Fusarium solani f. sp. fabae Yu & Fang was isolated from root-rotted field bean (Vicia faba)plants at the Research Farm, Hudeiba Agricultural Research Station, Northern Province, Sudan. This is the first record of this fungus on field beans in the Sudan. Cultural and morphological characteristics of the fungus on potato-dextrose agar (PDA) and the symptoms caused are described.

Results of a co-ordinated trial carried out at 20 centres indicated that increasing the dietary crude-protein percentage by 2·5 and the lysine by about 0·2 over the ARC recommended levels failed to improve performance or carcass quality, whereas decreasing these nutrients to a similar degree below the recommended levels adversely affected performance and carcass quality.

At four centres there were six to eight replicates. Substantial differences in estimates of both the level of response to a given treatment and the magnitude of treatment effects were observed between individual centres.

Factors affecting the size of these co-ordinated trials are discussed.

Selected herbage samples from a 6-year experiment in which nitrogen rates between 0 and 897 kg/ha were applied annually on perennial ryegrass swards were analysed for nitrate-nitrogen, true-protein and non-protein nitrogen, water-soluble carbohydrate, potassium and sodium content and for amino acid composition. The nitrate-nitrogen content of the herbage increased with increasing nitrogen rate from 224 kg/ha upwards, but the potentially toxic level of 220 mg/100 g dry matter was not reached until the annual nitrogen rate was about 560 kg/ha. On average, at the 897 kg nitrogen/ha rate the non-protein nitrogen content had increased to 27·5% of the total nitrogen yield, and 40·3% of the non-protein nitrogen yield consisted of nitrate nitrogen. Nitrate content was shown to be a sensitive indicator of the level of nitrogen nutrition of the herbage, the optimum nitrogen rate for dry-matter production coinciding with a nitrate-nitrogen content of approximately 100 mg/100g dry matter. The amino acid composition of the herbage varied little with either the rate of nitrogen or the date of cutting. It was demonstrated that, on average, a 1% unit increase in the crude-protein content of the herbage was accompanied by a 1% unit decrease in the carbohydrate content. The sodium content of the herbage increased with increasing nitrogen rate up to between 448 and 560 kg/ha, but the potassium content showed little variation.

Plasma copper levels were determined at intervals of 9 weeks over a period of 1 year on 131 female sheep of a grassland flock starting at the age of 5 months in September. The 107 survivors were re-bled 3 years later. There was a steady decline in copper levels from about 100 µg/100 ml plasma in November to about a third of that level at the beginning of the following June. Thereafter there was a partial recovery in level.

Three breeds, Scottish Blackface, Cheviot and Welsh Mountain and their crosses were represented. There were marked differences in plasma copper level among the breeds with cross-breds having levels as high or higher than the corresponding pure breeds. Breed differences in copper levels were already present at 5 months old. Part of the breed differences in copper levels were attributable to differences among the breeds in the frequency of the HbA and HbB alleles.

Correlations were calculated among the plasma copper levels from successive bleedings for individuals within breeds and subclasses. From the time the sheep reached about 9 months old these correlations ranged from 0·4 to 0·9 including bleedings more than 3 years apart in time.

Seeds of cowpea, melon, and tomato were planted in moist soil and subjected to a heat stress of 45 °C for 10 h on the day of sowing (day 0), 1 day after sowing or 2 days after sowing. The heat stress subsequently resulted in retarded hypocotyl elongation for all the crops, but the greatest retardation was due to heat stress applied on day 1 for cowpea, day 2 for melon, and day 0 for tomato. The growth-retarding effect of heat stress was associated with a delay, by 1 day, of the maximum rate of elongation of the seedlings.

Five sugar beet experiments were made from 1964 to 1968 to measure yields of roots, of sugar and of tops from dressings of 0, 63, 126 or 188 kg N/ha. In 1964 and 1965 the sugar-beet tops were ploughed-in on all plots, but afterwards on only half of the total number of plots. Barley followed the sugar beet and was given 0, 41, 83 or 126 kg N/ha, in all combinations with the dressings of N to the sugar beet; grain was weighed and analysed for % N.

The maximum yield of sugar (8·24 t/ha) was with 126 kg N/ha. The yield of barley was increased greatly by giving it 83 kg N/ha, but not with more. When the barley was not given N, the residues of 126 kg N/ha for sugar beet increased grain yields by 0·17 t/ha, where the tops were carted away, and by 0·77 t/ha, where the tops were ploughed-in, but when the barley was given 83 kg N/ha, the residues increased yield negligibly (by 0·07 t/ha). Together the two sources of residue were equivalent to giving about 30 kg N/ha to the barley. Percentage N to the grain was consistently increased by both kinds of residue, but the grain never recovered more than 10 kg N/ha from them. So, sugar-beet tops had little residual value for barley, but offer a largely unused source of animal feed, rich in N.

The deposition of dust and the sulphur it contained were measured at 10 sites for three dry seasons in northern Nigeria. Amounts of dust deposited varied between seasons and sites depending on the concentration of dust in the air and the duration of dust storms. Deposits ranged from 226 to 52 kg/ha (mean value 146) measured in a south-westerly direction across the area studied; the S deposition ranged from 0·099 to 0·429 kg/ha (mean value 0·226). The most south-westerly sites received plant ash from clearing fires which increased the S deposited, but not the net gain of S to the whole area. The agricultural significance of the results is briefly discussed and other sources of atmospheric-S are considered.

The results of 216 field experiments with sugar beet (1957–69), testing K and Na fertilizers, were re-examined. There were only small increases in yield with K or Na on peat or peaty mineral soils but on mineral soils, 100 kg K/ha without Na increased sugar yield by about 0·4 t/ha and 100 kg Na/ha without K increased yield by 0·6 t/ha. Although the average response per kg of nutrient was approximately in inverse proportion to their atomic weights, K and Na were only partially interchangeable; their relative effects differed from field to field and year to year.

K seemed most effective in years with more than 80 mm rainfall in March–April but responses were halved when rainfall was 50 mm or less. Sowing date and the interval between giving fertilizer and sowing also influenced response to K; with late-sown crops, K fertilizer given within two weeks of sowing was usually ineffective. Response to Na differed much less with season so Na was on average more effective than K, especially in dry springs. It seems, therefore, that instances of near-perfect substitution between K and Na fertilizers result from chance combinations of weather and crop husbandry.

Since in some experiments yields from a combined dressing exceeded those from either nutrient alone, and as the weather is largely unpredictable, both K and Na fertilizers should be given on all mineral soils, except those very rich in K, to be certain of avoiding yield loss. Texture and exchangeable soil K and Na also affected both the amount and rate of response, but did not much influence optimal fertilizer dressings and so are not very useful for making differential fertilizer recommendations.

Comparisons of the effects of harvesting sugar-beet seed by the traditional method of tripodding with barn drying, swathing followed by threshing with a pick-up combine or desiccation with diquat followed by direct combine harvesting showed that there were no consistent or large effects on seed yield, germination, monogermity or size distribution. Thus the best method will be the one which is easiest and/or cheapest, which at present is swathing followed by pick-up combine threshing.

Sprays of NAA or 2,4,5-T at 10 or 100 mg a.i./l water before or after flowering had no effect on seed yield or germination and efforts to restrict the loss by shedding of large viable seed failed. Neither chemical decreased germination percentage by setting parthenocarpic seed. Attempts were made to dwarf the 2 m high seed crop to make it suitable for direct combine harvesting. Daminozide sprayed at 1000, 5000 or 10000 mg a.i./l water before or after the winter did not affect plant height, seed yield, germination, monogermity or size distribution. Chlormequat chloride applied similarly dwarfed plants by up to 18% but this was not enough to give a crop less than 1 m high suitable for direct combine harvesting. It did not affect seed yield, germination, monogermity or size distribution. Ethephon sprayed at 10, 100 or 1000 mg a.i./l water when plants were bolting had no detected effects. Chlorflurecolmethyl was sprayed at 10 or 100 before bolting or 1, 10 or 100 mg a.i./l water afterwards. Plants sprayed with the 100 mg/1 solution were dwarfed to less than 1 m high but the treatment was unsuccessful because it greatly reduced seed yield and germination; monogermity was not affected but a much greater proportion of seed fell into the small size grades.

Wool samples from 49 ewes representing four breeds of sheep, Ossimi, Rahmani, Barki and Merino were used to study the seasonal variation in wool growth. The first three breeds are of the local carpet-wool types of Egypt.

Consistent differences were found between breeds in diameter and length of fibres (i.e. genetic effects). These effects were not modified by the environment (i.e. time of year) although the latter had different effects on diameter than on length. Medullation, however, was not consistent from breed to breed in all seasons (i.e. there was genotype x environment interaction). It is concluded that seasonality in wool growth exists under the semi-arid conditions of Egypt in local breeds but to a lesser extent in imported Merino sheep.

The frequency of natural crossing in 1972 was estimated, in two subsets of a composite cross grown in F6 in Nairn and in Fife, as 2·61±0·25% and 4·59±0·35% respectively. The estimated inbreeding coefficients of the parental generations were less than would be expected if all types of pollination were equally fertile and gave equally fertile offspring.

Ammonium nitrate was applied to a kikuyu (Pennisetum clandestinum) dominant pasture at annual rates of 0, 134, 336 and 672 kg N/ha. Each nitrogen (N) rate treatment was continuously grazed at three stocking rates (SR) designed to apply similar grazing pressures at each N level and covering a range from 2·2 to 16·6 Angus weaner cattle/ha.

The N status of these pastures was periodically assessed 8–10 weeks after seasonal N applications by temporarily excluding stock and measuring D.M. and N response to additional ammonium nitrate application. Pasture growth response to additional N was constant and independent of SR and of annual N rate over the range 0 to 336 kg N/ha, despite wide variation in pasture availability. N concentration of plant shoots was increased by high SR and rate of N uptake was not significantly affected by SR. Pasture growth rate was positively related to annual N rate.

Herbage yield of kikuyu leaf, stem and litter on offer, was negatively related to SR but weight of underground organs was unaffected. Increasing SR increased the proportion of leaf and the rate of tillering. Pasture availability was positively and linearly related to N rate from 0 to 336 kg N/ha and maximal at 336 kg N/ha; the size of the litter fractions and underground organs was generally independent of N rate. N% in leaf and stem was reduced at low SR; N% of leaf, stem, litter, rhizome and root was positively related to N rate which was more influential than SR. The effect of SR on the size and relative distribution of the N in plant tops and litter fraction is discussed.

Kikuyu dominance was positively related to N rate and independent of SR. White clover invaded at No and N131 levels especially at a high SR.

Individual live-weight gain (LWG) of Angus weaner cattle continuously grazing (Pennisetum clandestinum) pasture was negatively and linearly related to stocking rate (SR) and independent of ammonium nitrate (N) application rate at similar grazing pressures.

Live-weight gain varied from 380 to 1056 kg/ha according to N rate in 1970–1 and from 637 to 1477 kg/ha in 1971–2. Calculated SR giving maximum LWG/ha was 3·4, 4·7, 7·6 and 9·8 animals/ha for the 0, 134, 336 and 672kg N/ha treatments respectively in 1970–1 and 6·1, 5·7, 9·1 and 10·6 animals/ha for the same treatments in 1971–2. Highest response to applied N (1·9 and 3·4 kg LWG/kg additional N in successive years) occurred between N131 and N336; response was greater at low and intermediate SR than at high SR. Carcass weight, quality score, depth of subcutaneous fat and area of eye muscle were negatively related to SR; SR's giving maximum output per unit area caused a reduction of ca.25% in production per head and adversely affected carcass quality at 18 months of age.

LWG/head was independent of feed availability in spring and summer and was positively related to availability of green kikuyu up to 600 kg D.M./head in the autumn/winter period.

Three field experiments are described in which the effect of plant density and date of stopping (removal of the apical bud) on the development of yield in several Brussels sprout cultivars was studied. In a fourth experiment, the effect of a leaf removal treatment was designed to assess the possible remobilization of dry matter to the buds from senescing leaves.

A total plant dry weight of 1·2 kg/m2 was achieved with a hybrid cultivar at commercial densities. Although the crop growth rate was low in midsummer, growth continued until mid-October. Bud dry weight yield was curvilinearly related to plant density with 2 plants/m2 giving the highest yields of 0·35 kg/m2 in stopped crops in November. Rapid bud growth did not begin until September but the increase in bud dry weight continued into December and January. Early stopping increased bud dry weight yield and the ratio of bud weight to total shoot weight. In November, bud dry weight accounted for 25–40% of the total shoot dry weight for most treatments.

In the leaf removal experiment, estimated net photosynthetic rate of the crop was greater than the bud growth rate up to the end of the experiment and there was no significant effect of removing leaves just prior to natural senescence on bud dry weight.

The production and partition of dry matter is discussed in comparison with other vegetative crops. It is found that the proportion of total dry weight partitioned to the useful parts in Brussels sprouts is comparatively low. Factors controlling the date at which rapid bud growth begins are discussed. It is concluded that the dry matter in the axillary buds is derived from photosynthesis occurring at the time of bud growth and that the remobilization of dry matter from other plant parts is not of great importance.

A method is suggested for estimating the mean bud size and standard deviation of a sample of sprout buds, separated into size grades by the use of riddles. From the standard deviation a potential size fraction is estimated, being the fraction of the buds occurring in a size grade of 10 mm width if the mean bud size were located at the mid-point of the grade. This estimate of bud size uniformity was independent of date of sampling for a period of at least 4 weeks.

The potential size fraction was increased by stopping (apical bud removal) and in some cultivars an optimum stopping date was indicated. Increased plant density also increased the potential size fraction, particularly in unstopped crops. Between-plant variation in bud size was significantly greater for the hybrid Thor than the outpollinating Seven Bills but within-plant variation was the more important component of overall bud size variation and was greatly reduced by stopping and by increased plant density in unstopped crops. Mean bud size at any harvest date was increased by early stopping and lower plant density.

It is concluded that the date of stopping should be chosen to minimize bud size variation and the plant density varied to spread maturity.

An analysis of marketable yield of sprouts is suggested in which the components are: number of plants/m3, number of buds/plant, acceptable size fraction, acceptable quality fraction and mean weight per marketable bud.

The number of buds per plant was dependent on date of stopping but was not greatly affected by plant density. This component was not found to limit yield.

Acceptable size fraction was related to the standard deviation of bud size and increased to a maximum at the time of optimum bud size. The maximum acceptable size fraction obtained from field samples could be reliably predicted from measurements of the standard deviation of bud size.

The acceptable quality fraction was of particular importance in later harvested crops and at higher plant densities. It was highly dependent upon cultivar but was little affected by stopping treatment. Unacceptable buds occurred most frequently at the base of the stem and it is argued that the importance of the blemishing diseases responsible for these losses has been increased by the single-pick harvesting technique.

The optimum plant density was related to the expected date of harvest but the practice of delaying maturity by increasing density is limited by the decreased acceptable quality fraction. Crops for harvest in October and November should undoubtedly be stopped both to reduce bud size variation and to stimulate bud growth.

The oestrogenic activity, coumestrol and formononetin content of white clover collected during the months May to December 1970 and 1971 was assayed in mice. The results showed considerable variations in oestrogenic activity which did not seem to be associated with a specific time of year or quantitatively related to the coumestrol content of the pasture.

During 1970–3 three experiments with winter wheat, three with spring barley, two with permanent grass and one with perennial ryegrass measured the effects of a liquid N-fertilizer (26% N) sprayed over the leaves either alone or with a herbicide added to it. ‘Nitro-Chalk’ (21% N) was used as the standard for comparison. The liquid N-fertilizer was made from urea and ammonium nitrate; the herbicide was a mixture of dichlorprop and MCPA. Each experiment tested all combinations of the two N fertilizers applied to give 38, 75 or 113 kg N/ha without the herbicide and with either 2·8, 5·6 (recommended dose) or 8·4 1/ha of herbicide. The 24 treatments were applied to winter wheat at growth stages 4–5 of the Feekes scale, to barley at growth stage 5 and to grass in late spring and again to regrowth after cutting.

Herbicide alone sometimes scorched the leaves but seldom badly. Liquid N-fertilizer nearly always scorched the leaves and the amount of scorch was increased by adding herbicide; scorch also was increased by increasing the amount of either and so was most severe when most liquid fertilizer and most herbicide were sprayed together; this damage did not decrease yields appreciably except when only 38 kg N/ha was given.

Spraying the herbicide with the liquid fertilizer always gave slightly better weed control than herbicide alone in the wheat, but not always in the barley; in the grass, weed control was no better than from herbicide alone.

‘Nitro-Chalk’ gave larger yields of wheat grain than the liquid N-fertilizer did in seven of nine comparisons without herbicide and in 20 of 27 with it, of barley grain in five of nine comparisons without herbicide and in 15 of 27 with it, of permanent grass in 25 of 27 comparisons without herbicide and in 70 of 81 with it, and of perennial ryegrass in nine of nine comparisons without herbicide and in 25 of 27 with it. Thus herbicide did not alter the advantage that ‘Nitro-Chalk’ had.

Percentages of N in the crops were larger with ‘Nitro-Chalk’ than with the liquid N-fertilizer but were changed little by herbicide.

Two digestibility and balance experiments were carried out using 12 growing heifers to compare first and second cut silages fed alone or with supplementary barley or barley and urea, and to measure the effects of the addition of urea to silage and barley diets at three levels of dietary energy.

Digestibility of gross energy (GE), N and modified acid detergent fibre (MADF) was higher in first cut than second cut silage diets, and although D.M. intake was slightly lower, metabolizable energy (ME) intake was significantly higher. Inclusion of urea increased the apparent digestibility of N but had no effect on the intake of D.M. or ME. Nitrogen retention was significantly higher on first cut than second cut silage diets and was significantly increased by the addition of urea when N intake was low. The relationship between daily N retention (DRN), ME intake (DME) and digestible N intake (DAN) was represented by an equation of the form:

DRN = C–2·164DME+0·447DAN–0·00512DAN2+0·0487DMExDAN,

but when apparent biological value (ABV) of dietary protein was high DRN was linearly related to DAN. These equations were used to estimate requirements for digestible N. The results of rumen fermentation studies suggested that the response in DRN to urea inclusion could be partially explained by the low rumen ammonia values on silage and barley diets.

Varieties of beans (Phaseolus vulgaris L.) were grown under both greenhouse and field conditions to determine the causes of inter-varietal differences in susceptibility to sodium toxicity injury. Varieties varied greatly in plant growth and survival on sodic soils under arid conditions. Environmental conditions were very important in determining differences in survival. Chemical analysis of plant parts indicated that varieties accumulated different amounts of sodium in the roots, stems and leaves. Sodium concentration in stems and leaves of sodium-tolerant varieties was controlled to a low level at lower degrees of injury.