In three field trials, three varieties of cow pea (Prima, Ife Brown and Vita-5) grown as mono-crops or interplanted with maize (in one trial) were sprayed with a combination of PKS or NPKS in solutions containing 100, 100, 100 and 41 mg/1 of N, P, K and S respectively at the onset of flowering or 2 weeks later, in order to evaluate the effect of foliar spray of mineral nutrients on the performance of the crop.

Early season sprayings of NPKS and PKS increased vegetative development and dry-matter accumulation in both mono- and mixed-croppings of Prima and Vita-5, but had little effect on Ife Brown. Seed yield was increased by 80–225 kg/ha in Prima and 160–218 kg/ha in Vita-5. In all cases of enhanced growth and yield, spraying at flowering was more beneficial than spraying 2 weeks later whilst NPKS evoked greater responses than PKS.

In two late-season trials, all treatment combinations enhanced vegetative development and dry-matter accumulation in Ife Brown and Vita-5. Seed yield of Ife Brown was increased by 206 kg/ha in the first late season and by 550 kg/ha in the second late season whilst that of Vita-5 was increased by 226 kg/ha in the first late season, during which it was planted. In the first late season of Ife Brown, late spraying was more beneficial than early spraying, whilst plants sprayed with PKS out-yielded those sprayed with NPKS. On the other hand, in the second late season, Ife Brown responded more to early spraying than late spraying and NPKS was more beneficial than PKS: Vita-5 grown in the first late season responded similarly.

In all cases of enhanced seed yield during the seasons, the pathway of response was through increased pod production and/or retention on the plants. The results therefore suggest that foliar spray of nutrients during the post-flowering period enhance seed yield in cow pea by ensuring prompt delivery of mineral nutrients to the site of photosynthesis at a time when nutrient depletion in the leaves and reduced efficiency of mineral nutrient uptake by the roots limit the supply of photosynthates to developing reproductive organs.

The growth and mortality of red deer hinds from 3 months of age were analysed using data from a farmed stock. Calf mortality from 3 to 15 months of age was 11 % and was highest in the 2 months immediately after weaning. Mortality in the 8 years subsequent to the hinds reaching 15 months was low and based on 924 yearly records of survival was 1·8% per annum.

The rate of growth of the calves during their first winter was markedly affected by the amount of feed given and slightly (though highly significantly) greater for the larger calves. In the subsequent summer there was no effect of weaning weight on gain. This varied considerably from year to year.

The subsequent growth of the hinds showed that an equilibrium weight of about 82 kg was achieved, and that body weight at the beginning of the year, age, and whether or not the hind produced a calf, all affected the increase in body weight during a particular year.

The results are combined to estimate the effects of culling the hind stock at different ages on the number of surplus female calves and the effects on lifetime reproductive performance of the body weight of hinds when 15 months of age. The latter can be predicted from weaning weight and winter feed intake provided gain from 10 to 15 months at pasture can be estimated. The partial effects of giving additional concentrated feed in the first winter were estimated and found to be appreciable.

Comparisons of the results are made with mortality rates and body weights estimated by others for wild populations.

Automatic plot covers were used in a study of the effects of drought on the yield and water use of two spring wheat genotypes. The experiment tested the effects of drought at different stages of growth on yield and yield components. There was complete control over the water supplied to the plots, and a fully irrigated control treatment was included.

The yields of the two genotypes were similar under fully irrigated conditions, but the yield components differed: Highbury had more grains per ear and TW 269/9/3/4 more ears per unit ground area and a higher mean grain mass. An early drought, which began 4 weeks before anthesis, caused a reduction in number of grains per ear in Highbury, which was outyielded by TW 269. Late drought also reduced yields differentially, reducing mean grain mass, and hence grain yield, more in TW 269 than in Highbury. Total shoot dry matter and grain yield were found generally to increase as water use increased. The average water use efficiency was found to depend upon the genotype and treatment.

Sowing winter oil-seed rape cv. Victor late in autumn (late September or October) in seven seasons from 1970 to 1977 gave enormously variable seed yields, from 120 to 450 g/m2. All crops made little growth before winter, and yield was related to the size of the crop at flowering, a function of the length of time for radiation interception and growth between the ‘beginning of spring’, when mean temperatures rose consistently above 5 °C, and full flower in late May. A late spring in 1970 gave the poorest growth and lowest yield, whereas in 1977 an early spring coincided with late flowering to give exceptional growth, and yields higher than from any early sowing.

Crops sown in early autumn (before mid-September) produced more consistent seed yields, 280–360 g/m2, except in the dry year of 1976. All grew well in autumn, overwintered with a large leaf area, and once temperatures rose in spring, rapidly reached peak area and full flower in early May. They were all large at flowering, and yield was apparently limited more by post-flowering events.

With all sowings numbers of pods and seeds were largely determined during a 3-week phase in late May and early June, extending from full flower until most pod hulls had finished growing. Late sowings produced 3000–6000 pods/m2, and the number of seeds retained per pod varied widely, from 7 on a poorly grown crop to 22 on a well grown crop, thus expressing the yield potential determined by crop size at flowering. Early sowings, however, produced apparently excessive numbers of pods (6000–12000/m2) and few seeds per pod (6–10), so that yield varied little, regardless of crop size. Early in the phase, when the number of seeds was determined, the mass of yellow flowers at the top of the crop reflected or absorbed up to 60 % of incoming radiation, and then the large number of pods increasingly shaded each other and competed for assimilate, resulting in heavy seed losses. A high-yielding crop type may therefore need to incorporate the restricted pod production and good seed retention of some well-grown latesown crops with the reliability and desirable agronomic features of early-sown crops.

Final seed weight varied more between seasons (3·7–5·3 nag) than between sowings. Seed growth mainly took place after the number of seeds had been determined, the duration depending on temperature, but rate of growth apparently more on assimilate supply, a function of environmental factors and the number of competing seeds.

Experiments started in 1976, 1977 and 1978 on Clay-with-Flints soil at Rothamsted tested the effects of combinations of eight two-level factors on spring-sown field beans. Factors tested, presence v. absence, were irrigation, nitrogen fertilizer, aldicarb, fonofos (dieldrin in 1976), benomyl to the seed bed, permethrin (fenitrothion in 1976), pirimicarb, benomyl foliar spray (not tested in 1976).

The main pests and diseases present were nematodes of the genus Pratylenchus, the pea aphid Acyrthosiphon pisum, the pea and bean weevil Sitona lineatus, root blackening associated with the fungal genera Pythium and Fusarium, the foliar diseases chocolate spot, Botrytis spp., rust, Uromyces fabae and bean leaf roll virus.

Incidence of these pests and diseases varied between years. Controlling those present increased yield by about 0·7 t grain/ha each year. The difficulty of apportioning this increase to particular pests and diseases is discussed.

Irrigation increased total dry-matter production and grain yield in 1976 and 1978 but only total dry-matter production in 1977, when grain yield was lost because of lodging. Nitrogen fertilizer had little or no effect.

The most favourable combinations of treatments gave yields of 3·4, 5·0 and 6·4 t grain/ha in the 3 years respectively. Small yields in 1976, despite irrigation, were attributed to premature senescence caused by exceptionally high temperatures. It is suggested that with good control of pests and diseases yields of at least 5 t/ha should be attainable on Clay-with-Flints soil without irrigation in years of average temperature and rainfall and yields in excess of 6 t/ha when the soil-moisture deficit is lessened by either above-average rainfall or irrigation.

Treatments applied to the beans had little or no effect on two following crops of winter wheat.

Six compounds which show juvenile-hormone-like (JH) activity (TH6040, JH-25, Altosid, Altozar, ZR-777 and ZR-619) were tested on larvae of Culex pipiens. The reproduction potential of the females obtained during two successive generations was not affected greatly, but there was a decline in pupation rate with some compounds. There seemed to be a direct relationship between the size of females of this species and treatment with JH compounds tested in the present investigation, since treatment with concentrations to inhibit the emergence of 10% or 50% of adults caused significant changes in the width of head, wing dimensions or length of hind legs.

Skin biopsy samples from imported Merino and ⅝ Merino/⅜ Barki were examined from birth to the age of 1 year. Birthcoat fibre type arrays and fibre-follicle relationships were also studied.

Merino lambs had a greater S/P ratio than ⅝ Merino at all ages; values at 1 year of age were 9·98 and 6·87 respectively.

The ⅝ Merino lambs showed a wider range of follicle diameters than Merinos from birth to 1 year of age.

The ratio of primary to secondary follicle diameters showed higher values in ⅝ Merino than in Merinos. Merino gave lower values of follicle wall thickness than ⅝ Merino.

In Merino birthcoat samples, only one array was plain, representing 4%, whereas the rest were saddle. In ⅝ Merino the majority of fibre type arrays were plain, representing 75 %, whereas the rest were saddle and plateau.

In Merino, because of the absence of halo hairs and super sickles, only two samples had few super sickle B; primary central follicles were occupied by sickle fibres, medium with large sickle ends as well as curly tips, and primary lateral follicles had mostly medium and fine curly tips, only four samples had sickle fibres, and secondary follicles produced medium and fine curly tips and histerotrichs.

In ⅝ Merino primary central follicles produced halo hairs, super sickle A, A', B and occasionally sickle fibres, primary lateral follicles grew super sickle A, A', B, sickle fibres and curly tip fibres, and secondary follicles had medium and fine curly tips and histerotrichs.

The aim of the experiments reported here was to investigate the possibility of minimizing yield losses due to late sowing by increasing leaf area and radiation interception during the pre-flowering period. The use of large seed did increase leaf area, radiation interception and crop weight at flowering. Normally this would be expected to lead to increased yield of late sowings, but hot, dry conditions severely affected all crops during seed growth. Applying fertilizer nitrogen in the seed bed boosted pre-flowering growth of early but not late sowings, probably because low temperatures prevented a response in the latter. Increasing plant population density did improve leaf cover and radiation interception until just before flowering, but leaf canopies in late-sown, low density crops were then able to expand more and function for longer owing to less shading by flowers and pods. Seed retention was improved and, even with as few as 8 plants/m3 in 1973–4, a worthwhile yield was still obtained.

The effects of various lengths of water deprivation were studied with Yankasa sheep fed either a high roughage or a high concentrate diet in two experiments. Water was given once in 24, 48, 72 and 96 h. Free water intake decreased linearly (P < 0·01) as the period of water deprivation increased but feed intake was not similarly affected. There was a marked decrease in live-weight gain and consequently a decline in feed efficiency (kg gain/kg feed). In the metabolism study, there was a tendency towards reduced mean faecal and urinary nitrogen excretion, faecal moisture content and increased mean nitrogen retention and nitrogen and dry-matter digestibilities as the period of deprivation increased. Rams given water once in 72 and 96 h were very inactive and dull and one and three rams respectively, died of severe dehydration from those treatments in Expt 2.

Four experiments were conducted to determine whether the products of fermentation in maize silage could limit food intake by lambs. In all experiments the lambs were fed ad libitum adietoi dried and pelleted lucerne, but were deprived of food for 4 h on the morning of intraruminal infusion. The infusions were made according to latin-square designs and commenced after 1 h of food deprivation. In Expt 1, the infusion of 3·5 I acetic acid solutions to provide 15, 30 and 60 g acetic acid had no effect (P > 0·05) on cumulative food intake compared with water. In Expt 2 infusion of three maize silage extracts differing in their composition of nitrogenous constituents suppressed (P < 0·05) food intake relative to acetic acid alone, but there were no significant (P < 0·05) differences among the extracts. When 2·71 of an extract from a low dry matter (D.M.) maize silage were infused in Expt 3 cumulative food intake was significantly (P > 0·05) decreased compared with acetic acid, but ruminal osmolality was increased to 430 mosmol/kg and ruminal pH declined to less than 5·5. In Expt 4, 1·5 1 of the low D.M. maize silage extract, an amount actually consumed by lambs during 4 h, decreased voluntary intake by 25% compared with the control but the effect was not statistically significant. Estimates of ruminal osmolality and pH ranged between 250 and 360 mosmol/kg and between 68 and 6·2 respectively. Measures of acid-base status were not affected (P < 0·05) by the infusion of acetic acid or maize silage extract. Whether specific soluble constituents of maize silage fermentation could limit food intake by ruminants was not proven.

Processed straw, both ground and ground–NaOH treated, has been compared with long straw in diets of straw and concentrates fed to yearling dairy heifers. Protein allowances were varied by the addition of fishmeal.

Improved growth rate was consistently observed with those animals receiving fishmeal. When a fixed amount of barley straw was offered neither digestibility nor growth was affected by the form of the straw. With wheat straw grinding–NaOH treatment resulted in increased growth when fed in diets containing some long roughage. Voluntary intake of straw was additively increased by grinding and by treatment with 5% (w/w) NaOH. Ground-NaOH treatment of straw increased in vitro digestibility.

The effects of water deficit on growth of spring barley were analysed under five irrigation treatments. One crop was irrigated at weekly intervals from emergence throughout the growing season, and one was not irrigated at all after emergence. Soil water deficits in the other treatments were allowed to develop early, intermediate or late in the crop's development.

Weekly irrigation produced a crop with a large leaf area index (maximum value 4) and maintained green leaf and awns throughout the grain-filling period. Early drought decreased leaf area index (maximum value 2) by slowing expansion of main-stem leaves and decreasing the number and growth of tiller leaves. Leaf senescence was also increased with drought. Drought late in the development of ears and leaves and during the grain-filling period caused leaves and awns to senesce so that the total photosynthetic areas decreased faster than with irrigation. Photosynthetic rate per unit leaf area was little affected by drought so total dry-matter production was most affected by differences in leaf area.

Early drought gave fewer tillers (550/m2) and fewer grains per ear (18) than did irrigation (760 tillers/m2 and 21 grains per ear). Late irrigation after drought increased the number of grains per ear slightly but not the number of ears/m2. Thus at the start of the grain-filling period crops which had suffered drought early had fewer grains than irrigated (9·5 and 18·8 × 103/m2 respectively) or crops which suffered drought later in development (14 × 103/m2).

During the first 2 weeks of filling, grains grew at almost the same rate in all treatments. Current assimilate supply was probably insufficient to provide this growth in crops which had suffered drought, and stem reserves were mobilized, as shown by the decrease in stem mass during the period. Grains filled for 8 days longer with irrigation and were heavier (36–38 mg) than without irrigation (29–30 mg). Drought throughout the grainfilling period after irrigation earlier in the season resulted in the smallest grains (29 mg).

Grain yield depended on the number of ears, the number of grains per ear and mass per grain. Early drought decreased tillering and tiller ear production and the number of grains that filled in each ear. Late drought affected grain size via the effects on photosynthetic surface area.

Drought decreased the concentrations of phosphorus, potassium and magnesium in the dry matter of crops, and irrigation after drought increased them. Concentration of nitrogen was little affected by treatment. Possible mechanisms by which water deficits and nutrient supply affect crop growth and yield are discussed.

Thirty-eight spring wheat genotypes of north temperate or low latitude origin, all reasonably well adapted to the English environment, were grown in controlled environments providing the four combinations of 10 and 14 h photoperiods and temperatures of 8 and 16 °C for 6 weeks. They were then transferred to a glasshouse to assess their responses to these treatments. In separate experiments the responses of the genotypes to vernalization for 2 and 4 weeks at 2 and 8 °C were compared with unvernalized controls. The genotypes were also compared in field experiments from early, intermediate or late sowing over 3 years.

Both high temperatures and long days hastened ear emergence. At the higher temperature more leaves and spikelets were produced on the main stem while in long days the plants had fewer leaves and spikelets.

Most genotypes of north temperate and low latitude origin were responsive to photoperiod but not to the vernalization treatments. As a group, the low latitude ones were as responsive as the north temperate group. Five genotypes of north temperate origin were responsive to vernalization but not to photoperiod and were designated as ‘winter’ ones. Pitic 62 and Hork, from low latitudes, were responsive to vernalization and Hork was unique in also being responsive to photoperiod. The main difference between the north temperate and low latitude genotypes was in time to ear emergence and it is suggested that these differences were due to the effects of earliness genes as distinct from those determining photoperiodic response.

Taking all genotypes individually there were no correlations between yield or its sensitivity to sowing date and any of the attributes measured in controlled environments. However, considering class means, the winter genotypes were the latest to reach ear emergence in the field, and their yields, while greatest from the earliest sowings, were proportionally more depressed by late sowing than the others of the north temperate origin. Thus, it may be unwise for plant breeders to incorporate a vernalization response in spring wheat varieties unless genes for ‘earliness’ are also included. The low latitude class gave only slightly lower yields than the north temperate class.

It is concluded that genes other than those controlling responses to photoperiod, temperature and vernalization were more important determinants of the differences in yield among this set of genotypes.

Five rumen-cannulated Cheviot lambs were used in two successive experiments to differentiate the effect of osmolality from the specific effects of the soluble compounds in maize silage on voluntary intake and ruminal motility. In Expt 1, extracts from fresh (FCE) and ensiled (CSE) maize were adjusted to pH 6·5 andtonicities of 200, 400, 800, and 1600 m-osmol/kg with NaCl, then infused into the rumen according to a 5×5 repeated latin-square design. Water was infused as the control. In Expt 2 solutions of NaCl, with tonicities similar to those in Expt 1, were also infused into the rumen. The lambs were fed ad libitum a diet of pelleted lucerne, but on the morning of infusion they were deprived of food for 4 h and infused continuously for 4 h commencing after 1 h of food deprivation. The infusion of FCE and CSE resulted in no significant difference in cumulative dry matter (D.M.) intake. However, increasing the tonicities of the infusates caused a linear increase (P < 0·05) in ruminal osmolality and a corresponding linear reduction in food intake during the first 30 min of feeding. Infusion of NaCl alone produced a similar effect on intake. The linear regression coefficients of food intake (Y) (g D.M./kg W0·75) against rumen osmolality (X) (m-osmol/kg) were –0·077±0·0085 (r2 = 0·78), –0·082±0·0095 (r2 = 0·76) and –0·073±0·0065 (r2 = 0·84) for FCE, CSE and NaCl, respectively, with no significant differences among the infusates. The frequencies of ruminal contractions during the infusion of FCE and CSE were similar (P > 0·05) and were unaffected (P > 0·05) by ruminal osmolality up to 550 m-osmol.

A breeding programme was initiated to develop populations of sunflower (Helianthus annuus L.), suitable for the semi-arid regions of Iran. Crosses were made between Chernianka 66 (having low yield, low oil content, short stem, and early maturity), as the female parent and VNIMK 8931 and Record (having high yield, high oil content, long stem, and late maturity) as the male parents. Selection, together with selfing and sib-crossing, resulted in six populations with high yields, high oil content, short stems, and early maturity.

Correlation coefficients of oil yield and its components, i.e. seed yield and oil content, were highly significant and significant respectively. Capitulum diameter had highly significant correlations with seed yield and oil yield. Earlier maturity was associated with shorter stems and lower oil content.

The weights of 44 twin foetuses, 99 triplets and 44 quadruplets, varying in gestational age from 55 to 145 days, were studied in relation to age, sex, litter size, uterine position, placental structure and weight, and ovulation rate. Triplet and quadruplet foetuses were more variable in weight, within litters, than were twins. The difference increased with foetal age and was attributed to increased competition between foetuses which were located within the same horn of the uterus. The effect was largely associated with differences in placental development, i.e. numbers of cotyledons and weight, but those differences did not entirely account for the reduction in foetal weight with increasing litter size. Differences in placental development, arising from embryo mortality, also accounted for the reduction in foetal weight when ovulation rate exceeded litter size. In contrast, differences in foetal weight associated with the sex of the foetuses were only partly mediated by differences in cotyledon weight. Foetuses in the larger litters are thus not only lighter in weight but are more variable in weight, the increased variability being controlled by events in early pregnancy.

Ten Scottish soils were cropped in a glasshouse with three sowings of perennial ryegrass (Lolium perenne, cv. Dutch Barenza) without added magnesium. After 25 cuts (185 weeks) growth was poor in some soils, but soil Mg was not limiting growth in others.

Uptake of Mg and the Mg concentration in the ryegrass correlated well over the entire cropping period with the equilibrium Mg-concentration ratio Mg/(Ca, Mg) = CR0, determined from the Mg quantity/intensity isotherms measured before cropping in 0·01 m chloride solutions. A CR0 value of 0·16 was required in the early stages of cropping to give 0·2 % Mg in grass dry matter.

Seven soils released 12–37 mg non-exchangeable Mg/kg, between one-fifth and one-third of the total Mg uptake. These reserves probably came from vermiculite minerals, but the release was too slow to maintain Mg concentrations of 0·2 % in the ryegrass.

Adult goats provided with permanent jugular and portal vein catheters were used to study the effect of feeding hay and concentrates on blood composition in order to determine which blood constituents might act as signals in the control of feed intake. Animals were fed limited amounts of feed, or were allowed to eat unlimited amounts for restricted periods, once or twice daily. Blood samples were collected at hourly intervals up to 9 h after feeding and often more frequently in the initial hour, and were analysed for volatile fatty acids (VFA), lactate, glucose, insulin and glucagon.

Feed consumption resulted in rapid and large increments of jugular blood acetate, propionate, n-butyrate and 3-methylbutyrate concentrations whereas isobutyrate and 2-methylbutyrate increased only slightly. Jugular propionate, n–butyrate and 3–methyl–butyrate increased within 10 min and acetate within 20 min after feed was offered, both when hay and when concentrates were eaten. Fasting decreased circulating VFA to very low values. As a rule changes of portal VFA paralleled those in the general circulation although both the concentrations and the changes were much greater. Plasma lactate increased within 30 min on a concentrate diet but not at all on a hay diet.

Blood glucose declined in the initial hour after feeding and subsequently increased, resulting in a more or less elevated plateau. In some but not all experiments glucose declined before feed consumption, probably owing to ‘anticipation’. Circulating plasma insulin and glucagon appeared to increase slightly, if at all, after feeding. Increased feed intake was reflected in higher base line glucose and insulin concentrations in the jugular vein but the jugular glucose and insulin response to feed consumption was unaffected. Jugular glucagon was not influenced by the amount of feed. Jugular insulin and glucagon sometimes showed a brief peak during eating. Portal glucose, insulin and glucagon gave essentially the same pattern as seen in the jugular vein.

In conclusion, it appears that, of the substances studied, acetate, propionate, nbutyrate and 3-methylbutyrate are most suited for the function of feedback signals in the physiological control of feed intake in goats under the conditions of the present experiment. It seems less probable that glucose, insulin and glucagon can play such a role.

Two strains of commercial layers, 42 weeks old, were fed ad libitum, 85 and 70% of ad libitum for five 28-day periods to study the effects of feed restriction on body weight, carcass characteristics, laying performance and mortality. There were highly significant strain effects on all traits (P < 0·01) except dressing percentage. Period differences were also observed for egg production, egg weight and feed efficiency. In addition, in all cases the relationship between period and these traits was non-linear and was affected by strain or treatment.

Feed restriction had significant effects (P < 0·01) on all traits except dressing percentage and mortality. Feed restriction to 70% of ad libitum reduced egg production, egg weight, body weight and feed consumption and improved feed efficiency. However, in most cases there was no difference between ad libitum feeding and 15% feed restriction.

Strain × treatment interaction had significant effects on egg production and feed efficiency.

Individual leaf blades of onion plants were treated with 14CO2 57, 71, 93 and 112 days after transplanting. The distribution of labelled translocates was determined 24 h after labelling. The older the plant the more of 14C-assimilate left the source leaf; 112 days after transplanting, leaves 1–7 all exported more than 70% with leaf 7 showing a maximum export of 93 % of the fixed carbon. In the early stages of the development, the leaves, pseudostem and the bulbs were the major sinks in decreasing order. But the bulbs became the dominant sink at 71 days and at 112 days the bulbs almost monopolized the import of the radiocarbon, with 90 % of the exported 14carbon being recovered from them. The bulbs received their 14carbon supply from all the leaves but particularly the basal and middle region leaves. Roots were a weak sink and received their 14carbon supply only from basal leaves. The stem and mature leaf blades were unimportant sinks throughout the life of the plant.