A pot experiment studied the effect of gypsum and green manuring on equilibrium soil solution pH, pE, Mn concentration and Mn equilibrium in three sodic soils. Submergence decreased soil solution pH and increased Mn concentration in all the soils. Addition of gypsum with green manure further decreased soil solution pH and increased Mn concentration. Maximum Mn concentration in all the treatments was observed at 4 weeks of submergence in Kaheru soil and at 6 weeks of submergence in Jagjitpur and Langrian soil followed by a decline up to 12 weeks. In spite of wide variations in pH, pE and Mn concentration in soil solutions, the solubility of Mn after peak values appeared to be mainly controlled by the MnC03-Mn2+ system irrespective of the treatments, and the Mn2O3-Mn3O4 system appeared to operate after 2 weeks of submergence in the control and gypsum-treated soils.

Two experiments examined the effect of improving the distribution of the pigeonpea plants in sorghum-pigeonpea intercropping by having an alternate row arrangement of the two orops (SP) instead of the two sorghum: 1 pigeonpea row arrangement (SSP) that was studied earlier. One experiment was under conditions of good moisture supply (a deep Vertisol site in the high rainfall year of 1978) but the other experienced early moisture stress and had much lower end-of-season soil moisture storage (an Alfisol site in 1979). In 1978 the proportional sorghum yield was not affected by row arrangement (86 and 85% of the sole crop yield for the SSP and SP treatments respectively). Under the drier Alfisol conditions of 1979, the proportional sorghum yield was lower, probably because of the increased competitive ability of the drought resistant pigeonpea, and it was adversely affected by the alternate row arrangement (72% for SSP and 60% for SP).

Compared with the SSP arrangement, the SP arrangement increased the level of light interception by the intercropped pigeonpea immediately after the sorghum harvest from 30 to 48 % in 1978 and from 44 to 60 % in 1979; the total energy intercepted during the whole post-sorghum period was increased by 23 and 12 % in the 2 years, respectively. However, these improvements in canopy cover were associated with only small increases in total dry matter of the intercropped pigeonpea at final harvest, from 69 to 74 % of the sole crop in 1978 and from 60 to 65 % in 1979. The increase in seed yield was even less than that in total dry matter in 1978 (from 90 to 93% of the sole crop) but similar in 1979 (71 to 76%); the value of this increase in 1979 was insufficient to offset the decrease in sorghum yield. None of the increases in total dry matter or seed yield of pigeonpea reached significance. It is concluded that with a good moisture supply alternate rows could be an alternative to the 2 sorghum: 1 pigeonpea arrangement, though it offers no additional yield advantage. With poorer moisture supply, alternate rows are not a worthwhile option because of the risk of reducing sorghum yield to an extent that cannot be offset by the small increase in pigeonpea yield.

Two experiments were conducted with eight rams in a latin-square design of four treatments with different lucerne hay (LH): maize grain (MG) ratios: 100:0, 80:20, 50:50 and 20:80. In Expt 1 the amount of food offered was restricted to 1 kg/day. In Expt 2 the rams were offered 1·5 kg/day, which was about the maximum amount the animals in the 100% LH treatment were able to consume. Animals were kept on each treatment for 4 weeks; during the final 8 days the faeces were oollected and weighed for each animal and analysed for dry matter, organic matter (OM), crude fibre and δC

The values of δC in LH, MG and different faeces samples were used for direct determination of LH and MG digestibilities of mixed diets in the different treatments.

The increase of MG in the ration and the decrease of LH improved the digestibility of total OM. The effect of MG was more pronounced at the low than at the high level of consumption. At the low level of intake, an increase in the amount of MG in the ration did not affect the digestibility of LH, and MG digestibility was close to the extrapolated value. At a food intake level 1·5 times that of Expt 1, the addition of grain to more than 50 % of the ration caused a marked depression in digestibility of LH.

Results of the δC method were discussed in comparison with calculated values of LH and MG digestibilities and with whole ration crude-fibre digestibility.

In the 350–600 mm seasonal rainfall ecological zone in northern Syria three-course rotations are commonly practised under rainfed conditions. The precipitation regimes at three sites in this ecological zone have been examined. These have been shown to exercise a powerful influence on crop management, and an enhanced understanding of the effect of precipitation on crop productivity would therefore assist in the development of improved strategies of agronomic and rotational management. Considerable variability has been demonstrated in characteristic elements of the precipitation regime at the selected sites and this has indicated the unsoundnesa of applying general management recommendations to the ecological zone as a whole.

To evaluate the effects of chronic environmental heat stress during mid-gestation on gravid uterine and foetal metabolism, mature Hereford cows were assigned to control (n = 8) or heat stress (n = 5) treatments beginning on day 100 of gestation. Uterine and umbilical blood flows were estimated by the steady-state diffusion procedure on day 169 ± 4 of gestation. Oxygen (O2), glucose, lactate, α-amino nitrogen and urea nitrogen concentrations were determined for uterine and umbilical blood samples collected during this procedure. Foetuses and foetal fluids were collected on day 174±4.

Uterine and umbilical blood flows were reduced and foetal weight also was less for heat-stressed than for control cows. In addition, foetal liver weight as a proportion of foetal weight and total foetal liver RNA and protein were less for heat-stressed cows. Uterine and umbilical arterial–venous concentration differences in metabolites were similar between the two groups. Uterine, foetal and utero-placental uptake or secretion rates of the metabolites measured in this study were reduced in the heat-stressed cows, primarily because of differences in blood flow. Thus, chronic heat stress during mid-gestation had an adverse effect on foetal development resulting, at least in part, from decreased uterine and umbilical blood flows, which led to a reduction in uterine, utero-placental and foetal nutrient uptake or secretion rates.

On 13 pastures grazed by beef cattle live-weight gain (range, 0·34–1·12 kg/head/day) was significantly correlated with non-green grass content of pasture. In turn, non-green grass in pasture was not significantly correlated with non-green grass in oesophageal extrusa. Live-weight gain was largely explained (adjusted R2 = 0·91) by non-green grass content of pasture, cell-wall content of green-grass leaf and pasture dry matter on offer in a quadratic model. The quadratic form was best understood in terms of pasture growth with which non-green grass content of pasture was significantly and negatively correlated.

Upward flux of water and deep-placed (8–10 cm) P was studied in columns of sandyloam and silty clay loam, with water tables of 60 and 90 cm, each subjected to potential evaporation rates of 2–2 and 7–5 mm/day, for 15 days. An amount of 300 mg P/kg soil, labelled with 20 /tCi 32P/g P, was applied as diammonium hydrogen orthophosphate.

Evaporation losses increased with increase in potential evaporation (PE) and decrease in depth to water table in both soils, but the ratio of actual to potential evaporation (AE/PE) decreased with increasing PE, indicating that the evaporative losses in both the soils were mainly controlled by their hydraulic conductive properties. Under no circumstances did AE equal PE. Evaporation, in general, was higher from sandy loam than from silty clay loam.

Corresponding to water flux, total upward P flux increased with increasing PE and decreasing depth to water. In the sandy loam, with 2–2 mm PE/day, 21 % of the deepplaced P moved to the soil surface with the 60 cm water table, against 5 % with the 90 cm water table. Under 7–5 mm PE/day, 39% P migrated to the surface with the 60 cm water table, but no 3aP was detected at the surface with the 90 cm water table. In the silty clay loam, however, P movement was much restricted.

Twenty-nine bunch groundnut genotypes were grown in the Kharifseason 1980 and the summer season 1981 at Bangalore. Growth and yield analysis showed that the total dry-matter accumulation was low up to 30 days after sowing and increased linearly up to the 86th day in the Kharifand up to harvest in the summer season. There were significant differences between genotypes in leaf area indices (LAI), the leaf area duration (LAD) and LAD between pod initiation and harvest (LADP) in both the seasons. The mean LAI of genotypes did not vary much between the Kharifand the summer seasons up to the 66th day. However, during the later stages of growth the LAD was higher in the summer. The higher biological yield and productivity in the summer was attributed to the high LAD and LADP during the later stages of crop growth. LAD and total dry-matter accumulation at harvest were significantly correlated both in the Kharif(r = 0–75) and the summer (r= 0–81). The mean total number of flowers over all 29 genotypes did not vary, but total number of pegs formed per plant differed significantly between genotypes in both the Kharifand summer seasons. The percentage of flowers which produced pegs was 72–2 in summer as against 51–2 in Kharif. The primary branches contributed 86'7 and 90–1 %to the total number of pods per plant in the Kharifand summer seasons respectively. The contribution of the first four nodes of primary branches was 85 %in both seasons. The number of fruiting points (nodes having mature pods) per plant, found to be the most important yield-determining component, showed significant variation amongst the genotypes in both the Kharifand summer seasons. In summer, length of mature-pod-bearing zone (MPBZ), number of nodes in MPBZ and number of kernels per plant were higher than in the Kharifseason. It is suggested that selection and breeding should concentrate on improving LAD and LADP, total dry matter per plant, more primary branches per plant, more pods in the distal nodes of primary branches and more fruiting points (nodes in MPBZ) per plant.

Predictions of nitrogen, oil and glucosinolate concentration in rapeseed samples were made by near infrared reflectance analysis after various grinding treatments. Also examined were the effects of normalizing reflectance data and the possible advantage of using all combinations of two and three wavelengths in the calibration regression analysis over forward stepwise regression. The main conclusion was that drying the samples prior to a controlled grinding treatment gave the best results, although acceptable results for selection purposes could be obtained using whole seeds to predict nitrogen and oil. None of the treatments of the seed or reflectance data allowed acceptable prediction of glucosinolate content.

Plants of Cucurbita pepoL. cvs Cinderella, Cobham Bush Green and Goldrush were inoculated with cucumber mosaic virus (CMV) and some grown at each of three temperatures (15, 20 and 25 °C) and three light intensities (13, 40 and 120 W/ma). Symptom severity in all three cultivars decreased with increased temperature but only for ovs Cinderella and Cobham Bush Green when the light intensity was raised. In general ov. Cinderella was most resistant and cv. Goldrush most susceptible, except at 25 °C, when most plants were symptomless.

A total of 15 rumen-cannulated sheep and four rumen-cannulated goats (Expt 3) were used in five latin square experiments designed to investigate the effects of carbohydrate supplements on ruminal ammonia concentration in animals given grass silage diets. In Expt 1 barley supplements were given at the same time, 1 h before or 2 h before a meal of silage. The treatments were designed to alter the synchronization between energy release from fermentation of barley and ammonia release from the degradation of silage N compounds. As compared with the unsupplemented control diet, barley supplements reduced (P < 0–05) rumen ammonia concentration and increased (P < 0–01) the number of total protozoa, but the time at which barley was given was without effect. In Expt 2 animals receiving silage or silage-barley diets were defaunated chemically. This treatment led to a 20–25 % reduction in rumen ammonia concentration. In Expt 3 supplements of maize starch, glucose and sucrose were compared. Mean ammonia concentrations were 231 mg/1 for the control unsupplemented diet and 205, 155 and 160 mg/1 (S.E. 21) for the starch, glucose and sucrose treatments. Corresponding numbers of protozoa were 7–7, 15–1, 6–1 and 6–3 x 10s/ml (S.E. 1–8). In Expt 4 the diets were unsupplemented silage or the same diet plus supplements of sucrose or xylose. Xylose reduced ammonia concentration more than sucrose, the values (mg/1) being 236 (control), 206 (sucrose) and 125 (xylose) (S.E. 19). There was no difference between the supplements in numbers of protozoa. Xylose induced a smaller reduction in pH, a higher (P < 0–05) proportion of acetate and a lower (P < 0–05) proportion of butyrate in rumen fluid than did sucrose. Effects of rumen pH were examined in Expt 5 where supplements of sucrose were given alone or together with NaHCO3. Rumen pH values were 6–38 for the control unsupplemented diet and 5–99, 6–28 and 6–55 (S.E. 0–06) for the diets supplemented with sucrose, sucrose plus 50 g NaHC03 and sucrose plus 100 g NaHCO3. Corresponding values for ruminal ammonia were 193, 151, 93 and 41 mg/1 (S.E. 10). Differences in VFA proportions between sucrose treatments were small and significant (P < 0–05) only for butyrate. It is concluded that there are important differences between carbohydrate sources in their effects on nitrogen metabolism in the rumen. Differences between starch and sugars appear to relate to the influence of the carbohydrates on the microbial population of the rumen, as was indicated by the differential effects of the carbohydrate sources on the number of total protozoa; differences between sugars appear to depend in part on the rates of sugar fermentation and the associated reduction in rumen pH.

Chick pea Rhizobiumstrain RG 4 was treated with 30 /tg/ml of N-nitrosoguanidine and four mutants isolated were resistant to 400 /tg carbendazim/ml. Only two of the mutants (M 1 and M 4) retained the capacity to form nodules. On the basis of number of nodules, their dry weight, nitrogenase activity, triphenyl tetrazolium chloride reductase activity and active iron content of nodules, mutant strains M 1 and M 4 were found to be equally effective for nitrogen fixation both with and without carbendazim (bavistine) and resulted in significantly greater grain yield than the corresponding uninoculated treatments.

Brassica oil seeds grown in India are occasionally damaged by frost, causing severe losses. A technique was developed to screen germplasm at the seedling stage. Twentyfour lines of B. campestris, B. juncea and B. napus were grown in plastic boxes in a glasshouse in a mixture of peat and sand. The seedlings were frozen after hardening for 2 days at 1 °C. Observations were recorded after 4 days, using a five-point scale. Frost tolerance index (FI) is calculated as the average value for injured plants for each line. Eight lines for each of the three species were tested. B. campestrisas a group showed better frost tolerance. Some lines of Indian mustard also showed good tolerance of low temperature (– 5·5 °C). These findings show good agreement with observations recorded in the literature. The method is detailed and discussed. Suggestions for future programmes are made.

The cellulolytic activity of cell-free extracts of 15 species of entodiniomorphid protozoa grown in vitro and under two conditions in vitrohas been measured using six different assays with substrates varying in complexity from carboxymethylcellulose to microcrystalline cellulose. Although there were differences between the assays, the highest activities were found in Eudiplodinium maggii, Epidinium ecaudatum caudatum and Ostracodinium obtusum bilobum with little or no activity in five Entodiniumspp. There was no consistent effect of growth conditions on cellulase content although with protozoa grown in vitro those grown on grass alone tended to contain more cellulase than those grown on starch and grass.

A survey of methods for the release of cellulase from other rumen fractions was made and mild treatment with ultrasound of the fraction suspended in water gave the maximal release of enzyme with the highest specific activity. Using this method 62% of the total rumen cellulase was found in the protozoal fraction and 27% was associated with the plant debris in a normal sheep, fed on hay and oats, with an A-type protozoal population.

Suckled single lambs, 6 weeks of age at slaughter, were used to study the melting point, iodine value, fatty acid composition and softness index of carcass fat. The lambs, born in mid-October in central Greece, were suckled from birth to slaughter and received no supplementary feed. They consisted of 43 Sarakatsaniko, 22 Karagouniko and 29 Chios x (East Friesland x Karagouniko). At slaughter, samples of subcutaneous fat from the base of the tail and perinephric fat were removed and stored at – 10 °C until analysed.

Melting point and iodine value were determined by the Association of Official Analytical Chemists (1980) and International Union of Pure and Applied Chemistry (1977) methods of analysis. Gas-liquid chromatography, on 12% diethyleneglycol succinate as stationary phase, was used for fatty acid methyl esters analysis. Softness index was calculated.

Component fatty acids in decreasing order of proportion in total fat were oleic, palmitic, stearic, myristic, palmitoleic, linoleic, linolenic, lauric and capric acids. The total of odd-numbered n-acids and branched chain acids occupied a position approximately mid-way. There was very little evidence of differences between the sexes. However, the differences between the two fat depots and those between breeds were significant in most of the traits. Significant correlations between some of the traits studied and also linear regression equations between selected variables were obtained.

Digestibility trials were carried out with five individuals each of domesticated oryx, sheep and cattle, using three diets ranging from 12·5 to 7·4% crude protein. Feed intake, water consumption and urine production were measured.

Intakes of dry matter (as g/day or g/kg W0·75/day) did not differ between diets for any species. On a metabolic weight basis the sheep and oryx ate the same amount. The cattle ate more than the sheep of all three diets, and more than the oryx in two of the three.

For all three species, digestibility of dry matter, crude protein and crude fibre was lower when the lower quality food was given. On any single diet, significant differences in digestive efficiency for any diet component between species were few and small.

Total daily intakes of water (ml/kg W0·85/day) were lower for each species when eating the diet with the lowest protein content. On each diet total intakes were significantly different in the decreasing order cattle > sheep > oryx, in the mean ratio 3·3:l·7:10.

Urine production (ml/kg W0·85/day) varied slightly between diets for each species. On each diet the cattle produced significantly more urine than the sheep or oryx. The ratio of urine produced to water drunk decreased in the order oryx > cow > sheep, in the mean ratios 0·63, 0·34 and 0·27. Despite some interspecific differences in nitrogen concentration, there were few differences in the proportion of total excreted nitrogen that was lost through the urine.

Calculations of evaporative water loss showed that loss of water by this avenue was significantly less in oryx than in sheep or cattle, which did not differ significantly.

In the absence of any evidence of a more efficient digestion, the low metabolic intake of food by oryx suggests a low metabolic rate. The oryx's low water consumption and small evaporative loss are obvious adaptations to its desert habitat.

Observations on oryx, sheep and cattle under natural grazing conditions in both a wet and a dry season are given and discussed.

Dry faecal outputs by the sheep and oryx were less in the wet than in the dry season. Output by the cattle was greater than both, and showed little seasonal difference. Faecal nitrogen concentrations showed no interspecific overlap, in the rank order sheep > oryx > cattle. All were greater in the wet season, and the rank order maintained.

Drinking water intakes were similar for oryx and sheep in both seasons. The cattle's water intake was greater in the wet season. Expressed as ml/kg W0·85/day, there were no overlaps in species' mean intakes, in the order cattle > sheep > oryx, in the ratio 100:57:24. In the dry season, the herd walked 16 km on non-drinking days, and a further 7 km on alternate days when receiving water. Under wetter conditions with more forage available, the herd walked only 11 km daily.

Slight interspecific differences in the times spent walking, feeding, standing and lying were found over a 48 h period. In the wet season less time was spent walking and feeding, with corresponding increases in the other activities. The oryx were notable in that rumination occupied far less of their daytime activity than for the sheep or cattle although the total times spent ruminating were similar.

The results are discussed in relation to differences in the species’ feeding habits and strategies of diet selection, combining the grazing results with observations from penned animals on a common diet. The intakes of water agree with the results from penned animals, confirming oryx's adaptation to hot, dry conditions. The advantages of a low water requirement, met by intermittent drinking, are discussed.

The possible detrimental effects on productivity of a regime of day-grazing and night-penning under hot conditions are discussed. In the light of these, some advantages to oryx of scheduling its rumination to the night hours are suggested.

A number of commercial varieties and advanced breeding lines of wheat and of barley were each sown successively in the field from early in September until late in February in 3 or 2 years. Shoot apex development was monitored throughout the growing season and the dates at which the double ridge stage and the terminal spikelet stage were attained are reported. There was considerable variation in the date at which these stages occurred, associated both with variety and date of sowing. When sown early, spring wheat varieties and the winter wheat, Fenman, developed more rapidly than the other winter wheats, but the difference disappeared in sowings made in the middle of October or later. Spring barley developed more quickly than winter barley and the difference persisted until sowings made in mid-November.

Length of the longest leaf sheath, number of emerged leaves on the main shoot and the time when stem elongation began (‘ear at 1 cm’), plant characters used to assess the stage for various agronomic treatments, were measured in parallel with apex development. The relationships between number of emerged leaves and the length of the longest leaf sheath and stage of development were found to vary with sowing date. The stage ‘ear at 1 cm’ provided a good guide to shoot apex development. Stem length and number of elongated internodes varied with date of sowing. Some of the variation in number of emerged leaves at a given stage and in the final number of elongated internodes was found to be correlated with total number of leaves on the main shoot. The form of analysis used indicated that sowing date may have important effects, via its effect on the number of leaves on the main shoot, on the duration of ear growth in wheat and barley and on the duration of ear formation in barley.

As part of an ongoing investigation of ovine neuroendocrine mechanisms relating to photoperiod and eventually to wool growth, the diurnal variation of depilation force (an index of the strength of attachment of wool fibres to the skin of sheep) was investigated in Merino wethers and Border Leicester Merino ewes. Circadian rhythms were demonstrated in depilation force in both ewes and wethers. Further experiments were performed to investigate circadian endocrine rhythms which may have some bearing on the observed rhythm in depilation force. Circadian rhythms 180° out of phase with the depilation force rhythm were observed in plasma cortisol concentrations and in pineal serotonin N-acetyltransferase activities in Merino wethers.