Dissection data from 341 carcasses collected over a period of 7 years at the Institute of Food Research, Bristol (Large White, 138 entire males and 112 females; Pietrain, 41 entire males and 31 females; Iron Age (European Wild Pig × Tamworth), 8 entire males and 11 females) were used to examine the growth of muscle, fat and bone in joints relative to the corresponding total tissue in the side, and the growth of the fat depots relative to total side fat.

The musculature of Iron Age pigs was early maturing, as indicated by a particularly slow growth of pelvic limb and fast growth of neck and thorax muscles relative to total side muscle. As a consequence, Iron Age pigs had a lower percentage of pelvic limb and a higher percentage of neck and thorax muscles than the other breeds. Pietrains had proportionately the heaviest pelvic limb muscles, a result which was apparently independent of the overriding effect of maturity. However, considering the large difference in body shape (conformation) between Pietrain and Iron Age pigs, the differences in muscle weight distribution were small. Entire males had faster growing and heavier neck and thorax muscles than females. This was considered to be due to the effects of sex hormones. Entire males had proportionately less muscle in the pelvic limb.

Within carcass fat, the order of increasing growth rate relative to total side fat was intermuscular fat <; subcutaneous fat <; perirenal-retroperitoneal fat. Pietrain and Iron Age pigs had higher relative growth rates for subcutaneous fat and lower relative growth rates for intermuscular fat than Large Whites, an indication of earlier maturity in carcass fat development. This was reflected in Iron Age pigs, but not Pietrains, in a particularly heavy weight of subcutaneous fat and light weight of intermuscular fat. Within the subcutaneous and intermuscular fat depots, the highest allometric growth coefficients were generally observed in the forequarter. There were no consistent breed effects on the distribution of subcutaneous fat whereas, in the intermuscular fat depot, Iron Age pigs had less fat in the earlier-maturing thoracic limb, and lumbar and abdominal joint. At the same weight of total side fat (8·80 kg), entire male Pietrains and Large Whites had more intermuscular and less subcutaneous fat than females. There was no sex difference in fat partition in Iron Age pigs.

In all breeds, bone in the pelvic limb had the slowest relative growth. Similarly, the femur and the tibia-fibula were the two slowest growing bones of the four major limb bones examined. Otherwise, there was no consistent pattern of relative growth throughout the skeleton. Breed effects on relative growth within the skeleton and on bone distribution were small and considered to be of little commercial significance. Pietrains had the highest muscle: bone ratio in each of the four anatomical joints. Entire males and females had a similar relative growth and distribution of bones. Females had consistently higher muscle:bone ratios.

Oestrous and ovarian activity were studied throughout the year in 29 subtropical Rahmani ewes using both vasectomized rams and intravaginal electrical resistance measurements. Percentages of ewes in oestrus and of ewes ovulating were consistently high throughout the year with a detectable drop in spring months. The drop was more pronounced and lasted longer in oestrous activity than in ovarian activity. About 33% of the ewes showed continuous ovarian activity throughout the year while almost all ewes had periods of behavioural anoestrus.

Effects of artificial light regimen on oestrous and ovarian activity were investigated in 21 Rahmani ewes over a 6-month period from January to June. Oestrous and ovarian activity were slightly lower in the light-treated (L) group than the control (C) group during the period of abrupt increase in daylength. With gradual decrease in daylength, the percentage of ewes showing oestrus was markedly higher in the L than in the C group (84·6 v.37·5% during May).

It was concluded that daylength change, although limited in this region, is a main factor controlling the seasonal changes in oestrous and ovarian activity in subtropical Rahmani sheep.

The precision of the capacitance probe in detecting herbage mass differences between treatments has been assessed on a cross section of field trials in Otago-Southland, New Zealand. Used thoughtfully, the probe appears at least as good as any other alternative. Corrected meter readings from the probe may be used directly for relative ranking of treatments although calibration is desirable for interpretation purposes, and becomes essential when swards of widely differing composition are to be related. Considerable overall time savings, especially in the laboratory, are possible in comparison with other methods.

Two separate short-term rotation experiments were conducted during 1982–5 in order to study the production and effect on subsequent barley of legumes grown in Cyprus. The treatment crops, seven legumes and three cereals, were grown in 1982–3 and in 1983–4 growing seasons and barley was grown in the subsequent growing seasons (1983–4 and 1984–5).

Among the treatment crops, cereals gave equal or higher dry-matter yields, but equal or lower nitrogen yields compared with legumes. Barley, the test crop, which followed the treatment crops, gave lower grain and nitrogen yields when following cereals than after legumes. There were differences among legumes in their residual effect on the subsequent crop.

Results are described of an experiment involving various pearl millet–cow pea or green gram planting and interplanting systems under four levels of nitrogen and two levels of phosphorus. Planting of pearl millet in paired rows of 30 and 70 cm gave as much yield as normal planting in uniform rows of 50 cm. The productivity per unit area was increased considerably when pearl millet was interplanted with one row of cow pea or green gram. Cow pea gave higher yield than green gram. Nitrogen fertilizer increased pearl millet as well as intercrops yield significantly. Pearl millet responded up to 60 kg N/ha and intercrops up to 30 kg N/ha. Phosphorus fertilizer did not produce marked improvement in either growth or yield of pearl millet. Application of 40 kg P2O5/ha increased grain yield of intercrops significantly

Relations between yield, water use and pre-anthesis growth were analysed for cropsof barley grown for three seasons at several sites in northern Syria. The relations obtained were compared with those for other cereal crops grown in similar regions of Mediterranean climates.

Phosphorus fertilizer application increased the rate of crop development from emergence to floral initiation and advanced anthesis by up to 11 days. Grain and total shoot dry-matter yields were increased by fertilizer (nitrogen + phosphorus) applications at all sites in all years, in most cases without increasing total evapotranspiration. The increased dry matter at anthesis was produced without having used a larger proportion of the total evapotranspiration in the whole season. Consequently, the ratio of grain yield to total above-ground dry-matter yield (harvest index) and kernel weight were also relatively stable between sites and years, despite some very low amounts of post-anthesis water use. Grain yield appeared to be largely determined by anthesis and there were strong linear relationships between grain yield or total dry-matter yield and number of kernels. Differences in water use efficiency of crops given fertilizer between sites and years were closely related to the differences in amounts of winter growth.

Some responses differed from those predicted from models of growth, water use and yield developed in other regions with similar climates. It is concluded that agronomists and breeders should increase amounts of early growth thereby increasing grain and dry-matter yields. Future research emphasis should also be on the development of dynamic simulation models of pre-anthesis growth and water use.

In two separate field experiments with green gram (Vigna radiata L. Wilczek) and black gram (Vigna mungo L. Wilczek), the effect of seed treatment of molybdenum at 4, 8 and 12 g of sodium molybdate/kg seeds as well as foliar nutrition of sodium molybdate at 0·4, 0·8 and 1·2 kg/ha was evaluated on the nodulation characteristics and leghaemoglobin content of nodules and growth and yield of crops. Both seed treatment and foliar application of sodium molybdate were found to be superior to controls in respect of the number of nodules per plant and dry weight of nodules. The leghaemoglobin content of nodules in both crops was maximal in the treatments with the highest dose of seed treatment followed by the highest dose of molybdenum for foliar sprays. Molybdenum favourably influenced the growth of green gram and black gram by increasing the number of branches and leaves and by nearly doubling the leaf area index. This resulted in increased D.M. and yield of pods.

Five experiments were carried out in two seasons which studied the effects of seed weight, seed rate and date of harvesting on yield of seed crops of Record (four experiments) and Maris Piper (one experiment) in Scotland. Small seed (35 g) produced more above-ground stems and tubers and higher seed yields at equal seed rates than large seed (105 g). Increasing seed rate with both seed weights increased yield of seed-size tubers. The value of the seed crop was measured as the number of ware hectares which could be replanted from the yield of 20–55 mm tubers and calculated using recommended seed rates (Ministry of Agriculture, Fisheries and Food, 1982). Small seed produced more replantable hectares than large seed at equal seed rates in all experiments with Record and increasing seed rate increased the number of replantable hectares. However, when seed retained for replanting at the same seed rate was taken into account, small seed produced more replantable hectares only when total yield reached approximately 40 t/ha. Seed yield was much higher in Maris Piper than in Record and effects of seed weight were small. Increasing seed rate increased the number of replantable ware hectares but the effect was much reduced after retention of seed for replanting.

The effect of pricing policy for seed and ware on returns to the seed grower was also established. The sale of seed (and ware tubers) at fixed prices per tonne produced lower returns than selling seed at varying prices per tonne in relation to tuber size and equivalent to a fixed ware cost per hectare planted especially where seed yields were high. Delaying harvesting increased sale value but crops reached 85–90% of the final value before many oversize tubers (> 55 mm) were found and large yields of such tubers from low seed rates produced lower returns than from increased seed rates.

The number of ware hectares produced per seed hectare (even net of seed retained for replanting) was high especially in Maris Piper. The results show that the area devoted to seed potato production in U.K. is much too high for the ware area and the significance for the future of seed production is discussed.

Soya bean variety Semmes failed to nodulate with a number of R.japonicum strains. Some of these were applied to the seed in a carrier based on Nile silt.

A three-strain composite in peat gave good nodulation and reasonable N fixation. Inoculation significantly outyielded 100 kg N/ha added as urea in three equal portions at sowing, 1 and 2 months after sowing. Plant dry matter, nodule dry matter, yield, yield components and seed protein were also significantly enhanced by inoculation.

Phosphorus applied at 50 and 100 kg P2O5/ha in combination with a starter dose of nitrogen (10 kg/ha) with inoculation both gave erratic and inconclusive results.

Data are reported on a phenomenon in which piebald lambs having a coat of intermediate hairiness have black wool which is not only longer and coarser than the white wool on the same animal, but which has a different coat structure in terms of the fibre type array. Possible explanations for this effect which is apparently caused by the gene that restricts the production of pigment to certain areas of the skin are discussed. Hairy lambs and woolly lambs did not have this coat difference between the two colours.

The effect of three herbicides and an insecticide combination on nitrogen fixation in three paddy soils was investigated in a laboratory incubation study. The influence of pesticide combination on N2 fixation was evaluated in the presence and absence of rice straw under flooded and non-flooded conditions. In a non-flooded alluvial soil single or combined application of butachlor and carbofuran significantly stimulated N2 fixation. There was no effect on N2 fixation when thiobencarb was applied alone; but with thiobencarb in combination with carbofuran higher N2 fixation occurred. Both oxadiazone and thiobencarb had no effect on N2 fixation under flooded conditions, but in combination with carbofuran the N2 fixation was high. In acid sulphate saline Pokkali soil, rice straw application stimulated N2 fixation; the stimulatory effect of carbofuran either alone or in combination became more pronounced under flooded conditions. N2 fixation was low in a laterite Sukinda soil and the effect of pesticides was not changed by rice straw amendment. A uniform stimulation of N2 fixation occurred in soils when carbofuran was applied either singly or in combination with other herbicides tested. Results indicate that the effect of pesticides on N2 fixation varied with the rice straw application and water regime.

The effect of previous rotations maintained for 21 years on wheat and potatoes grown after 5 years of uniform cropping are described and discussed. Effects of length of ley in the rotation were detected in soil organic carbon, yield of wheat and yield of potatoes 6, 6 and 7 years respectively after the last ley was ploughed up. The effect of grazing the leys compared with mowing was detected in soil organic carbon and in yield of potatoes, and that of applying dung was detected in soil organic carbon and in yield of potatoes 12 and 13 years, respectively, after the last application.

Eighteen bulls were used to investigate the influence of feeding frequency on feed consumption, nutrient utilization and nitrogen metabolism in growing zebu cattle.

Results indicated higher feed intake, nutrient utilization and average daily live-weight gains for animals fed two or three times daily compared with those fed once daily. Feed efficiency and feed cost per kg gain as well as nitrogen metabolism also increased as the frequency of feeding increased from once to three times daily.

More frequent feeding could evidently be of practical advantage in intensive beef cattle production where zebu cattle are raised on tropical hay diets.

The effects of four irrigation treatments on the growth and yield of poppies were studied in two ‘drought’ seasons in Tasmania. Irrigation increased total dry-matter production, leaf area index and delayed leaf senescence in both seasons. Irrigation, which continued until leaf senescence, increased total morphine yield by 5–20 kg/ha compared with no irrigation. This yield increase was attributed to the increase in the number and yield of lateral heads, the yield of terminal heads and capsule morphine concentration.

As the effects of irrigation on head yield reflect the effects on total dry-matter production, irrigation guidelines for poppies were developed from an analysis of plant growth during theseason. For maximum yield, one irrigation of 50 mm should be applied at the 50% hook stage, at 50% flowering, at the end of flowering and 2 weeks after the end of flowering. Growers who currently cease irrigation at 50% flowering can expect yield increases of 4–13 kg/ha ifthey apply two further irrigations thereafter.

The effects of drilling date (18 August–22 September) on the growth and yield of oil-seed rape (Brassica napus) was studied in a series of five experiments over three seasons. Autumn and winter growth of the crop, as measured by dry weight of tops and leaf area, was severely reduced by delayed drilling, especially if it was later than 10 September. However, during the spring and early summer the differences in crop weight due to drilling date declined and in four of the five experiments there were no detectable differences in seed yield between early- and late-sown crops. The yield decline in the fifth trial was small. Measurements of components of yield showed that later-sown crops had fewer pods per plant and slightly smaller seeds but apparently more seeds per pod. The practical significance and reasons for the recovery of late drilled crops from early poorer growth are discussed.

Effects of plant density ranging from 44444 to 133333 plants/ha and tillage practices (planting in flat beds (control), in the furrows of open ridges, on the top of open ridges, in the furrows of tie-ridges and on the top of tie-ridges) on growth and grain yield of sorghum were investigated at Kobo, a typical semi-arid area in Ethiopia, during 1980, 1981 and 1982 cropping seasons. Plant growth was limited in the flat beds because they were likely to be deficient in soil moisture and sometimes in the tie-ridging treatments, due to waterlogging. However, planting on the top of tie-ridges produced 1·6, 0·4 and 1·8 t/ha more yield than in the flat beds, the method commonly practised by the Kobo farmers, during 1980, 1981 and 1982 respectively. In all seasons, the effect of plant density did not show marked differences. The plants rather adjusted their reproductive growth and development to the seasonal rainfall and presumably to the available soil moisture at the grain-filling periods. It was concluded that the highest plant density did not reach the optimum for the area. Planting sorghum on the top of tie-ridges is recommended.

A 2-year field study to investigate the potassium nutrition of groundnut in the lowland tropics showed that a low rate of K is beneficial to the crop. Applied K significantly increased leaf N, seed S, seed P, seed Fe, seed oil and protein content of groundnut. Leaf Ca significantly decreased with increased K application but K treatments significantly increased the seed and shell Ca. Potassium and Ca concentrations were highest in the leaf and lowest in the shell and seed respectively. The significant increases in shell P, shell Ca and shell Fe with increased K application would greatly improve the groundnut shell quality as an animal feed component. The relationship between seed oil and protein content was positive and significant.

Linkage was detected between brown planthopper resistance and anthocyanin or nonanthocyanin pigmentation in rice cultivars. The crossover values were: 21·9–37% for leaf sheath, 31% for junctura, 41% for auricle, 12·5–40% for ligule, 14·32–1% for leaf tip and margin, 19·7–37% for stigma, 19·7–36% for apiculus and 46·7% for pericarp colour. Genes governing resistance and black hull colour or glabrousness of leaf blade assorted independently. The genes identified and designated for brown planthopper resistance and pigmentation have been tentatively proposed to linkage groups II, IV and V.

Cell walls from mature stems of three tropical grass species (Digitaria decumbens (pangola), Setaria anceps (cv. Kazangula) and sugar cane), and temperate barley straw, were analysed for lignin, carbohydrate, and the maj or acyl groups ferulate, ρ-coumarate and acetate. Samples were incubated in nylon bags in the rumen of sheep in a 4 x 4 latin-square design, and rates of disappearance of cellulose, hemicellulose, xylose, arabinose, ferulate, ρ-coumarate and acetate were determined during 60 h incubation. Interspecies differences in cell-wall chemistry appeared largely in the variable degree of acylation with p-coumaric acid (1·0–3·3%) and acetate (0·5–3·6%), and the high glucose concentration in the hemicellulose from pangola (17%) and Setaria (9%). Barley had much lower concentrations of these components than the tropical species. After 24 h incubation, losses of cellulose and acyl groups were greatest from pangola, whereas hemicellulose and its major components xylose and arabinose were degraded to the greatest degree from barley straw. Setaria cell-wall components were generally more resistant to degradation than the other species. No relationship was found between the concentration of any cell-wall constituent and degradability measurements. Nor were changes in microbial population, indicated by measuring the accumulation of cystine on the fibres, related to the rate or degree of degradation of any of the measured cell-wall constituents. Lignin was fractionated with alkali into insoluble and soluble fractions. The latter (25–50% of original lignin) gave high interspecies correlations with the degradability of total hemicellulose and its component monosaccharides. It was concluded that variability in the biodegradability of the cell walls was more likely due to in situ structural features, such as cross-linking between polymers, than to the concentration of any particular cell-wall constituent.

Experiments were made over 2 years at two sites using three varieties to investigate the relationship between total yield, number of tubers > 1 cm and the yield of tubers in the 60–80 mmsize range. Regressionanalysisrevealed that yield of tubers in the 60–80 mm size range was a linear function of total yield and number of tubers > 1 cm. The effect of changes in tuber shape on this relationship is discussed.