In a series of five irrigated cotton sowings (T2, T7, T9, T11, T14) evapotranspiration (Et) was determined for the period between October 1961 and October 1962 by observing frequently the changes in soil moisture storage, calculating through drainage, and solving for evapotranspiration in the water balance equation. Thus a water balance was obtained for each sowing extending over the entire crop.

The average evapotranspiration in wet season sowings was of the order of 6·5 mm day−1 and in dry season sowings of the order of 4·5 mm day−1. The highest evapotranspiration values ranged between 10 and 12 mm day−1 in T2, T7 and T9 and between 7 and 9·5 mm day−1 in T11 and T14.

An observed positive correlation between tuber sprout growth in store and yield and tuber weight was due to the association of short sprouts with small tubers (less than 75 g). Sprout growth in larger tubers appears to be unaffected by tuber weight.

Colchicine induced 64-chromosome white clover was compared at a number of centres with control material (2n = 32), as spaced plants and in broadcast plots with and without companion grasses.

The chromosome-doubled material generally conformed to the well-known reaction of polyploids; the plants were later flowering, had thicker petioles and stolons, broader leaflets and spread less vigorously. Yield of green matter of spaced plants was much less, and in broadcast plots the gross yield (grass + clover) and that of the clover fraction was 7% less than in comparable S. 100 plots. The Finlay-Wilkinson analysis indicated that the chromosome-doubled form did not respond to improved conditions to the same extent as did the control varieties. The presence of grass in the mixture partly compensated for low clover yield, but was insufficient to increase total yields to that of S. 100 controls.

The gross energy of forages can be classified into three fractions, namely the unavailable fraction, the digestible energy fraction and the potentially digestible energy (PDE) fraction. The PDE fraction can only be made available by appropriate treatment and supplementation (Pigden & Heaney, 1969). In young forages the PDE fraction is relatively insignificant, but as the plant matures, the PDE fraction increases very rapidly. By treating matured forages with delignifying agents, increased nutrient digestibilities have been demonstrated Chandra & Jackson, 1971; Wilson & Pigden, 1964), but no significant improvement on the voluntary intake was achieved unless the treated material was supplemented with a source of nitrogen (Donefer, Adeleye & Jones, 1969). While Zafren (1960) used ammonium hydroxide (NH40H) as the treatment alkali, with the claim that the ammonium acetate resulting from the neutralization of the excess alkali could serve as an extra source of nitrogen in the treated straw, other investigators (Donefer et al. 1969) have adopted the method of supplementing the treated straw with a source of nitrogen. Since the efficiency with which dietary nitrogen is converted to microbial nitrogen in the rumen has a considerable influence on the efficiency the animal as a whole, studies herein reported were carried out to test the effectiveness with which rumen micro-organisms utilize different nitrogen sources in degrading cellulose in vitro.

Effects of mepiquat chloride on gradients of shoot growth within spring barley plants (cv. Koru) were determined in two small-scale field experiments. Mepiquat chloride was applied at either the lemma primordium stage or the late carpel primordium stage of spike development in the main shoot. The shoot dry weight, stem length, spike length, number and size of florets and floret developmental score were measured for all shoots, over the period from the lemma primordium stage of main shoot spike development to the late milk stage of grain development.

Lemma primordium mepiquat chloride increased the size and developmental score of later-formed shorter shoots pre-anthesis while delaying the spike development of the main shoot and other longer shoots by up to 4 days. The overall effect was to produce plants with a reduced range of shoot and spike sizes from the end of floret initiation in the main shoot until maturity. In addition, there was a slight increase in the number of shoots per plant in both experiments. Gradients of carpel development and carpel width along the spike were reduced in all treated spikes by the time of floret abortion in the main shoot but the effects were more noticeable in shorter shoots. The number of florets initiated per plant was increased by 21–22%. All shoots contributed to the larger number of florets but again the major additions came from the shorter shoots. The few extra florets initiated in longer shoots were lost during abortion of distal florets while the 2–5 extra florets on shorter shoots were retained to give extra grains at maturity.

Application of mepiquat chloride at the late carpel primordium stage had little effect on gradients of spike size or on number, size and development of florets.

Coles (1957) has reported the results of a hatchability trial in which four pens of hens each received 10% of a different sample offish meal (A–D) in their diet as the only experimental variable. There was a high level of egg production in each pen, but differences in hatchability as indicated in Table 1. The pen with lowest hatchability received fish meal D, which was darker in colour than the others. It was suggested that this might indicate a scorching of the meal with heat damage, and that in turn this might be responsible for the lower hatchability. The meals have now been analysed to investigate this point.

A new tillage procedure was examined for the improvement in physical environment it might provide during the establishment of a vegetable crop, particularly in a dry spring. This procedure, of cultivating the soil mainly in autumn, was compared with the conventional method of cultivating in the spring on a sandy loam soil. The physical condition of seed beds prepared by the two methods was assessed by in situ measurements of soil temperature, water retention characteristics, hydraulic conductivity and surface roughness. Plant responses were compared by monitoring the emergence of onion seeds. Dry spring conditions were simulated by sheltering some plots from rain.

Final emergence, emergence time and rate of emergence were all superior following autumn cultivation for both dry and wet seed beds. The major factor affecting emergence was the coarseness of the seed bed which influenced the mechanical impedance to shoot growth. Differences in soil temperature between treatments were small, as were hydraulic conductivities under dry conditions. Preparing a seed bed in autumn rather than spring resulted in a good tilth with lower mechanical strength. This minimized the constraints on emergence when soil strength increased under dry conditions.

In a previous communication we have summarised the results obtained by us in a study of the nature and extent of atmospheric pollution in different parts of the city of Leeds and in further studies of some of the effects of smoke upon plant growth.

Of the two available methods for the determination of hydrogen-ion concentration, the electrometric is the more fundamental and satisfactory but it requires somewhat elaborate and expensive apparatus. The colorimetric method, on the other hand, though not lacking in difficulties if accurate results are wanted, requires no special apparatus and the actual procedure is simple. It is based on the electrometric method, and involves the use of buffer solutions of known hydrogen-ion concentration determined originally electrometrically.

In a study of two coarse-wool breeds (Awassi and Hamdani) the birthcoat and adult fleece were sampled from six body positions. Mean fibre diameter, mean fibre length, mean staple length and the percentages of fibre types were studied in relation to the birthcoat fibre type arrays.

The birthcoat of the two coarse wool breeds showed only plateau and saddle fibre type arrays. In Awassi lambs, plateau arrays were all P3 type whereas in Hamdani 28·6% of the plateau arrays were Po and the rest were P3 indicating a stronger base in the latter. S/P ratios, calculated from fibre types, were 2·22 and 2·27, at birth, and 3·56 and 2·93 at 4–8 weeks of age, in Awassi and Hamdani respectively. Awassi birthcoats showed more precipice within the CT group than those of Hamdani and plateau arrays were more endowed with the precipice than were saddle arrays.

A composite sample from the back and mid-side, in Awassi, and from the back and britch, in Hamdani, was found to be most representative of the birthcoat fibre types.

In the adult fleece of the Awassi breed, the mean fibre length following plateau arrays exceeded those following saddle arrays.

In Hamdani, the saddle arrays developed into coarser fibres in average diameter than those of plateau arrays whereas in Awassi no difference occurred. Awassi plateau arrays were followed by higher within-staple variability in distribution of fibre length than were saddle arrays, whereas in the distribution of fibre diameter there was no difference. In Hamdani, however, saddle arrays were followed by slightly higher within-stable variability in both length and diameter than were plateau arrays.

Birthcoat samples that had a transition in the CT group or had saddle array developed into adult fleeces with greater frequency of normal distribution in both fibre length and diameter, within staple. Adult fleeces that showed frequent bimodal distribution of both diameter and length, within staple, were those with birthcoats that had a precipice in length, or in coarseness and length, within their CT group or those with birthcoats that had plateau arrays.

1. The apparent cleanliness of the premises in which chicks are reared has little bearing on the growth rate of chicks within a given environment.

2. Bacterial counts of faeces from chicks reared under clean or extremely contaminated conditions showed no difference between the two sets of conditions.

3. Delaying feeding until 72 hr. after hatching retarded growth to at least 7 weeks of age. If the age of the chicks was calculated from the time at which the chicks were fed rather than the date of hatch, the weights of the chicks fed 72 hr. after hatching corresponded with those of the chicks fed immediately.

4. The contents of the duodenum and mesenteric intestine showed higher bacterial counts when feeding was delayed for 72 hr. than when feed was given shortly after hatching. This effect was no longer evident after the chicks were 1 week old.

5. Administration of penicillin in the water did not reduce the difference in growth rates between the chicks given feed immediately and those from which feed was withheld.

6. Antibiotics may decrease the thickness of the intestinal wall without stimulating growth.

is generally used to describe the lactation curve in cattle, where yn (kg) is the average daily milk yield in the nth week of lactation (n = 1, 2, 3, …, N), a is a scale parameter, and b and c are shape parameters. The model was first proposed by Wood (1967) and is widely used in practice to describe the lactation curve for fat, protein, lactose and wholemilk production; it has also been used as a basis of a mathematical model for poultry egg production (McNally, 1971). Having estimated a, b and c by regression analysis, the total lactation yield Y (kg) can then be calculated as

Data for the quantity of ammo acids consumed and their flow rates at the proximal duodenum for 33 diets fed to sheep have been statistically analysed by both univariate and multivariate methods. Analysis of variance of net loss (g/day) between mouth and duodenum of individual and total acida was not conclusive. Canonical variate analysis which takes regard of the correlations between different acids both within and between diets provided a conoise method of discriminating between diets. The advantage of this method in generating a unified account of digestion within the rumen is that it effectively reduces the problem from one of many dimensions to a situation where only the first few transformed variables need to be considered.

Black pigment is very frequently, but not invariably present in the mammary tissue of Large-Black, Berkshire and other dark-coloured sows. It is stated that the presence of this pigment (apart altogether from the question of the pigs being “on heat”) renders the bacon less saleable, owing to its discoloured or “seedy” appearance. If this is the case, it ought to be possible to remedy this fault, by breeding from individuals in which this pigment is absent, and so building up a strain of increased commercial value.

If on the other hand it be the case that the presence of black pigment is not in itself objectionable, but that the changes in the mammary area due to the occurrence of heat are what are not desired, the remedy is to be sought in spaying, a practice which must be carried out on a sufficient scale and be efficiently performed. That imperfect spaying (in which one, or a part of one, ovary is left behind, while the bed is wholly or partly removed) sometimes happens is shown by the facts described in this paper.

The expenses of the investigation described in this paper have been very largely defrayed by a grant made by the Development Commissioners through the Board of Agriculture and Fisheries.

Isocitrate dehydrogenase (ICDH), succinate dehydrogenase (SDH), malate dehydrogenase (MDH), glutamate dehydrogenase (GDH), β-hydroxybutyrate dehydrogenase (β-OH-BDH) and glucose-6-phosphate dehydrogenase (G-6-PDH) were histochemically located in the testes of buffaloes, goats and rams. The enzyme activities varied with the enzyme, species and cell type. The activities in the seminiferous tubules were correlated with the stages of seminiferous epithelial cycle (SEC). During this cycle, the activities in the Sertoli cells, spermatogonia and spermatocytes remained unaltered in contrast to those in the spermatids. The activities of SDH, ICDH and MDH were relatively greater in buffalo, while goat and ram resembled each other quite closely. ICDH and MDH preferred NADP to NAD. In the three species, the activities of ICDH, SDH and MDH generally followed an increasing order. G-6-PDH was greater in the interstitial tissue of buffalo than in goat and ram; the maximum activity of this enzyme in each species was found in the spermatogonia. In comparison with G-6-PDH, GDH was less evident in the interstitial tissue of buffalo and goat; Sertoli cells and spermatogonia also showed relatively less MDH activity whereas the other germ cells may have relatively less, similar or more, GDH activity depending on the species. β-OHBDH activity was similar in the interstitial tissue of the three species, but in the seminiferous tubule, the activity was less in goat. But for GDH and β-OH-BDH which could show different results, the activities of other enzymes generally decreased from spermatogonia through spermatocytes to spermatids but increased during spermiogenesis. In spermatozoa, the enzymes were observed only in the mid-piece. The possible physiological significance of the results is discussed in relation to different metabolic pathways.

Flow rates of metabolites in an open-compartment model can be calculated from specific activity measurements taken at equilibrium during continuous infusion of an isotope. The within-animal variance gives an estimate of the precision of the flow rate.

The Jack-knife method of calculating within-animal variances is described. It was evaluated using simulated data, and shown to be superior to a simpler method, the Single Section method.

The increase in experimental accuracy caused by increasing the number of specific activity samples per animal depends on the ratio of between- to within-animal variance components (B/W). For three experiments with sheep, 23 of the 30 values B/W for the different flow rates ranged from 0·25 to 1·5. For this range between six and 12 samples per animal are needed.

Fifteen cultivars of orchardgrass (Dactylis glomerata L.) were grown in the field at Hiroshima University, Japan, to investigate seasonal changes in leaf water relations and cell membrane stability (CMS) measured by the polyethylene glycol (PEG) test. Leaf water potential and osmotic potential were measured from August 1988 to August 1989. Solute concentration in leaf cell sap was also estimated.

Cell membrane stability increased, leaf water potential and osmotic potential decreased and turgor potential increased with decreasing environmental temperatures during autumn and winter. The significant increases observed in CMS may enable plants to tolerate freezing temperatures during winter. Decrease in leaf water potential may be a result of water-deficit effects due to soil freezing at low temperatures and the decrease in osmotic potential may help plants to maintain turgor and tolerate freezing conditions. Plants maintained higher turgor as the osmotic potential decreased to values as low as – 3·98 MPa during winter; the maintenance of turgor helps to maintain water uptake under water deficit conditions at low temperatures.

Sugar and K were the major osmotic contributors in orchardgrass leaves. Sugar and Ca concentrations increased and Mg and P concentrations decreased at cold temperatures. K concentration increased in six cultivars and decreased in nine others at cold temperatures. Sugar concentration in cell sap was negatively correlated with osmotic potential. It was concluded that seasonal changes in CMS may be mainly associated with the osmotic potential of the leaf tissues.

Over a 12-day fattening period the use of maize in the poultry-fattening ration has no detrimental effect on the consistency of the body fat.

When fattening is rapid and live-weight gains are satisfactory, the type of fat deposited in the bird is harder than that laid down on a normal ration containing mixed cereals and a protein supplement.

1. Four experiments in 1958 and five in 1959 compared responses to potassium (as combinedrilled muriate of potash) in the absence of nitrogen and in the presence of single and double doses of nitrogen (as broadcast sulphate of ammonia) on soils selected because they contained very little acid-soluble potassium.

2. Responses to 0·5 cwt. K2O/acre were obtained at six centres (two significant), but the effects of a further 0·5 cwt. K2O/acre were more variable and gains and losses (each at four centres) were almost equally balanced.

3. Gains from nitrogen were associated with previous cropping. N1 raised yields at seven centres (six significantly), but N2 raised yields further at only five centres (three significantly) and depressed yields significantly at three centres where barley followed a root crop or ley.

4. Potash did little to improve the strength of straw and therefore standing capacity in a wet season (1958) and had little effect upon the size of the grain, whereas nitrogen increased lodging and reduced the average size of the grain.

5. Increases in potassium uptake were associated with yield increases, whereas increases in nitrogen uptake were associated with both higher nitrogen percentage in grain and higher yields.

The ability to detect and measure water stress accurately is critical for optimizing crop production. The Crop Water Stress Index (CWSI), the linear relationship of the difference between foliage and air temperatures as a function of the air vapour pressure deficit, is one widely used method. Under well-watered conditions, a ‘baseline’ is derived that is crop specific and presumed fairly constant, despite differences in development and physiology. This study reports changes in the baseline of the CWSI for lucerne crops not subjected to water shortage over 3 years. Studies of lucerne in California from April 1986 to October 1988 used the CWSI to plan irrigations. It was necessary to re-establish the baseline periodically throughout the experiment. In the first year it was similar to that reported in the literature, but in the second year it had a statistically significant steeper slope and higher intercept. In the third year, the regression equation was similar to that in the first year. The changes in the baseline are thought to be a result of crop age rather than year-to-year weather fluctuations. The baseline needs to be determined periodically as the crop matures, to ensure accurate interpretation of plant water stress.