Biosystematic studies in Allium L. section Cepa

VAN RAAMSDONK, L. W. D. & DE VRIES, T. 1992. Biosystematic studies in Allium L. section Cepa. Principal component analyses and hybrid analyses, according to Wells, using 31 morphological characteristics were used to study the biosystematic relationships between six Allium species of section Cepa and A. roylei of section Rhizirideum. Seventeen interspecific hybrid populations were included. Based on these analyses and on additional information from geography, chromosome banding pattern, DNA amount and seed epidermis texture, the species of Allium section Cepa can be divided into three groups: 1. A. galanthum and A. pskemense , 2. A. cepa, A. oschaninii and A. vavilovii and 3. A. futulosum and A, allaicum. Presumed evolution of both groups 2 and 3 from the basic group 1 is indicated by the development of new morphological characteristics, a change in genome structure and migration.     

Photothermal Responses of Flowering in Rice (Oryza sativa)

Durations from sowing to panicle emergence in 16 diverse genotypesof rice (Oryza sativa L.) were recorded in 13 different photothermalregimes, comprising constant and diurnally alternating temperaturesbetween 16 and 32 °C and photoperiods between 10.5 and 15.0h d^–1—all provided by controlled-environment growthcabinets. In 11.5 h days and at sub-optimal temperatures, relationsbetween the rate of progress towards panicle emergence and meantemperature were linear in all genotypes, and amongst thesethe base temperature at that photoperiod varied between 6.6and 11.9 °C. In most cases progress was most rapid at 24–26°C, i.e. the optimum temperature was much cooler than expectedfrom previously published values of times to panicle emergencein a less extensive range of photothermal regimes. Only in threecultivars was it warmer than 28 °C, and in these there weresufficient data to establish that relations between rates ofprogress to panicle emergence and photoperiod in the diurnallyalternating temperature regime of 28–20 °C are alsolinear. Also, the responses of these three cultivars provideno evidence of any interaction between the effects of photoperiodand temperature. We conclude, then, that the model in whichrate of development is a linear function of both temperatureand photoperiod with no interaction, which has been shown tobe common to many other species, also applies to rice. Differencesamong genotypes in relative sensitivity of rate of progresstowards panicle emergence to both temperature and to photoperiodwere considerable; japonica cultivars tended to be more sensitiveto temperature and less sensitive to photoperiod than indicacultivars. Four indica cultivars bred and selected at The InternationalRice Research Institute (IRRI) in the Philippines did not differ(P > 0.10) in their relations between rate of progress towardspanicle emergence and sub-optimal temperatures in a daylengthof 11.5 h, but the optimum temperature for cv. IR 36 was appreciablywarmer than that for the cvs IR 5, IR 8 and IR 42. Oryza sativa, rice, flowering, temperature, photoperiod, photothermal responses     

The impact of nitrogen deposition on carbon sequestration in European forests and forest soils

An estimate of net carbon (C) pool changes and long‐term C sequestration in trees and soils was made at more than 100 intensively monitored forest plots (level II plots) and scaled up to Europe based on data for more than 6000 forested plots in a systematic 16 km × 16 km grid (level I plots). C pool changes in trees at the level II plots were based on repeated forest growth surveys At the level I plots, an estimate of the mean annual C pool changes was derived from stand age and available site quality characteristics. C sequestration, being equal to the long‐term C pool changes accounting for CO₂ emissions because of harvest and forest fires, was assumed 33% of the overall C pool changes by growth. C sequestration in the soil were based on calculated nitrogen (N) retention (N deposition minus net N uptake minus N leaching) rates in soils, multiplied by the C/N ratio of the forest soils, using measured data only (level II plots) or a combination of measurements and model calculations (level I plots). Net C sequestration by forests in Europe (both trees and soil) was estimated at 0.117 Gton yr^?1, with the C sequestration in stem wood being approximately four times as high (0.094 Gton yr^?1) as the C sequestration in the soil (0.023 Gton yr^?1). The European average impact of an additional N input on the net C sequestration was estimated at approximately 25 kg C kg^?1 N for both tree wood and soil. The contribution of an average additional N deposition on European forests of 2.8 kg ha^?1 yr^?1 in the period 1960–2000 was estimated at 0.0118 Gton yr^?1, being equal to 10% of the net C sequestration in both trees and soil in that period (0.117 Gton yr^?1). The C sequestration in trees increased from Northern to Central Europe, whereas the C sequestration in soil was high in Central Europe and low in Northern and Southern Europe. The result of this study implies that the impact of forest management on tree growth is most important in explaining the C pool changes in European forests.     

Isolation of additional polymorphic tri‐ and tetranucleotide microsatellite loci for the giant Australian cuttlefish (Sepia apama)

We isolated 10 polymorphic microsatellite loci for the giant Australian cuttlefish, Sepia apama, from a genomic library enriched for (AAC)_n and (AAAG)_n repetitive elements. In the nine loci that reliably amplified, the number of alleles ranged from four to 12 per locus with observed heterozygosity ranging from 0.343 to 0.926. These and a previously developed set of six loci will be useful for analysis of genetic structure of populations and determining input to a massive seasonal breeding aggregation in northern Spencer Gulf, Australia.     

Rates of Respiration and of Increase in Structural Dry Matter in Young Wheat, Ryegrass and Maize Plants in Relation to Temperature, to Water Stress and to Their Sugar Content

A method to determine the rate of conversion of reserve materialsinto structural dry matter in living, whole plants is presented.It is based on a brief measurement of plant respiration. Therate of increase in structural dry matter and of decrease ofreserve materials is calculated by subtracting the maintenancerespiration component from the total respiration. The remainder,the growth respiration rate, is multiplied by a factor thatis derived from the biochemical composition of the structuraldry matter formed. This method is applied to determine the relations of the rateof conversion of reserve material into structural dry matterto temperature, water stress and the level of reserve carbohydratesin plants of three species. The weakest part of the method is in the determination of therate of maintenance respiration. Consequences of different assumptionsconcerning the rate of adjustment of this respiration componentto modified environmental conditions are discussed. Lolium perenne L, Triticum aestivum L, Zea mays L, ryegrass, wheat, maize, respiration, maintenance respiration, water stress, sugar content, structured dry matter     

Ant species distribution in a sandy coastal plain

Abstract.

• 1 Three species of ants, Lasius niger, Myrmica rubra and Myrmica scabrinodis, have been recorded in a 20-year-old coastal plain on the Dutch Wadden Zee island, Schiermonnikoog.
• 2 The habitats of these species appeared to be clearly segregated, both horizontally (different parts of the plain) and vertically (along dune slope gradients in the plain).
• 3 Lasius niger is distributed throughout the plain in sparsely vegetated sand-dunes and in mounds covered with turf of Festuca rubra ssp. litoralis, but always in areas that are only waterlogged or inundated in winter.
• 4 Myrmica rubra is limited to Festuca-turf, occurring in a distinct zone along the bases of small dunes and on isolated mounds.
• 5 Myrmica scabrinodis only occurs in mounds covered with Festuca-tutf and rarely in the small dunes.
• 6 Analysis of soil, vegetation, inundation and salinity of the ground-water demonstrated that Myrmica scabrinodis is dominant in areas with more silt and salt in the soil, characterized by a vegetation with more typical halophytes, whereas Myrmica rubra occurs most frequently in sandy habitats without much salt stress. The populations of both Myrmica species and Lasius niger do not seem to be affected by inundation during winter.
• 7 The distribution of the ant species is discussed in relation to data about ants in more stable habitats. In particular, attention is given to the absence, in this coastal plain, of Lasius flavus which is a dominant species in the sand-dunes and neighbouring parts of the salt-marsh on Schiermonnikoog.

     

Exotic No More: Anthropology on the Front Lines

Exotic No More: Anthropology on the Front Lines. Jeremy MacClancy, ed. Chicago: University of Chicago Press, 2002. 456 pp.