Four field experiments in 1972–6 investigated the effect of undersowing trefoil or ryegrass in barley, and of fodder radish sown after barley, on yield and nitrogen requirement of following sugar beet. Autumn applications of isobutylidene diurea or glycoluril (slow-release nitrogen fertilizers) were also included for comparison with green manures. The plots were split in the following spring and dressings of 0, 50, 100 and 150 kg N/ha as ‘Nitro-Chalk’ tested on the sugar-beet crop.

The undersown green manure crops slightly decreased the yield of barley but, at the time of ploughing, returned up to 3·7 t dry matter/ha and 50 kg N/ha. In the absence of spring-applied nitrogen fertilizer for the sugar beet, green manures increased root and sugar yield, but when more than 50 kg N/ha was applied for the sugar beet they had no effect on yield. Autumn applications of nitrogen fertilizers such as isobutylidene diurea decreased the requirement for nitrogen in spring, but yields were no greater than from spring-applied nitrogen alone. Top and subsoils sampled in late winter and early summer from plots where green manures had been grown showed no detectable increase in soil organic carbon or total nitrogen, but soil mineral-nitrogen concentrations were increased slightly by green manures as was the potentially available mineralnitrogen released in an incubation test. It is concluded that, on loamy soils, green manures decrease the nitrogen requirement of sugar beet but give no benefits in yield which cannot be obtained from nitrogen fertilizer in spring before sowing the crop. assistance and Miss G. Smith for statistical analyses.

Experiments at Sutton Bonington in 1973 and 1974 compared the growth and yield of sugar beet which was handweeded at different stages with that where weed control was entirely by pre- and post-emergence herbicides, used alone and in various combinations. Data from the series of handweeding treatments enabled the crop's minimum weed control requirements to be specified. They indicated that an ideal herbicide would kill all the weeds present when applied at the six-leaf stage, persist in the soil to prevent weed infestation for 4 weeks, but not check the crop to the extent that recovery was incomplete. That the crop was capable of recovering from a degree of early check was clearly evident from the handweeded treatments; it proved possible for crops whose weights had been depressed by 25–30 % when first weeded to recover completely by harvest.

The performance of all post-emergence treatments fell short of these requirements. When the crop was at the six-leaf stage, the earliest emerging weeds were too far advanced to be killed by the herbicide. By themselves, pre-emergence herbicides gave weed control equivalent to only 2 or 3 weeks of handweeding but they did pave the way for more effective use of post-emergence treatments by restricting the spectrum of weed sizes present and sensitizing those plants which did establish. The most effective herbicide regime used in the experiments was the sequence of chloridazon applied pre-emergence followed by two post-emergence applications of phenmedipham. However, phenmedipham clearly checked the crop. Two weeks after application crop dry weight was usually depressed by one-third. Provided weed control was adequate, recovery was usually complete by the end of the season.

The effects of homozygous and heterozygous loci of 20 seedling lethal mutants on yield and yield components of barley (Hordeum vulgare L.) were studied. Nine of the 20 populations studied exhibited one locus heterosis (positive or negative advantages of Aa genotype compared with AA genotype) for yield per plant or one or more components of yield. In five instances of significance all showed positive single locus (Aa) heterosis for number of seeds per spike. Seedling lethal mutants, Ac ac and Alb,, p alb,, p showed three yield-component-heterosis. These two mutants might be suitable for hybrid barley production.

Three spring oil-seed rape cultivars were drilled on five dates during 1979 and 1980. Delayed drilling (1) reduced seed yield, (2) increased the main stem contribution to seed production, and (3) increased the percentage of damaged pods at harvest. The results indicated that cultivars similar to those used in this trial should be drilled between the 3rd week of March and mid-April.

Nitric phosphates containing 80, 50 and 30% water-soluble phosphorus, and Mussoorie rock phosphate, alone or with Amjhore pyrites, farmyard manure or straw, were compared relative to concentrated superphosphate for each of three cycles of a clusterbean–wheat and a groundnut–wheat rotation. Both the field experiments were made on alkaline P-deficient Samana sands. All phosphatic fertilizers were applied to each crop at the rate of 10, 20 and 30 kg P/ha. Dry forage of clusterbean, groundnut pods and grain yield of wheat were measured. The model of concurrent straight line response was employed to calculate availability coefficient ratios which express the relative effectiveness of the different phosphatic fertilizers.

Nitric phosphate containing 80 % water-soluble phosphorus and concentrated superphosphate were almost equal in their effectiveness in both 3-year rotational studies of clusterbean–wheat and groundnut–wheat. The relative efficiency of the nitric phosphates increased with the amount of water-soluble phosphorus they contained. Mussoorie rock phosphate was the least effective source of fertilizer phosphorus, although its efficiency is considerably higher for the legume clusterbean and for groundnut than for the cereal wheat. The efficiency of Mussoorie rock phosphate increased when it was mixed with the soil together with Amjhore pyrites, farmyard manure and straw respectively. These materials were more effective for clusterbean and groundnut than for wheat.

A sample of twelve buffalo, nine O Friesian × ♀ Egyptian native Baladi (½ Friesian) and nine ♂ Friesian ×♀½ Friesian (¾ Friesian) bulls were individually penned and fed commercially cubed concentrates and roughages from weaning at 100 kg and slaughtered over the live-weight ranges 161–560 kg for buffaloes and 176–448 kg for cattle. Weights of gut fill (GFW), empty body (EBW), offals (TOW) and carcass were recorded. Right sides of all carcasses were jointed then dissected into muscle, fat, bone and ‘other tissues’. Analysis of covariance based on the allometric equation Y = aXb was applied to assess growth patterns (estimated from the slopes) and compositional differences (estimated from the intercepts).

The effect of genotype-group was not statistically significant on EBW at the same fasted body weight and cold carcass weight at the same EBW. However, the buffalo empty body contained (P < 0·05) more offal than the ¾ Friesian empty body and heavier TOW and lighter hot carcass than ½ Friesian empty body of the same weight.

No significant genotype-group differences were found in the slope of the regression of weight of total side muscle (TSM), total side fat (TSF), subcutaneous fat, intermuscular fat and total side bone (TSB) on dissected side weight (DSW) and ½ EBW. Comparison of adjusted means, however, showed buffaloes to have significantly more TSF and TSB but less TSM than the Friesian cross-breds. Most of the difference in TSF was due to more subcutaneous fat in the buffaloes than in the Friesian cross-breds. In all comparisons the two Friesian cross-bred groups did not significantly differ from one another.

The results indicate that Egyptian buffaloes may be earlier maturing than Friesian cross-bred cattle and buffaloes of other countries. It was also concluded that in order to produce desirable carcass of fat:muscle ratio of 1:5, Egyptian buffalo bulls should be slaughtered to produce carcasses of slightly more than 230 kg whereas ½ Friesian and ¾ Friesian bulls can be taken to heavier weights. Methods for reporting carcass compositional data are discussed.

The tissue copper concentrations of Black Najdi sheep at the Hofuf Agricultural Research Centre (HARC) are reported. Lambs suffering from a delayed neonatal ataxia had low concentrations of copper in blood, liver and kidney, consistent with a diagnosis of copper deficiency, which was supported by histological examination of their brains and spinal cords.

Low concentrations of copper and high concentrations of molybdenum and sulphate in forages produced at the HARC appear to contribute to the high incidence of neonatal ataxia observed there.

The parenteral administration of 40 mg of copper to pregnant ewes improved the viability and weight increases of lambs over lambs born to untreated control ewes, even though all lambs had received an injection of 20 mg of copper soon after birth.

The provision of supplementary barley to the lambs running with their mothers and with access to lucerne hay increased their growth and blood copper concentrations over animals restricted to the hay diet.

The blood copper, haemoglobin and packed cell volumes of lambs born to ewes maintained on Rhodes grass were significantly lower than lambs born to ewes given lucerne, all ewes having received copper during pregnancy. This effect was attributed to the low copper and high molybdenum and sulphate content of Rhodes grass (Chloris gayana).

Thirty-six Friesian and Friesian cross-bred cattle about 11 months old were fed to grow at the rates of 0·50 (low) and 1·08 (high) kg/day in a 12-week winter feeding period and then turned out on high quality pasture. For 12 weeks after turning out the ‘low’ and ‘high’ animals gained weight at 1·17 and 0·90 kg/day respectively. There was a negative correlation (– 0·57, P < 0·01) between winter and grazing live-weight gain.

On two occasions herbage intake was estimated. Average intake of ‘low’ animals was 12% higher than of ‘high’ animals although herbage digestibility, estimated from faecal N, was similar for the two treatments. Differences in live-weight gain on pasture between treatments were largely accounted for by differences in intake.

The low rate of winter growth did not have any significant effects on age at slaughter, carcass weights or grades attained by the restricted animals.

Beverage tea is produced from the immature shoots manually harvested from the perennial shrub Camellia sinensis (L.) O. Kuntze. Fresh green leaf is mechanically comminuted and converted to the black tea of commerce by a series of partially controlled biochemical oxidation reactions (Sanderson, 1972). The final, unrefined dried product represents some 20% of the initial fresh weight of crop, the actual dry-matter content of the harvested shoots determining the percentage made-tea return (Keegel, 1955). Dry-matter content, hence, influences yield in terms of black tea produced. Although theeffectsof environmental, agronomic and cultural factors on green leaf yield have been studied intensively, little work has been done on the influence of such factors on dry-matter content. The present study examines the effects of nitrogen application rates on dry-matter content in four genetically diverse clonal populations throughout the main production season and during the first period of the Central African off-season.

The extent to which proteins fed to ruminants are degraded in the rumen is determined by their rate of degradation and retention time in the rumen. It is known that retention times in the rumen are much longer for poor quality than for good quality roughages. Thus, it is possible that protein supplements may be more extensively degraded when fed with poor than when fed with good quality roughages. The present experiment was designed to determine the relationship between retention times of roughages and a protein supplement fed with them.

The Indian subcontinent has witnessed a spectacular improvement in yield of wheat during the past decade (Rao, 1978). This is reflected in the improvement of the average national yields as well as of those regions where wheat is grown as an irrigated crop (Sinha & Aggarwal, 1981). However, after the release of the double dwarf variety Kalyansona, only marginal improvement in yield has occurred in recent years. Despite this, the semi-dwarf character continues to be considered a major factor for improvement of wheat. Asana & Chattopadhyay (1970), Konar & Asana (1975), and Wattal & Asana (1976) observed no significant difference in yield between tall and semi-dwarf (medium tall) varieties in pot culture experiments where lodging was prevented and competition was partly reduced. They ascribed prevention from lodging and improvement in the ratio of grain to total above-ground dry matter as major advantages in the modern varieties. Somewhat similar conclusions have recently been drawn by Austin et al. (1980). However, a detailed comparison of various physiological and biochemical characters lias not been made to determine whether any advance has occurred in basic processes such as photosynthesis and nitrogen assimilation. The present study was an effort in this direction.

Field experiments with chick peas (Rawat & Sanoria, 1977) and peas (Sanoria & Ram, 1979) showed a synergistic effect of a particular Rhizobium and Azotobacter on yield and quality of seed. Isolates of R. leguminosarum revealed differences in the yield and quality of lentil grown in pots and in the field (Mallik & Sanoria, 1980). As there is no evidence in the literature regarding the simultaneous use of Rhizobium and Azotobacter on lentil (Lens esculenta), this study was undertaken to assess their effect on the yield and quality of lentil in field.