Ten winter wheat varieties, representing a range of milling and bread-making quality were grown in a split-plot field trial with two levels of irrigation and three levels of nitrogen fertilizer. Grain yield was increased by irrigation and by fertilizer treatments. Application of 90 kg N/ha applied in granular form increased yield by 12.4 and 6.1% and grain protein by 13.0 and 33.7% for the irrigated and non-irrigated plots respectively. A further 45 kg N/ha applied as an aqueous foliar spray of urea (0.125 kg/1) at anthesis increased protein by 12.4% for the irrigated plots and by 8.8% for the non-irrigated plots with little effect on yield. The varieties differed significantly in yield and protein content, resulting in negative regressions of yield and protein content at each N treatment. The production of protein (weight N/unit area) was similar for all varieties, but flour extraction was reduced by the urea treatment. Varietal differences in flour extraction were stable and not correlated with either 1000-grain weight or test weight. Loaf volume was increased by the granular N fertilizer but not by the urea spray, despite the increase in flour protein and a decrease in flour α-amylase activity, indicating that applications of nitrogen after anthesis are likely to be later than the optimum for improving bread-making quality.

Leaf samples were collected, at weekly intervals, throughout the growing season, from potato (Solanum tuberosum L.) plants supplied with varying amounts of nitrogen (0, 60, 120, 180 and 240 kg N/ha) and analysed for total N. Application of nitrogen increased the N concentration in the green leaves at all stages of growth. There was a significant curvilinear relationship between the final tuber yield and the total N concentration in the leaves at 48–90 days after planting in 1968–9 and at 79–107 days after planting in 1969–70. The N concentration at 70–90 days after planting was consistently related to the final tuber yield in both years. Thus this period was ideal for assessing the nitrogen status of potato plants. The critical concentration of total nitrogen generally decreased with advance in age. It ranged from 4·65% at 76 days to 3·30% at 90 days during 1968–9, whereas in 1969–70 it ranged from 4·20% at 79 days to 3·80% at 93 days. During the period from 83 to 86 days the critical percentage was around 3·6% in both the years.

The effect of six intervals between harvests and three levels of N application on the dry-matter yield of total herbage, the proportion and yield of green leaf, dead leaf, ‘stem’ and inflorescence of the sown species, the proportion and yield of unsown species, the digestibility and digestible yield and N content and yield was studied in S. 23 and S. 321 perennial ryegrass during a 30-week period in the second harvest year in a field experiment. In S. 23 the ‘stem’ was divided into true stem, leaf sheath, unemerged leaf and unemerged inflorescence.

The results supported the main findings from the first harvest year (Wilman et al. 1976a, b).

There was marked ingress of unsown species in the second harvest year with 3-, 4- and 5-week intervals in S. 321. The combination of 262–5 or 525 kg N/ha/year and 8- and particularly 10-week intervals over 2 years was too severe a treatment for the satisfactory survival of S. 23. With 525 kg N and 10-week intervals, S. 321 was equally badly affeoted.

The application of 525 kg N/ha/year compared with nil reduced the proportion of green leaf in total herbage of the sown species by 11 percentage units, on average, and increased the proportion of ‘stem’ by 12 percentage units, in the second harvest year. The effect of N application on the proportion of crop fractions was found in both varieties and in all months of harvest. The effect was much greater than in the first harvest year. In S. 23 the application of 525 kg N compared with nil in the second harvest year increased the proportions of both true stem and leaf sheath (in total herbage of the sown species), true stem being the more important of the two, in this context, with the longer intervals and leaf sheath being the more important with the short intervals.

Digestibility was not in general affected by N application despite the higher proportion of stem and leaf sheath and the lower proportion of green leaf blade resulting from N application. N did, however, tend to reduce digestibility at the harvests at which the proportion of stem was highest.

Digestibility varied from one time of the year to another with a constant interval between harvests, but not as much as in the previous year. Lower digestibility of leafy crops in summer and autumn than in April and early May in both years may have been partly due to a higher proportion of dead material.

Three periods were distinguished approximately in both years: May-June, July-August, and September-October. Only in the first of these periods was there a substantial increase in yield of digestible organic matter as a result of doubling the interval between harvests. Doubling the interval reduced digestibility in all three periods, but especially at harvests within the second period. Yield response to N was large in the first period, intermediate in the second, and low in the third. Apparent recovery of N was low and N content of herbage unduly high in the third period. N content of herbage was low with the long intervals between harvests at harvests in the first two periods. Applied N increased N content at these harvests and at all other times.

Inbred lines and hybrids of English tick and horse beans and exotic stocks were studied with respect to pod set, floral structure and pollen production and germination to find out why most inbred lines set few or no seeds without tripping whereas most hybrids and some inbred lines set equally well with or without tripping. The most important outcome was new information on variation between genotypes in flower structure and pollen quantity and on how these two characters affect the mechanics of self-pollination. Though heterosis in terms of abundant pollen production could be a factor in the self-pollinating ability of hybrids, some of the inbred lines were capable of self pollination despite limited pollen production, because the structure of the flower permitted the pollen to reach the stigma via a short route. The floral features associated with the ability to self-pollinate in the inbred lines included a relatively short style bending at more or less a right angle, few and short stylar hairs and stigmatic papillae, and less pronounced ridges on the inside of the keel petals. The implications of these findings to the development of self-pollin ated varieties of field beans are briefly discussed.

Changes in the amounts of the trace elements iron, zinc, manganese and copper, present in intact grain, endosperm, testa pericarp and embryo throughout the developmental period were recorded. Accumulation of iron and zinc in intact grain was extremely rapid, rising in the case of iron from 40 ng/grain to 1600 ng/grain between 5 and 40 days after anthesis. Manganese accumulated steadily throughout, reaching a final value of 475 ng/grain. Significant amounts of copper were present throughout and a small peak was observed at 38 days after anthesis. Some variation from this overall pattern was found in the different morphological parts as development proceeded. This was notable in the case of embryo manganese, which was undetectable until 45 days after anthesis, when levels rose dramatically to reach a steady maximum of around 100 ng/embryo. The results are discussed in relation to the biochemical events accompanying maturation.

The rate of evaporative water loss has been studied in domestic fowls in the ambient temperature range from 0 to 40°C.

Results for whole-body evaporation were similar when obtained by the open-flow and direct-weighing methods. At low levels of absolute humidity the rate increased by 0·03 mg/(g.h.°C) from 0 to 22 °C and by 0·17 mg/(g.h.°C) from 23 to 40 °C. Wholebody evaporation decreased with rising ambient water vapour pressure by 0·7 mg/(g.h.kPa).

Cutaneous water loss was greater than respiratory water loss below 21 °C; it accounted for 78% of whole-body evaporation at 0 °C, falling to 25% at 40 °C.

The rates of respiratory and whole-body evaporation could both be expressed as linear functions of respiratory frequency.

Five rumen-cannulated sheep were given a diet of ground barley, ground hay and flaked maize in quantities which were increased progressively throughout the period of study. The rumen concentration of total short-chain fatty acids increased (P < 0·05) and the pH decreased (P < 0·05) as the level of feeding was raised and pH was correlated with the fatty acid concentration. There were no systematic effects of the level of feeding on the volume, outflow rate or clearance rate of the rumen liquid phase or on the ruminal concentration of ammonia. The molar percentage of acetic acid in the rumen fluid tended to decrease as the level of feeding was raised and there were compensatory increases in the percentage of propionic acid. However, there were wide variations in the composition of the mixture of rumen acids between sheep at each level of feeding and changes in fermentation pattern with level of feeding were not consistent between animals.

A broad inverse relationship was observed between the molar percentage of propionic acid and the clearance rate of the rumen liquid phase which supports the suggestion that there is an important association between the pattern of fermentation in the rumen and the liquid clearance rate.

Dissection data for 753 steer carcasses comprising 17 breed-type × feeding system groups were used to examine the distribution of lean between 14 standardized commercial joints. Breed types included Ayrshire, Friesian, Friesian × Ayrshire and crosses out of Friesians by Angus, Charolais, Hereford, Limousin, Simmental and South Devon sires. Most cattle were grown on cereal or grass/cereal systems of feeding. Group means for weight of lean in the side (half carcass) ranged from 60·0 to 85·2 kg with a pooled within-group S.D. of 7·81 kg.

The increase in lean weight in each joint relative to that in the side was examined using the allometric equation. Pooled within-group growth coefficients (b values) indicated that relative lean tissue growth was lowest in the leg (hind shin) and rump (b = 0·84 ± 0·03 and 0·85 ± 0·03 respectively) and highest in the clod and sticking (b = 1·19 ±0·03). The result for the combined higher-priced joints was 0·95 ±0·01.

The pooled growth coefficients were used to adjust the weight of lean in each joint to equal total lean weight in the side where this was legitimate. Statistically significant (P < 0·001) but relatively small differences were recorded between groups in the adjusted means for all joints tested. At equal total lean weight, Charolais × Friesian, Limousin × Friesian and Simmental ×; Friesian groups had the highest weight of lean in the combined higher-priced joints and the Ayrshire and Friesian × Ayrshire groups the lowest. The difference between the two extreme groups was 2·1 kg (for one side).

In capacity studies on adult White Leghorn hens during exercise it was found that the maximum velocity of the bird was 2·4 km/h.

Metabolic rate increased linearly with running speed and, between the speeds of 1 and 2 km/h, was 53–65% higher than the metabolic rate at rest.

The bird moved faster largely by increasing its stride.

The cost of bipedal locomotion for hens, in contrast to men and rhea, is lower than the cost of the quadrupedal locomotion of mammals.

Designs for experiments that allow the independent estimation of the effects of treatments to neighbouring plots (units) on each side were constructed by use of an electronic computer. Their utility (e.g. in the study of air-borne disease of field crops) is indicated and methods of analysis are discussed.

The influence of standing, spontaneous activity and eating on heat production was determined.

The extra heat production of standing is negatively correlated with the length of standing period. In a short standing period of 30 min the associated activity, pecking against the respirometer wall and fluffing the feathers, was high and the heat production was increased by 25% compared with that during sitting. After standing for 1½ h spontaneous activity was very low and the difference in heat production between the standing and sitting bird was reduced by 9%.

During eating the heat production increased by an average of 37% (range 11–68%); this was due mainly to the act of eating per se and not to the work of digestion.

The mean energy cost of eating was calculated to be 143 J/kg0·75/min spent eating.

A standardized impregnated filter-paper bioassay technique was specially developed for screening insecticides against adults of the whitefly Bemisia tabaci Genn. (Homoptera, Aleyrodidae). It was found that the most suitable exposure period, after which mortality counts should be made, was 11·7 ± 2·1 h. Two different techniques for applying the insecticide solutions to the filter paper disks were tested and verified.

Two field experiments were made to examine differences in wheat variety response to applied superphosphate. In the first experiment, conducted under dry conditions, both yield and yield response to superphosphate were low; in the second experiment some semi-dwarf wheats showed a greater response than standard-height wheat varieties. The semi-dwarf wheats had a greater proportion of plant phosphorus in the reproductive sections of the plant at maturity. The semi-dwarf variety Israel M 68 also showed the greatest increase in root production following the application of superphosphate.

Finnish Landrace sheep with low red cell GSH concentrations resulting from a defective transport system for certain arnino acids were crossed with Tasmanian Merino sheep with a red cell GSH deficiency due to impaired activity of the enzyme γ-glutamyl cysteine synthetase. Inheritance data showed that the two types of GSH deficiency were under independent genetic control. In the Finnish Landrace breed, the gene coding for the transport defect (Trn) was inherited as an autosomal recessive and sheep homozygous for this gene had high red cell concentrations of lysine and ornithine (Ly ×) as well as low levels of GSH. In the Tasmanian Merino breed the GSH deficiency behaved as if controlled by an autosomal dominant gene (GSHL). Backcross breeding experiments resulted in lambs which had inherited both types of GSH deficiency. Evidence suggested that such ‘double low’ GSH lambs had an impaired viability. In Tasmanian Merinos the GSH deficiency was established prior to birth. Newborn Finnish Landrace lambs were clearly separable into two types on the basis of their red cell lysine and ornithine content but not on their GSH concentrations.

Seventy-four field experiments on the nitrogen requirement of sugar beet were made in eastern England in. 1966 to 1974. Considerable differences in sugar yield response to nitrogen were found between the six soil types used, and these differences were found (on five of the six soils) to be related to sugar yield. Nitrogen response was large on chalk and limestone soils in Lincolnshire, intermediate on East Anglian boulder clays and least on East Anglian chalk and light drift soils. On the lighter soils (limestones, East Anglian chalks and light drifts) nitrogen response was greater with high summer rainfall than with low. Fenland silt soils were very high yielding, but nitrogen response was moderate.

Optimum nitrogen rates differed between soils, in the range 100 kg/ha on East Anglian chalks and light drifts to 180–200 kg/ha on Lincolnshire chalks and limestones.

The growth and development of two varieties of Phaseolus vulgaris (Purley King and Limelight) were compared in two experiments in 1973 and 1974 at a range of planting density from 20 to 100 seeds/m2. Within this range, the relationship between seed yield and density in Purley King was asymptotic, although there was a suggestion that if even higher densities had been tested, a downward trend in yield might have occurred. The optimum density of planting for Purley King in Expt 1 was 50 seeds/m2 while that for Limelight was 40 seeds/m2. The corresponding densities in Expt 2 were 75 and 50 seeds/m2 respectively. Although number of branches per plant generally decreased with increasing density, there was no significant density effect on the number of nodes per plant. Thus stabilization of seed yield occurred even at quite low densities. Although in the low-density treatments, less vegetative tissue was produced, the peak of dry-matter yield occurred later after flowering and the slower subsequent senescence ensured the presence of active photosynthetic tissue throughout the pod-fill stage. Less pod retention occurred at high density which, combined with the ability of widely spaced plants to produce pods over a longer period, resulted in a similar number of pods per unit area over a wide range of density.

Although the variety Purley King produced more than double the number of mature pods from its extra nodes and branches, it was outyielded by Limelight by 35% from the combined effect of more seeds per pod and a higher mean seed weight. Limelight also produced this high yield with less vegetative tissue. In both varieties it appeared that pod photosynthesis could take place, in Purley King because the pods were borne on higher nodes above the canopy and in Limelight due to the earlier senescence of its smaller leaf area. However, in spite of the apparent physiological advantages of Limelight, the pods are not borne high enough on this plant to enable satisfactory mechanical harvesting.

Three nitric phosphate fertilizers with 30, 60 and 70% of their phosphorus in watersoluble form were evaluated relative to superphosphate and rock phosphate on neutral to alkaline soils. The test crops were wheat, paddy and berseem. Linear grain yield and dry-matter yield responses were obtained up to 100 kg P2O5/ha for wheat and berseem, respectively. Quadratic response functions were fitted to paddy grain yield. Yields of the various crops were well related to the water solubility of the P fraction in different sources. Availability coefficient ratios were calculated for each fertilizer. These indicated that the minimum water solubility of the phosphorus fraction in nitric phosphates required for high crop yields is dependent on the nature of the crop, on soil characteristics and on the method of application which together determine the shape of the response curve. Band placement of sources with higher water solubility of their P fraction (70% or more) resulted in fertilizer efficiency similar to wholly water-soluble sources. Nitric phosphates of 30 and 50% water-solubility were inferior to water-soluble sources when applied broadcast. However, where curvilinear responses were obtained, low water-solubility sources (30 or 50% water-solubility) performed better at higher than at lower rates of application.

Three field experiments were carried out on sandy loam soil at Levington, Suffolk, on the effect of irrigation on nitrogen requirements of sugar beet. Four nitrogen rates (0, 67, 134, 201 kg/ha) were examined with and without irrigation. Nitrogen increased sugar yield each year, as did irrigation in 1969 and 1970, but not in 1968 when the soil moisture deficit was small. There was a significant nitrogen x irrigation interaction in 1970 only, but on average there was a greater response to nitrogen with irrigation than without it.

These results and other published data suggest that on sandy soils in eastern England moisture deficit can restrict nitrogen response, and that the economic optimum nitrogen rate is appreciably higher with irrigation than without it.

A tightly autumn-calving herd of British Friesian cattle, running throughout the year as a single group, received two different amounts of mineralized barley supplement per day during the winter of 1973/4. As they calved, alternate cows were allocated to one of two rates of supplementary feeding differing in the approximate ratio 2:3 which was applied according to the calendar and not specifically related to milk yield.

Average herd size for the year was 140 cows; average milk sales were 4680 kg/cow at a total supplementary concentrate use of 650 kg/cow. All cows had free access to selffeed silage reinforced with brewers' grains. Cows which received 50% more supplement from 8 September to 31 January (an extra 235 kg/cow) showed an improvement in total lactation milk yield of 248 kg/cow. Standard lactation curves were used to demonstrate a significant interaction between quantity of concentrates fed and season of production and showed that most of the improvement took place during the winter period.

A basal diet, or the basal diet supplemented with equi-nitrogenous amounts of either ammonium lactate, ammonium acetate or urea was fed to four re-entrant cannulated sheep in a randomized block design.

Collections of duodenal digesta were carried out automatically for a continuous period of 4 days following a 10-day equilibration period for each sheep on each diet.

Supplementation with non-protein nitrogen increased the passage of total amino acids to the duodenum and increased the proportion attributed to microbial protein. It improved pre-duodenal digestibility of modified acid-detergent fibre and increased post-abomasal digestibility of non-ammonia nitrogen, dry matter and gross energy.

Supplementation with non-protein nitrogen increased the energetic efficiency of microbial protein production in the rumen.

Ammonium lactate and acetate were safe and effective sources of non-protein nitrogen for dietary supplementation.

Supplementation with ammonium lactate led to a greater passage of microbial protein to the duodenum than did equi-nitrogenous supplements of urea or ammonium acetate.