ALBERT

Description: The effect of medium dissolved-oxygen tension on the molar growth yield, respiration and cytochrome content of Beneckea natriegens in chemostat culture (D 0·37 hr-1) was examined. The molar growth yield (Y), the specific rate of oxygen (qo2) and glucose consumption, and the specific rate of carbon dioxide evolution were independent of the dissolved-oxygen tension above a critical value (〈 2 mmHg). However, the potential respiration rate increased with reduction in the dissolved-oxygen tension at values of the dissolved-oxygen tension well above the critical value. Changes in the cytochrome content occurred at dissolved-oxygen tensions well above the critical value. An increase in cytochrome c relative to cytochrome b was observed as the dissolved-oxygen tension was decreased. Reduction of the dissolved-oxygen tension to less than 1 mmHg caused a switch to fermentative metabolism shown by the apparent rise in Y o2 and decrease in the molar growth yield from glucose. At this point the potential respiration rate (q o2) increased to its highest value, while the cytochrome pattern reverted to that observed at dissolved-oxygen tensions above 96 mmHg. There appeared to be no correlation between cytochrome content, potential q o2, in situ q o2, and cyanide sensitivity of the organism at various dissolved-oxygen tensions.

Description: The ommastrephid squids are large active animals occurring in most of the world's oceans. Luminous organs or bioluminescence have been observed only in members of the subfamily Sthenoteuthinae, containing the genera Ornithoteuthis, Symplectoteuthis (= Eucleoteuthis), Hyaloteuthis, Ommastrephes and Dosidicus. The light organs of Ommastrephes pteropus are small sub-spherical bodies randomly distributed over the ventral surface of the mantle, head, arms and tentacles (Roper, 1963) and are aggregated dorsally to form a large luminous patch (Clarke, 1965). Relatively little is known about the organs, capabilities and biochemistry of luminescence in cephalopods (Harvey, 1952; Herring, in Press), and the size of the light organ and availability of O. pteropus provide an unusual opportunity for such studies. Although among the molluscs the luminescent systems of the gastropod Latia and the bivalve Pholas have been partially characterized (Shimomura & Johnson, 1968; Henry, Isambert & Michelson, 1970, 1973) the only cephalopod system which has been investigated to date is that of the enoploteuthid Watasenia scintillans (Goto et al., 1974; Inoue et al., 1975). This investigation examines the anatomy and biochemistry of the dorsal light organ of O. pteropus, which differs markedly in these respects from the brachial organs of Watasenia.

Description: Squids (teuthoids) fall into two distinct groups according to their density in sea water. Squids of one group are considerably denser than sea water and must swim to stop sinking; squids in the other group are nearly neutrally buoyant. Analyses show that in almost all the neutrally buoyant squids large amounts of ammonium are present. This ammonium is not uniformly distributed throughout the body but is mostly confined to special tissues where its concentration can approach half molar. The locations of such tissues differ according to the species and developmental stage of the squid. It is clear that the ammonium-rich solution are almost isosmotic with sea water but of lower density and they are present in sufficient volume to provide the main buoyancy mechanism of these squids. A variety of evidence is given which suggests that squids in no less than 12 of the 26 families achieve near-neutral buoyancy in this way and that 14 families contain squids appreciably denser than sea water [at least one family contains both types of squid]. Some of the ammonium-rich squids are extremely abundant in the oceans.

Description: Terms, dimensions and ratios for statolith description are defined. The form of the calcareousstatoliths in the Teuthoidea, Sepiodea and Octopoda is described by reference to Loligo forbesi, Sepia officinalis and Eledone cirrosa. While statoliths change in form and size during the growth of a cephalopod, the adult form is often characteristic for a species, despite some variation. Description of statoliths is important in studies of the fossil remains of cephalopods lacking calcareous shells, and will probably become important in the taxonomy of living species, in food analysis of cephalopod predators and in the study of deep sea deposits.

Description: Little work on vertical distribution of cephalopods was possible before the development, in the 1960s, of sophisticated opening-closing devices usable on midwater trawls such as the 10 ft Isaacs Kidd trawl (IKMT; Foxton, 1963; Aron et al. 1964) and the series of rectangular midwater trawls developed by the Institute of Oceanographic Sciences (previously the National Institute of Oceanography) (Clarke, 1969 a; Baker et al. 1973). These developments have resulted in three papers on vertical distribution of cephalopods in the North Atlantic (Clarke, 1969 ft; Gibbs & Roper, 1970; Clarke & Lu, 1974) and one for the Mediterranean (Roper, 1972). The present paper describes the vertical distribution of cephalopods caught at 40° N 20° W, 53° N 20° W and 60° N 20° W in the North Atlantic based upon day and night series of horizontal hauls between the surface and 2000 m using the RMT combination net (Baker et al. 1973).

Description: The present work is part of an analysis of catches made with rectangular midwater trawls (RMTs) in the North Atlantic at about 20°W and at 60°N, 53°N, 40°N (all in Lu & Clarke, 1975), 30°N (Clarke & Lu, 1974), 18°N and 11°N (Lu & Clarke, 1975). The collections were made for the ecological programme of the National Institute of Oceanography, Wormley, England (now part of the Institute of Oceanographic Sciences).

Description: This is one of a series of four papers dealing with vertical distribution of cephalopods in the North Eastern Atlantic at six stations near 20° W and at about 10° intervals from 60°N to 11° N (Clarke & Lu, 1974, 1975 a; Lu & Clarke, 1975). The present study is based upon a series of hauls made at discrete horizons between o and 2000 m with opening-closing nets during both daylight and darkness. The collections were made for the ecological programme of the National Institute of Oceanography, Wormley, Surrey, England (now part of the Institute of Oceanographic Sciences).

Description: The response of a heated circular cylinder to impulsive and sinusoidal variations in the velocity of flow past it has been simulated by numerical integration of the governing equations. The fluid has been treated as viscous and incompressible and as having constant properties. The range of Reynolds number investigated was 1 ≪ R ≪ 40. Since vortex shedding normally does not occur in this range, the flows were treated as symmetrical. The thermal and flow transients are presented for the following cases.: (i)impulsive starts from rest to final steady state Reynolds numbers 1, 5, 10, 26·67; (ii)impulsive increases in velocities of 50% magnitude from steady state Reynolds numbers 1, 10 and 26·67; (iii)sinusoidal variation in velocity with amplitude of 10% impressed on a mean flow at Reynolds number 10. Results are also given for the thermal transients associated with instantaneous changes in cylinder temperature at Reynolds numbers 1, 5 and 40. The results obtained for transient and steady state flow parameters are in agreement with those obtained numerically and experimentally by other workers and the results for steady state heat flux from the cylinder are in agreement with experimental values. The new results obtained for heat transfer in unsteady flows provides information which is relevant to the operation of hot-wire anemometers. © 1979, Cambridge University Press

Description: The motion of two immiscible fluids with arbitrary viscosities flowing through a capillary with an almost flat fluid-fluid interface is investigated in the limit of small capillary and Reynolds numbers. A complete description of the dynamics of the fluids is presented. It is shown that the motion of the fluid away from the moving contact line can be completely determined in terms of one material parameter, and how the capillary can be viewed as a device for measuring it. The dynamic behaviour of various contact angles, measured by others, is calculated. It is shown that they all depend on the radius of the capillary; hence, they do not represent properties of only the materials of the system. © 1979, Cambridge University Press

Description: Natural convection flows induced by localized heating of the base of a thermally stratified enclosure are examined. The enclosure is a vertical circular cylinder with height equal to radius. The wall temperature increases linearly with height, and a small heat source is centrally located on the floor. Parameters of the problem are the ambient stratification rate (Γ−1), the Prandtl number (Pr), and a Grashof number (Gr) based on the temperature and the diameter of the heated spot. Over wide ranges of Γ and Gr, vertically layered convection cells are observed in the upper part of the enclosure in both laboratory experiments and numerical calculations. For the case of strong buoyancy and weak stratification, plume-like flows exist immediately above the heat source. Streak photographs are in qualitative accord with the numerical calculations, except for a range of Gr when an azimuthal rotation of the laboratory plume is observed. All flows are otherwise laminar. The theoretical results reveal a √Gr scaling at large Gr for the velocities and heat transfer rates, and a correlation of strongly stratified, viscous flows with the group Gr Pr Γ−1. © 1979, Cambridge University Press

Description: The turbulent velocity fluctuations at eight positions on sections of a plane wake and a boundary layer have been sampled simultaneously and recorded in digital form on magnetic tape for subsequent numerical analysis. Two configurations have been used (lines of equally-spaced sensors in planes normal to the flow, and arrays with three rows) with sensors responsive both to streamwise and cross-stream components of the fluctuations. To the extent that the Taylor approximation of “frozen” flow is valid, the recorded fluctuations may be interpreted as instantaneous values at grid points in the volume swept out by the array. The records have been examined, (a) to find evidence for flow patterns with marked periodicity in one direction, and (b) to select dimensions and orientations for simple eddy flow patterns whose random superposition would lead to correlation functions with a close resemblance to those calculated from the recorded data. In the wake, clear evidence was found for periodic flow patterns that resemble the eddies of a von Kármán street, but, although the spacing of eddy centres in each group was uniform, it varied considerably from one group to another, suggesting that groups are being observed in different stages of development. Two kinds of correlation were calculated from the records, (i) simple mean values of velocity products, and (ii) mean values of the products weighted by the total intensity or Reynolds stress in the effective volume swept by the array of sensors. For both kinds, the correlations are well described by simple inclined roller-type eddies, but the correspondence is greatly improved by weighting in favour of intensity or Reynolds stress. It appears that the eddies contributing most to intensity or Reynolds stress are less variable in form than all the eddies together, and that those contributing most to Reynolds stress are significantly different in shape and in orientation from those contributing most to turbulent energy. © 1979, Cambridge University Press

Description: A model equation is derived to study trapped nonlinear waves with a turning effect, occurring in disturbances induced on a two-dimensional steady flow. Only unimodal disturbances under the short wave assumption are considered, when the wave front of the induced disturbance is plane. In the neighbourhood of certain special points of sonic-type singularity, the disturbances are governed by a single first-order partial differential equation in two independent variables. The equation depends on the steady flow through three parameters, which are determined by the variations of velocity and depth, for example (in the case of long surface water waves), along and perpendicular to the wave front. These parameters help us to examine various relative effects. The presence of shocks in a continuously accelerating or decelerating flow has been studied in detail. © 1979, Cambridge University Press

Description: For a particle with two or three perpendicular planes of symmetry rotating at low Reynolds number in a Couette flow field, there are three orbits in which the motion is simply periodic. The three scalars Bi involved in Bretherton's shape tensor are found experimentally from periods of rotation in these orbits. Experiments on right parallelepipeds, ranging from thin platelets through cubes to rectangular section rods, are described. Each of the Bi is found to depend on the aspect ratio of one of the particle cross-sections, with only slight influence from its third dimension. Results are expressed in terms of a relationship between this aspect ratio and that of an equivalent ellipse, incorporating a weak function of the third particle dimension. The equations of motion governing a general doubly periodic motion, and incorporating experimental Bi values, are integrated numerically and compared satisfactorily with experimental observations. © 1979, Cambridge University Press

Description: The flow of closely fitting neutrally buoyant elastic spheres through a circular cylindrical tube is considered under the assumptions that the Reynolds” equation is valid in the fluid and equations of linear elasticity hold in the solid. Computations are carried out for several values of Poisson's ratio. The results are compared with the results of previous models on elastic compressible particles. © 1979, Cambridge University Press

Description: A submerged sphere is considered to be absorbing power from an incident wave through an integrated mooring and power take-off system. It is shown that the power absorbed (as characterized by the absorption length) depends on the hydrodynamic properties of the sphere; in particular on the added-mass and damping coefficients. These coefficients are determined and the results used to study the power absorption properties of the sphere. Curves are given showing the variation of the absorption length with wavenumber, for differing depths of submergence. © 1979, Cambridge University Press

Description: Numerical solutions of the inviscid equations that describe standing waves of finite amplitude on deep water are reported. The calculations suggest that standing waves exist of steepness, height and energy greater than the limiting wave of Penney & Price (1952). The computed profiles are found to be consistent with Taylor's (1953) experimental observations. © 1979, Cambridge University Press

Description: A plane horizontal layer of a fluid with depth d is considered into which heat is introduced. Within the Boussinesq approximation an exact expression is obtained for the efficiency of convection γ in transforming the rate of heat supplied into the generation of kinetic energy. It agrees with results of numerical and laboratory experiments whose data can be used to calculate this value. In laboratory experiments γ is usually of order 10−8 to 10−6. Using this quantity estimates are obtained for the r.m.s. velocity of convective motions [formula ommited] and their time scale [formula ommited] for a regime where viscosity is important. These estimates agree with the results of a number of previous numerical experiments over a wide range of Rayleigh, R, and Prandtl numbers. Dimensionless convection equations normalized by these scales show the existence of thermal boundary layers and of almost isothermal regions within the bulk of the fluid. From this, the main regimes of heat transfer follow immediately: the Nusselt number N ∼ (R − Rcr)¼ for moderate R and [formula ommited] for sufficiently large R. A number of simple experiments have been carried out to measure [formula ommited] and τ for convection in water. Their results confirm the theoretical dependences of [formula ommited] and τ on external parameters and show that a smooth transition region exists from the viscous regime of convection to the more fully-developed turbulent one. The latter regime is considered by a scaling analysis. The results are compared with the author's measurements and other experimental data. Similarly density convection is considered which arises by the separation of a medium into light and heavy fractions. Differences and analogies with the thermal convection are established. Elementary experiments confirm qualitatively the predicted dependences for [formula ommited] and τ. Applications of the results obtained are briefly discussed for studies of heat and mass transfer in the ocean and of convection in the Earth's mantle. In the last section some general properties are considered for various forced flows, convection, turbulence and some types of atmospheric circulation, that allow one to formulate a “rule” of the fastest response, which asserts that the kinetic energy of a fluid system is of order of the supplied power times the fastest relaxation time which the system possesses. © 1979, Cambridge University Press

Description: A model for the kinematics of a turbulent flow close to a solid boundary is explored. The field is assumed to be homogeneous in the direction of mean flow. The equations of motion are solved numerically for a flow which is periodic in time and in a direction transverse to the direction of mean flow. The period is taken to be the time interval between “bursts” and the wavelength, the spacing of the streaky structure close to the wall observed by a number of investigators. Good agreement is obtained between the calculated flow field and experimental results, especially for y+ 〈 15. This agreement suggests that the flow oriented eddies in the viscous wall region can be represented by a model which views the flow in this region to be coherent and to be associated with spanwise flow deviations in a well-mixed outer region. The model allows for the periodic movement of low momentum fluid from the wall, which, because of the assumption of a well mixed outer region, gives rise to a shear layer. This seems to correspond to the observed “bursting” phenomenon. The calculations confirm the suggestion by Fortuna and Hanratty (Fortuna 1970; Hanratty, Chorn & Hatziavramidis 1977) that the secondary flow in the viscous wall region generated by these spanwise flow deviations gives rise to the development of large velocity fluctuations in the direction of mean flow and accounts for the experimentally observed maximum in the velocity fluctuations close to the wall. Also, the comparison of calculations with measurements of the average velocity and with an experimental quadrant analysis of the Reynolds stress suggests that the secondary flow is making a major contribution to the Reynolds stress. © 1979, Cambridge University Press

Description: The linear perturbations of the flow of a non-diffusive fluid are considered. The classification of the normal modes of parallel flow of an inviscid stratified fluid presented by Banks, Drazin & Zaturska (1976) is here extended to encompass modes which propagate at infinity. When the basic flow is unbounded and the buoyancy frequency is non-zero at infinity the five classes presented earlier are augmented by three further classes: for a given flow and wavenumber they are (a) a continuous class of non-singular stable modes which are modifications of internal gravity waves by shear; (b) a continuous class of stable modes which are singular at each critical layer but otherwise similar to those of class (a); and (c) a finite number of marginally stable singular modes with over-reflexion. This classification is illustrated by many new results. Some asymptotic properties of the stable and unstable modes are found for large values of the Richardson number and for long waves. Two prototype problems, in which the basic flows are a piecewise-linear shear layer and a triangular jet, are solved analytically. The modified internal gravity waves for a Bickley jet with uniform buoyancy frequency are treated to illustrate the complementary nature of the propagating and evanescent modes. This treatment is both analytical and numerical. The general ideas are further illustrated by a numerical study of the stability characteristics of a hyperbolic-tangent shear layer. Finally the modes for a basic flow of boundary-layer type are found in exact terms of a hypergeometric function. © 1979, Cambridge University Press

Description: The high-Reynolds-number (K) flow through a symmetric channel, with walls whose shape is time dependent, is studied. The distortion of the walls is of non-dimensional height [formula ommited]) and length O(1), this particular size of perturbation being chosen such that (for the first regime of unsteadiness studied) the effects of the unsteadiness, viscous diffusion and advection all interact nonlinearly in the region of the fluid near the walls. For this first regime of unsteadiness the problem is solved numerically. This leads on to analytic descriptions for progressively faster time variations of wall shape, and in fact the entire range of unsteadiness is covered for this particular size of distortion. © 1979, Cambridge University Press

Description: A new economical finite-difference method is described for the calculation of three-dimensional heated surface jets discharging into stagnant water. The equations solved are for continuity, lateral and longitudinal momentum, and thermal energy. The turbulent shear stresses and heat fluxes in these equations are determined with a turbulence model involving simplified forms of the transport equations for these stresses and fluxes and the solution of differential transport equations for the turbulent kinetic energy κ and the rate of its dissipation ε. The experimentally observed entrainment reduction due to buoyancy is reproduced by this model. The predictions are compared in detail with the recent measurements of Pande & Rajaratnam, which are judged to be superior to those of other investigators. The agreement is generally satisfactory. © 1979, Cambridge University Press

Description: The well-known class of self-similar solutions for an ideal polytropic gas sphere of radius R(t) expanding into a vacuum with velocity [formula ommited] is shown to be convectively unstable. The physical mechanism results from the buoyancy force experienced by anisentropic distributions in the inertial (effective gravitational) field. An equation for the perturbed displacement ξ(r, t), derived from the linearized fluid equations in Lagrangian co-ordinates, is solved by separation of variables. Because the basic state is non-steady, the perturbations do not grow exponentially, but can be expressed in terms of hypergeometric functions. For initial density profiles [formula ommited] modes with angular dependence Ylm(θ, φ) are unstable provided l 〉 0 and κ 〈 1/(γ − 1), where γ is the ratio of specific heats. For large l, the characteristic growth time of the perturbations varies as l−½ and the amplification increases exponentially as a function of l. The radial eigenfunctions are proportional to rl, and the compressibility and vorticity are both non-zero. © 1979, Cambridge University Press

Description: When heat is applied at the bottom of a stable salinity gradient a series of layers with uniform temperature and salinity is formed. The evolution of this system is investigated in the laboratory and a numerical model of the process is developed. New layers are formed sequentially at the top of a growing convection region while lower down adjacent layers merge. For given fluid properties the convection depends upon one parameter Q, which is proportional to the (suitably non-dimensionalized) ratio of the salinity gradient to the heat flux. We find that the depth of the top of the convecting region and the number of layers present increase like the square root of time over the range of Q examined. This permits the definition of an effective conductivity, KT, for the total series of layers which is directly proportional to κT, the molecular thermal diffusivity, and inversely proportional to Q. The vertical growth of the layers is thus retarded by increasing Q. The average thickness of the layers decreases with increasing salinity gradient and appears to be independent of the applied heat flux. © 1979, Cambridge University Press

Description: The adiabatic approximation for a solitary wave in a channel of gradually varying breadth b and uniform depth is tested by experiment and by numerical solution of the generalized Korteweg-de Vries (KdV) equation. The results for a linearly diverging channel show good agreement with the prediction α (dimensionless wave amplitude)[formula ommited]. The experiments and numerical solutions for the linearly converging channel show that the wave growth is well approximated by α ∞ b−½. The discrepancy between the diverging and converging channels is shown to be due to nonlinear effects associated with the choice of the spatial variable as the slow variable in the generalized KdV equation. The measured and computed profiles display the predicted “shelves” of elevation and depression in the converging and diverging channels, respectively. © 1979, Cambridge University Press

Description: Numerical solutions have been obtained for the problem of steady, incompressible, viscous flow between two infinite concentric cylinders, the cross-sections of the inner and outer cylinders being circular and square respectively. The square cylinder is fixed and the flow is driven by the rotation of the circular cylinder. Solutions are given for Reynolds number in the range 1–1400 and for several values of the parameter B, defined as the ratio of the side of the square to the diameter of the circle. © 1979, Cambridge University Press

Description: SUMMARYUnder experimentally controlled nutritional levels, using Hereford, Hereford x Dairy Shorthorn, Dairy Shorthorn and Friesian breed-types, 288 animals were studied for age of eruption of the four pairs of front permanent teeth. Standard deviations are similar to those of other reports on Bos taunts. Breed differences were negligible and there is no evidence of heterosis. Lower nutritional levels delayed and higher levels advanced eruption. This effect had a maximum difference of 72 days if the differential nutrition was applied in calfhood. Differential nutrition later produced a smaller effect. It is concluded that in practice, the age of teeth eruption cannot be used to determine accurately the previous nutritional status of individual animals.

Description: In an earlier paper (Little, McLean & Winter, 1977) we reported a technique for the measurement of the phosphorus content of the diet consumed bygrazing cattle, which recently has been used successfully to measure the dietary intake of phosphorus by sheep grazing Mitchell grass (Astrebla spp.) pastures in western Queensland (Beale & McMeniman, 1978). In this technique, phosphorus of salivary origin is distinguished from that of plant origin in samples extruded by oesophageally nstulated animals by prior labelling of salivary phosphorus with the isotope 32P following the intravenous infusion of Na2H32PO4. The difference in specific activity between saliva and extruded bolus is used as the basis of the calculation of the phosphorus content of consumed herbage. Oesophageally nstulated animals may graze experimental pastures for an hour or more while samples are collected from them. It is important to have an accurate measure of saliva speoific activity, representative of that secreted during the grazing period; therefore, application of the technique is facilitated if the rate of change in saliva specific activity during collection periods is slow and linear.

Description: SUMMARYA laboratory incubation study followed by a field experiment was made in a silty clay loam soil (pH 6·9) at Pantnagar, India, on the effectiveness of ordinary urea, coated urea (sulphur and shellac-coated), urea-isobutyraldehyde condensation product (isobutylidenediurea, IBDU) and urea blended with nitrification inhibitor AM (2- amino-4 chloro-6-methylpyrimidine) and neem (a non-edible oil seed obtained from Azadirachta indica) cake. Whereas untreated urea and IBDU hydrolysed rapidly leaving no trace of urea-N after 2 weeks, sulphur-coated urea mineralized quite slowly and retained urea-N for as long as 4 weeks after incubation. Urea blended with neem cake was intermediate. Of all the materials tested, sulphur-coated urea showed maximum nitrification inhibition. A combination of one third sulphur-coated urea at planting + two thirds ordinary urea 30 days later yielded 12·3% more maize grain than ordinary urea in the same proportion at the same times of application.

Description: SUMMARYField experiments at Sutton Bonington between 1970 and 1974 tested how crop yields were affected by hand weeding at different stages in the life of early- and latesown crops. Losses where weeds were never controlled ranged from 95% where tallgrowing Chenopodium album L. predominated to 50% when Stellaria media (L.) Vill. and Tripleurospermum maritimum L.) Koch ssp. inodorum Hyl ex. Vaarama (T. inodorum) were most involved.In five of the seven crops examined the latest date (X) at which weeding had to commence to prevent irreversible effects on growth and yield and the earliest date at which weeding could cease without yield loss (Y) coincided. For late March/early April sowings this occurred 6 weeks after crop emergence, while for late April/early May sowings in which events were more rapid the same stage was reached 4 weeks after emergence. For an early-sown crop in 1973, when rainfall was frequent and heavy and C. album prolific, X preceded Y with an interval of 4 weeks between the two dates (4–8 weeks after crop emergence, mid-May to mid-June). In complete contrast for a late-sown crop in 1974, when the weather was exceptionally dry and C. album virtually absent, Y preceded X and a single weeding at any time between 2 and 8 weeks after emergence would have prevented yield loss.Sugar beet had generally reached the late singling stage (4–6 true leaves) by the time weeding must have commenced. During the next 6 weeks, final yield was depressed by 120–150kg/ha (1·;5%) with each day that weeds were allowed to remain. However, leaf production continued throughout the season and the crop was capable of recovering from early checks caused by weed competition. It proved possible for crops whose weights were depressed by 25–30% when first weeded to recover completely by harvest.

Description: SUMMARYExperiments testing the effects on leafless peas of aldicarb, triazophos and a mixture of benomyl with zineb, were made on clay-with-flints soil at Rothamsted and on sandy loam at Woburn in 1977 and 1978.The crop was shown to be susceptible to a wide range of pests and pathogens including the pea and bean weevil Sitona lineatus, the migratory nematode genera Pratylenchus, Tylenchorhynchus and Tylenchus, the pea moth Cydia nigricana, the aphids Acyrihosiphon pisum and Macrosiphum euphorbiae, the bean leaf roll and pea enation mosaic viruses and the powdery mildew fungus Erysiphe polygoni.The mean yield of the four experiments when none of the treatments was applied was 3·6 t grain/ha, increased to 4·3 t/ha when all were applied. Aldicarb had the largest effect and increased mean yield at Rothamsted by 0·3 t/ha, attributed mainly to control of S. lineatus, and by 0·8 t/ha at Woburn attributed to control of S. lineatus and perhaps also to migratory nematodes, particularly Tylenchorhynchus. Triazophos and benomyl plus zineb did not individually increase yield but at Woburn when both aldicarb and triazophos were applied benomyl plus zineb increased mean yield by 0·7 t/ha.All crops lodged severely, irrespective of treatment but perhaps because of experimental conditions. We suggest that susceptibility to lodging under field-scale conditions requires further study.

Description: SUMMARYA series of laboratory silages were prepared and opened after 2, 20, 60 and 150 days. The silages were made without any additive and with formaldehyde, formic acid, hexanoic acid, benzoic acid or sulphuric acid. The cellulose, hemicellulose, acetyl, alkali-labile phenolic acids and core lignin were determined in all silages as well as the composition of the hemicelluloses. In all the silages, the core lignin remained unchanged while the cellulose content only decreased by up to 5%. Large losses of acetyl residues and alkali-labile phenolic acids were observed in all the silages and losses of 10–20% of the hemicelluloses were found. The losses of hemicellulose were not uniform. The arabinose side chains were preferentially cleaved relative to the xylose residues. It was shown that part of the loss of carbohydrate could have been caused by the acidic conditions in the silage as well as by microbial activity. The silages made using the acidic additives with the highest pKa values lost the greatest proportion of carbohydrate. The implications of these results on rumen activity are discussed.

Description: SUMMARYThe results of 84 experiments with six levels of nitrogen were used to investigateresponse curves relating the dry-matter yield of grass herbage to fertilizer nitrogen. Of the five curves tested, the inverse quadratic represented the relationship well, although no one curve fitted best on all experiments.

Description: SUMMARYA study of the birthcoat and its relation to kemp succession in the adult fleece of coarse-wool Awassi and Hamdani sheep was carried out, as an aid to early selection. Lambs were covered, at the age of 2 months up to 15 months, by fixing patches of canvas on six body positions.Both Awassi and Hamdani birthcoats had high halo hair grades. The animals played the dominant role in affecting different traits of the birthcoat which indicated the importance of genetic factors in further development of the birthcoat. The birthcoat of both types of lambs showed only coarse (plateau) and less coarse (saddle) fibre type arrays.Hamdani had more kemp as Gt and G2 (first and second generations respectively) than Awassi sheep. The shed Gx following the different fibre type arrays, showed some overlapping between plateau and saddle. The same arrays of the birthcoat behaved differently on the different positions, where generally the anterior positions had less kemp than those posteriorly. Percentages of shed fibres were 100, 17·14, 2·38 and 0·35 of halo hairs, super sickles, sickles and chalky curly tips respectively in Awassi. Corresponding figures were 100, 29·26, 5·87 and 7·73 in Hamdani. In Awassi, halo hairs, of the birthcoat, showed a relatively high correlation (P 〈 0·01) with G1 kemp on the hip and britch. Within saddle array, in Awassi, the correlation between halo hairs and Gx kemp showed the highest values (P 〈 0·01), whereas in Hamdani the correlation between super sickles in the birthcoat and G2 kemp showed medium values (P 〈 0·05).Selection of high halo hair grade lambs, in the birthcoat, that have saddle arrays, with high percentage of sickle fibres in Awassi and with low percentage of super sickles in Hamdani, would result in low percentages of kemp in the adult fleece. High halo hair grades would be necessary for early survival of lambs.

Description: SUMMARYSeed treatments and methods of sowing sugar beet were tested in the laboratory and in field trials in 1975, 1976 and 1977 on a range of soil types including a sand, several loams and a peat.‘Advancing’ the seed by controlled imbibition of water followed by drying before sowing, gave 2–3 % more emergence. Seedlings appeared 3–4 days earlier and were up to 50 % heavier at the four to six leaf stage, but by final harvest yields of sugar per unit area were similar from advanced and untreated seed. ‘Priming’ in osmotic solutions of salts or polyethylene glycol, to bring all seeds to the point of germination, before drying back and sowing gave inconsistent effects in the field with emergence percentage frequently being below that of the control. Steeping seed in water, aimed at removing germination inhibitors, improved germination and reduced the time to, and duration of, germination when tested in the laboratory but gave poorer results than the untreated control in the field. ‘Chitting’ the seed in the laboratory greatly improved emergence characteristics but treatment effects in the field were very variable. Chitted seeds were sown in carrier gels in the field to try to protect the radicles from damage but seedling establishment was no better from fluid drilling than from normal dry seed sown ‘raw’ or pelleted in clay, even when only chitted seeds were put into the fluid. Possible reasons for this are discussed.Fluid-drilled seeds consistently gave quicker emergence and larger seedlings. Even when these were 30–50 % heavier, differences had usually become negligible by the end of the average 230 days long growing season, so that sugar yields were not consistently affected by the treatments tested.

Description: Quantitative information concerning preejaculation sexual preparation of bulls was published some years ago by Collins, Bratton & Henderson (1951), who concluded that about 40% more motile sperm could be obtained by imposing one false mount before ejaculation. It had been suggested that one false mount in bulls is essentially as efficient as two such attempts in terms of sperm output (Branton, D'Arensbourg & Johnston, 1952). More recently Hafs, Knisely & Desjardins (1962) have shown that bulls given a planned 5 min sexual preparation yielded 30% more sperm than those given no preparation. Similarly 10 min preparation resulted in a 12% increase in sperm output when compared with a 5 min preparation. These authors also showed that zero, one, two or three false mounts significantly affected motile sperm output.

Description: SUMMARYThree field experiments at the University of Nottingham, in 1976, 1977 and 1978, examined whether a growth retardant chemical, ancymidol, could be used to restrict stem extension, delay the onset of lodging and thereby increase the seed yield of S. 24 perennial ryegrass. Applications of ancymidol increased seed yield by up to 60% by increasing number of seeds per unit area, although this was associated with a delay in the onset of lodging in 1977 and 1978 only. Application of ancymidol increased the percentage of the total above-ground crop dry matter harvested as seed, but it was not possible to relate this to the growth of the crop between anthesis and harvest.

Description: SUMMARYSamples of soya-bean meal, groundnut meal, sunflower meal and fish meal were incubated in nylon bags in the rumens of sheep receiving either whole barley or dried grass. For the vegetable sources of protein the rate of disappearance of protein was greater when they were incubated in the rumens of sheep receiving dried grass than in sheep receiving whole barley. The rate of disappearance of fish meal did not vary between sheep fed whole barley or dried grass.Rate of outflow of protein particles from the rumen was determined by rendering the protein supplement totally indigestible by a treatment with sodium dichromate. The rate of outflow was greatest with sheep receiving dried grass and increased with increasing feeding level.The mathematical expressions of degradation rate and outflow rate were combined to give the total amount of protein degraded in the rumen for the grass and barley diets at two levels of feeding.The amino acid composition of residues left in the nylon bags after 9 h of incubation were shown to be almost identical to the amino acid composition of the original protein supplement, indicating that the composition of the amino acid in the undegraded protein entering the abomasum essentially resembled that of the supplements.

Description: SUMMARYNineteen NP experiments were carried out with wheat and barley mostly in the Mesaoria plain of Cyprus over the period 1968–78. The fields were fallowed over the season preceding the experiments. Rainfall ranged from 68 to 405 mm. Kyperounda, a tall durum wheat, Pitic 62, a semi-dwarf aestivum wheat, and Athenais barley were the test varieties. No yield was obtained when rainfall was below 100 mm. Athenais barley consistently outyielded the wheat varieties, particularly Kyperounda, by up to 200% presumably because of earlier heading, which helpedthe crop to escape drought to a certain extent.Kyperounda wheat and Athenais barley mostly responded to 35 kg N/ha but Pitic 62 benefited from up to 70 kg N/ha. Fertilizer N not taken up in a year of extremely low rainfall remained in the soil and was available to the following crop.Response to P was more marked when rainfall was below 250 mm being linear over the rates tested (highest rate 26 kg P/ha). Athenais barley responded to P more than the other varieties. Bicarbonate-soluble soil P was between 1 and 10 mg/kg.Since rainfall is unpredictable it is recommended that 20–40 kg N/ha be applied atseeding together with 13–26 kg P/ha. A similar amount of N should be top dressed in late January. The higher amount refers to the semi-dwarf Pitic 62 wheat and could be increased further if the December-January rainfall, which normally constitutes 40% of the total, is high. These rates refer to crops grown after fallow. For continuous growing the rates would probably have to be increased.

Description: SUMMARYAn analysis has been made of the reproductive performance of Red Sokoto goat of Nigeria. Data are based on records of 140 kiddings from 96 does. Age at first kidding was 435 ± 18·9 days. The mean litter size at first kidding was 1·45. Prolificacy increased with parity, the kidding percentages from first to third parities being 141, 186 and 200 respectively. Doe weight was significantly correlated with litter size (r = – 0·27). Repeatabilities of litter size per doe kidding and of litter weight were negative. Heritability of litter size was 0·08 ± 0·02. Birth weights were low, the mean weight of kids during the 3 years ranging from 1·48 to 1·64 kg. Doe weight was related to litter weight in a manner such that litter weight as a proportion of doe weight tended to decline as doe weight increased. The ratio of litter weights of singles to twins at any given weight of the doe was 100:180. Kid mortality by 3 months of age was 30·8 %. Mortality among twins was only slightly higher than singles. However, mortality in kids born in multiple births (triplets and quadruplets) was much higher. Birth weights of surviving kids were significantly higher than of those that died.

Description: SUMMARYDuring summer the morning (08.00 h) to afternoon (15.00 h) increases in rectal temperature, respiratory rate and pulse rate of free grazing Marwari and Magra sheep (rams) of the desert areas of north-western India were compared with those of Corriedale rams, which are being imported into India to improve the productivity of local stock through cross-breeding. Basal (morning) values for all three measurements were similar in the three breeds. While the afternoon values in respect of all three characters were significantly higher than the morning values in all the breeds, the increases were greatest in the Corriedales.

Description: SUMMARYA Kenya Highland maize was planted at three altitudes, 1268, 1890 and 2250 m. Development rate, dry-matter accumulation and leaf area production were recorded during vegetative growth, together with grain formation and dry-matter accumulation in the primary cob. Rainfall, insolation, soil and air temperatures were continuously recorded at all sites. Maize developed faster at low warm altitudes, the rate being dependent on soil and air temperature. During vegetative growth, this relationship could be satisfactorily explained by an integrated temperature, but during the reproductive phase, some allowance had to be made for over optimal temperatures at low warm altitudes. Altitude had little effect on crop leaf area at any particular development stage, but leaf area production rates were closely related to leaf emergence rates. Before establishment of complete ground cover, large differences in dry-matter accumulation rates were observed which appeared related to rate of leaf area production. Once full ground cover was established, crop growth rates became much more similar. Potential number of grains per embryonic primary cob was greatest at low altitudes, but the final number of grains per cob at harvest was greatest at high altitudes. Rate of increase of grain weight was constant and very similar at all sites until growth stopped abruptly at 69, 83 and 96 days after tasselling at low, medium and high altitudes respectively. Rate of accumulation and partition of total dry matter in the primary cobs was similar at all sites, but owing to greater duration of development at high altitudes, dry matter per cob increased with altitude. Large yield differences were found at harvest, yield decreasing with decreasing altitude. Yield differences were mainly due to variations in number of grains per plant, although grain size also contributed. In this and other trials it was shown that the number of grains per plant at harvest was closely related to the mean thermal growth rate (expressed in units of g/plant/growing degree day) during the grain site initiation period.

Description: Great Britain relies heavily on imported food and Cantell (1977) has estimated that within urban areas there are over 100000 ha of dormant land (i.e. derelict and awaiting development) for which the most fundamentally valuable temporary use is growing food, since such land, Cantell claims, could yield 25 million tonnes of potatoes or 4 million tonnes of carrots annually. The national waiting list for allotments exceeds 100000 and, according to Thorpe (1969), vegetables are grown on nearly all (98·3%) urban allotments. Underlying the case for encouraging the agricultural or horticultural use of dormant land is the supposition that, once cleared of junk, urban soils differ little in potential quality from farmland. But this is not necessarily so: Purves & Mackenzie (1970) have reported that vegetables grown in Scottish urban soils were contaminated by trace metals as have Warren, Delavault & Fletcher (1971) in Canada, Beavington (1973) in Australia and Davies (1978) in England. Lead, is one of the commonest urban pollutants and many countries set limits on the concentration permitted in food. In Great Britain the present limit is 2 mg/kg (fresh weight) but it is planned to reduce this to 1 mg/kg.

Description: SUMMARYExperiments, conducted over 3 years, investigated the effect of all combinations of two storage periods at low temperature (0 or 2 °C) and two storage periods at 10 °C on the sprout growth, numbers of stems per tuber, foliage development and subsequent tuber yield of the two maincrop varieties Maris Piper and Désirée.Although the number of day-degrees accumulated during sprouting was the same for all treatment combinations, there were large effects of treatments on the number of sproutlets per tuber and the total sprout length per tuber. However, there was no effect on the number of stems per tuber, foliage development or saleable ware yield inany year.