Consideration of the composition of pig depot fats from the point of view of Callow's growth-rate theory (Callow, 1935a,b), shows that the theory appears to explain the iodine values of fats both of groups of animals and of depots of an individual pig. When, however, the fatty acid compositions of the fats are considered, the theory is untenable in respect of the depots of an individual pig. Differences in unsaturation between outer back fat, inner back fat, and perinephric fat are essentially determined by differences in the ratio of oleic acid to stearic acid, differences in linoleic acid content being inconsiderable.

It can equally be shown that the growth-rate theory does not explain the results obtained by Hilditch & Pedelty (1941) for depot fats of sheep. Differences between different depots both of the pig and of the sheep seem to be characteristic of the species and cannot readily be altered by altering either the quantity or the quality of the diet.

The contemporary comparison method of evaluating the progeny test of sires has been employed in estimating the breeding values of bulls used in the development of the Jamaica Hope breed. The need to test a larger number of bulls by combining the programme at the national level is stressed.

Rape (Brassica campestris) was labelled, during cultivation, with 15N and then prepared into rapeseed meal (RSM) and rapeseed straw (RSS). Three non-lactating cows, equipped with ruminal and Tshaped duodenal cannulae, were used to incubate both feeds in the rumen for various periods of time in mobile bags contained within larger mesh bags. Some of the mobile bags were then inserted into the duodenum and collected from the faeces. The effects of rumen incubation time and contamination by non-feed N during the rumen incubation and subsequent intestinal digestion on the intestinal feed N digestion values so obtained were assessed. The intestinal digestion of intact RSM nitrogen was also measured in vivo by dosing directly into the duodenum and measured as the net loss of excess 15N not recovered in the faeces.

With RSM, microbial contamination did not affect the disappearance values of feed N from mobile bags in the rumen, the difference in the disappearance between 15N and total N (NT) being negligible. However, the decrease in the disappearance from the mobile bags in the intestine with increasing rumen incubation time tended to be smaller with 15N than with NT, resulting in significantly increasing differences between 15N and NT with increasing rumen incubation time. The average in vivo net loss within the intestine of 15N of labelled RSM was much lower (50·0%) than the 15N disappearance from the mobile bags (80·9%).

With RSS, the disappearance values of 15N and NT from the mobile bags in the rumen were different. The disappearance of 15N was always higher than that of NT, and it also increased significantly more with increasing incubation time. The disappearance of 15N from the mobile bags within the intestine decreased with increasing rumen incubation time, but that of NT remained rather constant.

It is concluded that the intestinal N digestion of a feed may vary significantly depending on the degree of preceding rumen degradation. Therefore, constant intestinal digestion coefficients may not be applied in the modern protein evaluation systems. With protein-rich feeds, such as RSM, the influence of non-feed N is small and does not interfere with the estimation of intestinal N digestibility by the mobile-bag method. With fibrous feeds with low N, such as RSS, intestinal N digestion values are seriously confounded by non-feed N. The present study with RSM did not confirm the correspondence between the value obtained by the mobile-bag method and that in vivo.

Downward movement of potassium (K) was studied in the soil profiles of a longterm fertilizer experiment. The distribution of different forms of K and the percentage K saturation of the CEC of soil, at various depths of the differentially treated plots, indicated that applied K moved down to 75 cm depth in the high-K plots after nine cycles of a maize-wheat-cow peas crop rotation. However, movement of K was not noticed in plots not given K fertilizers. Plant uptake of K far exceeded the amounts of applied K. Application of K fertilizer reduced the release of K from the non-exchangeable reserves. Forms of K and the percentage K saturation of the CEC of soils were significantly correlated.

Variation of cotton yields from year to year has been a major problem in the Sudan Gezira for a long time. Previous studies indicated involvement of pest attack, soil nitrogen levels and lengths of growing season in this and suggested that adequate control of these factorswould lead to consistently high yields. Factorial experiments to test this hypothesis, comparing plots sown in early or late August, with or without frequent insecticide spraying and with orwithout nitrogenous fertilizer were therefore carried out at each of five sites in the Sudan Gezira and the first five years’ results are presented.

There were large, positive responses to nitrogen, spraying and early sowing at all sites. Nitrogen and spraying interacted positively, i.e. the response to nitrogen was much greater on sprayed plots and the response to spraying much greater on fertilized plots. Where plots were sprayed, early sowing also increased the response to nitrogen.

Treatment responses varied from year to year in such a way that the optimum combination resulted not only in much higher average yields but also in greatly improved stability of yield from year to year. The average yields, and the response to nitrogen on sprayed plots, were up to the levels which previous regression studies had estimated would be obtained in the absence of serious pest attack and were similar to peak yields in earlier years. During the course of theseexperiments commercial crop practice has changed towards earlier sowing, heavier nitrogen dressing and more frequent spraying, with apparently beneficial effects on yield and consistency of cropping.

The rain analyses summarised in this paper bring out very clearly the marked difference in the purity of the atmosphere between the industrial-rural area to the west and south and the purely agricultural area to the north and north-east of Leeds.

They show that the sulphur-content of the rain falling at a given station affords a fairly reliable diagnosis of the degree of pollution of the atmosphere by smoke, provided the observations be prolonged over several months. Further, evidence has been obtained in confirmation of that adduced by earlier observers, that the sulphur-content of the leaves of trees may afford useful assistance in the diagnosis of smoke-pollution. In preliminary tests the proportion of sulphur present in the leaf as sulphate gave a sharper grading of the pollution in different districts than the total sulphur.

The rain analyses show further that appreciable smoke-pollution still remains throughout the agricultural area at distances of seven miles from the city, the rate of improvement of the atmosphere on passing away from the city into the purely agricultural areas being appreciably slower in the direction of the prevailing winds than in other directions.

In a general way the analyses tend to show that the smoke, though in greater quantity, is in a higher state of oxidation in the dirtier or more industrial districts—due to more efficient combustion of the coal.

Throughout the industrial-rural area abundant evidence of damage to leaves was found, and there can be no doubt of the consequent check to growth.

The body weight and fleece weight of Marwari and Magra sheep (rams) of the desert areas of north-western India are compared with those of Corriedale rams, which are being imported into India for improving the productivity of the local stock through cross-breeding. All three breeds showed marked seasonal fluctuation in their body weight. While the Corriedales lost more body weight than the indigenous breeds during peak summer, they appeared to endure the relatively poor winter pasture conditions somewhat better. Between July and October, with the availability of lush monsoonal pasture, all three breeds increased in body weight.

The greasy fleece weight of Corriedale rams was nearly double that of indigenous rams. The potential of the Corriedale ram for improving the productivity of the local stock is discussed.

Kalla & Ghosh (1975) and Hopkins, Roberts & Evans (1975) recently reported finding a negative correlation between wool production and the erythrocyte concentration of reduced glutatione. Both groups also found a higher rate of wool production in GSH-low type animals than in GSH-high types. Because erythrocyte GSH types are genetically controlled and the GSH concentration within these types is highly heritable (Board, Roberts & Evans, 1974), Hopkins et al. (1975) concluded that selection for GSH-low type sheep may provide a method for manipulating wool production.

A comparison has been made over 2 years of spring shedding in cattle maintained in two environments experiencing a similar photoperiod but vastly different seasonal temperatures. At each location (Walcha and Narrabi, N.S.W.) experimental animals were divided into two nutritional groups, namely a Feed group and a Pasture group.

2. In 1961-62 both the Feed and Pasture groups in the warmer climate of Narrabri shed their winter coats in October, while animals maintained under the cooler conditions of Walcha did not acquire their summer coats until January of the following year. The Narrabri groups, however, also displayed superior live-weight gains than the corresponding groups exposed to the more severe winter conditions prevailing at Walcha.

3. The following year (1962-63) a differential feeding programme was adopted for the two Feed groups which resulted in their live-weight gains for the experiment being similar. Although the low ration of hay fed to the Narrabri Feed group to achieve this parity of weight gains introduced a nutritional stress factor in the group, these animals displayed a slightly superior shedding ability than did those in the Walcha Feed group.

During the winter of 1956, an experiment was conducted, using seventy beef steers of three different age-groups to determine intake and digestibility, by means of the indicator method, of mixed rations differing in ration concentration.

In the first part of the experiment, six pairs of steers of three age-groups receiving two types of rations were used. The pairs were selected on the basis of their rate of gain and constituted the fastest and slowest gaining steers of their respective age and ration groups. The object of the experiment was to ascertain whether any correlation could be found between the rate of gain of the steers and the degree to which the ration was digested.

Two indicators were used, namely, the internal indicator lignin and Cr2O3, administered twice daily by means of gelatin capsules, containing 7·5 g. of the indicator.

Using lignin as an indicator of digestibility, it was found that the calculated digestibility coefficient of both rations varied. A larger variation occurred, however, in the case of the ration with a concentrate to roughage ratio of 2:1 than in the case of the ration with a ratio of 1:3·6.

The effects of varying the timing of nitrogen application and the frequency of fungicide sprays on the incidence of foliar disease and on the grain yield of winter barley (cv. Panda) were investigated at two sites in Ireland over three years, 1986–88. Nitrogen application timing had little effect on the amount of foliar necrosis due to disease but delaying application of all the nitrogen until April significantly reduced grain yields in two of the three years when compared with standard split dressings in March and April. The reductions in yield reflected small differences in 1000-grain weight.

The number of fungicide sprays applied had significant effects on the amount of foliar necrosis and on grain yields. One-spray and two-spray programmes increased average yield by 16 and 32%, respectively. The yield increases were attributable to more ears/m2 and larger grains (greater 1000-grain weight). Fungicides also delayed the onset and significantly reduced the amount of brackling. Delaying nitrogen application in the spring did not decrease the number of fungicide sprays required to achieve maximum yield.

Two examples are given of field trials for which randomized blocks would seem the most suitable design, but in which special considerations of the future of the trial or the nature of the treatments make complete randomization impossible or impracticable. A type of design which takes account of these difficulties is described, together with the appropriate methods of analysis.

The author wishes to thank Mr S. C. Pearce for much valuable advice throughout this investigation.

Pod and seed growth were studied in two experiments in which the plant's source-sink relationships were modified by (a) manually pruning an autumn-sown, indeterminate white lupin variety, Lunoble, to a determinate form, and (b) by growing a determinate variety, Lucyane, at densities ranging from 7 to 35 plants/m2. The pruning experiments indicated that the faster pod growth rate of determinate genotypes was not an inherent genetic trait but an indirect physiological consequence of the plant's changed architecture. In the density experiment, crop dry matter (DM) and nitrogen (N) were maximum at the end of pod extension in late July and similar across the plant density range at c. 12 t DM and 320 kg N/ha. Therefore, the amount of dry matter per plant decreased proportionately with the increase in plant number. The DM and N contents of the pod walls were also maximum at the end of pod extension, but seeds contained only a third of their final DM and a quarter of their final N. Protein accumulation during the final stages of seed growth, therefore, depended on the remobilization of nitrogen from other plant organs, primarily the leaves and pod walls. Nitrogen withdrawn from the leaves accounted for 44% of the gain in the pods, and N withdrawn from pod walls for 50–60% of the gain in the seed.

Seed number/m2 was the major yield component. Seeds and pods mainly aborted during early development, but seed number per pod was also decreased by some seed abortion after full pod extension, especially in first-order pods of plants grown at high density. The number of late-aborted seeds was negatively correlated with the amount of N remobilized from the pod wall. In determinate lupins, which have highly synchronous flowering and pod development, the large and sudden remobilization of nitrogen from leaves and pod walls for seed growth and protein accumulation triggered crop senescence.

Three field experiments were carried out on sandy loam soil at Levington, Suffolk, on the effect of irrigation on nitrogen requirements of sugar beet. Four nitrogen rates (0, 67, 134, 201 kg/ha) were examined with and without irrigation. Nitrogen increased sugar yield each year, as did irrigation in 1969 and 1970, but not in 1968 when the soil moisture deficit was small. There was a significant nitrogen x irrigation interaction in 1970 only, but on average there was a greater response to nitrogen with irrigation than without it.

These results and other published data suggest that on sandy soils in eastern England moisture deficit can restrict nitrogen response, and that the economic optimum nitrogen rate is appreciably higher with irrigation than without it.

1. A number of soils—treated with acid and washed free from it—have been found to possess in high degree the power of destroying phenol. Soils derived from certain geological formations seem to possess this property more than those derived from others.

2. This effect has been obtained from soils treated with sulphuric, hydrochloric, nitric, phosphoric, formic, and acetic acids.

3. The bulk of the loss of phenol is instantaneous; but the maximum loss is attained within about 20 hours.

4. An inverse relation seems to exist between the period of contact of acid with soil and the extent of the subsequent loss of phenol.

5. The loss of phenol is prevente d by several treatments—ignition of soil before or after acid-treatment; treatment with alkalis or sulphurous acid after acid-treatment; autoclaving the soil after acid-treatment and also in less degree before acid-treatment.

Experiments were made over a 3-year period in order to evolve a production package for yam that would eliminate the laborious operations of hand weeding and staking. First, nine herbicides were applied to yam plots before or after yam emergence. On the basis of weed control effectiveness and low phytotoxicity to yam plants, ametryne (2-(ethylamino)-4-(isopropylamino)-6-(methylthio)-S-triazine) was chosen for subsequent experimentation. Next, ametryne at 2, 4 or 6 kg/ha was applied to yam plots either immediately after planting, or with 1 kg/ha paraqviat (l, 1'-dimethyl-4,4'- bipyridinium ion) 3 weeks after planting. The delayed applications gave more effective weed control and higher yields than the early applications. For the delayed application, 4 and 6 kg ametryne/ha did not give significantly different yields, but yielded significantly more than 2 kg/ha. When a combination of ametryne at 4 kg/ha and paraquat at 1 kg/ha was applied 3, 6 or 9 weeks after planting, the weed control effectiveness was greatest at 6 weeks after planting while the 3- and 6-week applications did not give significantly different yields. Herbicide applied 9 weeks after planting gave the poorest weed control and the lowest yields.

Finally comparisons were made between the conventional staked, hand-weeded yam production, and a new production package in which the yams were not staked and weeds were controlled with ametryne (4 kg/ha) + paraquat (1kg/ha) applied at or just before emergence. When small (150g) setts were used, yields from the new package were not significantly lower than those from the conventional system, even though the new package was considerably less laborious. Cultivation with large setts, however, resulted in a decrease in yield when the plants were not staked. Strategies that could further enhance the attractiveness of the new production

1. Under artificial conditions of plant growth, the relative development of carotene is very poor. The absence of sunlight appears to be the main cause.

2. Under field conditions, the maturity of a plant plays an active part in determining the carotene content, which gradually decreases with age. This phenomenon is less discernible among the legumes. The nitrogen content generally runs parallel to the carotene.

3. The species of the plant seems to be a determining factor in the capacity of the plant for carotene formation.

4. A study of the distribution of the carotene in different parts of the same plant shows that the leaves of grasses contain 3·1–11·0 times more carotene than the stems. The earheads and stems have almost equal amounts. With the growth of berseem and lucerne, the ratio of carotene in leaf to carotene in stem shows a tendency to increase, suggesting that the deterioration in the stem is comparatively more rapid than in the leaves when the plant becomes older.

The herbicide chlorsulfuron is commonly applied to cereals and may persist in alkaline soil long enough to damage subsequent sensitive crops. Sewage water, a potential source of the heavy metal cadmium (Cd), is used to irrigate agricultural soils in many developing countries. The current work evaluated the effects of the residual herbicide chlorsulfuron and Cd on maize seedlings, with particular attention to the mechanism of their action on plant growth. Maize seeds were planted in soil that had been sprayed with chlorsulfuron and Cd, after which residues in both seedlings and the soil were measured. The chlorsulfuron dose was correlated with the amount of residue found in seedlings but not in the soil. In all, 39 metabolites were identified in seedlings using the Automated Mass spectral Deconvolution and Identification System software program and the retention index method. The combination of chlorsulfuron and Cd significantly reduced multiple metabolites in the shikimate pathway, malic acid and citric acid production in the tricarboxylic acid cycle, and lactic acid, glucose, aspartic acid, asparagine and 3-glycerophosphoric acid production. In addition, chlorsulfuron caused an increase in multiple amino acids, including tyrosine, methionine and asparagine, and a marked decrease in caffeic and cinnamic acids (the secondary metabolites derived from the shikimate pathway and galactose). Finally, chlorsulfuron and Cd stress markedly increased shikimate acid, decreased 3-glycerophosphoric acid and caused negative correlations between the amounts of phenylalanine and tyrosine and those of quinic- and cinnamic-acid. In conclusion, chlorsulfuron and Cd did not have a synergistic effect on maize seedlings; rather, the combination of these pollutants had an antagonistic effect on some amino acids.

During the month of February, 1913, an examination was made of a number of celery plants, grown in the gardens attached to the South-Eastern Agricultural College, Wye, for the purpose of ascertaining the amount of damage produced at that time of the year by the parasitic fungus Septoria Petroselini var. Apii. Some of these plants were found to be in an advanced stage of decay, the affected portions being discoloured and pulpy, and showing every evidence of a soft, brown rot. As numerous pycnidia of the fungus were to be found on most of the plants examined and as that parasite is known to continue its ravages during the winter, even when the plants are dug and placed in storage, it was thought that the Septoria was the primary cause of the damage. It was found, however, in most cases, that when the soft pulp was subjected to microscopic examination, there was no trace of either pycnidia or mycelium, while bacteria and often eelworms were swarming in such material.

The production of haploids in large numbers is of great value to plant breeders and geneticists and this has led to the development of new techniques for haploid production (Nitzsche & Wenzel, 1977). In cultivated barley, Hordeum vulgare, there are four principal methods of isolating haploids: the culture of microspores, the isolation of embryos following the interspecific hybridization of Hordeum vulgare with H. bulbosum, ovule culture and the use of the haploid initiator gene (Kasha & Reinbergs, 1982). The present paper focuses attention on the use of the haploid initiator gene (hap) and compares this method with the H. bulbosum and microspore culture methods of haploid production.