Three pastures, pangola–clover, setaria, and tropical grass–legume, were grazed for a 9-month period by 12 steers of initial live weight of 199 kg on each. For the first 5 months live-weight gains were, respectively, 1·2, 0·76 and 0·43 kg per day, mostly higher than could be expected for estimated dietary energy concentrations of 10·1, 8·9 and 8·7 MJ of metabolizable energy (ME) per kg of dry matter. The high live-weight gains were not explained satisfactorily by dry-matter intakes as measured from faeces voided and dietary digestible dry matter, but were possible if published values for the requirements of ME for growth and fattening were too high. Cell wall, in vitro digested cell wall and nitrogen in separated leaf and stem fractions were useful indices for evaluating pasture for grazing cattle, but they did not predict live-weight gain.

Botrytis allii, grey mould, is the major cause of bulb and seed yield losses of growing onion seeds in Israel. Nursery treatments with iprodione or vinclozolin significantly decreased the number of diseased onion bulbs which were supplied to the farmers from 24% in the control to 8% in the treated plots and resulted in higher yield of seed with increases of 45% in seed weight per plant. Onion bulbs under non-irrigated conditions in the mountains were found to be more susceptible to the disease, as well as to secondary infection, than irrigated onions that were grown in the plains. Chemical treatment of the bulbs before planting significantly reduced the rate of secondary infection in the field and decreased seed losses. The survival of B. allii propagules and their importance as a primary source of inoculum in growing onions for seed were studied in the central mountainous region of Israel. From 197 to 1532 B. allii propagules per g soil were found in the field plots, this as the result of only one season growing onion seed. Ninety-one per cent of the total planted healthy bulbs were infected in the highly contaminated plots after 150 growing days. The surviving B. allii propagules reduced the seed yield, from 14·4 in the less contaminated plots to 10·4 g/plant in the highly contaminated.

Three adjustment methods using control plots to adjust for soil variation in a modified augmented design (Lin & Poushinsky, 1983) were studied by simulation. The results show that adjustment by design structure (row and column correction factors) is best when soil variation is relatively uniform in one or two directions, while adjustment by regression analysis is best when the variation is multi-directional. Adjustment using the control plot as a fertility index is least satisfactory. A modified augmented design in a replicated experiment is generally inferior to a balanced lattice square design but is competitive when the percentage of environmental variation attributable to soil factors is less than 70% of the total variation.

Yield variability of spring barley and winter wheat varieties is investigated in National Institute of Agricultural Botany trials sown to assess the influence on varieties of fungicide treatment. The extent of the variation in relative variety performance due to years and centres is estimated for untreated and treated yields and for yield response to fungicide. The consequences for the design of future trials systems are considered.

The incidence of lamb mortality from birth to 8 months of age has been studied over a 6-year period in an upland, grassland flock of sheep comprising the Scottish Blackface, Cheviot and Welsh Mountain breeds and the crosses among these breeds. Each breed and cross-bred type was maintained at varying levels of inbreeding. Approximately half the lambs which died were stillborn or dead on the day of birth, nearly 40% died thereafter but before weaning and about 10% after weaning.

Post-mortem examinations on 586 of the 632 lambs which died from among the 2453 born attributed death on average to two causes per lamb. Approximately 11% of the causes were stillbirths or delayed births; 11% were cases of dystokia; congenital defects of various types accounted for about 10% of the causes; 25% made reference to weakly lamb, exposure or starvation; 14% to infectious diseases and 16% to noninfectious diseases. The extent to which causes of death occur together is examined.

Breeds differed in mortality rate with the Welsh the lowest and Cheviot the highest. Cross-breds were better than the average of the pure breeds but this advantage emerged only in the period between 3 days and. 6 weeks of age. Inbreeding, both of dam and of lamb, increased mortality. Lambs from dams which were crosses of inbred lines had the best survival. Litter size, type of rearing, parity of dam, sex of lamb and birth weight also had significant effects on mortality rate.

The incidence of a number of causes of death of lambs around the time of birth was examined in relation to breed, inbreeding, birth weight, birth type, sex of lamb, week of birth and parity. Data were from a grazing flock on an upland farm over a 6-year period. The breeds were the Scottish Blackface, Cheviot, and Welsh Mountain and the crosses among them. Each breed and cross was maintained at five levels of inbreeding ranging from zero to 59% inbreeding coefficient.

The incidence of delayed birth varied significantly among the breeds and crosses with the Welsh having the lowest incidence. Compared with the pure breeds the crosses showed a lower incidence of both delayed birth and preparturient deaths, but significantly only for the latter.

Dystokia was classified according to whether it arose from the relative dimensions of lamb and dam or from malpresentation. For both types the heaviest lambs had the highest incidence but the association with birth weight was much stronger for dystokia involving dimensions. Breed variation was not significant, but cross-breds had the highest frequency for the dimensions category and the lowest for malpresentation. Singles were at greater risk than twins as were lambs born to a first parity.

Congenital defects as a cause of death were divided into six categories. Only skeletal defects varied significantly among breeds and the incidence increased with inbreeding, but crosses of inbred lines did not have the lowest frequency. For congenital defects overall and for hydrocephalus and hydronephrosis in particular, line crosses (noninbred) had the lowest incidence and 25% inbred lambs the highest, the frequency declining with further inbreeding. None of the other factors considered affected variation in the incidence of any of these defects to a significant extent.

Liver rupture and brain haemorrhage were most frequent in heavy lambs, singles and lambs born to a first parity dam.

The incidence of lamb mortality from weakness at birth, underdevelopment, exposure and starvation was examined over 6 years in an upland flock and analysed in relation to breed, breeding system and other factors. These causes accounted for more than a quarter of the deaths and contributed to many more.

The frequency of death due to these causes was greater in lambs light at birth. The incidence of these causes of death differed significantly between the breeds, Scottish Blackface, Cheviot and Welsh Mountain and their crosses, but for the separate categories breed variation was significant only for the incidence of death by starvation, which was also less frequent in cross-breds than purebreds. Mortality from several of these causes was increased by inbreeding (25–59%), but decreased by crossing inbred lines. Lambs born to line-cross or other non-inbred dams had a relatively low incidence of these various causes of death. For underdeveloped lambs variation due to maternal inbreeding was significant. When classes were adjusted for difference in birth weight, breed variation in mortality was greatly enhanced but variation due to inbreeding much reduced.

Slightly more twins than single-born lambs died from these causes and triplets fared worst, but such variation was significant only for death from exposure. Mortality from these causes varied significantly with parity of dam, being highest in the first, and mortality in males was slightly but not significantly higher than in females.

The incidence of various infectious and non-infectious diseases as causes of death in lambs up to 8 months of age was studied in relation to breed, inbreeding and other factors. The data from an upland grazing flock covered 6 years and involved the Scottish Blackface, Cheviot and Welsh Mountain breeds and the crosses among them.

Infectious and non-infectious diseases were directly responsible for almost a quarter of the mortality and their presence contributed to many more deaths. The organisms mainly responsible were Escherichia coli, Pasteurella spp. and Fusobacterium necrophorum.

The incidence of infectious diseases in general and enteritis in particular varied significantly between the breeds and was lower in the cross-breds than in the purebreds. Variation between the breeds in the incidence of non-infectious diseases was statistically significant only in respect of digestive upsets for which there was a similar ranking of breeds to that for infectious disease.

Inbreeding of the lamb (25–59%) significantly increased the incidence of infectious diseases, especially respiratory diseases, but not of non-infectious diseases. There was little difference between singles and twins in susceptibility to disease. The lower the birth weight of the lamb the greater the risk, particularly of non-infectious disease.

Diurnal and seasonal changes in the total, osmotic and turgor potentials of winter wheat leaves are compared in two seasons of mild and severe soil water stress. Gradients of total water potential in the soil-plant system are also presented. In both seasons the total water potential of the leaves decreased in parallel with the soil water potential, concurrently leaf osmotic potential also decreased sufficiently to maintain positive leaf turgor potential. Eventually, under severe water stress, soil water potential approached –1·5 MPa and leaf turgor potential tended to zero during the middle of the day.

The potential drop across the soil-root system was twice that along the stem. Estimates of the water potential at the root surface varied diurnally and were often lower than the bulk soil water potential. In dry soil plants were unable to equilibrate with the soil water potential overnight. These results are consistent with the existence of significant resistance to water flow across the rhizosphere.

A simple model is presented which can account for the hysteresis observed in the relationship between leaf water potential (χ1) and water flow per stem (Q) in winter wheat. Using this model the total hydraulic resistance (R) and capacitance (C) of the soil-plant system were estimated from measured diurnal changes in χ1 and Q. Daily mean values of R were constant when the soil water potential (χ1) was above – 0·6 MPa, but R increased by about 40% when the soil dried to – 1·5 MPa. R also appeared to vary during the day, increasing in the afternoon and evening.

The results of experiments on the recovery of χ1 in plants from which transpiration was prevented suggested that the major resistance to flow was in the soil-root system and that it was an increase in this resistance which gave rise to the overall increase in R as the soil dried.

There was substantial variation in the estimates of hydraulic capacitance (C) and no systematic diurnal or seasonal trend was evident. Despite the variation in C the mean value for the season, 8 x 10-7 m3/MPa, predicted realistic changes in plant water storage. Estimates of the components of C indicated that the major capacitance was located in the soil-root complex. More information is needed about the components of R and C, particularly those in the soil-root system.

Experiments are described which study the effect of density and chop length on the rate of diffusion of oxygen into silage and equations are presented which enable the rate of diffusion to be calculated under laboratory conditions. The concept of zero porosity is also discussed and methods of calculating the density at which it occurs are given. The effect of carbon dioxide on the rate of diffusion is also discussed.

Nitrosoguanidine-induced acid-tolerant mutants S1 and M1 of Lens esculenta Rhizobium leguminosarum were used for nodulation and symbiotic N2-fixation in acid soils having different pH and associated factors of acidity. The range of soil pH and associated acidity factors in which nodulation and N2-fixation responded varied, depending on mutant strains. However, strain M1 was more responsive and effective than S1. Antagonistic effect of Mn to Fe was found when the active Fe2+ and total Mn were determined in fresh nodules.

An experiment is described which investigated the combined effects of fertilizer nitrogen and a medium-large-leaved variety of white clover on the production from a mixed sward. Over a period of 3 years six rates of nitrogen fertilizer ranging from 0 to 750 kg/ha were applied annually on three different sward types cut five times per year. The swards consisted of S. 23 perennial ryegrass alone, S. 23 ryegrass plus Blanca white clover, and Blanca white clover alone. Averaged over the 3 years the nitrogen rate required on the pure-grass sward to give the same yield of dry matter as the grass plus Blanca clover sward with no fertilizer nitrogen applied was 265 kg/ha; the corresponding application rate to achieve equal crude-protein yield was 322 kg/ha. Blanca had an additive effect on the yield from the mixed sward at nitrogen rates up to at least 300 kg/ha. The results from this experiment are compared with those from experiments in which medium-small-leaved varieties of white clover were used. The role of white clover in providing savings in nitrogen fertilizer input on grassland is discussed. Estimates from the results indicate that the nitrogen rates required to produce an annual herbage dry-matter yield of 12 t/ha were 340 kg/ha on the pure ryegrass swards, and 140 kg/ha on the ryegrass plus Blanca sward. The nitrogen fertilizer saving due to the inclusion of Blanca white clover in the sward was, therefore, 43%. A similar estimate from the results of an earlier experiment with the medium-smallleaved variety Aberystwyth S. 100 suggests a nitrogen fertilizer saving of 21%.

Results relating to a 4-year study of early reproductive traits in traditionally managed flocks of indigenous goats and sheep under semi-arid conditions are reported. Mean weights (least-squares estimates) at first conception of 16·9 kg for goats and 23·4 kg for sheep were recorded, and animals raised under the better environmental conditions of the irrigated rice system had a 2·2 kg advantage at this stage over animals raised under the rainfed millet system. Animals from young and old dams were heavier at first conception than those born of middle-aged dams. Neither season of birth nor type of birth (single or multiple) had any effect on weight at first conception. Age at first parturition was 443 days and at second parturition was 709 days. Animals born of young and of old dams were later at both first and second parturitions than those born of middle-aged dams while age at first parturition was younger for those animals reared in the rice system. Age at first parturition was within the range normally found for these types of animals under these environmental and social conditions. An early first parturition, even with a high death rate of offspring, may contribute to a greater total lifetime production than a later parturition with a lower death rate.

One hundred and forty different varieties of grass, from seven species, were harvested in spring, in 1, 2 or 3 years, at a D-value of 67 and dried at 25 °C. Moisture content was determined every 3 h for at least the first 48 h and less frequently thereafter until the grass was about dry enough to store as hay.

Rate of drying was in the order tall fescue > Italian ryegrass = meadow fescue > timothy = cocksfoot > perennial and hybrid ryegrass. The perennial and hybrid ryegrass took twice as long to dry as did tall fescue. Tetraploid varieties of the ryegrasses took appreciably longer to dry than the diploid varieties. Apart from this there were some differences between varieties within a species in rate of drying. Differences in moisture content at cutting, in the proportion of leaf blade and in the number of leaf sheaths per ‘stem’ may have accounted for some of the differences between species and varieties in rate of drying. Further research is suggested.

The effect of pesticides on nitrogenase activity in rhizosphere soil from rice fields was investigated. The differential response of insecticides on nitrogenase depended on the method of field application. Results also showed that the differential response to the pesticides of. specific groups of nitrogen-fixing micro-organisms depended upon the method of application.

Soil incorporation of carbofuran stimulated the rhizosphere nitrogenase, while endosulfan and hexachlorocyclohexane inhibited it. Carbofuran and hexachlorocyclohexane stimulated nitrogenase when applied to the standing water. Seedling root dips of isofenphos stimulated nitrogenase, while endosulfan, BPMC and carbaryl showed a variable effect. Quinalphos inhibited nitrogenase irrespective of method of application.

Accessions of green and dry-podded Phaseolus vulgaris beans were tested for resistance to seven isolates of bean yellow mosaic virus (BYMV) originating from a wide geographical area. Based on their level of resistance, the beans could be divided into four groups, (i) accessions with a high level of resistance to most BYMV isolates; (ii) accessions containing previously known sources of resistance in germplasm derived from the cv. Great Northern, which were mainly susceptible to the BOS 25 isolate, but had high levels of resistance to most other isolates; (iii) and (iv) groups showing increasing levels of susceptibility with the accession Red Mexican (common) the most susceptible bean tested. The seven BYMV isolates induced distinct reactions when inoculated to arange of plant species, indicating that they possessed different pathogenicity genes.

In Expt 1, four groups of seven hypocupraemic ewes were repleted with a semipurified diet containing 7·2 mg Cu, 3·5 gS and 0·5, 2·5, 4·5 or 8·5 mg Mo/kg D.M. as ammonium molybdate for 65 days. The first increment in Mo caused the largest reduction in plasma Cu repletion and the second completely inhibited repletion but the final increment led to a partial recovery. The highest Mo level caused marked increases in plasma Mo and reduced rumen sulphide concentrations.

In Expt 2, five groups of four hypocupraemic ewes were repleted with hays containing 7–8 mg Cu, 3–3·4 g S and 0·4, 2·8, 4·3, 14·2 or 18·7 mg Mo/kg D.M. for 21 days. The hays were made in June from pasture sprayed earlier with 0–800 g Mo/ha as sodium molybdate. Qualitatively the changes in plasma Cu distribution and Mo content showed the same curvature with increases in dietary Mo as those in Expt 1.

In Expt 3, four groups of five hypocupraemic ewes were repleted on pastures which had received a spring foliar dressing of 0–800 g Mo/ha. Herbage in the four plots was grazed in July, when it contained 0·7, 3·5, 5·9 or 12·4 mg Mo, 6'4 mg Cu and 2·7 g S/kg D.M. and again in September. Quadratic responses to Mo were demonstrated on both occasions, but, for a given Mo level, responses in caeruloplasmin synthesis were much lower than in Expt 2.

It is concluded that Cu absorption is inhibited most by 4–6 mg Mo/kg D.M. and that inhibition of S2- production at higher Mo levels may give rise to a recovery in Cu absorption. Semi-purified diets give responses which lie roughly between those for fresh herbage and hay.

Twenty-seven Hereford weaner steers (mean age 11 months, and live weight 142±17 kg) were used to study the effect of supplementation of an energy-rich grain (sorghum), and/or a protein meal on the live-weight change of cattle on a basal diet of low-quality grass hay over 48 days (Expt 1). The basal hay had an estimated energy value of 6·2 MJ metabolizable energy (ME)/kg dry matter (D.M.) and a nitrogen content of 6·2 g/kg D.M. Corresponding values for the sorghum supplement were 12·4 and 14·4, and for the protein meal 9·6 and 65. The daily rates of supplementation in Expt 1 were (g/head) 0 (nil), 600 (P1) or 1200 (P2) of protein meal pellets or 0 (nil), 560 (S1) or 1120 (S2) of sorghum and all combinations of P1 or P2 with S1 or S2. The carry-over effect of such supplementation on subsequent growth was recorded in Expt 2 when the steers grazed a kikuyu grass pasture for 100 days.

In Expt 1, organic-matter intake of hay (HOMI) was increased (P < 0·01) by protein but decreased (P < 0·01) by the sorghum supplements. By 48 days, P1-supplemented steers were eating 29·5% more hay than non-supplemented steers, and P2 steers were eating 43·5% more hay than the non-supplemented steers. S1 supplemented steers were eating 29·5% less, and S2 steers 23% less hay than non-supplemented steers. Steers lost weight on the basal hay diet, and at the lower level of sorghum (S1) supplementation, but were able to maintain weight at the higher level (S2) of supplementation. In contrast, steers supplemented with protein gained weight (P < 0·01): 430 g/day on P1 and 700 g/day on P2 treatments. None of the steers offered combinations of P and S had live-weight changes as high as those offered only protein supplements. There was no evidence of compensatory gain by the smaller steers in Expt 2 when grazing and unsupplemented.

Glucose kinetics in plasma were studied in each steer on day 35 of Expt 1 by means of a single intravenous injection of [2-3H]glucose. The quantity of glucose in the sampled pool and the total rate of glucose entry into the pool (GER) were higher (P < 0·01) in steers that were protein supplemented, with GER being related to both ME intake and to N intake per unit ME intake.

Urea pool size and entry rate were also estimated on day 35 of Expt 1 using a single intravenous injection of [14C]urea. The quantity of urea in the sampled pool, and entry rate into the pool were increased significantly (P < 0·01) by protein, but reduced (P < 0·05) by sorghum, supplementation. Rumen ammonia concentrations were low in steers given the hay alone, and when supplemented with sorghum (10–15 mg N/l), but were significantly higher (70 mg N/l; P < 0·01) during protein supplementation.

It was concluded that growth of cattle on the basal ration was restricted by low voluntary intakes of hay. Intake was increased substantially by protein supplementation. The consequent increase in live weight was due to a greater intake of organic matter which was accompanied by a greater synthesis of glucose and availability of amino acids in the animals.

In the Mediterranean region, chickpeas are traditionally spring-sown since humid winter conditions encourage the development of Aschochyta blight which often causes complete crop failure. Lines resistant to this blight have been selected at the International Centre for Agricultural Research in Dry Areas (ICARDA) and thus winter planting has become feasible. The best selection, ILC 482, was sown in both winter and spring at three locations in northern Syria with contrasting precipitation patterns. Crop growth and soil moisture analyses were undertaken on all treatments, and relevant meteorological data were collected at each location. At all locations maximum greenarea and dry-matter production of the winter-sown crop was nearly double that of the spring sowing. Large differences were also observed between sites, with green-area and dry-matter production decreasing with precipitation. Depth of profile recharge, amount of extractable moisture and crop evapotranspiration also decreased with precipitation, but only small differences in these moisture variables were observed between winter and spring sowing. Duration of green-area production, as determined by the onset of rapid leaf senescence, was closely related to the fraction of extractable moisture in the soil profile, rapid senescence occurring in all treatments when extractable moisture fell below 40% of its maximum value. Differences in the maximum rates of green-area production are discussed both in relation to the depth of profile recharge, hence the depth of rooting and moisture extraction and to the ambient evaporative demand. The differences observed in green-area and dry-matter production was clearly reflected in final seed yield. The components of yield, number of pods, percentage of empty pods and seed size are related to the variations in moisture stress experienced by the crop.