Nutrient Uptake by Different Parts of the Intact Roots of Plants

An apparatus is described for studying the uptake of ions byshort segments of intact root systems grown in water culture. When the entire root systems of young cereal plants are suppliedwith o'I ppm, P or Sr the quantities of both ions accumulatedin segments 3–5 mm long, or translocated from them toother tissues, are considerably smaller than those which movelongitudinally in the cortex for short distances. This process,which is under metabolic control, causes ions to be releasedto the external solution from parts of the root a few mm distantfrom the site of entry. The contribution, to the nutrition of barley plants 3–4weeks old, of different parts of the root system has been investigated.Between seminal axes, nodal axes, and laterals total uptakeper unit length of root varies largely, though not entirely,with volume. The ratio in which phosphate and strontium areabsorbed is not constant throughout the root system, the absorptionof phosphate being relatively greater by laterals. Little translocationoccurs from the apical 3 mm of roots and the fraction of theabsorbed ions translocated to shoots from older root segmentsis considerably greater for nodal axes than for seminal axesor laterals. The significance of the distribution of absorbing power throughoutthe root system is considered in relation to the nutrition ofplants grown in soil, especially when the rate of diffusionto the root surface may limit nutrient uptake.     

A Study of the Absorption and Utilization of Phosphate by Young Barley Plants: I. THE EFFECT OF EXTERNAL CONCENTRATION ON THE DISTRIBUTION OF ABSORBED PHOSPHATE BETWEEN ROOTS AND SHOOTS

The effect of the external concentration on the distributionof phosphate absorbed by young barley plants was studied inexperimental periods varying from 1 hour to 7days.The experimentalwere carried out in water culture with radioactive phosphorusas a tracer. The concentration of labelled phosphate suppliedto the plants ranged from 0·0003 to over 30 p.p.m. P. When the external concentration of phosphate is reduced below10 p.p.m. P, the proportion of the absorbed phosphate foundin the shoots is markedly reduced. Plants which have been treatedwith low concentrations of phosphate lose recently absorbedphosphate to the outer medium when transferred to phosphate-freesolutions. Plants treated with higher concentrations lose asmaller proportion of recently absorbed phosphate. Different balances of other nutrients do not affect the generalrelationship between the absorption and distribution of phosphate,though quantitative changes occur.It is concluded that the retentionof phosphate in the roots induced by dilute media is a directconsequence of the small quantity of phosphate entering theroots and is not attributable to the effects of other ions whichmay be simultaneously absorbed.     

Response of Deer to Containment by a Poly-Mesh Fence for Mitigating Disease Outbreaks

Abstract: Rapidly deployable and effective methods are needed to contain free-ranging deer (Odocoileus spp.) during acute disease outbreaks. We evaluated efficacy of a 2.1-m-tall polypropylene mesh (poly-mesh) fence for containing ≥15 free-ranging white-tailed deer (O. virginianus) within a 42-ha area in eastern Nebraska, USA. We observed a 99% decrease in deer leaving the enclosure area after we installed fencing (1 deer jumped; 0.02 deer/hr) compared with prefence rates (5.26 deer/hr). However, 8 deer (53% of censused population) escaped the enclosure during a census drive after our study. Poly-mesh fencing may be effective in temporarily containing free-ranging deer during minimally disruptive deer removal actions such as trapping or sharpshooting.     

Tree Selection and Landscape Analysis of Eastern Red Bat Day Roosts

ABSTRACT Declining bat populations and increasing demands on forest resources have prompted researchers to investigate tree roost selection of forest bats. Few studies, however, have investigated different spatial scales and landscape pattern as criteria for selection of tree roosts. In 1999 and 2000, we radiotracked 23 eastern red bats (Lasiurus borealis) to 64 day roosts. Using univariate and multivariate comparisons, we tested roost tree variables with random tree data at 3 circular spatial scales: roost tree, plot, and landscape. We found 15 variables that were entered in a stepwise discriminant analysis to best differentiate between the roost and random samples; 11 (73.3%) were landscape variables measured with a geographic information system. On average (x̄ ± SE), red bats roosted in deciduous trees (42.0 ± 2.1 cm dbh) that were located in plots with more (3.1 ± 0.1 m²) basal area, higher (84.0 ± 1.3) percentage of canopy closure, and lower (27.2 ± 2.2) percentage of groundcover than random plots. At the landscape scale (by percent magnitude), red bat buffers (1,000-m-radius circle) had significantly less development (81.6%), less feeding operations (70.4%), more deciduous (52.9%) and pine forest (63.8%), and fewer local roads (5.4%) but more trails (94.1%), open water (61.4%), wetland areas (80.4%), and stream areas (63.1%) than random buffers. Red bat roost trees were significantly closer (χ² = 22.0088, df = 1, P < 0.001) to trails (106.2 ± 13.3 m) than to streams (279.4 ± 28.5 m). Our results suggest that red bats in our study area select roosts in mature riparian forests near trails, open water, and wetlands. The high percentage of landscape values in the discriminant analysis lends support to using landscape metrics as an investigative technique of resource selection. We recommend that managers consider landscape factors when protecting red bat day-roost habitat.     

Laboratory evidence showing the separate species status of Schistocerca gregaria, americana and cancellata (Acrididae, Crytacanthacridinae)

Abstract. Results are given of experimental crosses of Schistocerca species from the New World and the Old World Desert Locust. It is concluded that S. cancellata (Serville), S. gregaria (Forskal) and S. americana (Drury) are separate species in their own right not subspecies of americana. The African Desert Locust should thus be called S. gregaria gregaria and its S. W. African race S. gregaria flaviventris (Burmeister). The name S. vicaria (Walker) is proposed for the Central American Locust. The relationship of S. paranensis to Sxancellata is discussed.     

A Study of the Absorption and Utilization of Phosphate by Young Barley Plants: III. THE RELATIONSHIP BETWEEN THE EXTERNAL CONCENTRATION AND THE ABSORPTION OF PHOSPHATE

The absorption of phosphate by young barley plants was studiedusing a series of solutions ranging in concentration from 00003to over 30 p.p.m. P. The duration of most of the experimentswas 24 hours. The relationship between the external concentrationand absorption was found to be sigmoid, the slope of the curvebeing maximal when the external concentration was in the rangeof 01 to 03 p.p.m. P. It was concluded that the reductionin the slope of the curve, when the external concentration wasreduced below 01 p.p.m. P was due to an increasing fractionof the phosphate which entered the plants being retained inmetabolic systems in the root, from which it was subsequentlyreleased and returned to the outer medium. These results indicatethat when the external concentration was lowered below 01 p.p.m.P the plants absorbed progressively decreasing fractions ofthe nutrient available to them. The significance of this fromthe viewpoint of the growth of plants under the condition ofphosphate shortage is discussed.     

Carminator, a new genus of Megalyridae (Hymenoptera) from the Oriental and Australian regions, with a commentary on the definition of the family

The taxonomic history of the family Megalyridae is reviewed. Carminator gen.n. from the Oriental and Australian regions is described and illustrated. Four new species are included in the genus: C.affinis, Cater, C.cavus and C.nooni. A key to the species is provided.
Twelve characters are evaluated for their phylogenetic significance, including those which historically have been regarded as important for the definition of the family. Carminator is provisionally assigned to the subfamily Dinapsinae, based on the reduction of Rs in the hindwing. The family Megalyridae is regarded as monophyletic based on their unique pattern of reduced hindwing venation and position of the 'pronotalrsquo; spiracle. The mesozoic Cleistogastrinae are excluded from Megalyridae. The cretaceous genus Maimetsha is reclassified as a dinapsine megalyrid.