Barley, wheat and oats were grown in field and in glasshouse-pot experiments without fertilizer-N, and with added ammonium sulphate or calcium nitrate. In the field fertilizers supplied 50 and 100 lb N/acre, in the glasshouse 100 and 200 lb N/acre (calculated from the surface area of the pots). Plant samples were removed at various stages, dry weights were measured, percentage N determined and N uptake calculated. Those taken after the ears had emerged were divided into ear and straw. The number of coleoptiles emerging and of ears in the later samples were counted. Soil samples were taken after removing the plants grown in the glasshouse, and analysed for ammonium and nitrate.

1. Cereal plant density affects yield and growth parameters of fundamental importance. An experiment is described in which growth and development, and yield and yield components of barley grown over a wide range of density were examined.

2. Four varieties of barley—Proctor, Plumage-Archer, Domen, and Moore—were grown at densities approximately equivalent to 35, 70, 140 and 280 lb/acre. Density was found not to affect seedling establishment or plant survival, but there was a variety effect on seedling establishment.

3. Varietal differences were seen in maximum tiller number, and the percentage of tillers surviving to form ears. These differences were most marked between the six-row variety and two-row varieties. The effect of increasing density was to increase the maximum tiller number, but this was followed by different rates of tiller death until early June, after which there was no further compensation for tiller number. Ear emergence and ear number were affected both by variety and density.

A co-ordinated trial has been carried out at eighteen centres to compare the following amounts and methods of providing water to growing pigs: (1) water in the feed in the ratio of 2½: 1; (2) water in the feed in the ratio of 4:1; (3) dry feeding with water available separately ad lib.; (4) water in the feed in the ratio of 1½: 1 and also available separately ad lib.

Pigs on dry feeding had substantially worse growth rate and feed conversion; carcass lengths were slightly smaller and eye muscles slightly wider. Fat measurements were not significantly affected.

1. Perennial ryegrass (S. 23 and S. 24 sown together) and cocksfoot (S. 37 and S. 143 sown together) were compared in grazing and individual feeding experiments during the summer months of 1960, 1961 and 1962, using spring-born calves.

2. Herbage samples indicated that more grass was available to the animals grazing on ryegrass than on cocksfoot in 1961 but no differences were found in 1962. The ad lib. method of feeding should have ensured that quantity did not affect the results in the feeding experiments.

The gas production in batch fermentation of vegetable matter found on farms is shown to lend itself to the application of monomolecular equations providing an active and well-developed starter material is used for initiating the fermentations. The reaction velocity constants as established for a common material found in the tropics, namely elephant grass, would seem to be some two to five times lower than that previously reported for sewage sludge. The higher rate of decomposition of the sewage sludge is attributed to its more favourable physical condition and possibly also to its greater content of more easily fermentable substances.

1. Fifty-one Scottish Blackface ewes were divided into three groups and individually fed throughout the latter half of pregnancy: (I) in excess of nutrient requirements, (II) to produce a uniformly moderate degree of undernourishment during the last 6 weeks of pregnancy, and (III) to produce a uniformly severe degree of undernourishment during the last 6 weeks of pregnancy,

2. The prescribed levels of undernourishment were maintained by weekly adjustments of feed intake based on plasma FFA levels (group II) and plasma ketone levels (group III). The use of the technique is discussed.

3. Undernourishment during the latter half of pregnancy reduced birth weights of single and twin lambs after adjustment for weight of the dams to the same extent. In the moderately undernourished ewes the reduction was approximately 10%, and, in the severely undernourished ewes, approximately 25%.

Fifty-one Scottish Blackface ewes were divided into three groups and individually fed throughout the latter half of pregnancy: (I) in excess of their nutrient requirements, (II) to produce a uniformly moderate degree of undernourishment throughout the final 6 weeks of pregnancy, and (III) to produce a uniformly severe degree of undernourishment during the same period.

Marked differences were evident in the amounts of feed required to maintain the prescribed nutritional states, and within the undernourished groups, between ewes with single and twin foetuses. In both groups of undernourished ewes the amount of feed required to maintain the prescribed level of undernourishment during late pregnancy was strongly related (P < 0·001) to birth-weight. The additional nutrient requirement of the ewe in late pregnancy was estimated to be 100 g D.o.m./kg foetus/day.

1. Using blood plasma FFA and ketone values to assess the nutritional state of individual ewes, high (H), medium (M) and low (L) planes of nutrition were imposed on 3 groups of Blackface ewes during pregnancy. By this method, ewes bearing single or twin foetuses were equally well or severely undernourished within treatment groups. The effects of these planes of nutrition during pregnancy have been assessed in terms of milk production, lamb growth, and live-weight changes by the ewes duriug their subsequent lactation. Immediately after parturition all ewes were individually fed a pelleted food ad lib. and their voluntary food intakes recorded. From 5 weeks of age individual voluntary intakes of solid food by the lambs were also recorded. Because of insufficient pen accommodation group-M ewes and lambs were discarded after 5 weeks of lactation.

The introduction of resistance to eyespot (Cercosporella herpotrichoides) from Aegilops ventricosa to Triticum aestivum is described.

In the hybrids, amphiploids and in the amphiploid derivatives investigated, the eyespot resistance was apparently simply inherited. Furthermore, this character was controlled by a chromosome, or chromosomes of the D genome of Ae. ventricosa and thus could be introduced into T. aestivum by recombination.

1. Swards of perennial ryegrass (S 24) were grown under conditions of high fertility and were cut at intervals of (a) 3 weeks, (b) 6 weeks, (c) 3 weeks changing to 6 weeks at later points in the growing season.

2. The rate of herbage production (kg D.m./ha/day) was higher throughout the season (April to November) under the longer cutting interval. Plots which were changed from 3- to 6-weekly cutting intervals subsequently showed the same rate of production as those cut every 6 weeks throughout.

Inflorescences emerged from a higher proportion of tillers after long growth periods; this could explain the higher rates of production up to July.

The activity of alanine aminotransferase (Al. T) was determined in serum and liver biopsy samples collected from cows over a period of more than a year. There were statistically significant fluctuations in both liver and serum activities during the period of observation. On the whole serum and liver activities appeared to fluctuate independently of one another and of climatic changes. The only possible correlation was between the rate of increase in hours of daylight and the increases in serum and liver activities in the period January to March. The cows were calving at intervals throughout the year, and their liver and serum Al.T activities did not change significantly during the last three months of pregnancy and the first 3 months of lactation.

Between 1924 and 1934 Uganda, in common with many other African territories, tested arable rotations incorporating legumo green manures to maintain soil fertility (Martin, 1944; Uganda Dept., 1931–32) and it was concluded that the green manures failed to maintain fertility and were not worth the trouble involved. The Uganda Department of Agriculture accordingly changed its official rotations to modified forms of the indigenous shifting cultivation, namely 3 years of elephant grass rest alternating with 3 years of cropping. This same failure of green manures, combined with the apparent lack of correlation between crop yields and soil nutrient contents and the obvious deterioration of soil structure under crops, led Martin (1944) to the view that it was the physical not chemical condition of the soil which was important. Using his wet sieving technique he showed that, provided soils contained enough clay, all grass increased the water-stable crumbs over ½ mm diameter in the top soil and that 3 years under elephant grass was about optimal for restoring crumb structure.

Sugar-beet plants require an appropriate sequence of environmental conditions to change from the vegetative to the reproductive phase during the first year of growth. When plants bolt, the stem lengthens and bears flowers and the stem and root become lignified. Bolting is normally induced by a period of low temperature followed by higher temperatures and long-day conditions. The minimum time necessary, under these conditions, for initiation of bolting varies greatly with individual plants, susceptibility to bolting being genetically controlled. Intensive selection for resistance to bolting has resulted in the production of varieties which are highly resistant to bolting (e.g. Bell & Bauer, 1942; Campbell, 1953; Campbell & Russell, 1964). Elongation of the stem can be induced, without normal vernalization, by spraying beet plants with the naturally occurring growth substance gibberellic acid (Gaskill, 1957; Campbell, 1958). It has also been reported that infection with virus yellows sometimes affects the incidence of bolting (Desprez, 1959), although it has not been recorded which of the two common yellowing viruses in Europe is responsible.

Elliott (1962) estimated that the average grain yield of wheat in the United Kingdom increased by 6·1 cwt per acre between 1947 and 1957. By considering results of yield trials carried out by the National Institute of Agricultural Botany he attributed 3·8 cwt of this increase to greater yielding ability of new varieties and the remainder to ‘other factors’, including the increased use of fertilizers, chemical weed control, better seed dressings and combine harvesters. The genetic improvement obtained by breeding new varieties is due partly to the incorporation of characters which are comparatively easily recognized, such as resistance to various diseases and lodging. However, even when these major limiting factors are absent from the environment the new varieties give higher yields, presumably due to physiological superiority. Many investigations, reviewed by Thome (1966), have sought to identify and establish the relative importance of the responsible physiological characters, but the information is still far from complete. This shortcoming is now the chief hindrance to more efficient choice of varieties for use as parents and selection of improved genotypes by the breeder. The objective of the three experiments reported here was to provide further information on the physiological basis of varietal differences in yield in wheat.