Over three grazing seasons a sward of perennial ryegrass, cv. Gremie, was grazed on a rotational paddock system by growing beef cattle weighing on average 185·5 kg when turned out to grass in April. Six grazing treatments were compared: grazing at 20- or 35-day intervals at each of three herbage allowances of 5·3, 4·3 and 3·3 kg grass D.M./100 kg live weight (4·0, 3·2 and 2·4 kg D.M./IOO kg live weight in the 1st year).

Measurements of net herbage accumulation and herbage consumption throughout each grazing season were made by taking grass sampling clips to ground level before and after grazing. Animal live-weight gain was assessed by regression on weighings of stock taken either every 7 or every 4 days depending on regrowth interval treatment. Adjustment of allocation treatment was made by varying the weight of stock grazing on a fixed paddock area.

In no year did annual net herbage organic-matter accumulation (NHA) differ significantly according to length of grazing interval. NHA showed a 4·7 % advantage for the longer interval in the first 2 years which changed to a deficit of 4·1 % in the final year of the experiment. Herbage allowance treatment produced no significant effect on NHA in any year. The interaction effect of herbage allowance and grazing interval was not significant.

Herbage consumption was greater in 2 years out of three under the 20-day regrowth period than with the 35-day treatment, although average degree of defoliation was slightly greater (44·0 v. 38·4%) with the longer interval.

Animal live-weight gain was significantly (P < 0·05) affected by herbage allowance in all 3 years; decreasing herbage allowance generally resulted in reduced live-weight gain. Only in 1 year was there a significant difference (P < 0·001) in live-weight gain with the different rotation length treatments.

The 65 spring and 14 winter cultivars of barley on the 1981 U.K. National List were examined electrophoretically for allozyme variants of phosphoglucoisomerase (PGI). Two different banding patterns were observed, a ‘fast’ and a ‘slow’ migrating type. With the exception of six spring cultivars in which the ‘slow’ type was found, all the cultivars were classified as ‘fast’. F2 progeny of crosses between ‘fast’ and ‘slow’ plants were used to interpret the banding patterns as resulting from the dimeric isozymes of two alleles (allozymes) each producing a triple band pattern, the faster two bands of which were considered to be ‘secondary’ or artefact bands. With the notable exception of Dragon and its sister line RPB 1115–75 all of the other ‘slow’ cultivars and breeders' selections were found to have the ‘slow’ cultivar Midas in their breeding history. Midas was bred using material from three ‘fast’ cultivars and a γ-ray mutant strain, the irradiation which produced this strain being regarded as the likely cause of the ‘slow’ isozyme. Unlike all the other cultivars tested, Midas was found to be a mixture of genotypes comprising 73% ‘slow’ and 27% ‘fast’ plants, a ratio which was most probably due to founder effects caused by the breeders' selection programme. In the light of the present investigation and other reports it is concluded that it is not an uncommon occurrence to find plants with different electrophoretic banding patterns within inbred cultivars.

This result has serious implications for cultivar registration as there is a possibility of selecting electrophoretically distinct plants from within existing registered cultivars. It is concluded therefore that the protection afforded to plant breeders under Plant Breeders' Rights schemes could be seriously threatened by the use of electrophoretic characters for cultivar registration except in some specific incidences where it may be possible to apply appropriate safeguards. The implications for plant breeders of the existence of isozymes of PGI, of possibly different efficiencies, within commercial cultivars of the genus Hordeum are also discussed.

Growth rates were compared of pigeonpea (Cajanus cajan), moth bean (Vigna aconitifolia), mung bean (Vigna radiata) and sorghum seedlings aged 2–5 weeks. The seedling growth rates were analysed in relation to leaf area development, net photosynthetic rate, nitrogen accumulation, nitrate reductase activity, and soluble protein content. Growth rates were highest in sorghum and lowest in C. cajan. Leaf area development was very fast in sorghum and very slow in C. cajan. Net photosynthetic rate of sorghum leaves was double that observed for the legume leaves. No significant difference was observed in nitrate reductase activity, nitrogen percentage or soluble protein content between sorghum and the legumes. In sorghum, early investment of assimilates into leaf development ensured a higher assimilation of carbon and nitrogen per plant. In the legumes, slow development of leaf area coupled with low photosynthetic rates probably resulted in slow growth of the seedlings. In the legume seedlings, vigour was related to the rates of leaf area expansion. Leaf area expansion rates were not related to the nitrogen status of the leaf in the species examined.

It was observed in a recently concluded study (O. O. BalogunandB. L. Fetuga, unpublished data) that methionine and palm-oil supplementation to a cassava flour-soya-bean meal diet encouraged satisfactory growth, efficiency of live-weight gain, nitrogen retention and carcass quality of weanling pigs. Our earlier reports (Balogun & Fetuga, 1981; Balogun, Fetuga & Oyenuga, 1982) also indicated that the muscles of pigs responded differently to dietary methionine and lysine and that the quantitative requirements of these amino acids for maximum development of the muscles were at variance with the methionine or lysine requirements for maximum growth performance and nitrogen retention.

The use of town stable manure enters so largely into the economy of farms, and especially market-gardens, situated within fairly easy distance of London or other large cities, that it is somewhat curious that but little information has been published in this country as to its chemical composition. In fact, with the exception of a couple of analyses made by myself as long ago as 1889, which were published at the time in the Mark Lane Express, and subsequently reprinted in Aikman's book on “Manures and Manuring,” I do not remember to have seen any analyses of London manure. The samples which were the subject of these analyses were collected from a very limited number of stables, some of which were littered with peat moss and others with straw, the object at the moment being to compare the manure produced with the two kinds of litter. I have more recently however made some fairly full analyses of two more representative samples of London manure, but before proceeding to give these it may be desirable to reprint in this place, for future reference, the old analyses just mentioned.

Seeds from individual heads of wild safflower (Carihamus oxyacantha Bieb.) plants collected from five locations were used in this study. Locations were situated on a roughly east-west transect passing through Shiraz, Iran. The western locations were cooler with higher annual rainfall than the eastern sites. Wild safflower plants of different locations produced about an average of 150 heads per plant, but only 60% of them contained seeds. Frequency distributions constructed for number of seeds per head, germination percentage, and seedling length showed trends of change in the skewness of the distribution for the latter two characteristics parallel to the environmental selective pressure, i.e. the skewness was towards the left for eastern locations but it gradually moved to the right for western ones. Striking amounts of polymorphism were also observed for these characters. A very high proportion of total variance was concerned with differences between heads of the same plant for number of seeds, germination ercentage, and seedling length. Very little variability was found among plants of the same ecotype.

Nine experiments in the East of Scotland were completed in the years 1966, 1967 and 1968 to test the response of potatoes grown for ware to five levels of a 15½–15½–21 fertilizer applied at rates of 0, 4, 8, 12, 16 and 20 cwt per acre.

1. Mean yield of ware tubers increased up to the highest fertilizer level.

2. Mean yield of small tubers increased only up to the 8 cwt per acre level and then declined.

3. Dry matter content of ware tubers decreased with increasing levels of fertilizer.

4. Increasing fertilizer levels lowered soil pH. At one site this was associated with a significant reduction of common scab on the tubers.

1. Symptoms of zinc deficiency and toxicity have been studied in guar, brinjal, maize, tobacco and Mosambi (Mozambique) using a sand-culture technique.

2. In zinc-deficient guar plants, depressed vegetative growth and smaller leaves than normal ones were found. Only few flower buds were seen, and there was abscission of leaves at the time of flowering.

3. Chlorosis followed by necrosis and finally the drying up of leaves was the most characteristic deficiency symptom in the case of brinjal; growth was stunted and flowers failed to set fruits.

4. In the newer leaves of maize, intermittent light yellow bands were formed just parallel to the midrib.

5. In the lower leaves of tobacco, chlorosis followed by necrosis was observed; growth was stunted and leaves were small in size.

6. In Mosambi (Mozambique), whitish yellow patches in between the veins were observed; leaves were small, pointed and quite unhealthy.

7. There was an increase in zinc uptake with increased rates of application of zinc.

8. Crude protein increased with increasing zinc supply up to levels beyond the optimum for growth.

The selenium concentration of cereal grain and herbage from 131 farms in England and Wales was, in general, low: the proportions of samples with values below 0·03 mg/kg D.M. were 60% for grain (primarily barley, from 96 farms) and 39% for conserved herbage (primarily hay, from 131 farms). Values for fresh herbage from 12 farms were similar to those for conserved herbage. There were no significant differences in selenium concentration among herbage species. For all samples, those from the Cambridge area contained more selenium than those from other parts of England and Wales.

The present communication is intended as a contribution to the study of the capacity of soils to retain moisture in equilibrium with the atmosphere. The experimental material with which it deals consists in part of the analytical data obtained in the investigation of one hundred soils of the county of Dorset, which has been carried out for the County Council, and in part of a series of determinations made for the purpose of elucidating this problem.

An inquiry has been made to determine whether shearling rams sire more good-quality offspring than would be expected from the proportion of them used in Swaledale flocks in northern England, 1951–3.

Quality was assessed at two levels, both concerning shearling rams: those passed for registration in the Flock Book, and those making £50 or more at Kirkby Stephen ram sale.

The expected percentage of lambs, and hence good-quality offspring, by shearling rams was estimated from the practice on a sample group of farms, using the formula

where E is the estimated percentage of lambs by shearlings, x the proportion of shearlings to all rams in use, and y the fractional value in numbers of ewes served where aged rams are regarded as having unit value.

The estimated percentage of lambs by shearlings is 28·7, with s.e. = 2·444.

The actual percentage of registered shearlings sired by shearlings in 1951–3 was 35·7 with s.e. = 0·764, and the actual percentage of shearlings sold for £50 or more in the same years was 32·8 with s.e. = 3·313.

That shearlings sire a slightly, but significantly, higher number of registered shearlings than would be expected is probably due to the transmission of earlymaturing qualities, since shearlings of high quality are consistently used in early-maturing, and therefore shearling-producing, flocks. Those likely to sire ‘£50’ shearlings often remain in early-maturing flocks throughout life and, by continuing to sire this high-quality progeny, depress the percentage of such shearlings sired by shearlings to a figure not significantly higher than the ‘expected’ figure.

Chemical-mutagen treatment of Ethiopian mustard (Brassica carinata A. Braun) line C-101 seeds (which contained about 441 g/kg C22[ratio ]1) led to isolation of a mutant, L-935, which contained about 190 g/kg erucic acid (intermediate C22[ratio ]1) in the seed oil. The objective was to determine the inheritance of the intermediate C22[ratio ]1 level in this mutant. The mutant L-935 was reciprocally crossed to C-101 and to the mutant line L-2890 (which contained 112 g/kg C22[ratio ]1; low). The F1, F2 and BC1F1 generations were obtained. Cytoplasmic effects were not observed in any of the crosses. The analysis of the fatty acid composition in the F2 populations from the crosses of L-935 with C-101 revealed a segregation pattern fitting a ratio 1[ratio ]2[ratio ]1 for intermediate, high and very high C22[ratio ]1 content. The segregation patterns fitted a one-locus (designated M2) model with two alleles (M2 and mi) and with partial dominance of high over intermediate C22[ratio ]1 content. The segregating generations of the crosses L-935×L-2890 showed a strong transgressive segregation with C22[ratio ]1 values ranged from 1·3–406·5 g/kg. The analyses of the F2, BC1F1 and F3 generations indicated that the combination of alleles at two loci, M1 and M2 controlled the transgressive segregation for C22[ratio ]1 content. The proposed genotypes (C22[ratio ]1 content) for each parent were as follows: L-935 (190 g/kg 22[ratio ]1)=MMmimiEEEE; L-2890 (112 g/kg C22[ratio ]1)=mmmmEEEE; and C-101 (441 g/kg C22[ratio ]1)=MMMMEEEE.

1. The principal change in the composition of adult fowls during fattening is an increase in the fat content of the body, the protein increase being subordinate in amount.

2. Within the limits studied, the efficiency of conversion of food energy to carcase energy is not affected by variation in the protein content of the ration.

3. A food mixture consisting of 5% dried skim milk of 95% Sussex ground oats proved as efficient for fattening fowls as a food mixture consisting of 20% dried skim milk, and 80% Sussex ground oats.

4. The food mixtures used gave satisfactory results in fattening when used in pellet form in a dry state.

A field experiment was conducted in 1990 and 1991 under intermediate deepwater conditions (15–50 cm) at Cuttack, India with two rice cultivars - Banaprabha, a semi-tall (130 cm), short duration (95 days), upland cultivar and Gayatri, a photosensitive, semi-dwarf (100 cm), lowland cultivar of long duration (170 days). The cultivars were direct-sown either in pure stands using 400 seeds/m2 at 20 cm row spacing or in mixed stands composed of alternate rows sown with 200, 300 or 400 seeds/m2 each at 10, 15 or 20 cm inter-row spacing. Mixed-row cropping of Banaprabha and Gayatri produced 17–21% higher grain yield than a pure crop of Gayatri. Panicles/m2 increased with higher seed rate and decreased with wider row spacing but a reverse trend was observed in panicle weight. Maximum grain yield was obtained at a row spacing of 15 cm but the effect of varying seed rates at each row spacing was non-significant. Gayatri produced up to 82% of its pure crop yield and contributed up to 70% of the total yield in the mixed crop system. Therefore, the yield advantage under mixed cropping was due to the late maturing cultivar benefitting from the increased area available after the harvest of the early cultivar. A crop stand using 200–300 seeds/m2 of each cultivar at a 15 cm row spacing was found to achieve the optimum productivity from the mixed cropping system.

The results are reported for an experiment in which nitrogen rates from 0 to 672 kg/ ha and potassium rates from 0 to 558 kg/ha were applied annually on an S. 24 perennial ryegrass sward. At each of the five crops cut annually the yields of herbage dry matter and crude protein, and the potassium content of the herbage dry matter were determined. The potassium content of the soil was also measured annually. Models relating each of these variates to the nitrogen and potassium rates were derived, and their validity is demonstrated with reference to the results from earlier experiments. The problems associated with determining the correct rate of potassium fertilizer to apply on swards receiving given rates of nitrogen fertilizer are discussed using the models to predict the effects of different nitrogen-potassium combinations. In order to relate the implications of this discussion more closely to practical grassland management, economic as well as biological criteria are taken into account by incorporating cost factors in the models.

Theory for the non-steady-state diffusion flow of a spheroidal body is discussed and solutions are presented for estimating the time-dependent diffusivities at small and largo times following sowing in soil of germinating soya-bean, cow-pea and blackgram seeds. The validity and also the limitations of the equation for large times to estimate time-dependent diffusivities are discussed. Assuming that the time of germination was at infinity it was possible to reduce the equation for small times to a simple form. Thus, with the help of these two equations it was possible to study changes in the diffusivity of seeds at different soil matric potentials throughout the period, immediately after sowing until germination. The diffusivities showed gradual decrease at 0 bar potential for soya-bean and cow-pea, and increase at – 2 and – 10 bar potentials for soya-bean, cow-pea and blackgram seeds with time. The decrease in diffusivity with time under non-stress soil water condition is explained as predominantly a physiological phenomenon of the seed due to the increase in seed water content with time, while its increase with time under water stress conditions is probably because of the decrease with time of the initially large seed-coat resistance and tortuosity showing small values of diffusivity. The discussion suggests that the role of area of contact on the water uptake of the buried seeds as reported so far is contradictory and, therefore, not convincing.

The present work was carried out on 24 coarse-wool Barki and ⅝ Merino–⅜ Barki ram lambs to study the effect of vitamin A supplementation on some skin and wool characteristics. Lambs, at the age of 6 months, were allotted to three groups receiving no vitamin A supplement, 50000 i.u. and 100000 i.u. of vitamin A/head monthly. Blood samples were taken monthly for the assessment of vitamin A in the plasma. It was found that vitamin A in the plasma ranged from 42·4 to 17·50 and from 41·67 to 50·03/ μg/100 ml in the control and treated groups respectively, from the start of the experiment till the end at the age of 17 months.

Vitamin A supplementation caused increments in external diameters, of primary and secondary follicles in Barki and primaries in ⅝ Merino, higher than those encountered in internal diameters. An increase in staple length and clean fleece weight of ⅝ Merino and a slight increase in Barki fibre diameter was observed in vitamin-A-supplemented animals.