Changes in dry weight and 14C contents of categories of shoots that did and did not survive to produce ears were examined in winter wheat grown in micro-plots in 1982–4. The weight of a group of tillers when dead was similar to their maximum dry weight when living. By anthesis dead shoots exceeded living ones in number but contributed less than 10% of total shoot dry weight.

14CO2 was supplied, near the time that number of shoots was maximal, to tillers in axils of first (T1) and third (T3) main stem leaves; T1 usually survived and T3 usually died. The percentage of 14C in the plant retained in T1 was 78–94%. That retained in T3 ranged from 9 to 81%. Little 14C moved from dying shoots into the rest of the plant in two experiments. In another, perhaps 70% of the 14C in living tillers was transferred as they died but this represented only a small proportion of total plant weight. 14C not retained in tillers to which it had been given was found in all parts of the plant, including about 7% in grain.

Two experiments were run over a 3-year period in the central rainlands of Sudan under two systems of production, rainfed and irrigated, to assess the effects of system of production, inoculation and nitrogen fertilizers on plant and nodule development and grain yield of soya beans. Nodulated plants could fix more than 80 kg N/ha under irrigation whereas under rainfed conditions nodulation was neither effective nor efficient. Soya bean was responsive to nitrogen fertilizers under both systems of production giving significant increments in grain yields. Non-nodulating plants with added nitrogen fertilizers produced more total dry matter than nodulating plants during the vegetative phase until flowering time. At 2 weeks after flowering total dry-matter production for both types was equal and from then on to maturity nodulating plants outyielded non-nodulating ones in total dry-matter production. In 1979 and 1980 yield of irrigated nodulating soya-bean grain was 0·53 and 1·54 t/ha higher than rainfed yields whereas the difference in grain yields of the non-nodulating soya beans was 0·21 t/ha and zero during the same two seasons, respectively. There was a contrasting inverse relation between the number of nodules and dry weights under the two systems of production. Fewer and heavier nodules were produced under irrigation whereas under rainfed conditions nodulation was profuse and nodules were light. On the evidence available 1–4 g/m length of the granular form of soil implant inoculant (Nitragin), i.e. 16·6·66.4 kg/ha, is to be recommended for irrigated soya-bean production in Sudan.

Ten yearling red deer stags (Cervus elaphus) and ten yearling Coopworth wether sheep were housed in individual pens and offered ryegrass-white clover silage, containing 9–10 mg Cu, 1·4–1·7 mg Mo and 2·4 g S/kg D.M., in amounts close to maintenance energy requirement. For six animals of each species the diet was enhanced with 4·8 mg Mo and 3 g S/kg D.M. Liver biopsy samples were obtained during weeks 1, 6 and 12. The animals were then re-randomized and five of each species offered the basal diet and the remainder the basal diet supplemented with 4 mg Cu/kg D.M. Liver biopsy samples were obtained after a further 4½ weeks. Plasma samples for estimation of total and trichloroacetic acid-soluble Cu were taken weekly.

The mean liver Cu concentration in sheep was 11-fold greater than in deer. Both diets induced liver Cu depletion, though there was a trend for a greater rate of depletion on the Mo- and S-enhanced silage. The rate of depletion (mg Cu/kg liver D.M./day) was 7-fold greater in sheep than in deer, although it was not possible to determine whether this reflected a species-, as opposed to a Cu status-induced effect. In both species highly significant linear relationships were observed between initial liver Cu concentration and rate of liver Cu depletion. This was interpreted to indicate that endogenous loss was directly proportional to liver Cu content in both species. Individual estimates for the minimum rate of endogenous loss of Cu (μg/kg W/day) ranged from 0·2 to 2·71, mean 1·43, and from 2·83 to 14·75, mean 8·35 in deer and sheep, respectively.

During repletion the rate of increase of liver Cu in supplemented groups tended to be greater in sheep than in deer and calculated minimum values for availability of Cu were 0·061 and 0·037, respectively.

Liver Cu concentrations of less than 20 mg/kg D.M. were maintained in deer for several weeks without apparent symptoms of deficiency.

Previous research has shown that sewage sludge can act as a source of nitrogen and phosphate fertilizer. Fen peat soils are organic soils derived from plant material and are known to differ from mineral soils in their plant-nutrient availability. The work reported in this paper compares the effects of liquid digested, liquid raw and dewatered digested sludge with inorganic nitrogen and phosphate fertilizers on a typical fenland rotation of winter wheat, sugar beet and potatoes.

It is concluded that sludge can replace inorganic nitrogen and phosphate fertilizer on fen soil, and it appears that applications of sludge containing large amounts of fresh organic matter can act as a soil conditioner and produce higher yields than can be obtained from the use of fertilizer alone.

The effect of oestradiol-17β on the response to fishmeal supplementation of grass silage was studied in young growing cattle. Voluntary intake and live-weight gain were recorded over 63 days with 36 British Friesian male castrates (initial live weight (LW) 119 kg) offered silage alone (C) or with 50 (FM1), 100 (FM2), or 150 (FM3) g fishmeal/kg silage dry matter. Twelve calves were allocated to each of treatments C and FM3 and six to treatments FM1 and FM2. Half of the calves on each treatment were ear-implanted with oestradiol-17β (Compudose 365) at the start of the experiment. The calves on treatments C and FM3 were slaughtered after 75 days and chemical analysis conducted on half of each carcass. The silage had an organic-matter digestibility in vivo of 0·794 and was well-fermented, with a pH of 3·7. Intake averaged 24·2±0·42 g D.M./kg LW over all the treatments and live-weight gain was 0·77 kg/day on the silage alone. There was a significant (P < 0·05) interaction between fishmeal and oestradiol-17β, such that response to the hormone was observed only in the presence of fishmeal at 100 or 150 g/kg silage D.M. A similar interaction was apparent between fishmeal at 150 g/kg silage D.M. and oestradiol-17β in the final weights of empty body and carcass. This level of fishmeal also increased protein gain from 96 to 147 g/day and this was further increased to 179 g/day in the implanted animals receiving fishmeal. However, the overall effect of oestradiol-17β on protein gain was not significant. Gross efficiency of energy utilization was significantly (P < 0·01) increased by fishmeal supplementation suggesting an improved balance of nutrients compared with the silage alone diet.

A method of assessing genotypic stability is proposed in the case where genotype yields are measured across environments but no concomitant environment data are available. The method is introduced in a practical context and two examples of its use with actual data are presented.

The method depends ultimately on the choice of a suitable measure of similarity between genotypes. Most of the stability information appears in a sequence of plots, where stable genotypes are immediately highlighted as consistently more remote points.

A field experiment is described in which three rates of pig and cow slurry were applied to a ryegrass sward over a period of 16 years. The experiment included control plots and plots receiving fertilizer supplying 200 kg N, 32 kg P and 160 kg K/ha per year.

The slurry nutrient concentrations were similar to published values. Pig slurry was more variable than cow slurry and both varied significantly from year to year. Slurry was applied at 50, 100 or 200 m3/ha per year, with each rate divided into three equal applications.

Even the highest slurry application rate did not depress herbage yield, which showed a typical response curve to the amount of soluble nitrogen applied. The ammoniumnitrogen content of slurry (61% on average) gave an adequate measure of its effect on herbage yield when it was applied three times per year in spring and summer.

Recovery of phosphorus in the herbage averaged 30% from pig slurry, 40% from cow slurry and 66% from-fertilizer. Pig slurry supplied more phosphorus than did cow slurry, and herbage phosphorus content was significantly correlated with the amount applied. Much of the slurry phosphorus may have been organically bound and not available to plants in the short term.

Recovery of potassium from pig slurry and fertilizer was nearly 90% and from cow slurry about 70%. Cow slurry supplied potassium in excess of crop requirements so that it accumulated in the soil under the largest dressing. Soil phosphorus reserves declined under the smallest dressing of cow slurry but were maintained at higher application rates. The pig slurry produced a marked accumulation of phosphorus under the largest dressing. The substantial accumulations of phosphorus and potassium from pig and cow slurry respectively gave marked penetration of the soil below 10 cm depth only at the highest application rate. The data suggest that at rates typical of farm practice significant losses of phosphorus and potassium from the rooting zone would be unlikely to occur.

The main invading plant species were Agrostis stolonifera L. and Poa spp. Small slurry dressings produced a similar botanical composition to that of plots given fertilizer. Increasing slurry application rates decreased the proportion of L. perenne and increased that of A. stolonifera but only under the largest dressing did L. perenne fall to a small proportion of the sward and A. stolonifera become very dominant. L. perenne made maximum contribution to herbage dry-matter yield early in the season while the proportion of A. stolonifera increased as the season progressed.

Under these conditions even extremely large slurry dressings did not depress herbage yield and may not necessarily have reduced herbage quality despite marked changes in sward botanical composition.

A field experiment on an alkali soil (ESP 94) studied the effect of gypsum applied at 0, 2·5, 5 and 10t/ha and zinc sulphate applied at 0, 10, 20, 30 and 40 kg/ha on the growth, yield and chemical composition of rice. The effects of gypsum and zinc applications were additive. Optimum response of rice was to 10 kg zinc sulphate/ha at the 5 and 10 t/ha gypsum levels. At low levels of gypsum, plant growth was poor owing to toxicity of Na and/or deficiency of Ca, and higher levels of zinc sulphate gave a yield response. Zinc-deficient plants had significantly lower Zn concentration but higher concentrations of Fe, Mn, Cu, Ca and Mg than the healthy plants. Application of gypsum decreased the concentration of Na, Fe and Zn in rice plants and increased the concentration of Ca, K, Mn and Cu. in plots not treated with gypsum, the Zn concentration of plants was higher but grain yield was lower than that of gypsum-treated plots. Application of zinc increased the DTPA-extractable Zn but gypsum decreased the soil sodicity and DTPA-extractable Zn in alkali soils.

In a 3-year plot experiment on a perennial ryegrass plus white clover sward the pH of the soil on the main plots was adjusted to, and maintained as nearly as possible at, target levels of 5·25, 6·00 and 6·75 by applying either sulphur or lime. Within the main plots the effects on herbage yield, clover content and crude-protein content of applying four fertilizers were compared at nitrogen rates of 225 and 450 kg/ha annually. The fertilizers were liquid manure (urine plus water), prilled urea, a urea solution and an ammonium-nitrate fertilizer. The applications of the urea and the ammonium-nitrate fertilizers were accompanied by dressings of a potassium fertilizer which supplied the same weights of potassium as in the liquid manure. On average the smallest yields of dry matter and crude protein were associated with the lowest soil pH with no significant interactions between pH and fertilizer treatment. The liquid manure gave slightly smaller total yields of mixed herbage dry matter than the other fertilizers, particularly at the low nitrogen rate. The herbage from the liquid manure treatment had a higher clover content and produced a greater total yield of clover dry matter. The effects of the liquid manure on the clover agree with those noted in previous experiments, but no evidence was found that these effects resulted from the liquid manure increasing the pH of the soil and improving the conditions for clover growth. Similarly, no proof was obtained that the clover effects were due to the nitrogen in the liquid manure being wholly in the ammonium form. However, the value of liquid manure as a fertilizer for grassland was demonstrated clearly.

Two Rhizobium strains and five lentil genotypes were most salt-tolerant under various salt stress conditions and strain LC 6 was the most sensitive. Salt-tolerant strains were more antibiotic-resistant and showed higher relative rates of oxidation of carbohydrates and tricarboxilic acid intermediates. The content and concentrations of root exudates of lentil genotypes were different and found to be attractants for the Rhizobium strains. Under salt stress, significant interactions between salt-tolerant strains and genotypes resulted in different responses of nodulation and host plant growth measurements.

F2, monosomic analysis involving crosses between the monosomic series of a resistant wheat variety, Chinese Spring, and a susceptible variety, Sicco, has located a major gene locus, designated Dfql, on chromosome 2B of wheat which determines the differential response of these varieties to treatment with the wild oat herbicide, difenzoquat. The allele from Chinese Spring conferring resistance is dominant and studies of the responses of Chinese Spring single chromosome substitution lines and nullisomic–tetrasomic lines for chromosome 2B indicate that this allele actively promotes resistance to the herbicide. It is suggested that this gene may prevent inhibition of DNA synthesis in the apical meristem, which is the site of action of the herbicide (Pallett & Caseley, 1980).

Other chromosomes were also implicated as carrying ‘modifier genes’ which affect the ratio of resistant: susceptible plants in F2 monosomic families, namely 1D, 2D, 3A, 3B, 5B and 5D. These chromosomes may affect the retention and translocation of the herbicide to the target site and hence the threshold of response.

The simple inheritance of difenzoquat resistance indicates that it should be easy by conventional breeding techniques to transfer the resistance into susceptible varieties.

Three experiments, involving a total of 294 Israeli Holstein cows, were carried out to study aspects of the grouping of cows in relation to timing of changes and the type of complete diet given. In Expt 1, 40 cows were changed from a high energy diet to a medium energy diet either at 60 or at 180 days post calving. The results indicated a larger reduction in milk and FCM yield following the later than the earlier change of diet.

Experiment 2 involved 64 cows subjected to two treatments, one involving a ‘uniform’ diet (25:75 forage to concentrate D.M. ratio) and the other a ‘step’ treatment where the same diet as in treatment 1 was given for approximately 74 days and then changed to a diet of 35:65 forage to concentrate ratio. The results showed that it is not necessary to adopt different feeding systems according to the potential yield of the cow and that cows could be given rather lower energy diets within the range offered without loss of efficiency.

In Expt 3, involving 190 cows, the cows were divided into one of two feeding treatments, ‘uniform’ and ‘step’ similar to Expt 2 and the effect of potential yield and parity was considered. The results emphasized the importance of potential yield rather than feeding system in relation to yield. The results showed a shorter period from calving to conception for the ‘uniform’ treatment.

A strategy for efficient cow feeding is outlined.

During 5 h of acute heat exposure (41 °C), there were increases in the heart rate from 43±2 (S.E.) to 51 ± 1 beats/min, respiratory rate from 26±4 to 86± 16 breaths/min and rectal temperature from 38·5 ± 0·1 °C to 39·7 ± 0·2 °C. The flow rate of liquid from the rumen and body water turnover significantly increased while biological half life of chromium-51 ethylenediaminetetra-acetate in the rumen and tritiated water decreased from 12·9 ± 2·5 and 87·7 ± 6·8 h to 9·3 ± 2·0 and 49·2 ± 5·7 h respectively. An increase in blood volume during acute heat stress occurred with an increase of both plasma and cell volume. An elevation of plasma water coincided with an increase in plasma protein and glucose. There is evidence that the increase in plasma water during heat exposure came from extravascular tissue space and/or from the digestive tract.

The development and proportions of muscle, fat and bone were studied in 341 entire male and female Iron Age (European Wild Pig × Tamworth), Pietrain and Large White pigs ranging in live weight from 12 to 370 kg. The number of pigs was: Large White, 138 entire males and 112 females; Pietrain, 41 entire males and 31 females; Iron Age, eight entire males and 11 females. The breeds and sexes were compared in terms of the allometric growth coefficients of tissues (b) and of tissue weights at constant side weight and constant weight of total side bone.

At the geometric mean for side weight (26·5 kg), Pietrain carcasses had the most muscle (16 kg), followed by Large White (15kg) and Iron Age (11 kg), but the least fat (6 kg). Large White and Iron Age carcasses had 7 and 12 kg of fat, respectively. Relative to side weight, the earliest maturing tissue, bone, was particularly slow growing in Iron Age pigs (b = 0·627) and relatively fast growing in Large Whites (b = 0·801). The opposite was true for fat, the latest maturing tissue, and consequently Iron Age (b = 1·345) and Large White (b = 1·164) pigs were identified as early and late maturing, respectively. Pietrains had a higher growth coefficient for fat relative to side weight (b = 1·249) and lower growth coefficient for bone (b = 0·713) than Large Whites. The difference in percentage fat between Pietrains and Large Whites decreased slightly between 65 and 120 kg live weight. In terms of tissue growth patterns, Pietrains therefore demonstrated early maturing characteristics compared with Large Whites, and it is possible that a low voluntary feed intake under ad libitum feeding conditions prevents them from expressing these characteristics in terms of percentage of fat in the side. Pietrains had a particularly high muscle:bone ratio (6·2 at the mean side weight) compared with Large White (5·2) and Iron Age pigs (5·3).

The difference in carcass composition between entire males and females was breeddependent. Entire male carcasses were slightly leaner overall and had a lower muscle: bone ratio than those of females, but tissue allometric growth patterns were similar in the two sexes.

Grain and straw yields of a range of spring barley cultivars were assessed in field experiments conducted from 1981 to 1983 in Northern Ireland. Mean straw yields varied between 2·75 t/ha in Inga and 1·94 t/ha in Golden Promise over the 3-year period. Both grain and straw yields varied from year to year, with straw production being more consistent for individual cultivars than grain yield. High grain yields were not associated with high straw yields, straw to grain ratios varying between 0·72 in Midas and 0·51 in Corgi. Neither grain yield nor straw length were good predictors of straw yield of cultivars. The role for and assessment of straw yield in cultivar evaluation is discussed.

The reliability of the soil series as a basis for crop yield prediction was examined by comparing the influence of soil and management (inter-farmer differences) on the variance of barley grain yield. Yields of barley were measured from farmers' fields for 2 years and in undisturbed soil cores for 5 years. Fields on different soil series within farms and on the same soil series across farms were used. Linear stepwise regressions of yield on a number of soil properties were also examined to assess the relative influence of soil and management on the properties that were significant to yield.

The results show that generally, soil classification has a strong influence on yield variance, but there is clear evidence that the influence of management, specifically the cumulative effect of P and K fertilizer applications, is considerable. Thus in an undisturbed core, for the first 3 years when N, P, K and Mg were applied, the influence of soil was stronger than that of management, but this was reversed in the 4th year when P and K were not applied. Similarly in the field, the influence of soil was stronger in the 1st year, but this was reversed in the 2nd year, although on different field-farm combinations. In all cases, the influence of neither soil nor management was significantly stronger than the other.

The results of the regression studies also confirmed those of yield variance in that in general, neither soil nor management has exclusive control of the yield variance. The soil was significantly stronger than management in the control of only coarse sand content at 0–15 cm out of the four soil properties (including Mg and pH (0–15 cm) and K (15–30 cm)) which were significant to yield in the cores. On the other hand, management was significantly stronger than soil in the control of only available P at O–15 cm out of the three soil properties (including Cu and Mg both at 0–15 cm) that were significant to field yield.

It is concluded that for soil classification to be a reliable basis for yield prediction and/or agrotechnology transfer, the effect of management must be emphasized.

Water-use efficiency and forage yield of irrigated oats depend to a large extent on water application during initial growth. Root distribution, growth and fodder yield of oats as influenced by time and amount of first irrigation were studied in the field for 2 years. Root-weight density of each layer, profile-root-weight density and yields decreased progressively when the first irrigation was delayed. Application of a small amount of irrigation (20 mm) at day 25 proved to be better than applications of 50 or 70 mm at later stages.

This management-oriented study of range, livestock and Maasai ecology in the wildlife conservation and pastoralist land use Ngorongoro Conservation Area (NCA) quantifies spatial and temporal variation in range resources for three main study sites over a 2-year period. Livestock response is analysed in terms of biomass densities, habitat and pasture utilization, activity, herd size, composition and dynamics. Milk production is investigated together with the main ecological factors influencing yields. A household survey of the Maasai food system suggests that pastoral products now provide an annual average of 40% dietary energy intake, the remainder being supplied by grain. These findings form the basis of our analysis of the growing friction between the Conservation Authority and the pastoralists. Pastoralist livestock closely resemble wild ungulate utilization of NCA range resources. A combination of disease interactions and administrative restrictions allow wildlife to establish preferential access to critical grazing resources. Our results in the context of other work suggest that contrary to popular opinion pastoralist land use is an ecologically appropriate and efficient form of livestock management. There is no adverse impact on the conservation values of NCA. Despite average fertility and mortality levels pastoralist herds show progressive decline due to offtake for grain purchase. Imposed policies restrict grazing, ban cultivation and maintain poor conditions for livestock trade and grain supply. Possible interventions and their potential impacts are considered and management compromises which could benefit both pastoralists and wildlife are proposed.

Six parental cultivars (Bragg, Bragg-black seed, Kalitur, Ankur, WT-125 and Glycine formosana), 15 F1's, eight F2's and eight F3's (Bragg × WT-125, Bragg × Glycine formosana, Bragg-black seed × WT 125, Bragg-black seed × Glycine formosana, Kalitur × WT-125, Kalitur × Glycine formosana, Ankur × WT-125 and Ankur × Glycine formosana) were evaluated for seed impermeability. WT-125 and Glycine formosana were identified as impermeable types (92·18, 77·46% impermeability, respectively). The other four varieties, namely Bragg (2·93% impermeable seeds), Bragg-black seed (11·7% impermeable seeds), Kalitur (no impermeable seeds) and Ankur (0·94% impermeable seeds) had soft seed or normal seed.

The segregation pattern for impermeability in the F2 and F3 generations of eight crosses showed the involvement of a pair of dominant genes in Bragg × Glycine formosana, Bragg-black seed × WT-125, and Bragg-black seed × Glycine formosana, three pairs of dominant genes in Bragg × WT-125, Ankur × WT-125 and Ankur × Glycine formosana, and four pairs of dominant genes in Kalitur × WT-125 and Kalitur × Glycine formosana for seed impermeability, assuming maternal control as hard seed was a seed-coat phenomenon.

Vr, Wr graphical analysis also indicated that WT-125 and Glycine formosana possessed mostly the dominant genes for seed impermeability, while the remaining four cultivars contained mostly the recessive genes. The correlation coefficient of Yr (parental mean) and Vr + Wr was negative and high (— 0·907) confirming that most of the dominant genes in the parental cultivars were acting towards high seed impermeability. Thus the overall results obtained through diallel analysis of 15 F1's were in agreement with those obtained through Mendelian analysis.

Soil NO3-N and NH4-N were measured to 90 cm depth in autumn and again in spring, under several sets of winter wheat experiments, on contrasting sites. Crop samples were taken throughout the growing season, both before and after the fertilizer N was applied, to measure N uptake. The amount of NO3-N in soil at the outset of growth in autumn was related to the uptake of N by wheat not given any fertilizer N until April.

The effect of sowing date (September v. October) on both crop and soil N was compared, as also was the effect of soil type (retentive of NO3-N v. readily leached) and previous crop (potatoes v. oats and wheat v. beans).

The amounts of NO3-N in the soils in autumn related well with previous crop and declined gradually during winter on the heavier soils, but rapidly on the sandy soil, in the latter case as a consequence of leaching. On the heavier soils, where little leaching occurred, the decline in soil NO3-N related well with the amount of N taken up by September-sown wheat during autumn and winter, but not with that taken up by October-sown wheat, where NO3-N accumulated in the soil during winter, because uptake was so small. Hence delayed sowing enhanced the likelihood of losses of NO3-N by leaching or by denitrification. On the sandy soil at Woburn, whilst the September-sown wheat removed more N than the October-sown, losses of NO3-N by leaching were severe, so that late winter growth was restricted by shortage of N in soil, and the amount of N taken up was far smaller than at Rothamsted.

The soil measurements distinguished between the NO3-N residues remaining after beans or wheat in the same field and between residues after oats or potatoes on soils of the same soil series, but in different fields on the same farm.

The amount of NO3-N in soil and the N taken up by wheat in February-March were together used to adjust the amount of fertilizer N applied in April, using a balance sheet approach to meet a specific yield objective. Some of the N uptake data from these experiments are presented. This should aid the calculation of N requirement during specific growth periods and thus help improve the prediction of fertilizer N dressings in spring.