Wheat and sunflower plants were grown in a temperature-controlled glasshouse in Melbourne, Australia (37° 50′ S, 145° 00′ E), from 9 August to 2 October 1991, in cylinders containing two soils (Walpeup loamy sand (LS) and Gombalin clay loam (CL)) of low and moderate N status, respectively. Nitrogen fertilizer was applied by immersion of leaves in 0·18 M urea solution (10·5 atom% 15N).

Plants were N-deficient in the Walpeup LS but not in the Gombalin CL soils. Both species had higher root: shoot ratios, and higher proportions of foliar-absorbed N were transferred to the roots, in the Walpeup LS plants. Plant N derived from the fertilizer and root or shoot dry matter were significantly correlated only when plants were N-deficient.

In the Walpeup LS soil, N-fertilized wheat harvested 33 days after sowing (DAS) took up significantly less soil N compared with unfertilized plants, whereas significantly more soil N was taken up by N-fertilized sunflower compared with unfertilized plants harvested at 54 DAS. The fertilizerinduced response in uptake of soil N was directly related to the observed response in production of root biomass for both species. The different responses were related to the severity of the N deficiency and the limited effectiveness of foliar applications of urea in ameliorating the deficiency.

In a 14-year experiment conducted at Athalassa in the central plain of Cyprus, phosphorus was applied (0, 30 or 60 kg P/ha) annually over the first 5-year period to rainfed barley continually grown and cut for hay at the milk stage of the grain. The bicarbonate-extractable P content in the surface soil was 4 mg/kg at the start and increased to 16 and 25 mg/kg after the five annual applications of 30 and 60 kg P/ha, respectively. The residual effect of P was monitored in the following seven crop seasons, by the end of which soil P had dropped to below the recognised 6 mg/kg threshold value for response to P. The application of P was resumed in the last two experimental seasons (1992/93 and 1993/94). In two cropping seasons, rainfall was < 140 mm and no harvestable yield was obtained. In another two seasons, in which there was adequate rainfall in December and January, there was no response to P, but in the other seasons 30 kg P/ha was sufficient for maximum yield. Concentration of P in the dry matter (DM) harvested increased in proportion to the P applied.

A P balance sheet made after the first five P applications and taking into account the amount of P removed in the DM and the increase in soil bicarbonate-extractable P indicated that 29 and 26 % of the P applied with the 30 and 60 kg P/ha rates, respectively, was accounted for.

The data indicate that the established threshold value of 6 mg P/kg is valid. The soil tested 180 mg/kg exchangeable K. but application of 240 or 480 kg K/ha did not increase yield.

Iron toxicity is a nutrient disorder associated with high concentrations of iron in soil solutions. Deficiencies of other nutrients, such as P, K, Ca, Mg and Zn, have been implicated in its occurrence in rice plants. Field experiments were carried out in 1992 and 1993 in Ivory Coast to evaluate the iron toxicity tolerance of promising rice cultivars available in West Africa, and to provide additional information for selecting breeding materials. Two sites, differing in their potential to cause iron toxicity, were used. Glasshouse and field studies were also conducted to test the role of other nutrients in the occurrence of iron toxicity. The results showed that genetic tolerance to iron toxicity can significantly improve rice production in iron-toxic soils, with some cultivars producing yields in excess of 5 t/ha. The application of N, P, K and Zn in the field decreased the uptake of iron in rice tops, and this can be a significant factor in the iron-toxicity tolerance of the cultivars.

The sowing of improved tropical forages in tree plantations can increase animal productivity considerably, but planted grasses often fail to persist under grazing, resulting in unstable pastures. An experiment was conducted in Brisbane, Australia during the summer of 1989/90 to investigate whether the failure of tropical grasses to persist in shade when regularly defoliated is related to their growth habit. Two shade-tolerant grasses of contrasting growth habit (prostrate Paspalum wettsteiniiv. erect Paspalum malacophyllum)were grown in simulated swards at light levels of 100, 50 and 20% of full sunlight and defoliated every 2 or 4 weeks. Shading and frequent cutting reduced total dry matter yield equally in the two grasses. Shading also reduced tiller density. Paspalum wettsteinii persisted poorly under frequent (2-weekly) defoliation in shade. Plant survival rate of this grass was 66% in the 2-weekly defoliation-20% light transmission treatment, compared with 94% in P. malacophyllum. The poor survival of P. wettsteinii was related to its high allocation of total yield to roots, low tiller density and low total nonstructural carbohydrate yield in residual biomass after defoliation. The inability of P. wettsteinii to adjust in shade to frequent defoliation led to a continual decline in photosynthetic area and light interception, resulting in the depletion of energy reserves, increased susceptibility to Rhizoctonia fungal infection and ultimately to death. It was concluded that growth habit per se cannot be used as a simple indicator for selecting tropical grasses for shaded environments. Instead, morphophysiological adaptation to defoliation in shade was critical for plant persistence.

The hardseededness and pattern of hard seed breakdown of 35 accessions of Medicago polymorpha, collected in Sardinia, were compared with Circle Valley, an Australian cultivar, near Sassari, northern Sardinia. The seed was produced in three consecutive years (1991–93), and the hardseededness measured at intervals in trie field during the summer following its production. The results were related to previously measured pod characteristics that separated the varieties polymorpha and vulgaris

The variety polymorpha, which had been collected mainly from coastal regions, was harder seeded than the variety vulgaris, which had been collected mainly from cooler, inland regions. Wherever the origin, hardseededness levels remained > 85% even in the year when seed softening was greatest (1992). In other years means of 94% (1991) and 97% (1993) of seed remained hard in late September. In 1992 and 1993 most hard seed breakdown occurred between early August and early September, while in 1991 hard seed breakdown occurred in September itself. There was little difference between varieties in the pattern of hard seed breakdown. Seedling emergence was related to the amount of seed that became soft during the previous summer. The results also confirmed that hard seeds soften sequentially from the proximal end of the pod (nearest the calyx) to the distal end.

The Australian cultivar was one of the hardest seeded accessions, showing very little hard seed breakdown during the experimental period. This result highlights the importance of selecting pasture legumes under the conditions in which they are to be used: in Australia, cultivar Circle Valley usually loses some 20% of its hardseededness in the first year, comparable with the softest Sardinian accessions in Sardinia. Even among the Sardinian accessions, most were probably too hard seeded in 1993. Nevertheless it is likely that material in this experiment will be released as commercial cultivars for Sardinia and other similar environments in the Mediterranean basin.

The effects of exchangeable sodium on emergence, growth, development and yield composition of oilseed rape were investigated at Buenos Aires, Argentina in 1992. A pot experiment was performed using five exchangeable sodium levels, expressed as Sodium Adsorption Ratio (SAR: 12, 20, 27, 34 and 44). Soil with nine different exchangeable sodium contents (SAR from 0·5 to 50) and seven different particle size distributions (from sandy loam to clay) were used in a parallel trial to study the effect of soil crusting on oilseed rape emergence. Soil crusts were made using a rainfall simulator after seeds were sown. Both experiments showed that the direct effect of sodium on emergence occurred with SAR values higher than those which caused clay dispersion (SAR > 20). Oilseed rape seedlings could penetrate crusts having a resistance of < 230 kPa. At SAR values > 20, main stem growth and yield decreased significantly (P < 0·05). These reductions were counterbalanced by an increase in the number of secondary stems. At SAR levels > 34, stem number, grain number per pod on the main stem, as well as pod number on both main stem and secondary stems, were reduced, leading to a marked reduction in total yield. The most important agronomic effect of soil sodium on oilseed rape would be at emergence stage, due to soil crusting.

Aspects of the photoregulation of phenological development in bambara groundnut were studied in a glasshouse experiment in The Netherlands. The influence of a 14 h photoperiod (which retards podding) during a period of variable length prior to an 11 h photoperiod (which induces podding) on flowering, yield and on the position of pods on the plants was determined. The third generation of three plants of genotype ‘Ankpa 4’ from Nigeria was used as the split-plot factor in a split-plot design with three replicates. The main plots were four daylength treatments: a period of 21, 28, 41 or 54 days under the 14 h photoperiod before transference to the 11 h photoperiod. Plants transferred after 28 or more days started flowering sooner the earlier they were transferred. Plants transferred after 21 and 28 days began flowering at the same time (51 days after sowing), thus indicating juvenility. At harvest, 135 days after sowing, the total seed dry weight per plant was higher for plants transferred after 41 and 54 days than for plants transferred after 21 days. Plants transferred after 28 days gave an intermediate value. Most (79–91%) pods were produced on branches that developed on nodes 1–4 of the main axis. There were no differences in the fractional distribution of the pods along the main axis in plants transferred after 28 or more days. Pods of plants transferred after 21 and 28 days were more evenly distributed over the nodes of the first two primary branches than pods of plants transferred after 41 and 54 days. Plants of the latter treatments produced their pods more towards the tips of the branches and concentrated on two neighbouring nodes (nodes 5 and 6 for plants transferred after 41 days and nodes 6 and 7 for plants transferred after 54 days). Delaying the induction of podding in this experiment therefore resulted in higher seed yields per plant and a more synchronized development and hence maturity of pods.

The response of four cowpea (Vigna unguiculata(L.) Walp.) cultivars to the warm, semi-arid tropical environment at the ICRISAT Sahelian Center at Sadore, Niger was studied during 1985 and 1986 interms of leaf area index (LAI), dry matter (DM) accumulation, net photosynthesis, stomatal conductance, total water use and yield. Among the three improved cultivars, IT82D–716 is early and erect, cv. IT83S–947 is early and spreading and cv. TVX4659–03E is a medium-duration, highyielding, dual-purpose type. The local cv. Sadore Local is a long-duration, photosensitive, spreading type used mainly for fodder. In both years, Sadore Local recorded the highest LAI. IT82D–716 and IT83S–947 produced < 1·3 t/ha of DM in both years, whereas TVX 4659–03E produced > 2 t/ha of DM and proved superior to Sadore Local in partitioning DM into pods. The four cultivars did not differ significantly either in stomatal conductance or in net phytosynthetic rates. Observed maximum photosynthetic rates of c. 20 μmol/m2/s lie at the bottom of the range 21–38 μmol/m2/s reported for 31 cowpea genotypes in an earlier study. Photosynthetic rates increased with increasing photon flux density. TVX4659–03E had an advantage in total seed plus fodder yields while the local cultivar gave significantly greater fodder yields in both years. Seed and fodder yields, as well as water-use efficiency, confirmed the advantages offered by the dual-purpose cultivar TVX4659–03E. Future breeding efforts in the Sahel should focus on dual-purpose (grain/fodder) cowpea types.

In autumn 1991, sugarbeet tops (Beta vulgaris L.) and different components of oilseed rape residues (Brassica napus L.), both labelled with 15N, were incorporated into the soil under field conditions at Askov Experimental Station, Denmark, using stainless steel cylinders to contain the treatments. The availability of this labelled N to a subsequent crop was measured, using as test crops autumn-sown rye (Secale cereale L.), wheat (Triticum aestivum L.) and spring barley (Hordeum vulgare L.). In spring 1992, cylinders with 15 N-residues received NH4NO3 and those without 15NH415NO3. In a parallel experiment, 15N-labelled beet tops were incorporated in lysimeters. A four-course rotation of sugarbeet, spring barley (undersown with perennial ryegrass Lolium perenne L.), perennial ryegrass and winter wheat at two rates of calcium ammonium nitrate (CAN) or animal slurry was grown in these lysimeters. Leaching and the availability of beet top N to successive crops were followed for 2 years. The soil in the cylinders and lysimeters was a light sandy loam (˜ 10% clay).

Of the 7·10 g N/m2 added in beet tops, 10–15% was harvested in two subsequent crops of barley and ryegrass and 13–19% was lost by nitrate leaching. Beet top N accounted for 3–7% of the total N offtake in 1992. In 1993 < 1·5% of the total N offtake in ryegrass was from the beet tops applied in 1991. Combining results from mineral fertilized treatments, it was found that 9% of the beet top N was removed in the first cereal crop, 9% was lost by nitrate leaching and 68% remained in the 0–20 cm soil layer (including roots), suggesting that the denitrification loss was < 15%.

Incorporation of oilseed rape stubble (1·35 g N/m2), two rates of pods (6·25 and 18·75 g N/m2) or mixed residues (12·25 g N/m2) contributed 0·5, 2·3, 7·4 and 4·6%, respectively, to the total N harvested in the following crop of winter wheat. The percentage of the added labelled N taken up by the wheat ranged from 4·9 to 6·1%, with 60–79% remaining in the 0–20 cm layer after harvest.

For beet tops it was calculated that 100 kg N/ha in residues incorporated in the autumn could replace 18 kg N/ha given in the following spring as mineral fertilizer. For oilseed residues, the corresponding average value was 9 kg N/ha.

In fertilized cropping systems, oilseed rape residues had minor effects on the subsequent crop, so that an uneven return of residues, as often occurs with combined crops, would do little harm. A considerable proportion of the N applied in sugarbeet tops was lost by leaching and the residual value of the sugarbeet tops to subsequent crops was low.

Six rumen-fistulated steers were studied over six periods of 3 days at Reading University's Animal Production Research Unit. In each period, eight dacron bags comprising two replicates of the 22 factorial treatment set consisting of untreated and NH3-treated barley straw in chopped (12–54 mm) or ground (2·5 mm screen) form were placed in the rumen of each steer. Bags were left in the rumen for a given time which was one of the set 6, 9, 15, 24, 48, 72 h. Percentage dry matter (DM) disappearance from dacron bags was consistently higher for NH3-treated than untreated straw and higher for ground than chopped straw. Analysis of variance gave F ratios for period and steer which were non-significant but of similar size, showing that using fewer animals could be compensated for by using more periods. Percentage DM disappearance as a function of time was well described by the model y = a — beet. The parameter defining rate of disappearance c, was similar for the four forms of straw. Differences between straws occurred in values of a (potential degradability) and b suggesting that physical form of material put into dacron bags needs standardizing if absolute values of a are to be used (e.g. for predicting roughage intake). Experimental designs need further research.

Milled grass particles were coated with n-alkanes and suspended in a xanthan gum solution. Experiments snowed that grass particles could be coated uniformly with alkanes by means of a rotary evaporator. Further experiments showed that the grass particles, in stable xanthan gum suspension, could be accurately dispensed. The coefficients of variation of the alkane content per dose delivered by means of a dosing gun and syringe were 2·6 and 2·3%, respectively. There was no significant difference between the concentration of faecal alkanes derived from alkanes dosed in suspension-form and alkanes placed directly into the rumen.

Twelve red deer (Cervus elaphus) hinds from a research facility in Eastern Scotland were randomly divided into two groups between June and September to study the physiological response to three management practices, given sequentially, which were expected to cause increasing levels of stress (herding; herding and handling; and herding, handling and a veterinary procedure). One group of animals received a long-acting neuroleptic (LAN; perphenazine enanthate and zuclopenthixol acetate) on three occasions at 4-week intervals. Automatic blood sampling equipment (ABSE) was used to obtain blood samples remotely before, during and after the application of each of the stressors. The plasma concentrations of cortisol, creatine phosphokinase (CPK), aspartate aminotransferase (AST), total protein (TP), 3,5,3'-triiodothyronine (T3), thyroxine (T4) and testosterone (T) were measured and heart rates recorded. The ABSE provided a useful means of collecting blood samples without the superimposition of stress factors associated with conventional sampling. Increases in plasma concentrations of cortisol (P <0·01), CPK (P <0·01) and AST (P <0·05) were observed in all animals in response to all three management practices. There were smaller increases in plasma cortisol concentration (P <0·05) in those animals treated with LAN. The results suggested a degree of habituation of the hinds to some procedures common to all treatments, in agreement with previous analysis of the behavioual response of these animals. Peaks of heart rate were recorded over the 30-min period stressors were applied. Higher heart rates and T3 and T4 concentrations were observed in LAN-treated animals. Heart rates returned to baseline more rapidly in the LAN-treated animals. Higher plasma concentrations of testosterone were recorded in the first week of the study (P <0·001). Physiological and behavioural evidence supports the view that LANs are effective long-term tranquillizers in red deer.

An experiment to measure the effects of cold conditions upon heat production in young sambar (Cervus unicolor) and red deer (Cervus elaphus) was conducted during winter 1994, at Massey University, Palmerston North, New Zealand (NZ), using four young animals of each species. Animals were fed a pelleted concentrated diet (total N 29g/kg DM; 11·9MJ metabolizable energy (ME)/kg DM) at approximately maintenance ME intake (MEI). Hair coat characteristics were measured on samples cut from a patch on the mid-side of the body. Pairs of animals (one sambar and one red deer) were confined in two open circuit calorimetry chambers (one deer in each chamber) for 18-day periods, and oxygen consumption was measured at 20 and 5 °C, with and without simulated wind (6 km/h). Heat production was calculated as 20·5 MJ/1 oxygen consumed.

Hair coats of sambar deer were less deep, lighter in weight (g/m2) and contained a lower proportion of undercoat than those of red deer. Fibre length of both guard hairs and undercoat were shorter in sambar deer than in red deer, whilst fibre diameter of both guard hairs and undercoat was greater in sambar deer. Heat production (HP) at 20 °C was lower in sambar than in red deer (P <0·05; 0·46 v. 0·48-0·53 MJ/kgW0·75 per day). Increases in HP from 20 to 5 °C and from 20 °C to 5 °C W (i.e. with wind effect) were greater in sambar than in red deer (P < 0·01; 34 v. 16% and 44 v. 20%, respectively). Calculated lower critical temperatures (LCT) were higher for sambar than for red deer (P < 0·10) both in the absence (0 km/h; 11·6 v. 8·9 °C) and in the presence of wind (6 km/h; 140 v. 11·1 °C). Under field conditions, young sambar deer are likely to require more shelter and better feeding during cold weather than do red deer.

Measurements of grazing, ruminating and idling time and number and duration of bouts of these activities were made on cows grazing a perennial ryegrass-white clover sward on a number of different occasions between 8 May and 10 July 1990 at the North Wyke Research Station, Devon, UK. Repeatabilities, calculated using the residual maximum likelihood method, were low for all measurements, the highest being for idling time. Coefficients of variation were generally lower between periods than between animals for total activity times and ruminating and idling bout duration but were higher for the number of bouts of all activities and for meal duration. Grazing time and meal duration increased significantly as the season progressed, while the number of bouts of all activities declined. Behaviour was not significantly correlated with meteorological conditions. There were no significant correlations between production traits and mean behaviour of cows across periods.

This study (conducted in Debre Zeit, Ethiopia in 1993) examined (i) the effect of source of inoculum on in vitro dry matter (DM) digestibility (1VDMD) and gas production (GP) and (ii) the IVDMD, GP and in sacco degradability as predictors of in vivo DM digestibility (DMD) and intake. Six ruminally cannulated male sheep (used in the degradability studies and from which rumen fluid was harvested for the in vitro studies) and six intact sheep (from which faeces for reconstitution was obtained) were given teff straw ad libitum supplemented with 200 g/day of concentrate (1:1 mixture of noug (Guizotia abyssinica) cake and wheat middlings). In determining IVDMD on 26 feeds, pepsin-HC1 digestion was replaced with neutral detergent extraction. Microbial GP was measured on these feeds incubated with rumen fluid or reconstituted faeces inocula at various time periods. The degradability of each feed was determined by the nylon bag technique in three sheep. Eighty-eight intact male Ethiopian Menz type sheep (mean liveweight 256 (S.D. = 1·98) kg) were used in a randomized complete block experiment to determine intake and digestibility.

Gas production using faeces inoculum (GP-F) was strongly related to GP using rumen fluid inoculum (GP-R) particularly at 48 h (R2 = 0·85; P <0·001) of incubation. The IVDMD obtained with reconstituted sheep faeces inoculum (IVDMD-F) had a strong positive relationship (R2 = 0·88; P <0·0001) with IVDMD measured using rumen fluid (IVDMD-R). The IVDMD values obtained by centrifugation were positively related to those obtained by filtration for the rumen fluid (R2 = 0·61) and reconstituted faeces (R2 = 0·47) inocula.

The relationship between degradability and in vivo DMD was generally poor for roughages but improved with the length of incubation for forage legumes, being strongest at 24 h (R2 = 0·54). The in vivo DMD had the strongest relationship with GP-R at 24 h of incubation for roughages (R2 = 0·64) and legumes (R2 = 0·84). Dry matter degradability was poorly related to DM intake for roughages (R2 <0·10), while these were closely related for legumes particularly at 6 h of incubation (R2 = 0·55). The relationship between GP-R and intake was strongest at 12 h of incubation for roughages (R2 = 0·41) but was generally weak for legumes. The IVDMD accounted for a very low proportion of the variation in intake of roughages and legume forages. The gas production method was the best among the methods tested in predicting voluntary roughage intake, but not the intake of legumes. The nylon bag technique gave the best predictors (solubility, rate constant ‘c’ and Lag phase) of legume intake (R2 = 0·98).

The discussion suggests explanations for why the nylon bag technique predicted performance from forage legumes better than from roughages, why the technique was much better as a predictor of intake than of in vivo DMD, and why the gas production technique predicted in vivo DMD and not the intake of legumes. Reconstituted faeces inoculum may replace rumen fluid inoculum in in vitro procedures. The IVDMD method is a less accurate predictor of in vivo DMD than GP and rumen degradability constants. Both feed factors and practices inherent in the methodologies may modify the predictiveness of indirect digestibility methods.