulated during each growing season. In Navasfrias a considerable resorption of P from senescing leaves was detected. Different patterns were found for the other nutrients studied (Na and N).     

Mass and nutrient loss of fresh plant biomass in a small black-water tributary of Caura river, Venezuelan Guayana

Decomposition rates and nutrient dynamic (N, P, K, Ca and Mg) were determined for green leaves and fine branches immersed in the water of a small tributary of Caura river (SE-Venezuela). 16% of the original dry weight of leaves and 11% of branches were lost at the end of the first sampling period: first month for leaves and second month for branches. This dry weight reduction was probably due to leaching of soluble material. After a 9-month period, the mass loss was 60% for leaves and 20% for fine branches. The pattern of dry weight and nutrient losses are in general agreement with previous studies of decomposition of leaf litter in both terrestrial and aquatic ecosystems. Potassium and magnesium are the elements most rapidly lost, showing the dominance of leaching processes; at the end of the first month 7% of the initial amount of K and 18% of the initial amount of Mg remained in leaves. The loss of calcium and phosphorus was much slower: 61% of Ca and 47% of P remained in the leaf material after the first sampling period. In contrast to K, Mg, Ca and P, the initial amount of nitrogen in leaves remained relatively unchanged during the first month of decomposition; in the subsequent sampling period, the amount of N decreased. The elements K and Mg in branches behaved similar to leaves: 4% of K and 22% of Mg were left at the end of the first sampling period. The initial amount of Ca and P in branches decreased slightly: 88% of Ca and 83% of P remained in branches at the end of this first sampling. Nitrogen behaved differently in branches than that in leaves. In branches the amount of N remained relatively unchanged during the first 5 months of decomposition; afterwards, N showed gradual increases, probably due to immobilization. At the end of the experiment the amount of N in branches was 16% higher than the initial amount.     

Influence of soil oxygen and soil water on the accumulation of nutrients in avocado seedlings (Persea Americana mill.)

Summary This experiment was conducted in a greenhouse to study the influence of 2 soil-oxygen levels and 4 irrigation levels on the plant response, root decay, concentrations of 12 nutrients, as well as on total amounts of nutrients per avocado seedling (Persea americana Mill.).Reduced soil-oxygen supply to the roots significantly reduced the amount of dry weight per seedling, increased percentage of root decay, and reduced the concentrations of N, P, K, Ca, Mg, and B in the tops, while Na and Fe were increased. Concentrations of K, Mg, Na, and Cl in the roots were decreased, while N and Ca were increased with decreased soil oxygen supply to the roots. Total amounts of N, P, Ca, Mg, Na, and Cl per seedling were decreased with the low soil-oxygen supply to the roots.Only slight differences in dry weight of the tops of seedlings were found. The highest degree of root decay was caused by the irrigation treatment where a water table was present. In the tops, concentrations of N, P, K, Mg, Na, Zn, Cu, Mn, B, and Fe were significantly influenced by differential irrigation treatments; in the roots, concentrations of P, K, Ca, Mg, Na, and Cl were also significantly influenced; and total amounts of N, P, Mg, and Cl the whole seedling were likewise significantly influenced.Significant interactions were noted between the soil-oxygen and irrigation treatments on the dry weight of tops, roots, and total amounts of dry weight produced per seedling. The lowest amount of dry weight of roots and the highest degree of root decay were found in the avocado seedlings grown under low soil-oxygen supply and the irrigation treatment where a water table was present. Several significant interactions between soil oxygen and irrigation on the concentrations of N, P, K, Ca, Zn, and Mn are discussed.University of California, Citrus Research Center and Agricultural Experiment Station, Riverside, California. The research reported in this paper was supported in part by NSF Grant GB-5753x.     

The Distribution of Nine Elements in Shoots of Lupinus albus L. and Lupinus angustifolius L. Compared with that of Silicon as a Measure of Passive Transport

The Ca, Mg, K, Na, P, Fe, Mn, Zn, Cu and opaline-Si contentsof leaves, stems and inflorescences from each order of shootaxis was determined in Lupinus albus L. and Lupinus angustifoliusL. The distribution of Si was used as a base for passive transportin the transpiration stream. All of the elements investigatedwere redistributed among the leaves, stems and inflorescencesof either L. albus or L. angustifolius. Most of the elementsinvestigated were enriched in the inflorescences and depletedin either the leaves or the stems. Sodium was enriched in thestems whereas Ca and Mn were redistributed only in L. albus.The pattern of element redistribution was similar in each ofthe lateral shoot axes except for the youngest. For the elementsenriched in the inflorescences, more than half was suppliedby redistribution. Calcium redistribution was similar to thatfor K, which is regarded as phloem mobile, but a mechanism forCa redistribution is uncertain. Lupinus albus L., Lupinus angustifolius L., mineral transport, leaves, inflorescences, transpiration, silicon, calcium     

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     

Effect of farm yard manure on the availability of Ca from Ca45CO3 in a sodic soil (ESP 77.7)

Summary Application of FYM caused a gradual increase in the dry weight of dhaincha (Sesbania aculeata Pers.) tops. It also caused a gradual increase in the content of Mg and K and a decrease in the content of Ca, Na, N and P in dhaincha tops. Increase in Ca: Na ratio was more steeper than (Ca+Mg): (Na+K) ratio. Total uptake of Ca, Mg, K, N and P increased and that of Na decreased in response to FYM. Contribution of Ca from Ca⁴⁵CO₃ did not differ much at different levels of FYM and it was less than 6 per cent of total Ca in plant tops in all the treatments. re]19721017     

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     

Redistribution of Nutrient Elements from Cotyledons of Two Species of Annual Legumes During Germination and Seedling Growth

The distribution of dry matter and various mineral nutrientsbetween testa and embryo of seeds of Lupinus albus and L. angustifoliusis described It was found that lupin seeds at either end ofa pod contained less dry matter and minerals than seeds in themiddle of the fruit. The transport of dry matter, N, P, K, S,Ca, Mg, Na, Fe, Zn, Mn and Cu from cotyledons of parent seedsof both species to the seedling axis was measured from germinationto the time of cotyledon death. N, P, K and S were retrievedfrom cotyledons with over 90 per cent efficiency, dry matter,Mg, Na, Fe, Zn, Mn and with 59–90 per cent efficiency,and Ca with 26–31 per cent efficiency. There was littlechange in the efficiency of nutrient retrieval from cotyledonswhen seedlings were grown in different culture media. Both speciesshowed a linear relationship between the loss of each elementand dry matter throughout the experiment, and a similar proportioningbetween root and shoot of the amount of a specific nutrientmobilized from cotyledons of parent seeds. Lupinus albus L., Lupinus angustifolius L., lupin, transport, of dry matter and mineral nutrients     

Phloem and Xylem Transport in the Supply of Minerals to a Developing Legume (Lupinus albus L.) Fruit

The economy of carbon, nitrogen, water and mineral elementsin fruits of Lupinus albus L. was studied by measuring accumulationof these quantities in the developing fruit and estimating itstranspirational losses and CO₂ exchanges. Combining this informationwith data on levels of mineral elements in the xylem sap andphloem sap supplying the fruit, it was possible to test whethertransport based on mass inflow through xylem and phloem wouldaccount for the observed intake of elements. A model of transportbased on water and carbon intake suggested that vascular intakeduring the fruit's life matched the recorded increment for mineralsto within ± 15 per cent for N, Na, Zn, Fe and Cu, andto within ± 23 per cent for P, K and S. However, estimatedvascular intake of Ca, Mg and Mn accounted for less than one–thirdof the recorded intake by the fruit, inadequacy of vascularintake being especially great early in growth. Transport inphloem accounted for more than 80 per cent of the fruit's vascularintake of C, N and S, and 70–80 per cent of its P, K,Mg and Zn. Xylem contributed 68 per cent of the vascular inputof Ca, 59 per cent of the Na, and 34–38 per cent of theFe, Mn and Cu. Enclosure and darkening of fruits reduced levelsof Ca and Fe but increased levels of N, P, K and Zn in fruitdry matter relative to unenclosed, illuminated fruits. Resultswere related to previous observations on fruit functioning. Lupinus albus, legume fruit, mineral supply, phloem, xylem     

Major Element Composition of Epidermal and Mesophyll Tissues2Commelina Communis L. and Vicia Faba L.: Some Further Considerations of the Role of Ions in Stomatal Functioning

Epidermal and mesophyll tissues of Commelina communis L. andVicia faba L. were analysed by atomic absorption spectrometryfor the major plant inorganic cations and anions (K, Na, Ca,Mg, P, NO₃-N, Cl) when stomata of the leaf were open and closed.Water-soluble and residual levels of the elements were estimatedand a charge balance of the soluble fraction made. The major portion of K, Na, Cl, and P was extracted in the water-solublefraction of the epidermal and mesophyll tissues of both species.In both species the bulk of Ca remained in the insoluble residueof the epidermis whereas in mesophyll tissue it was equallydistributed be-between the two fractions in C. communis butmainly in the insoluble residue in V. faba. Magnesium was predominantlyfound in the water-soluble fraction of V. faba mesophyll tissueand distributed approximately equally between the two fractionsin the epidermal tissue. In C. communis Mg was slightly moreabundant in the water-soluble fraction of both mesophyll andepidermis. In both species no statistically significant differences inthe levels of the elements could be detected between epidermaland mesophyll tissues from leaves with open stomata and thesame tissues from leaves with closed stomata, suggesting thatthere was no major flux of ions between mesophyll and epidermisduring stomatal movements. Regardless of whether the stomata were open or closed, therewere considerably more water-soluble inorganic cations thananions present in all tissues of both species with K being themajor cation and Cl being the major anion. In V.faba and C-communis epidermis there was 49–53 per cent and 56%68per cent excess cation respectively. In the mesophyll tissuethe excess cation was 63–75 per cent and 75%78 per centin V.faba and C. communis respectively. When the partitioning of the levels of the elements betweenepidermis and mesophyll of a leaf is considered, except forNO₃-N in both species and Na in V. faba, 20 per cent or lessof each element was present in the epidermis.     

Availability of Ca from Ca45SO4 in a highly saline-sodic soil

Summary Application of gypsum (tagged Ca⁴⁵SO₄.2H₂O) caused a considerable increase in dry matter yield and content of Ca, Ca⁴⁵, Mg and K and Ca:Na and (Ca+Mg): (Na+K) ratios and a decrease in the content of Na, N and P in dhaincha tops. There was a considerable increase in the total uptake of Ca, Mg, Na, K, N, P and Ca⁴⁵ by plant tops in response to gypsum. Contribution of Ca from applied Ca⁴⁵SO₄ varied from 78.3 to 84.7 per cent of the total Ca in plant tops, whereas, its uptake from this source varied from 52.18 to 98.73 me per 100 g plant tops. re]19720705     

Nitrogen Relations in a Douglas-fir Plantation

A 42-year-old Western Washington Douglas-fir [Pseudotsuga menziessii(Mirb.) Franco] plantation which was N-deficient was studiedin relation to the application of N applied as urea to the forestfloor, and carbohydrate applied to the forest floor to widenthe C/N ratio and thus intensify the existing N deficiency.After 1 year, needle size was measured and needles were alsoanalyzed for pigment content N, P, K, Ca, Mg, and Mn. As a resultof N fertilization needle size and weight had increased. Needleretention (years) was increased in the N treatments and reducedin the carbohydrates treatments. This effect was reflected inthe quantities of leaf litter-fall. Nitrogen concentrationswere increased in treatments where N was applied as were pigmentcontents but other nutrients decreased in concentration probablyas a result of growth dilution. While there was no significantdecrease in needle N concentration where carbohydrate was applied,the N uptake was reduced because of needlesize and retentiontimechanges. The results are discussed in relation to nutrientdiagnostic work.     

Increase in the Formation and Nitrogen Fixation of Soybean Nodules by Vesicular-Arbuscular Mycorrhiza

Symbiotic interactions of the tripartite association of soybeanplant, vesiculararbuscular (VA) mycorrhizal fungus and Rhizobiumjaponicum were shown. Mycorrhizal plants absorbed more P, Ca and Mg and had higherP, Ca and Mg contents in their stems or leaves than non-mycorrhizalplants. Phosphorus concentration was also higher in the nodulesof mycorrhizal plants. VA mycorrhizae increased nodule number, nodule weight and acetylenereduction activity of nodules. Concomitantly seed productionand N content of leaves were enhanced. Both nodulating (A62-1) and non-nodulating (A62-2) cultivarsof soybean plants [Glycine max (L.) Merr.] were colonized byVA mycorrhizal fungi, identified as belonging to the genus Glomus. (Received August 12, 1985; Accepted January 14, 1986)     

Under-storey Nutrient Content in an Age Sequence of Douglas-fir Stands

The nutrient concentrations and contents of the under-storeyspecies were estimated for a series of Pacific North-west Douglas-fir[Pseudotsuga menxiessii (Mirb.) Franco] stands ranging in agefrom 9 to 95 years. Analyses were carried out for ash, N, P,K, Ca, Mg, Mn, Fe, Zn and Na and significant differences innutrient concentrations were found to exist between species;species rejecting certain nutrients and accumulating others.General trends for mean concentrations of some nutrients areassociated with stand maturity in that ash, K and Mg decline,P and Mn increase and N and Ca reaches a peak at 20–30years and then declines. The nutrient contents (kg ha^–1)of the under-storey component of the stands are presented andtrends discussed. Mineral nutrient content, under-storey vegetation, Pseudotsuga menziessii stands, Douglas-fir