Mechanism of phosphorus-induced zinc deficiency in cotton. III. Changes in physiological availability of zinc in plants Is mail

The effect of varied supply of P (2.5× 10⁻⁵ to 6× 10⁻⁴ M) and Zn (0 to 10⁻⁶ M) on uptake and concentrations of P and Zn was studied in cotton ( Gossypium hirsutum L. cv. Deltapine 15/21) grown in nutrient solution under controlled environmental conditions. At a given Zn supply, increasing levels of P had no significant effect on the concentrations of total Zn in plants. However, increasing levels of P induced or enhanced visual Zn deficiency symptoms when the Zn concentration in the nutrient solution was low. The concentrations of water-soluble Zn in roots and shoots constituted 60% of the total Zn concentrations for plants grown with low P and 30% for plants grown with high P. The concentration of water-soluble Zn in leaves, but not total Zn, was closely correlated with visual Zn deficiency symptoms, levels of chlorophyll, super oxide dismutase and membrane permeability. The critical deficiency concentration of water-soluble Zn in cotton leaves was in the range of 6 to 7 μg (g dry weight)⁻¹ or about 1.0 μg (g fresh weight)⁻¹. The results show that high P concentrations in plant tissue decrease the physiological availability of Zn. Water-soluble Zn in the tissue appears to be a suitable indicator for Zn nutritional status in general and phosphorus-induced Zn deficiency in particular. Also in field-grown orange trees (Citrus sinensis) visual Zn deficiency symptoms in leaves were closely related to the concentration of water-soluble Zn.     

Genetic diversity within and among 11 juvenile populations of green alder (Alnus crispa) in Canada

Germinated seeds from 11 populations of green alder [ Alnus crispa (Ait.) Pursh] sampled in four Canadian provinces were analysed for electrophoretically demonstrable diversity of 10 enzymes encoded by 15 structural loci. Of these, nine were polymorphic, and on average, 52% of the loci per population were polymorphic. Assuming a diploid model of expression, average level of expected heterozygosity was 0.11 with nearly all populations in Hardy-Weinberg equilibrium for the set of polymorphic loci analysed. No significant inbreeding and associated subpopulation structuring were noted. Rates of gene flow appeared high within and among populations. Although little divergence was observed among populations, genetic and geographical distances between populations were related. Discriminant and cluster analyses revealed a pattern of genetic variation associated with geography. Populations from northern Quebec were poorly differentiated, whereas western populations from Alberta exhibited a larger degree of genetic differentiation. Introgresive hybridization with the sympatric species Alnus sinuata (Regel) Rydberg and partial isolation in the West are suggested as an explanation for this larger differentiation. The occurrence and significance of rare alleles is discussed in relation to the importance of geographical distance in the process of population differentiation in this species.     

The effect of lime on phosphorus adsorption and barley growth in three acid soils

For three acid soils from Santa Catarina, Brazil, lime application and time of incubation with lime had little effect on the adsorption of added phosphorus. In two soils with high contents of exchangeable aluminium, solution P and isotopically exchangeable P were decreased by incubating with lime for 1 month: phosphorus was probably adsorbing on freshly precipitated aluminium hydrous oxides. In one soil with less exchangeable aluminium, P in solution was increased by liming. After 23 months lime increased solution and exchangeable P possibly due to crystallization of aluminium hydrous oxides reducing the number of sites for P adsorption. All these changes were however small. In a pot experiment, lime and phosphorus markedly increased barley shoot and root dry matter and P uptake. Although liming reduced P availability measured by solution P, isotopically exchangeable P and resin extractable P, it increased phosphorus uptake by reducing aluminium toxicity and promoting better root growth. The soil aluminium saturation was reduced by liming, but the concentration of aluminium in roots changed only slightly. The roots accumulated aluminium without apparently being damaged.     

Prediction of heavy-metal concentrations in mature plants by chemical analysis of seedlings

Five plant species were cultivated on a soil from the Neckar alluvial fan near Heidelberg (FRG) polluted by the emissions of a cement plant. Thallium, cadmium and lead concentrations in seedlings and mature plants were determined by atomic absorption analysis. AdditionallyBrassica napus L.napus was grown on soils containing 5 different concentrations of heavy metals, achieved by mixing two similar soils, from the same area but with different metal concentrations. Thallium and cadmium were shown to be taken up by roots whilst lead which was also absorbed, was deposited mainly on the plant surface. However during cultivation in the winter months, a remarkable deposit of lead via the roots was found. Thallium in the soil from a anthrorogen source was more available to plants than thallium of geological origin. During the lifetime of a plant concentrations of thallium and cadmium were always highest in the seedling. The decrease in metal concentration with maturity depended on the plant species and the element, but was not a function of the metal concentration in the soil.     

Induction and floral determination in the terminal bud of Nicotiana tabacum L. cv. Maryland Mammoth,a short-day plant

Floral determination in the terminal bud of the short-day plant Nicotiana tabacum cv. Maryland Mammoth has been investigated. Plants grown continuously in short days flowered after producing 31.4±1.6 (SD) nodes while plants grown continuously in long days did not flower and produced 172.5±9.5 nodes after one year. At various ages, expressed as number of leaves that were at least 1.0 cm in length above the most basal 10-cm leaf, one of three treatments was performed on plants grown from seed in short days: 1) whole plants were shifted from short days to long days, 2) the terminal bud was removed and then rooted and grown in long days, and 3) the terminal bud was removed and then rooted and grown in short days. Whole plants flowered only when shifted from short days to long days at age 15 or later. Only rooted terminal buds from plants at age 15 or older produced plants that flowered when grown in long days. Only terminal buds from plants at age 15 or older that were rooted and grown in short days produced the same number of nodes as they would have produced in their original locations while buds from younger plants produced more nodes than they would have in their original locations. Thus, determination for floral development in the terminal bud, as assayed by rooting, is simultaneous with the commitment to flowering as assayed by shifting whole plants to non-inductive conditions.Abbreviations LD long day(s) - SD short day(s) - DN dayneutral     

Single potassium channels in membranes of isolated mesophyll barley vacuoles

Summary Voltage-dependent K channels could be identified in on-cell and excised patch-clamp records on membranes of isolated plant cell vacuoles. The current through a membrane patch is dominated by a channel population with a conductance of about 121 pS in symmetrical 250mm KCl solution. The single channel adopts at least two conducting levels the 121-pS state being most frequently observed. The channel shows outward rectification, representing a cation flux into the vacuoles. The rectification appears to be caused by a vanishing open probability and a short channel lifetime at hyperpolarizing voltages. A selectivity ratio of potassium over sodium of about 6 was derived as an estimate. Occasionally, an additional population of K channels with a single-channel conductance of approximately 18 pS is observed. This channel type exhibits outward rectification as well.     

Effect of Hirschmanniella caudacrena on the Submersed Aquatic Plants Ceratophyllum demersum and Hydrilla verticillata

In vitro pathogenicity tests demonstrated that Hirschmanniella caudacrena is pathogenic to Ceratophyllum demersum (coontail). Symptoms were chlorotic tissue, deformed stems, and, finally, death of the plant. Inoculum densities of 500 nematodes per 5-cm-long cutting in a test tube containing 50 ml of water resulted in death and decay of some of the cuttings within 8 weeks; 100 nematodes killed the plants in 12 weeks, and 50 and 25 nematodes killed them in 16 weeks. The lowest inoculum level of 10 nematodes did not seriously affect the plants at 16 weeks when the experiment was terminated. A second test conducted outdoors in glass jars containing 3 liters of water and two cuttings weighing a total of 15 g fresh weight showed damage, but results were not statistically significant. Hydrilla verticillata inoculated with H. caudacrena was not affected seriously.     

Quantitative Development and Molecular Forms of Acetyl-and Butyrylcholinesterase During Morphogenesis and Synaptogenesis of Chick Brain and Retina

The embryonic development of total specific activities as well as of molecular forms of acetylcholinesterase (AChE, EC 3.1.1.7) and of butyrylcholinesterase (BChE, EC 3.1.1.8) have been studied in the chick brain. A comparison of the development in different brain parts shows that cholinesterases first develop in diencephalon, then in tectum and telencephalon; cholinesterase development in retina is delayed by about 2-3 days; and the development in rhombencephalon [not studied until embryonic day 6 (E6)] and cerebellum is last. Both enzymes show complex and independent developmental patterns. During the early period (E3-E7) first BChE expresses high specific activities that decline rapidly, but in contrast AChE increases more or less constantly with a short temporal delay. Thereafter the developmental courses approach a late phase (E14-E20), during which AChE reaches very high specific activities and BChE follows at much lower but about parallel levels. By extraction of tissues from brain and retina in high salt plus 1% Triton X-100, we find that both cholinesterases are present in two major molecular forms, AChE sedimenting at 5.9S and 11.6S (corresponding to G2 and G4 globular forms) and BChE at 2.9S and 10.3S (G1 and G4, globular). During development there is a continuous increase of G4 over G2 AChE, the G4 form reaching 80% in brain but only 30% in retina. The proportion of G1 BChE in brain remains almost constant at 55%, but in retina there is a drastic shift from 65% G1 before E5 to 70% G4 form at E7.(ABSTRACT TRUNCATED AT 250 WORDS)     

实夜蛾属二近缘种对寄主植物次生物质的反应:次生物质对幼虫生长和食物利用的影响

实夜蛾属(Heliothis)的棉铃虫(H. armigcra)和烟青虫(H. assulta)是近缘种,幼虫期取食多种相同的植物,其中含有不同的次生物质.本项工作是在人工饲料中分别加入0.5%的烟碱、番茄苷、棉子酚、丹宁酸等饲养早期六龄的幼虫,测定它们对生长和食物利用的影响.结果表明这些次生物质对两种幼虫有不同的作用:烟碱对棉铃虫没有明显影响,但对烟青虫的取食却有一定的刺激作用.丹宁酸、棉子酚、番茄苷可抑制两种幼虫的生长,而以番茄苷抑制烟青虫的生长最为显著.番茄苷主要通过抑制取食来影响幼虫的生长,而丹宁酸和棉子酚则具有降低消化率的作用.通过次生物质对这两种幼虫效应的比较可知,棉铃虫有较大的忍耐力.     

Revision of the plant geographical territories of Israel and Sinai

The phytogeographical territories of Israel and Sinai are revised using a large mass of species distribution data. With the help of chorotype frequencies for 25 km² individual squares in Israel, territories were defined on the basis of the first two most frequent chorotypes. The similarity of boundaries in the resulting phytogeographical map with a physiognomic map suggests that the latter may be used in preliminary stages of the preparation of plant geographical maps.