Symbiotic variability in Vicia faba. 1. Genetic variation in the Rhizobium leguminosarum population

Summary Twenty isolates taken at random from indigenous populations of Rhizobium leguminosarum sampled near Aberystwyth were each inoculated into plants of a standard Vicia faba variety grown aseptically under conditions free of combined nitrogen. Plants in association with the individual rhizobium isolates exhibited large differences in dry matter yield, nitrogen content, efficiency of nitrogen utilization and date of first flower. The implications of these differences to the productivity and reliability of varieties of field beans are discussed.     

Genetic interpretations of the effects of bulk breeding on four populations of beans (Phaseolus vulgaris L.)

Summary The effects of bulk breeding on yield and its components in two high-yeilding and two low-yielding bean populations when grown at crop densities are interpreted in terms of gene action and selection. There was considerable additive variation in the crosses, dominance effects were variable but tended to be negative. The results were compared with results obtained at low density by another worker with the same populations, and this showed that interpretations of gene action in hybrid vigour depend on the test environment used. The interpretations were also compared with plant breeding interpretations made on the same material (Hamblin, 1977), and it was found that a single pattern of response to natural selection, in plant breeding terms, may be explained by more than one genetic interpretation and, conversely, a single genetic interpretation may result in different patterns of response in plant breeding terms. The value of composite crosses in plant breeding are discussed and it is concluded that there is a greater chance of producing improved lines from a large number of simple crosses than from a smaller number of composite crosses.     

Effects of photoperiod and temperature on flowering in mungbean (Vigna radiata (L.) Wilczek)

Summary Forty strains of mungbeans, including all of the entries in the 1st and 2nd International Mungbean Nurseries (IMN), were grown in plant growth chambers in photoperiods of 12, 13, 14, 15, and 16 hours and mean temperatures of 18, 23, and 28°C. Results show that (1) mungbean strains differ in their flowering response to photoperiod and to mean temperature; (2) increasing the photoperiod of reducing the mean temperature delayed flowering, the amount of delay varied with the strain: (3) variations in mean temperature may alter the effect of the photoperiod on flowering in particular strains. Twenty-five strains which flowered in all photoperiod-temperature treatments could be divided into four groups, each group being successively later in flowering. The remaining 15 strains could be divided into four groups, according to their failure to flower within 105 days in specific photoperiod-temperature treatments. Flowering response in the growth chamber is useful in explaining flowering response in the 2nd IMN at three locations varying from 14°N to 49°N latitude.Contribution No 7516 from the Missouri Agricultural Experiment Station.     

Relation in the inheritance of resistance to Pseudoperonospora cubensis rost and Sphaerotheca fuliginea poll. in cucumber (Cucumis sativusl. L.)

Summary Among the genes for resistance against Sphaerotheca fuliginea, the gene s for resistance of the hypocotyl is linked to or identical with gene p for resistance to Pseudoperonospora cubensis. This gene s is present in the cultivars Ashley, Poinsett, Natsufushinari, Pixie, Taipei and in accessions PI 179676. PI 212233 and PI 234517.Although gene s initially brings about some resistance of the true leaf, it appears that when s is present. other genes are necessary for complete resistance to S. fuliginea.     

Skeletal muscle protein turnover in broiler and layer chicks

Dietary infusion of L-[U-14C]tyrosine was used to estimate the fractional protein synthesis rates (FSR) in broiler and layer chickens. Six 2-wk-old birds of each strain were placed in individual metabolism cages and given a purified diet in agar-gel containing 2 microCi L-[U-14C]tyrosine for 6 h. The birds were sacrificed and the pectoralis major (PM) and two combined leg (LM) muscles (gastrocnemius and peroneous longus) were removed for analysis. Subgroups of chickens were sacrificed 3 d before and 3 d after infusion to observe changes in muscle composition to calculate fractional protein accretion rates (FAR). Fractional protein breakdown rates (FBR) were calculated by difference (FBR = FSR-FAR). Protein, ribonucleic acid (RNA) and deoxyribonucleic acid (DNA) concentrations were determined to observe relationships between these cellular constituents and FSR. Fractional whole body growth rate and FSR in PM was greater (P less than .05) in broiler than layer birds. The FSR in LM of the layer was not different (P greater than .05) from that of broilers, and from the FSR of the PM in each bird-type. The calculated FBR in the layer PM was at least 17% higher than that of the other muscles. Ratios of FSR to FBR indicated that 16% of the protein synthesized in the layer PM was retained, compared with 45% in the broiler PM. The RNA activity of the layer PM was less (P less than .05) than that of the other muscles investigated. Deoxyribonucleic acid activity was lower (P less than .05) in the PM than LM of either bird-type.(ABSTRACT TRUNCATED AT 250 WORDS)     

The efficiency of nitrogen in cattle manures when applied to a double‐annual forage cropping system

The use of cattle manure (CM) for fertilization presents challenges for optimizing nitrogen (N) use. Our work aimed to assess N efficiencies, in a 6‐year experiment with three biennial rotations of four crops: oat–sorghum (first year) and ryegrass–maize (second year) in a rainfed humid Mediterranean area of Spain. Fertilization treatments included the following: control (no N), 250 kg mineral N ha^?1 year^?1 (250MN), three CM rates (supplying 170, 250 and 500 kg N ha^?1 year^?1) and four treatments where the two lowest CM rates were complemented with either 80 or 160 kg mineral N ha^?1 year^?1. Treatments were distributed randomly in each of three blocks. Maximum dry‐matter yield (~44–49 t ha^?1 rotation^?1) was achieved in the third rotation, and only the control and the 170CM yielded significantly less. Within the limitations of the EU Nitrate Directive, the N steady state supply of 170CM always requires a complement of mineral N (80 kg N ha^?1) to maximize N agronomic efficiency. The maximum N‐fertilizer replacement value (250CM vs. 250MN) was 0·67, without significant differences between the two treatments in other N‐related efficiency indexes, which indicates that plants took advantage of residual‐N effects. Nitrogen losses by leaching in the 250CM treatment were around 5–7% of the N applied. This reinforces the sustainability of manure recycling in long cropping seasons.     

PEDOGENIC GRADIENTS OF THE POLAR REGIONS

Soils of the polar regions are divided into three zones—Arctic Brown, Polar Desert, and Cold Desert. The Arctic Brown soil coincides approximately with the arctic tundra belt, the Polar Desert zone is penecontiguous with the high arctic, and the Cold Desert zone is represented by the ice-free sectors of Antarctica. The zones are broad and diffuse. Well-drained soils of the southern sectors of the Arctic Brown soil zone have embryonic podzolic affinities whereas soils of the northern portions of this same zone exhibit a low temperature calcification process akin to a cold steppe condition. Vascular plants form a continuous mat in the Arctic Brown soil zone but within the Polar Desert soil zone they are patchy or at times completely lacking. In the Polar Desert soils algae and diatoms appear to be the main contributors of soil organic matter. The Cold Desert soils of Antarctica are virtually void of organic matter. The above three soil zones, in effect, are sectors of a pedogenic gradient. Progressing from the northern fringes of the forested land, to colder climates, precipitation decreases, organic matter content of the soil decreases, and soil pH values tend to increase. In the Polar Desert soils, alkaline reactions are common whereas the Cold Desert soils of Antarctica are usually saline. Polar Desert soils and Cold Desert soils have many morphologic affinities. Tundra and Bog soils dominate areally in the main tundra belt but are confined to the local swales and depressions in the high arctic. Both Tundra and Bog soils tend to have higher pH values as one progresses to colder, drier climates. Neither Tundra nor Bog soils have, as yet, been recorded in Antarctica.     

THE MEASUREMENT AND MECHANISM OF ION DIFFUSION IN SOILS

Integral diffusion coefficients for K in two contrasting soils, containing different levels of exchangeable K, are calculated from measurements of diffusive flux to a hydrogen resin paper. The diffusion coefficients are larger, the higher the exchangeable K level or moisture content. Diffusive flux of K in these soils can be accounted for entirely by diffusion through the soil solution in the pores. Impedance factors calculated compare satisfactorily with values for similar soils reported by other workers. The concentration dependence of the diffusion coefficient is shown to be causally related to the nature of the sorption isotherm. A method for estimating the differential diffusion coefficient at any concentration is described. It can also be calculated from the slope of the sorption isotherm at the chosen concentration, if the value of the impedance factor at the relevant moisture content is known and if diffusion other than through solution only is negligible.     

Peru coastal currents during el nino: 1976 and 1982

Year-long measurements of subsurface current and temperature on Peru's continental shelf included the onset of El Ni?o in 1976 and 1982. The Peru Coastal Undercurrent more than doubled in speed and advected anomalously warm water poleward. El Ni?o began in different seasons in 1976 and 1982, but the current and temperature responses were very similar. Acceleration of poleward flow at 10 degrees S occurred several days after sea level rose at the Galápagos Islands in October 1982, suggesting the onset of El Ni?o propagated as a Kelvin wave.     

Haematological evaluation of ethanolic extract of Allium ascalonicum in male albino rats

The haematological effect of ethanolic extract of Allium ascalonicum was evaluated in male albino rats during a 21 day administration at the doses of 50, 100 and 200 mg/kg b.w, orally. Parameters evaluated include the serum lipids, red and white cell indices. The results showed that the extract administered decreased most of the parameters relating to red cell and increased most of those parameters relating to white cells. It also decreased the total cholesterol (TCH), high density lipoprotein cholesterol (HDL) and low density lipoprotein cholesterol (LDL) with no significant effect on the triglyceride levels.