The effects of applications of sodium chloride (NaCl) and potassium chloride (KCl) ranging from 0 to 720 kg Cl/ha on the yield and uptakes of chloride (Cl) potassium (K) and sodium (Na) by fodder beet were studied in field experiments at two sites in New Zealand. At 360 kg Cl/ha applied, both NaCl (590 kg/ha) and KC1 (758 kg/ha) increased significantly yields of fresh roots, dry roots and fresh sugar content of fodder beet over the minus-Cl plants. Compared with the sulphate anion, chloride application stimulated K uptake in tops and roots. Results indicated that in the beet crop, uptake of K is enhanced with the presence or addition of Cl (as NaCl) compared with SO4 (as NaSO4).

In both soils, total (tops and roots) uptakes of K, Cl, and Na were significantly correlated with fresh roots, dry roots and fresh sugar content. Multiple regression analyses showed that total K uptake was the main nutritional factor which determined yields of fresh and dry roots in the Templeton soil, whilst in the Wakanui soil total Cl uptake and total K+total Cl uptakes determined fresh root and dry root yields, respectively. In both soils, high Cl uptake was required for increased sugar yields.

Growth and visceral organ weights of male guinea fowl (Numida meleagris) given different levels of oxytetracycline have been studied in two experiments. In the first experiment 0, 5·0, 10·0, 15·0 and 20·0 mg oxytetracycline per kg diet were given to male guinea fowl from day 1 to 12 weeks. Body weight showed significant (P < 0·05) increases with incremental levels of the antibiotic up to 10 mg/kg diet. No further increases in growth were recorded with supplementation above this level. There were no treatment effects on the gizzard, lungs and male reproductive organs. Only the heart, liver and intestine weights were significantly (P < 0·05) affected by the treatment, and then only at the highest (20 mg/kg) of the inclusion rates examined. A second experiment was conducted to find out if the growth response obtained with 10 mg/kg oxytetracycline could be produced with a smaller dose. This was achieved at 6·6 mg/kg.

The response of 4 crops of autumn- and spring-sown field beans cv. Maris Bead to irrigation applied during the vegetative, flowering and pod-filling phases was examined during 1981–2 and 1982–3. The crops, grown on a Templeton silt-loam, were irrigated weekly in amounts equal to the difference between the estimated evapotranspiration and rainfall of the previous week using trickle irrigation.

Seed yield of fully irrigated autumn- and spring-sown crops (averaged over the two seasons), was 5·2 and 3·3 t/ha respectively, about 45% greater than the yield of unirrigated crops. The increase in yield due to irrigation was mainly associated with an increase in total dry matter (TDM) production as harvest index varied little within each sowing. The yield response to each mm of applied irrigation water ranged from 0 to 9 kg/ha and did not appear to be related in any way to the developmental phase of the crop when irrigation was applied.

Seed yield within each sowing was closely correlated with the number of beans per unit area and the number of pods per plant. Autumn sowings yielded about 55% more than spring sowings mainly due to a higher harvest index which was associated with a much heavier mean weight per bean.

The growth and yield of four crops of field bean cv. Maris Bead in response to irrigation and sowing date were analysed in relation to leaf area expansion and senescence and their absorption and utilization of photosynthetically active radiation (PAR). Total dry matter (D.M.) production and seed yield were strongly correlated with total green area duration (GAD) and post-flowering GAD respectively.

Total D.M. production was also strongly related to radiation absorbed by the green surfaces of the crop although autumn sowing and drought both decreased the constant of proportionality, i.e. the growth efficiency (Eg). Autumn sowings yielded more than spring sowings because they grew for longer and received 22% more radiation. Their harvest index was also about 40% higher than in spring sowings. These more than compensated for their smaller Eg. Drought decreased yield mainly by decreasing radiation received and Eg. Growth duration was shorter and harvest index was smaller.

The rate of phenological development was strongly dependent upon temperature and to a lesser extent on photoperiod. The average thermal duration from emergence to flowering was 790 °Cd above a base of 0 °C. The time from sowing to the end of the pod growth was well represented by a simple multiplicative model in which development rate was a linear function of temperature above a base of 0 °C and photoperiod above a base of 6 h. The average photothermal duration required for 10 crops was 980 °Cd.

An attempt was also made to determine the crop physiological and environmental factors which govern the change in size of the yield components of field bean crops caused by irrigation and sowing date. The final number of pods per plant was closely correlated with the rate of supply of assimilates during pod filling. Irrigation increased assimilate flux by increasing leaf area, growth rate and total dry matter during pod growth. Both the rate and duration of pod growth were little affected by irrigation. Autumn sowings produced heavier pods and beans due to both a faster rate and a longer duration of growth which were associated with a greater production of assimilate during the seed growth period. Seed growth depends on both the current assimilate and stored reserves, the latter especially when plants were subjected to environmental stress.

In weeks 1–6 of lactation, 11 goats were fed diets adequate in phosphorus content, supplying a basal intake of 2·8 g P/day plus 1·4 g P/kg milk produced. In group 1 (three goats), this scheme was continued until week 16. In group 2 (four goats), P supply was changed from an adequate one to a reduced amount by restricting the variable intake to 1·0 g P/kg milk during weeks 7–16 and the basal intake to 0·8 g P/day during weeks 12–16. In group 3 (four goats), P deficiency was caused during weeks 7–11 by a basal intake of 0·8 g P/day plus only 0·4 g P/kg milk. During weeks 12–16 these goats received the same supply of P provided in weeks 1–6.

Milk yield was depressed in group 3, but not in group 2. Composition of milk was not affected by P intake in either group. Digestibility of organic matter was reduced from 0·73 to 0·64 by P deficiency treatment. Reduction of faecal P excretion in group 2 appeared to enable P homoeostasis even at the reduced level of P intake. The amounts of P and Ca secreted in milk during P deficiency in group 3 clearly exceeded the corresponding net absorptions. During this period, daily faecal P excretion was reduced to 17 mg/kg live weight. P concentrations in blood plasma, saliva and particle-free rumen fluid were also drastically reduced. Faecal excretion of P increased after the animals returned to the diet supplying adequate P. The increase occurred before the pre-depletion P status had been restored.

Five rumen-cannulated dairy goats were fed diets supplying 2·8 g P/day plus 1·4 g P/kg milk (adequate P) for weeks 1–6 of lactation. Two goats then continued to receive this adequate P supply while three goats were fed deficient diets supplying only 0·8 g P/day plus 0·4 g P/kg milk. Solutions containing CrEDTA and (15NH4)2SO4 were infused into the rumen continuously for 96 h during weeks 5–6 and 11–12, respectively. At intervals following the intraruminal infusion, 15N enrichments of rumen ammonia-N, rumen bacteria-N and milk protein-N were determined. Cr concentration was measured in particle-free rumen fluid.

P deficiency did not significantly affect rumen fluid kinetics. It caused a significant increase in pH and reduced the size of the rumen ammonia pool and its outflow rate. Digestibility of organic matter as well as efficiency of microbial protein synthesis were decreased significantly and thus net microbial yield was reduced from 34·1 to 13·7 g N/day. The transfer of N of microbial origin to milk protein decreased from 5·3 to 2·7 g/day, whereas secretion of N in milk protein not originating from rumen microbes remained unchanged at 5·6–5·8 g/day.

There has been little study on the growth and morphology of individual plants constituting the population of white clover in mixed swards under grazing. Such information is required if the mechanisms governing plant productivity and persistence are to be understood.

Intact white clover plants were sampled from intensively sheep-grazed pastures under set stocking, rotational grazing, and a combination of both systems, by taking turves (250 × 250 mm), and washing out the plants, every month for a year. Characters measured for every stolon of each plant were: presence of a growing point; numbers of leaves, roots and axillary buds; stolon length. Total plant leaf and stolon dry weight were also recorded. Plants were classified according to degree of branching, and the contribution of each branching order to the population determined.

There were strong seasonal variations in plant size (leaf and stolon dry weight, stolon length, and numbers of stolons and leaves per plant) which showed a significant decrease in spring with recovery over the following summer. This was paralleled by a rapid increase in the proportion of less branched plants (1st and 2nd branching order) in the population from 60 to 80% in spring, as higher-order plants broke up into smaller- and lower-ordered plants at this time. Numbers of roots per plant increased over winter to peak in early spring then declined in the following summer-autumn. While system of grazing management had no significant effect on branching structure of plants, it had a large effect on plant dry weight; rotationally grazed plants were 2·5 times larger than set stocked plants (0·182 cf. 0·073 g respectively).

Other general features of plant morphology were that each successive order of branch stolons was shorter and length before branching was less than that of their preceding parent stolon. The highest branching order observed was 6th order. There was no relationship between branching and numbers of roots; in branched plants only 55% of stolons were rooted regardless of plant order, but rooted stolons accounted for 85% of total stolon length and carried 62, 48 and 90% of the leaves, growing points and axillary buds per plant, respectively.

Comparison with other studies suggests that the processes outlined in this report may be common to white clover growth under grazing over a wide range of favourable environments.

Measurements were made at intervals during 1983–4 on the main stem and on tillers having defined morphological positions on plants of winter wheat cv. Avalon growing in a multifactorial experiment testing combinations of the following five factors: rotation, sowing date, amount of autumn N, amount of spring N, and timing of spring N. Some observations from similar experiments in the two previous seasons are also reported.

The tillers in the axils of the first three leaves (Tp, T2 and T3) appeared on most plants. An average of 1·8 other tillers were produced on each plant, including 0·14 at the coleoptile node. When number of shoots was maximal, main stems (M), T1 and T2 together accounted for 64% of the total number of shoots, 76% of the total green area and 87% of the total above-ground dry weight. More than half of the T1s died before maturity, two thirds of the T2s and almost all of the other tillers. The final population of 566 ears/m2 was made up as follows: M 56%, T1 26%, T2 16%. The differences between categories in dry weight per shoot at maturity were relatively less than earlier. Contributions to the mean grain yield of 9·9 t/ha were: M 60%, T1, 22%, T2 14%. M had more grains per ear than T1, or T2 which had similar numbers. Dry weight per grain was similar in all three categories.

Most of the effects of treatments on dry weight/m2, which have been described previously by Prew et al. (1986), were due to effects on all shoot categories. Several treatments increased the number of shoots/m2 by increasing the average number per plant of tiller categories that were produced later. This was always the result of an increase in the proportion of plants having many tillers. Neither the maximum number of tillers found on a plant, nor the duration of tiller production, was affected.

Both within and between tiller categories, shoots that were produced last died first. Plants which started tillering late produced fewer, smaller, tillers than average and relatively few of these survived. The standard hierarchical order of tiller production and survival was disrupted when plants were damaged by stem-boring insects and when the period shortly before a tiller category was due to emerge was unusually dull and warm.

With the current high prices for livestock, forage legumes are increasingly attractive to farmers in west Asia. There has been very little genetic improvement of the main species, of which three vetches, Vicia saliva (common vetch), V. villosa subsp. dasycarpa (woollypod vetch), and V. narbonensis (Narbon vetch), show promise. As a first step in genetic improvement 23 genotypes of common vetch and one each of woollypod vetch and Narbon vetch were grown at four sites in Syria and one in Lebanon over three seasons. Since local climatic conditions were considered to be of considerable importance, each site in each year was treated as a separate environment, to give 15 environments in all. genotype × environment (G × E) interactions were analysed using linear regression.

There was considerable variation in herbage and seed yields within both genotypes and environments, and G × E interactions were highly significant. In the case of herbage yield good environments could be defined as those receiving high rainfall and low incidence of frost. Several genotypes appeared to possess wide adaptation, in terms of both yield and stability. Climate, except for late spring rains, had little effect on seed yield, nor were any of the genotypes widely adapted. However, in the broad sense heritability was much higher for seed than for herbage yield.

There is a need to define good and bad environments for seed yield. Based on observations during the study it is likely that good environments for Narbon vetch are those where broomrape (Orobanche crenata) is absent, while root-knot nematode (Meloidogyne artiella) may affect seed yield of common vetch. In view of its high seed yield the possible role of Narbon vetch as a grain legume is briefly discussed.

Egg production and body mass changes were measured in six groups, each containing 10 single comb White Leghorn (SCWL) hens, in which each group received decreasing amounts of dry matter (D.M.) in decrements of 10%. Group 1 received 101·2 g D.M./day (100%), an amount normally offered these hens, whereas group 6 received 52·8 g D.M./day (50%). Egg production remained relatively high but body mass declined rapidly in the feed-restricted groups when compared with group 1 in the first 4 weeks (period I); in the second 4 weeks (period II), egg production declined to a great extent but body mass remained constant. Egg production and egg mass were significantly lower in period II than in period I in the feed-restricted birds. In period I egg production did not decrease significantly until the hens were restricted in feed by 30%; in period II this occurred at 20% feed restriction. Energy of eggs produced as a fraction of metabolizable energy intake (MEI) tended to increase in the feed-restricted groups when compared with group I in period I, but decreased significantly at the 40% and 50% group in period II. Maintenance energy requirements for the hens were 569·2 kJ/kg0·75 per day and the efficiency of utilization of energy for egg production was 88·2% in period I; these values were 551·6 kJ/kg0·75 per day and 74·0%, respectively, in period II. Energy yielded from the catabolism of body tissue per gram body mass loss was 23·08 kJ.

It was concluded that the hens initially maintained near-normal egg production at the expense of body energy reserves and then at the expense of egg mass. The efficiency of utilization of energy for egg production was higher when the energy source was mainly from body energy reserves than from MEI (88·2% v. 74·0%). The level of feed restriction and its length of imposition, the body energy reserves of the hen and the source of energy for egg production can explain many of the different responses reported in feed-restricted laying hens. In addition, reduction of 20 to 30 % feed intake in laying hens had little effect on egg production for a short period (4 weeks) during which time the hens mobilized body energy reserves. If these hens were to be sold, then this would add an additional option to this enterprise; that is, reduce feed cost at the expense of body mass prior to the sale of the hens.

A number of mutant lines showing different levels of improved quantitative resistance to bacterial leaf blight (BLB) were obtained through selection of plants or lines derived from seeds of the rice cultivar Harebare exposed to thermal neutrons and gamma-rays. The selections were made on M2–M4 materials under natural BLB-epidemic conditions and/or by artificial inoculation of one of the BLB isolates. Bacterial isolates predominating under the natural conditions were identified as belonging to the differential BLB isolate group I, and the isolates of this group were used in the artificial inoculation for selection of mutants. The selected M4 mutant lines were tested in M5 for BLB resistance by artificial inoculations of four differential bacterium isolates, groups I, II, III and IV. The M6 mutant lines showed quantitatively elevated resistances to the isolate of bacterium group I and also to the other three differential isolates. Analysis of variance of the data demonstrated that the observed elevated quantitative resistances of the mutants to the isolates I, II, III and IV were isolatespecific. Host-parasite interactions in quantitative resistance to BLB and their modification by induced mutations are discussed.

Yields of the three ‘test’ crops, winter wheat, potatoes, spring barley in the Rothamsted Ley–Arable experiments 1949–69 increased by about 100%, 80%, 40% respectively, each in a period of 19 years. The wheat variety was changed once during the period and this change is enough to explain most of he increase of yield. For potatoes there was no change of variety; the estimated effects of changes in manuring, etc. explain less than one third of the observed increase. For barley two changes of variety explain about one third of the increase; most of the remainder may be explained by improved manuring of preceding crops, especially potatoes. After 1969 the cropping was drastically changed but a few recent yields from other experiments at Rothamsted indicate that the steady rates of increase may have continued at least up to 1980.

Field studies were conducted at Ilorin and Bacita during the 1985–6 cropping season to evaluate the use of hexazinone [3-cyclohexyl-6-(dimethylamino)-l methyl-1, 3, 5-triazine-2, 4(1 H, 3H)-dione] alone, and in combination with diuron [3,(3,4-dichlorophenyl)l-l dimethyl urea] in crops of sugar cane. Hexazinone, alone or in combination with diuron, effectively controlled a broad spectrum of weeds in a loamy sand soil at Ilorin. Most of the herbicide rates used were, however, severely phytotoxic to the crop. On silty clay-loam soils at Bacita, the same herbicide treatments, while giving effective control similar to that obtained at Ilorin, were not phytotoxic to the crop. Weed control effectiveness was influenced by the percentage of organic matter in the soils and by the amount of herbicides used. A broader spectrum of weeds was controlled by the mixture of hexazinone plus diuron than by hexazinone alone. There was no difference between the performance of the tank and formulated mixtures of hexazinone plus diuron.

Two scries of simulation experiments were used to investigate the accuracy of treatment and variance estimation with a neighbour analysis of field trials proposed by Gleeson & Cullis (1987). The first series examined the accuracy of residual maximum likelihood (REML) estimation of seven theoretical error models applicable to field trials. REML estimation provided accurate estimates of the variance parameters, but the Ftest of treatments was slightly biased upward (to +2·4%) for first differences models and slightly biased downwards (to –1·4%) for second differences models. The second series of simulations, based on 19 uniformity data sets, illustrated that treatment effects were consistently estimated more accurately by the REML neighbour (RN) analysis of Gleeson & Cullis (1987) than by incomplete block (IB) analysis with recovery of interblock information. The relative gain in accuracy of RN over IB depends on the amount of systematic variation or ‘trend’ in the trial, and ranged from 6 to 18% with an average of 12% for a range of trend and error variances commonly encountered in field trials. The predicted average standard errors of pairwise treatment differences from the RN analysis were in close agreement with their empirical estimates, indicating that the predicted average S.E.D. is approximately valid.

A study has been made of the distribution of 14carbon-labelled assimilates in flowering oilseed rape plants. Up to 10 days after anthesis individual flowers were strong sinks for assimilates for 2 days after opening but thereafter became weak sinks for a period of 24 h. This period coincided with pollination and subsequent fertilization. After fertilization the young pods again became strong sinks. Between 13 and 16 days after anthesis other flower buds, flowers and young pods which had previously been strong sinks failed to attract assimilates and aborted. This fall in sink capacity occurred at about the same time on all branches and appeared to be co-ordinated on a whole-plant basis.

Removal of basally positioned pods on the terminal inflorescence at anthesis and 6 days thereafter increased the duration of flowering and resulted in the formation of a larger number of smaller pods.

Removal at 12 days after anthesis did not affect flower production but increased the number of flowers setting pods. Application of benzyladenine to the apices of intact plants from 8 days but not 14 days after anthesis greatly extended flower but not pod production. Liquid scintillation counting showed that the benzyladenine treatment led to more 14C-labelled assimilates moving to the apices.

Data on gestation period of 701 indigenous East African and Galla does and pre- and postweaning growth of 810 pure-bred and cross-bred kids were analysed by least squares statistical analysis. Breeds of kids were East African, Galla, Toggenburg × East African, Toggenburg × Galla, Anglo-Nubian × East African and Anglo-Nubian × Galla. Average gestation length was 149 days and was significantly (P < 0·05) affected by type of birth of the kid, year–month of kidding, and age of dam. Does carrying twins had shorter gestation length than does carrying singles. Sex and breed of kid did not have significant effect on gestation length.

Significant (P < 0·05) factors affecting birth weight, weight at 30, 60, 90, 120, 150, 210 and 270 days of age, and preweaning growth rate were breed and sex of kid, type of birth, year–month and age of dam. Male kids grew faster and were heavier than females. Kids born single were heavier and grew faster than twin-born kids. Kids from dams less than 3 years old weighed less than kids from older dams. Cross-bred kids had higher preweaning growth rates than indigenous pure-bred kids. The Anglo-Nubian × Galla cross was heaviest while the East African ranked lowest. The results point to importance of cross-breeding with temperate breeds to increase growth rates of indigenous goats. Comparison of Toggenburg and Anglo-Nubian sires for cross-breeding showed both buck breeds produced kids with roughly equal growth rates. Evaluation of indigenous Galla and East African dams for cross-breeding showed Galla dams produced heavier kids than East African but preweaning growth rates were not significantly different.

Four systems of harvesting grass for silage were evaluated in terms of in-field losses, in-silo losses and milk output per hectare. The systems were: single-chop flail harvester direct cutting (SCD); doublechop flail harvester direct cutting (DCD); mown with a rotary mower and picked up with a precisionchop harvester either immediately (PCU) or after wilting until the dry-matter concentration had increased by approximately 100 g/kg (PCW). The in-field and in-silo losses were measured at each of three consecutive harvests during 1984 and during the following winter the resulting silages were evaluated through eight British Friesian cows in a balanced change-over design experiment using four periods each of 5 weeks duration.

There was a greater quantity of herbage ensiled with the two direct cutting systems (SCD and DCD) than with the systems involving pre-mowing and picking up with the ensiled yields, being 12·4, 11·8, 10·8 and 10·8t OM/ha for the SCD, DCD, PCU and PCW systems respectively. These differences were only partly reflected in greater mechanical in-field losses with the pre-mown systems.

Losses during the in-silo period tended to be greater with the wilted than the unwilted silages being 98, 76, 83 and 132 g/kg OM with the SCD, DCD, PCU, and PCW systems, respectively.

Animals offered the PCW silage tended to have a higher silage organic-matter intake and had a significantly higher milk yield than those offered the other silages with fat corrected milk yields being 25·1, 24·5, 24·5 and 25·9 kg/day for the SCD, DCD, PCU and PCW systems, respectively. Milk outputs per hectare, at 30·3, 27·8, 25·7 and 240 for the SCD, PCD, PCU and PCW systems respectively, was lowest for the PCW treatment.

In a long-term cultivation experiment comparing mouldboard ploughing, shallow cultivation and direct drilling, soil compaction was identified as a problem. Root growth was restricted and this possibly caused a decline in grain yield of spring barley. The residual effects of a slant-legged subsoiler (Trade name, ‘Paraplow’) on the growth and yield of spring barley up to 34 months after its use were measured.

In 1982, soil not loosened with the ‘Paraplow’ had a grain yield of 5·16 t/ha and cultivation with the ‘Paraplow’ either 22 or II months previously had a negligible effect. Although the implement improved mean plant establishment by up to 12 plants/m2, compensatory tillering occurred in the treatments that initially had fewer plants, thus reducing differences in dry-matter production and grain yield at harvest. The long-term system of cultivation had a larger effect on grain yield than the ‘Paraplow’ did. Grain production on direct-drilled and shallow cultivated soils exceeded that after mouldboard ploughing by up to 0·55 t/ha (P < 0·05). The ‘Paraplow’ used 22 months previously increased grain yield by 0·47 t/ha on a direct-drilled soil that had become compacted.

In 1983, the emergence of seedlings was low (54%) due to waterlogging of the seed bed between germination and emergence. The ‘Paraplow’ used 8 months previously increased the mean number of plants that emerged by 20 plants/m2. More seedlings survived on the soil loosened by the ‘Paraplow’ because it drained more freely than the undisturbed soil. Cultivating with the ‘Paraplow’ 11, 23 and 34 months previously increased grain yield by 0·27, 0·29 and 0·13 t/ha respectively, but the mean grain yield was only 2·70 t/ha. This improvement was caused by a greater number of grains per m2 on the soils loosened with the ‘Paraplow’. Grain weight was unaffected by cultivation system or by ‘Paraplow’ treatment.

Tetrapleura tetraptera (Schum & Thonn) is a member of the Family Mimosaceae. It is a perennial, wild West African tropical forest tree (Hutchinson & Dalziel, 1973) and is extensively used in many traditional medicines. The fruit is used in Nigeria as a spice added to soup for nursing mothers from the day of delivery to about 1 month postnatally, to prevent post-partum contractions.