ALBERT

Description: SUMMARYA method is described for economizing in the use of fertilizers on deficient soil by soaking the cereal seeds in nutrient solutions containing the deficient element at a sufficiently high concentration to supply a large part of the total requirements of the plants.The result of greatest potential practical importance was obtained on oats. Soaking oats in molecular tribasic potassium phosphate brought about an increase in yield from 17 to 25 cwt./acre (46 %) on phosphate-deficient soil at the cost of 13·6 lb./acre of the potassium phosphate (or 4·6 lb. P2O6) without the addition of any phosphate to the soil. There was a correspondingly large increase in the weight of straw. Nearly 75% of the P2O5 introduced in this way was recovered from the harvested grain. Sodium phosphate appears equally efficaceous for oats. Strikingly beneficial effects were also obtained on barley and wheat.

Description: SUMMARY1. The results of a study of sampling for ginning percentage in cotton variety trials are given. The investigation was undertaken to determine the most satisfactory method of obtaining the necessary ginning percentage factors for conversion of yield of seed-cotton to yield of lint.2. The material consisted of a widerange of strains derived from the jassid-resistant Upland, U4, planted out in trials of randomized block design, in different seasons.

Description: SUMMARYThe loss of viability of seeds of Chewing's Fescue Grass has been a serious problem to both the producers in New Zealand and the trade in the United Kingdom. It has been shown by Foy (1934) that seeds with a high moisture content (20 %) held at 30° C. deteriorated rapidly after 10–14 days and even more quickly at 40° and 50° C. Seeds with a water content of 13 % deteriorated more slowly but it was not until the water content was reduced to and maintained at 5 % that seeds retained their viability at 30°, 40° or 50° C. for 42 days. Even at room temperature (16–20° C.) the loss of viability occurred after 4–5 months at 20 % water content and after 8–9 months at 13 % but at 5 % water content there was no loss. Foy discusses the effects of temperature and humidity that may occur during transport; Hyde (1935) has examined the effect of heating seeds to 50°, 60°, 70°, 80° and 90° C. with a view to working out the conditions for artificial drying of the seeds before transport, and Lewis (1934) has found that, in some seasons, there was a marked loss of viability in storing these seeds in the United Kingdom.

Description: SUMMARY1. Sexually immature White Wyandotte pullets have been treated with gonadal hormones with the object of simulating those changes in calcium and phosphorus metabolism which normally take place during the fortnight or so before laying begins.2. It is shown that certain treatments of the sexually immature pullet with oestradiol dipropionate evoked hypertrophy of the oviduct and changes in blood calcium and phosphorus similar to those encountered in the normal laying pullet, but did not produce any significant increase in the rate of calcium or phosphorus retention.

Description: SUMMARY1. The physiological effects of severe hyperthyroidism on five sheep are described.2. Increases in pulse rate of more than 100% were observed. The increase in pulse rate was proportional to dosage with the exception of one sheep which had lesions on the chordae tendinae of the left ventricle.3. The heart, even though beating at this elevated rate, reacted normally to severe exercise, but there was a tendency for the sheep to carry out its normal functions at a slower rate so such large increases in pulse rate did not occur as the result of voluntary activity.4. Considerable cardiac arrhythmia was noticed in all hyperthyroid sheep.5. The relative increases in pulse rate of the cow and the sheep given iodinated casein of the same potency suggest that as between species dosage of iodinated casein is proportional to ‘metabolic body size’—the between species unit of basal metabolism—rather than to body weight itself. On this basis the stimulation of the sheep was between 1 and 4 times the dosage accepted as normal for the cow.6. Body temperatures increased in the most severely affected animals. Respiratory rates quadrupled in some cases.

Description: SUMMARYIn the investigation described, we have observed a t monthly intervals throughout gestation the changes taking place in a series of similar ewes, in lamb to the same ram, and each receiving the same standard diet.In following the live-weight growth curves of the ewes it was found that on a constant level of feeding the weight gains became greater during each succeeding month of pregnancy, and at corresponding stages were larger for ditocous than for monotocous ewes. This was found to be due to the fact that, although on our diet the ewes did gain slightly in actual body weight, the main increases in live weight resulted from the growth of the gravid uterus itself, and this increases in weight far more rapidly in the later stages of gestation, and is also heavier where twins are carried.

Description: SUMMARYComparative digestibility trials have been carried out on hays top-dressed with nitrogenous fertilizers 8–13 days before cutting and on similar hays which were not top-dressed.The top-dressing resulted in an increase of 2·0% crude protein and 1·2% true protein.The digestibility of the protein was significantly higher in the top-dressed hays and no other constituents were affected.The protein equivalents in hay dry matter were increased from 4·4 to 6·0% by the top-dressing.

Description: SUMMARYEvidence is provided to prove that the nutritional malady, Coast Disease, which affects sheep de-pastured without change on the shell-sand littoral of South Australia is due solely to the inability of the pastures to provide the quantity of cobalt and copper necessary to fulfil the nutritional requirements of grazing sheep.An experiment started in 1936 in which five evenly matched groups of young cross-bred ewe hoggets were dosed thrice weekly with cobalt, copper, cobalt plus copper, and with cobalt plus copper together with iron, manganese, zinc and nickel is described.

Description: SUMMARYTen fully grown Border Leicester-Cheviot ewes were divided into two groups of five; the heavier ones being about 150 lb. live weight, and the lighter ones about 70 lb. The former were placed on a low plane of nutrition, and the latter on a high plane. As the weights changed by successive amounts of 20 lb. animals were killed and dissected, and their organs and tissues weighed.

Description: SUMMARY1. Pot and field experiments were made to compare the effects of thiosulphates and sulphur on the incidence of manganese deficiency in oat, beet and pea grown in two manganese-deficient soils.2. The addition of sodium or calcium thiosulphate to oat plants growing in a manganese-deficient fen soil in boxes markedly reduced symptoms of ‘grey speck’ and increased the soluble manganese content in the leaf tissues, but the effect was transient.3. The growth of beet in this soil in clay pots was improved by the addition of thiosulphates, and also by painting the exterior of the pots with bitumen paint or by covering the surface of the soil with a thin layer of sand. The thiosulphate treatments increased the manganese uptake by the plants and reduced the symptoms of manganese deficiency, particularly when applied to pots painted with bitumen paint.4. Field experiments with an old garden soil deficient in manganese showed that thiosulphate treatments increased the manganese uptake of beet. Placement treatments were more effective than broadcast treatments and greatly improved the growth of beet and reduced or eliminated manganese-deficiency symptoms, without producing any change in soil pH.

Description: SUMMARY1. A study of different methods of staple-length measurement of material from a cotton variety trial, of the comparative accuracy of three persons' measurements and of the number of seeds which it is necessary to measure in order to achieve various degrees of accuracy in the determination of differences in variety trial and single plant material is described.2. If, in making single plant selections, the breeder is satisfied with a level of significance of P =0·1 when using a sample of only five seeds per plant, he would be justified in discarding material falling one and a half millimetres below the standard of staple-length at which he was aiming.

Description: SUMMARY1. Metabolism experiments have been made with five sheep fed iodinated casein in doses sufficient to give symptoms of hyperthyroidism, ranging from moderate to severe. Two comparable sheep were included to serve as controls.2. The same ration was used throughout each experiment, and it was found that the digestibility of its dry matter and of its crude protein content declined when the sheep were made hyperthyroid. This was due to increased peristalsis.3. The treated sheep lost body N when iodinated casein was given, the loss being proportional to dosage. Calculations indicated increases in the endogenous catabolism by up to 120%, and also increases in deamination.4. There was an increased excretion of urea and ammonia during hyperthyroidism, the latter being associated with a decrease in the plasma carbon dioxide combining capacity.5. Purine catabolism was accelerated by more than 50% in some sheep. Starvation of one sheep did not depress nucleoprotein catabolism as it does in the normal sheep.

Description: SUMMARYMoisture content and temperature are of first importance in the storage of seeds. Seeds are usually stored in porous containers like sacks and paper bags, and their water content fluctuates with the humidity of the surrounding atmosphere. In sealed chambers, on the other hand, the humidity of the atmosphere will be determined by the water content of the seeds and, with different kinds of seeds in an enclosed space, an exchange of water will occur until equilibrium has been reached. This does not mean, however, that different kinds of seeds, or even different samples of the same kind will have exactly the same final water content, since the water content/humidity relations are affected by differences in structure, chemical composition and previous drying treatment; it is permissible, however, for practical purposes, to ignore the slight differences which occur between samples of the same kind of seed.

Description: SUMMARYThe available data on calcium, phosphorus and carbonate balance experiments with laying and non-laying birds have been collected and condensed. From this condensed data the following relationships have been derived:(1) Calcium excretion is a function of calcium intake.(2) Phosphorus excretion is a function of phosphorus intake.(3) Carbonate excretion is a function of carbonate intake.(4) Carbonate/calcium ratio of the excreta is a function of carbonate/calcium ratio of the intake.(5) Calcium/phosphorus ratio of the excreta is a function of calcium/phosphorus ratio of the intake.

Description: SUMMARYThe effects of cobalt deficiency and of varying degrees of copper deficiency in young sheep were investigated.Five of six evenly matched groups of hoggets aged about 8 months when transferred to the deficient pastures were supplemented with the equivalent of 1 mg. Co/day, 10 mg. Cu/day, 1 mg Co + 1 mg. Cu/day, 1 mg. Co + 5 mg. Cu/day, 1 mg. Co + 10 mg. Cu/day, respectively, administered thrice weekly as a drench; the sixth group was untreated.All individuals that received no cobalt developed typical symptoms of cobalt deficiency and most of them died within a year. After 11 months the remaining cases were removed to the laboratory. They were then in the advanced stages of the terminal cachexia.

Description: SUMMARYThe metabolism trials described in the present communication were undertaken with the object of testing the conclusions arrived at in farm-scale feeding trials, designed in accordance with the requirements of the modern statistical lay-out, respecting the minimum protein supply needed to support the maximum rate of growth in bacon pigs.

Description: SUMMARY1. The importance of uniform production of herbage for crop-drying is emphasized.2. A replicated experiment is described which compared four crops, two annuals and two leys under four manurial treatments which included a control and three applications of fertilizer (3½ cwt. ‘nitrochalk’) distributed during the season in three ways.3. Vetches yielded 2500–3000 lb. dry matter per acre of 28–30% crude-protein content in two cuts.Barley yielded 2500–3000 lb. dry matter per acre of 18–21% crude protein in five to six cuts.Leys yielded 4000–5000 lb. dry matter per acre of 15–18% crude protein in four cuts in their first year, and 5000–6000 lb. dry matter per acre of 15–18% crude protein in five cuts in their second year.

Description: SUMMARYBy measurement of single fibres from tattooed squares the variation in hip region mean cross-sectional area, mean fibre length and area of skin covered by fibre substance in a small flock of Romney sheep has been studied for a few years—see Part I.We find that under good growing conditions the area of skin covered by fibre is a constant percentage of the skin area for all sheep in all years. The number of fibres per unit area varies from sheep to sheep, and the mean cross-sectional area is inversely proportional to the number of fibres per unit area. The mean length/day is a constant for all sheep. When conditions are unfavourable the percentage of the skin area covered by fibre on a particular sheep falls below the good growing conditions percentage by an amount that is smaller the bigger the skin expansion ratio, but is greater the worse the season.

Description: SUMMARYThe effects of copper deficiency and of copper excess on mature Merino and Border-Leicester ewes were studied experimentally over a period of 3½ years with five evenly matched groups of each breed which were all depastured together as one flock on terrain where sheep develop cobalt and copper deficiency. All were treated with the equivalent of 1 mg. Co/day. Copper was administered thrice weekly in doses which provided for individuals of the respective groups the equivalent of nil, 1, 5, 50 and 100 mg. Cu/day.All of the individuals that received only cobalt became anaemic; they lost weight and developed marked symptoms of copper deficiency.The supplement of 1 mg. Cu/day was sufficient to delay the onset of these symptoms, but it failed to increase significantly the concentration of copper in the blood and it was insufficient to ensure normal myelin formation in the central nervous system of lambs born of the ewes which had received this treatment for 2 years prior to mating.

Description: SUMMARYThe writers are at present engaged in carrying out investigations into the relative supplemental values of the proteins in certain feeding stuffs that are commonly used to correct the protein deficiencies, in respect both of amount and quality, of the cereal grains and their by-products. As a preliminary to this work, it was necessary to obtain information about the digestibility of these protein supplements and their content of digestible protein and ‘total digestible nutrients’.

Description: SUMMARYAn experiment using eight pens each of twenty-five pullets was conducted to investigate the suitability of sesame cake meal as a protein concentrate for laying pullets. In meal mixtures supplying equal amounts of crude protein, sesame cake meal gave slightly lower production than fish meal and earthnut cake meal, but the differences were of doubtful statistical significance. Body weights appeared to be maintained less well on sesame cake meal, but only by an unimportant amount.The authors thank Prof. R. G. Baskett for his advice and constructive criticism, and Miss M. E. Osborne for the care and attention devoted to the management of the pullets.

Description: SUMMARYChanges in the percentage of dry matter, sugars, starch and nitrogen present in Arran Banner and Majestic potato tubers during storage in clamps until July or later were studied in two seasons. In the first season, the ascorbic-acid content and the distribution of nitrogen between three fractions (insoluble, soluble coagulable, soluble non-coagulable) were also determined. In the second season, weighed samples of tubers were introduced into the clamps, so that changes in absolute amounts of the different constituents present in the tubers or sprouts could be measured. The effects of removing or retaining the soil cover on the clamps after early April were compared.

Description: SUMMARYThe changing of treatments during the course of an experiment is discussed both from the point of view of designing trials in which changes are anticipated and of modifying trials that have fulfilled their original purpose. Cases are distinguished according to whether the interactions of original and new treatments are or are not important and recommendations are made for each case.We are indebted to Miss J. M. S. Thom for preparing the diagrams fot publication.

Description: SUMMARY1. A method is described whereby fructose content and fructolysis can be assayed accurately in small samples of semen. The advantages of this method lie in its simplicity, accuracy and practical convenience as a tool for the assessment of semen quality, applicable also under field conditions.2. The content of fructose in fresh semen depends upon the secretory function of accessory glands which is influenced directly by the activity of the male sex hormone. A low level of seminal fructose may coincide with other symptoms of hormonal malfunction and poor quality of spermatozoa. A high level of seminal fructose indicates satisfactory functional ability of the accessory glands, but it does not necessarily coincide with high quality of spermatozoa as expressed in terms of density and motility.3. The normal level of fructose in fresh semen undergoes frequent fluctuations which can be observed if semen collections are made from the same individual at different times. Considerable variations in the sperm/fructose ratio may also occur in the semen of the same individual as illustrated by the results of an ‘exhaustion test’.4. Fructose disappears from semen incubated in vitro. The rate of fructose disappearance forms a convenient measure of sperm fructolysis. The normal rate of fructolysis in bull semen is 1·4–2 mg. fructose per 109 sperm cells in 1 hr. at 37° C. At this high level it can be maintained until almost the whole reserve of fructose has been exhausted. Azoospermic and necrospennic semen, as well as that from vasectomized animals, are unable to utilize fructose. A reduced rate of fructolysis is found in low quality semen of subfertile and infertile animals.5. The conditions of sperm survival in semen incubated in narrow tubes as used for the fructolysis test as well as for storage of semen in the practice of artificial insemination, are almost purely anaerobic. Under such conditions the survival of spermatozoa must largely depend upon fructolysis and not upon respiration.

Description: SUMMARYIn the investigation described in this third part of the work, we have studied the effect of imposing two extreme levels of diet upon the pregnant ewe during two periods, one of early and one of late, gestation. In order to build up a comprehensive picture of the effect of these treatments we have been concerned, first, with the changes that they have wrought in the tissues and organs of the mother's body; secondly, with the effect upon the growth and development of the genital tract and its major components, and lastly with the way in which the growth of the tissues and organs of the foetus have responded to the different nutritive levels. While the latter has been our primary concern, the former have been studied in some detail so that we may view the effects produced as a whole, and gain an understanding of any competition that may have occurred between maternal and foetal tissues.

Description: SUMMARY1. Picton, a winter-hardy variety of oats selected from the cross Argentine x Grey Winter, contains plants which have irregular meiotic divisions.2. Two types of irregularities were observed: first, univalents and the products of their division; and secondly, bridges and fragments at both first and second divisions.3. Plants selected for a low frequency of irregularities produced offspring with a low frequency of irregular divisions. On the other hand, plants with regular divisions were also obtained from parents which had a high frequency of irregularities.4. It is pointed out that the genetical effects of bridge chromatid formation and breakage is the production of gametes deficient for chromosome segments. There is some evidence that chlorotic plants are produced when such deficiencies become homozygous.5. It is suggested that the meiotic irregularities produce a certain degree of heterozygosity which may make Picton more adaptable, and at the same time give it a certain degree of hybrid vigour.

Description: SUMMARY1. The ventilation of two byres, one of large (1248 cu.ft.) and one of small (567 cu.ft.) cubic capacity per cow, was studied. The CO2 concentration in the atmosphere was used as a measure of the rate of air change and the dry katathermometer to determine the cooling power of the atmosphere. Temperatures and relative humidities were recorded and the actual air movements were studied by using smoke trails. The investigations were made under a variety of weather conditions and with a wide range of outlet and inlet areas.2. It was shown that the atmospheric conditions in the large byre were almost always superior to those in the small byre, and this was undoubtedly due to the greater cubic space per cow in the large byre. Adequate ventilation was, however, readily attained in the small byre provided the outlet area was sufficiently large.

Description: SUMMARYWhen maize forms a large part of the diet of any group of people, pellagra can be prevented by increasing the amount of nicotinic acid or by increasing the amount of tryptophane in the diet. The possibility of increasing the nicotinic acid content of maize by genetical means presents a promising field.

Description: SUMMARY1. The weights of muscular tissue, fatty tissue, bone, and tendons, etc. in the carcasses of twenty-nine cattle, fifty-five sheep and forty pigs are given. The weights of fat, dry fat-free residue, and water in the muscular and fatty tissues from the carcasses of twenty-nine cattle, twenty-nine sheep and two pigs (one wild and one domesticated) are also given. The cattle represent eight breeds, the sheep nine breeds and the pigs two breeds. Ages range from newly born to over 12 years and there are fifty females, seventy castrated males and four newly born males. The animals thus represent a very wide cross-section of the meat industry.

Description: SUMMARYIn presenting the results of these investigations, we have attempted to discuss in each section the findings that have been described, and here we will merely be concerned with summarizing the major points that have emerged.

Description: SUMMARYCertain vegetable seeds show such a marked loss of viability on storage that they are generally useless after 1–2 years storage under average commercial conditions; the most valuable seeds which store particularly badly are parsnip, onion and carrot. Storage experiments were therefore designed and set up to show the effect of the following factors on the viability of the seeds:(a) The water content as determined by the humidity of the atmosphere in which the seeds were stored.(b) Atmospheric conditions, viz. ventilated air, unventilated air and nitrogen.(c) Temperature.

Description: SUMMARYIt has been shown in a previous communication that the meal-replacement value of young grass in actual pig-feeding practice is considerably poorer than would be anticipated from a consideration of its content of ‘total digestible nutrients’ as determined by means of pig digestion trials. This is because the figure for ‘total digestible nutrients’ takes no account of the energy expended by the pig in consuming and masticating its food. Although this wastage of energy does not represent a serious loss in relation to the rate of live-weight increase in the case of ordinary pig meals fed in the form of a thick slop, it becomes of considerable significance when grass forms a major component of the diet, on account of the bulkiness of the grass and its unfavourable physical texture from the standpoint of consumption by pigs.

Description: SUMMARY1. Some data are given for the relative buffer-index values of saps from underground parts of wheat, barley, oats, potatoes and turnips.2. The correlation of these values with limits of tolerances of soil-pHranges by the plants is discussed.3. Some possible practical applications for these data are indicated.

Description: SUMMARY1. In a ration containing paddy straw, the large amount of oxalate ingested does not act in the same way in the ruminant system as has been observed when oxalate-rich spinach is fed to rats. About 10 % of the ingested oxalic acid is recovered in the faeces, and this can be explained as arising out of pre-formed insoluble and unabsorbable calcium oxalate present in paddy straw; the remaining 90%, which is soluble potassium oxalate, does not react with the calcium of the Tation to form unabsorbable calcium oxalate.

Description: SUMMARY1. The effect of iodinated casein feeding on the respiratory metabolism of the female sheep has been studied, using a spirometer technique with direct analysis of expired air.2. The effect of iodinated casein on basal metabolism was linearly related to the dosage expressed in mg./kg. W0·73. The effect on pulse rate was not linear: there was a greater acceleration at the higher levels.

Description: SUMMARY1. The compositions and digestibilities of ten selected typical Northern Irish meadow hays have been ascertained and compared with similar data published by other workers for meadow hays produced in the British Isles.2. It is suggested that average Northern Irish meadow hay of reasonably good quality has a starch equivalent value in the region of 35 on a drymatter basis. Poor samples will have a value in the region of 25.

Description: With the installation of more factories for the decortication of cotton-seeds in Pakistan, the utilization of cotton-seed hulls as a feed is likely to assume great importance. During 1949–50, the writers made determinations of the chemical composition and the feeding value of Pakistan cottonseed hulls by conducting a digestibility trial on dry Sahiwal cows. They are found to contain 39.89–56.47% total digestible nutrients (mean value = 48.68%) and 0.0–0.38% digestible protein. It was observed during the trials that the cows could eat about 20 lb. of hulls per head per day without difficulty. The cows also ate hulls in preference to wheat straw.Being low in calcium and phosphorus, cotton-seed hulls should not be used as a sole roughage for long periods, unless supplemented with calcium or phosphorus in mineral form, or preferably with silage, legume hay or green fodder of good quality.Pakistan cotton-seed hulls appear to be equal, if not better, than wheat straw as a cattle feed. From the economic point of view, hulls should be used as a cattle feed only if they are purchasable at about the same price as wheat straw.

Description: 1. The relation between the soluble-nitrogen content of grass silage and the pepsin digestibility has been investigated, and formulae have been derived for calculating the protein digestibility in the silage dry matter from the determined solublenitrogen content.2. Comparisons have been made between the calculated results for protein digestibility, the results using the formulae of Watson and Dijkstra and the digestibility as determined on sheep.3. The peculiarities of molassed silage in the above connexion have been noted.

Description: Designs are given for factorial experiments with three, four or five factors at two levels each, using thirty-two plots in a 4 × 8 lay-out on the ground. The effects of both rows and columns can be eliminated from the estimate of error. Provided that three-factor interactions can be ignored, information can be retained on all two-factor interactions.

Description: The influence of growing plants on nitrification in the soil was studied by means of small lysimeters of which four were planted to a perennial grass, four to an annual millet crop and four were left fallow.Nitrification was entirely repressed under the grass from the second season after its establishment onwards, and did not take place even when the grass was dormant in winter. This was due to a direct influence of the living root, since in the fallow soil which was treated similarly, nitrification took place freely throughout the winter. Under the annual crop a repression of nitrification could be detected only towards maturity of the crop and the soil solution was completely depleted of nitrates at this period. Nitrification was resumed, however, immediately after the crop was ripe and had died off and continued through the winter.During the period that nitrification was depressed replaceable ammonia made its appearance in the soil in more than normal quantities. This fact is hold to indicate that the plant exerts its influence on the mineralization of nitrogen in the soil by paralysing the autotrophic dehydrogenase system of the nitrifying organisms without interfering with the process of ammonification and not, as has been claimed, by excreting such quantities of carbonaceous matter that nitrates are reassimilated by micro-organisms.By virtue of the constancy of the carbon-nitrogen ratio in soils this influence of plants on the mineralization of nitrogen has a very important bearing on the conservation of soil humus and consequently on any system of alternate husbandry. Some of its implications were discussed with particular reference to local fertilizer practice and field experience.

Description: For three consecutive years American hybrid maize was grown, under replicated experimental conditions, in the south of England. Each season, the influence of the spacing of the plants and the use of nitrogenous fertilizer on the yield and composition of the crop and of its separate portions of leaf, stem and cob was investigated.The growth of the maize, and especially its yield of dry matter, were influenced by the weather conditions during the season. The weight of fresh crop varied, with season and treatment, from 126 to 278 (averaging 209), and of dry matter from 20 to 70 (averaging 50) cwt./acre.Thinning below the established plant populations of up to 30,000 plants per acre regularly reduced these yields. Top-dressing with sulphate of ammonia increased them in 1947 and 1949, but decreased them in 1948.The yield of crude protein varied from 2.2 to 5.0, and of soluble carbohydrates from 12 to 46 cwt./acre. The top-dressing increased the protein content of all portions of the plant.The cob contributed, on a weight basis, 46% of the fresh crop, 49% of its dry matter, 54% of its crude protein and 54% of its soluble carbohydrates. Details are given of the chemical composition of the whole plant, and of its separate leaf, cob and stem, for each season and treatment.A later paper will deal with the making of silage from the maize crops and with the yield, composition and nutritive value of the silage.

Description: Mating Wessex Saddleback with Gloucester Old Spot pigs shows clearly that the former are of the three genotypes expected if the belt pattern is primarily determined by a single dominant gene (Be). Breeding tests and measurements of belt width agree in showing that homozygotes tend to have medium to wide belts, heterozygotes tend to have medium, narrow or broken belts, while pigs homozygous for the recessive are black. Crosses of Wessex with black-spotted pigs produce black piglings with or without wide symmetrical belts depending on the genotype of the Wessex parents.Selection of breeding pigs with narrow belts maintains a high incidence of recessive blacks. Solid blacks which are nevertheless genetically belted may occur, but if so their numbers are likely to be very small.Evidence is given which suggests that pigmentation in the skin and hair of Wessex × Large White pigs is much reduced if the Large White parents have blue eyes.

Description: 1. A statistical study of factors affecting variation in persistency of lactation has been made using 5000 lactation records from twelve leading herds of Ayrshire cattle in south-west Scotland for the period 1930–9.2. It is suggested that a satisfactory numerical expression for the shape of the lactation curve could be obtained from the formula, Persistency = where A is the milk yield during the first 180 days and B is the initial milk yield, namely, the milk yield during the first ten weeks of lactation.3. The interrelationships of persistency, initial milk yield and 180-day milk yield showed that these three characteristics are positively correlated with one another on a between cows within herd basis. This meant that it should be possible to combine high initial milk yield with high persistency to obtain increased total production.4. The effect of month of calving on persistency of lactation varied significantly between herds. On the average, the highest persistency was attained by cows calving in the winter, and the lowest by summer calvers.5. The variation of persistency with age showed that it is necessary to correct for the high persistency of first calvers when comparing cows with different lactations.6. The average repeatability of persistency was 0.242 in the present material, while heritability was of the order of 0.10–0.15.7. It has been concluded that improved feeding and management would bring about the greatest returns in the direction of improved persistency.

Description: 1. Differences in cattle population (4 June returns) and in average body size of fat cattle (data from the collecting centres) have been illustrated for the three counties (Cardiganshire, Carmarthenshire and Pembrokeshire) constituting this region. They indicate the superiority of Pembrokeshire.2. The six westerly collecting areas of Pembrokeshire produce the heaviest cattle of better grading. It has a higher proportion of steers to heifers than the rest of the region.3. The statistical analysis of the data has made it possible to partition the region into four main groups of centres, which show significant differences in the size of the fat cattle.4. The superiority of group 1 has been demonstrated in relation to (a) the seasonally of deliveries, (b) the percentage grading and (c) in the average live weights.5. These differences are examined in greater detail by comparisons of the deliveries to the Pembroke and to the Llandilo centres. These show that Pembroke is superior in average live weights, percentage grading and in the proportion of steers to heifers.6. The ungraded cattle are also examined, and the results indicate the same trends within the region as for the graded cattle.7. The possible explanation of the variations or the ecology of beef production has been discussed in the light of Ashton's (1930) suggestions that variations in body size between cattle of different breeds is mainly due to the calcium and phosphorus content of the soil.8. The conclusion is drawn that differences of climate dominate the whole picture, because of the effect of rainfall on leaching and soil erosion, as well as on the quality of the harvested fodders, the effect of temperature on the length of the growing season and of the beneficial influence of sunshine on the quality of both grass and hay.

Description: A study has been made of the bias in error which occurs when Latin-square change-over trials conducted on dairy cattle are analysed by the usual method for Latin-square experiments, with modification for carry-over effects. Bias is present for adjusted direct effects and for permanent effects (direct plus carry-over), but does not exist for unadjusted direct effects.Analyses of fifteen sets of experimental data showed that the bias is of no importance in 3 × 3 designs but might be serious for some practical situations in the 4 × 4 designs. A tentative factor to correct for bias was given for the latter case.

Description: 1. The structure of the cattle population (4 June returns), as well as of cattle sales to the Ministry of Food, have been illustrated.2. The trends in cattle production show the definite changes from that of the traditional storestock rearing to that of milk selling.3. A considerable part (38·2%) of the total graded animals slaughtered for beef are the ‘wastage’ animals from the breeding and dairying herds.4. Reference has also been made to the high proportion of ungraded cows (36·7% of the total cows) purchased by the Ministry. The ungraded cattle, however, are only 17% of the total sales. On the other hand, the ungraded ‘wastage’ cattle contribute 90% of the total ungraded cattle.5. More heifers than steers were sold for slaughter, and it has been shown that the average live weight of the graded steers is nearly 224 lb. heavier than that of the heifers.

Description: Between 1941 and 1946 some twenty-five field experiments were carried out at various centres in England to assess the factors which determine the yield level and seed composition of linseed (oil flax). The experiments were of multifactorial design, and the main variables studied were varietal differences, levels of mineral nutrient supply and plant population. Additions of nitrogen (35 lb./acre) over all experiments raised the yield of seed by 10%, whereas additional phosphorus (50 lb. P2O5/acre) or potassium (80 lb. K2O/acre) had small and inconsistent effects. A significant interaction between nitrogen and variety was recorded in one trial, but in twelve out of fourteen experiments the varieties reacted uniformly to a combined application of nitrogen, phosphorus and potassium, while in the remaining two experiments the interactions were contradictory.

Description: 1. The experiment previously described (series 4, Holmes, 1949) on the effect of massive applications of nitrogenous fertilizers on the productivity of a ryegrass dominant pasture was continued for 3 years (1946, 1947, 1948). The manurial treatments ranged from none to the application of 312 lb. nitrogen per acre and this was applied with and without 135 lb. P2O5 and 168 lb. K2O per acre. Farmyard manure was applied to one block in 1948.2. With the heaviest nitrogen treatment plus phosphate and potash the average yield for 3 years was 8000 lb. dry matter and 1640 lb. crude protein (similar to the yield in 1946) compared with a control yield of 4720 lb. dry matter and 590 lb. crude protein. The yields declined from year to year when phosphate and potash were not applied, the decline being greatest with the heaviest application of nitrogen.3. The seasonal distribution of the yield of herbage was very considerably modified by the time when fertilizers were applied.4. The botanical composition of the swards was related to the yield, 70% of the grasses in the highest yielding sward being perennial ryegrass and cocksfoot while the lowest yielding sward contained only 35% of these grasses.5. The manurial treatments had no effect on the pH, loss on ignition or the content of readily soluble P2O5 in the soil, but in the first year there was some evidence of a general reduction of readily soluble K2O to a low level.

Description: 1. Studies were made of the effects of varying ground water-levels upon the productivity and composition of Italian Ryegrass grown on a calcareous light peat in the Fenland area. Six cuts were taken throughout the season at 3 to 4-weekly intervals.2. High ground water-level (approximately 15in. below ground surface) had a very deleterious effect on the total yield of fresh grass and of dry matter. Yields were little more than half of those obtained at medium and low water-levels (24 and 38 in. below ground surface, respectively).3. High water-level apparently interfered with nitrogen metabolism in the soil, and considerably lower percentages of crude protein were found in the grass growing on the high water-level plots than at the other levels. On the other hand, the percentage of crude fibre remained fairly constant for all levels of ground water.4. High water-level also had a depressing effect on the percentage of potassium, magnesium and chlorine in the grass. It had no obvious effect upon the calcium and phosphorus levels in the plants. The silica content of the grass rose steadily as the season advanced, this being most marked on the high water-level plots.5. Physical examination of typical plants showed the effect of the various ground water-levels upon the development of the root systems, with consequent effect upon the chemical composition of the grass.6. The composition of hay and aftermath showed similar changes to those reported for the green herbage.7. The findings are discussed in relation to grassdrying policies in Fenland areas.

Description: SUMMARYHerbage samples were collected in late June, and again in early September (1987) from permanent mountain meadows situated in North-western Spain (León). Botanical composition was determined by grouping the species into grasses, legumes and herbaceous ‘weeds’. Rumen degradability of the dry matter (DM), crude protein (CP) and neutral detergent fibre (NDF) of the botanical groups in each harvest season was determined by the nylon-bag technique.Grasses and legumes differed in their degradation characteristics, and the comparisons between forage species were different for the two harvest seasons. There were no significant differences between September grasses, June legumes and September legumes in the potential degradabilities of the DM (86·9, 87·1 and 88·4%) and CP (94·2, 92·4 and 93·8%). The NDF of grasses harvested in September was degraded to a greater extent (80·6%) than that of legumes from both harvests (70·9 and 73·6% in June and September respectively). However, June grasses showed significantly lower potential degradabilities for the DM (77·0 %), CP (84·3%) and cell wall (65·9%). Legumes were degraded at a faster rate than grasses (mean DM degradation rates of 0·143 and 0·057 respectively), and lag times were longer for grasses (4·7 h) than for legumes (2·5 h). Rumen degradation characteristics of the herbaceous ‘weeds’ were estimated, but it should be remembered that many other factors may limit their utilization by ruminants.It was concluded that the major constraint to the nutritive value of these permanent swards would be the maturity of the grasses harvested in June, which markedly reduced the rumen degradability of the forages.

Description: SUMMARYQuinoa produces a cereal-like grain with a higher protein content and a better balanced amino acid composition than the major cereals. It is cultivated at high altitudes in the Andes, and is believed to have potential for temperate regions. In the development of quinoa as an arable break crop, sowing date, sowing rate and row spacing are identified as agronomic variables having a high priority for investigation. The variety Baer, from high latitudes at sea-level in Chile, and the variety Blanca de Junin, from the inter-Andean valleys of Peru, were sown on 25 March, 14 April and 7 May 1982 at spacings between rows of 0·8 and 0·4 m and sowing rates within rows of 0·2, 0·4 and 0·6 g/m, at Cambridge, England. These varieties were chosen for their strongly contrasting origins and plant types. In another experiment sown on 15 March 1984, Blanca de Junin was replaced by another valley variety, Amarilla de Marangani, somewhat better adapted for cultivation in England. Between-row spacings of 0·4 and 0·2 m, and sowing rates of 15, 20 and 30 kg seed/ha were used. Weed competition was more intense after later sowings, causing the plots sown in May to be abandoned. At the higher sowing rates, plants were shorter, a higher proportion were stunted, branching was reduced and maturity was earlier. These effects were more marked in the valley varieties, particularly Blanca de Junin. Increases in within-row density caused greater increases in competition effects than corresponding reductions in row width, except for the effect on the proportion of branched plants. The highest grain yield, 6·96 t/ha, was obtained with Baer sown in March in rows 0·2 m apart at 20 kg seed/ha. However, Amarilla de Marangani produced a higher yield at 30 kg seed/ha than at 20 kg seed/ha, which is surprising since valley varieties are normally sown with low target population densities or in intercrop, and Amarilla de Marangani was, in other respects, less tolerant of competition than Baer. The implications of these results for the cultivation of quinoa in mechanized farming systems, both in temperate and in highland tropical regions, are discussed.

Description: SUMMARYHand harvesting is a major constraint to lentil production in North Africa and West Asia. This study, in north Syria, compared hand harvesting, cutting by mower (double-knife) and cutting with angled blades on two lentil cultivars differing in standing ability and using two sowing methods (broadcast and drilled) both with and without the use of a heavy bar for field levelling in the 1984/85 season. Seven treatments were selected for testing in five locations in the 1985/86 season; and in the 1986/87 and 1987/88 seasons, agronomic comparisons of mowing v. hand harvesting were conducted on five farmers' fields.Both machine methods of harvesting resulted in significant harvest losses compared with hand harvesting. The angled blades performed well on a ridged broadcast crop, but tended to mix soil with the harvested crop. The loss of straw associated with harvesting by mower was reduced by levelling the seedbed after sowing. The superiority in seed yield of cultivar 78S26002 over the local cultivar increased from 9% when hand harvested to 39% with mowing because of its lower likelihood of lodging. In the 1986/87 and 1987/88 seasons, the seed yield from a hand harvest was 1650 kg/ha compared with 1508 kg/ha following harvest by mower, representing a loss of 8·6% from mechanization. The corresponding straw loss was 16·6% of the mean from a hand harvest of 2140 kg straw/ha. However, the harvest losses from mechanical harvesting by mower were compensated for by the reduced labour costs compared with hand harvesting.

Description: SUMMARYThe effect of phosphorus fertilizer on the performance of an improved semi-dwarf (100 cm), long duration (170 days), photosensitive rice variety CR 1016, grown under conditions of intermediate deepwater (15–50 cm) and simulated flash flooding (80 cm), was investigated at Cuttack, India in 1985, 1987 and 1988. Growth and yield of rice subjected to overhead flash flooding (complete submergence) at the vegetative stage for 10 days was decreased significantly compared with partial submergence in water of intermediate depth. The adverse effect of complete submergence was due to greater tiller mortality and lower number and/or weight of panicles at maturity. Rice plants fertilized with P tolerated flooding better and produced significantly higher grain yields than when no P was applied. There was no significant effect of P application on the crop grown under natural unsubmerged conditions, except when it was raised in the same plots as the previous year and may therefore have benefited from residual effects. Therefore, application of 8.7–17.5 kg P/ha along with 60 kg N and 16.7 kg K/ha at sowing was essential to overcome the deleterious effects of submergence on rice grown under waterlogged conditions.

Description: SUMMARYOptimum applications of N fertilizer, Nopt have been related successfully to the amount of mineral N in the soil, Nmin in some parts of Europe but not always in the UK. If there is a body of mineral N, QN, that ultimately lessens the need for N fertilizer, it will not remain constant in its amount or its position. Mineralization will add to QN, while the nitrate component of QN will be leached downwards.Also, part of QN will be taken up into the crop where it will continue to lessen the need for fertilizer N but will be safe from leaching. A computer model was used to simulate these processes for 23 experiments, covering five sites and five years, in which N opt had been estimated. From these simulations we derived trial values of QN that took account of mineral N to a series of depths on a series of dates. For each date we used the trial values to find the depth for which Nopt was best correlated with QN andassumed that this was the depth, dL, of the lower boundary of QN on that date. Thus dL was a collective value for all 23 experiments. The value of dLincreased throughout the winter and the spring and was very closely related to the cumulative average drainage through 0·5 m soil at Rothamsted. By 15 April, dL, was 1·66 m, a depth that was compatible with observations by others that winter wheat can remove mineral N to a depth of at least 1·5 m. We inferred two likely reasons why Nmin may fail as a predictor of Nopt in the UK: insufficient depth of sampling, and too wide a spread of sampling dates. The values of Nopt were shown to be related satisfactorily to the values of QN computed, without any measurements of mineral N, for appropriate depths on single dates.

Description: SUMMARYIn 1989 three experiments with up to three different treatments each were carried out in North Germany to determine the ammonia flux densities after the application of liquid slurry using the micrometeorological mass balance method.In Expts 1 and 2, pig slurry was applied with a conventional surface spreader to wheat stubble. The results demonstrated the influence of meteorological conditions and that of incorporation on the extent of ammonia volatilization. In comparison to warm and windy conditions, NH3 losses decreased from 56% of the NH4-N applied to wheat stubble to 42% during a cool and rainy period. When slurry was incorporated immediately into the soil, ammonia losses were significantly reduced to 20 and 10%, respectively, of the applied NH4-N. The highest losses (67% NH4-N) were found when slurry was applied during warm weather on wheat stubble covered with chopped straw. Soil cultivation of the wheat stubble before the application of slurry diminished the ammonia emission from 42 to 28% of the NH4-N.In Expt 3, cattle slurry was applied to rape. It was found that compared with a conventional surface spreader the ammonia volatilization was reduced from 68 to 58% of the NH4-N when an alternative distribution system consisting of drag hoses was used for the application.

Description: SUMMARYThe nutritive value of taro leaf (Colocasia esculenta) silage, with or without various crop or crop byproducts as additives, was evaluated in two experiments in Western Samoa in 1988 and 1989. In Experiment 1, laboratory silos were used to assess the quality of eight taro leaf silages which were either ensiled fresh or wilted overnight. Taro leaf ensiled alone was poorly preserved with a pH of 5·4 and high concentrations of ammonia-N and volatile fatty acids. In contrast, silages with crop byproduct additives rich in water soluble carbohydrates (WSC), mainly molasses, ripe banana or papaya pulp, were of high quality with pH levels of c. 4 and low concentrations of volatiles. Copra meal, although low in WSC, was able to produce a satisfactory silage when added to taro leaf through its ability to restrict fermentation.Despite only a small increase (14·2%) in silage dry matter (DM) content, wilting of taro leaves resulted in silage of significantly higher quality than that made from fresh leaves. Most of the benefit of wilting was attributed to better fermentation conditions rather than a restricted fermentation.Two of the better silages from Experiment 1, taro/molasses and taro/banana, were prepared on a larger scale in earth pits and fed to goats in a second experiment. Both silages were highly palatable and digestible; DM intakes of 47 and 63 g/kg W0·75 per day and organic matter digestibilities of 69·0 and 74·9% were recorded for the banana and molasses silages, respectively.It was concluded that taro leaf is a suitable forage for ensilage, and when combined with additives rich in WSC, a forage of high nutritive value can be produced.

Description: SUMMARYLentils were grown in 1984/85, 1985/86 and 1988/89 in Canterbury, New Zealand. Results showed that lentil canopies were capable of intercepting a maximum of 95% of incident solar radiation at a leaf area index of 7. Autumn sowings attained canopy closure, but late spring sowings did not. At the highest population density used (500 plants/m2), only 65% of incident solar radiation was intercepted by a late spring-sown crop. In all three growing seasons there was a highly significant positive relationship between cumulative absorbed radiation and dry matter (DM) production. Over all seasons, 1·6 g DM/m2 was produced per MJ of absorbed photosynthetically active radiation (PAR). The final utilization coefficient (u) was not affected by sowing date but in a late-sown, diseased crop, u was 38% less than in a disease free crop. In 1984/85, dryland crops had a utilization coefficient of 1·39 while irrigated crops had a u of 1·54. Growth efficiency of lentils was low, at 2·5%.

Description: SUMMARYTwo experiments, each involving a set of six sweet potato clones, the first set developed in sites differing in altitude, and the second in sites differing in soil type, were done at three locations in 4 years in Cameroon. Data obtained were subjected to analyses of variance to determine the presence of genotype × environment (G × E) interactions, and to joint regression analyses to measure the performance of clones across environments. The first experiment produced higher yields and contained more stable clones than the second. In both experiments, mean yields were almost twice as high in 1984 (21·1 t/ha) as in each of the other years (c. 11·0 t/ha), and highest at Nyombe (18·0 t/ha). In Expt 1, the G × E interaction mainly concerned interaction with location, whereas in Expt 2 it concerned interaction with years.Clones 1611 (Expt 1) and 048 (Expt 2) yielded above average and gave linear regressions significantly above unity (b 〉 1·0) for most traits, indicating specific adaptation to high-yielding environments and hence below average stability. Clones 1112, 1639 and TIbl (Expt I) yielded above average and had regression slopes equal to unity (b = 1·0), indicating average stability and thus general adaptability. Clones TIb2 (Expt 1) and 1487 (Expt 2) produced below average yields (b 〈 1·0), indicating specific adaptation to low-yielding environments. Since sweet potato is grown mainly for human consumption in Cameroon, a preferred clone must have stable marketable yields. Only clones 1112, TIbl and 1639 could be considered desirable for release to growers.

Description: SUMMARYChinoli (Brassica campestris subsp. oleifera × subsp. chinensis), Marnoo and Apetalous (B. napus), with contrasting morphological characters, were compared over four seasons in Tasmania in 1985/86 and 1986/87. The total water use estimated from a depth of 70 cm increased in proportion to irrigations. Before irrigation all the crops had a similar pattern of moisture extraction but differences between the lines, and due to irrigations, emerged after the irrigation treatments. The genotypic differences were clearer in the winter sowing of 1986/87, when the growing season was longer. Apetalous, when unirrigated, extracted a greater amount of water from the lower, wetter regions of the soil profile, particularly in the longer winter sowing when its water use was the same as in the treatment receiving one irrigation. With consistently higher stomatal conductance, Apetalous used more water than chinoli or Marnoo. It also maintained a higher turgor at lower osmotic potentials, suggesting a greater degree of drought tolerance than found in the short duration chinoli which, although it had a lower water use, also gave lower seed yields.

Description: SUMMARYSpring barley and spring oats were strip-seeded into crops of the white clover cultivar Alice at Hereford in 1987 and cultivar S184 at Aberystwyth in 1988. Drilling was done with or without a band-spray of glyphosate, a moderate or low (1988 only) dose of paraquat or into plots where the clover had been killed by herbicide 2 months previously.In the first experiment, initial cereal emergence was sparse; growth was suppressed in the unchecked (unsprayed) clover base but was vigorous in the clover-free plots; the cereals also became dominant in the swards sprayed with herbicide. Whole-crop yields in mid-August were 13, 3–4 and 8–10 t DM/ha in the plots in which clover was killed, unchecked or checked with herbicide. Clover contributed 4–12% of the harvested herbage in the latter treatment. This treatment also yielded c. 70 % as much N, carbohydrate and fibre as that without clover. Grain yields exceeded 7 t/ha without clover but were only 0·3 t/ha for barley and 1·1 t/ha for oats with unchecked clover; in the checked clover plots, barley yielded 60% and oats 78% as much as on the clover-free plots. Four and 5 weeks after whole-crop harvest, residual clover growth was 27 and 39% of that on unchecked plots for oats and barley, respectively.In the second experiment, the cereals emerged thickly but were later dominated by the clover, and an equitable balance was achieved only with the larger dose of paraquat. However, the oat cultivar Emrys was suppressed less than the tall barley cultivar Dandy; the short barley cultivar Digger was the most suppressed. Mean whole-crop yields were 11 t/ha in the treatment without clover, about half this in the unchecked bases and c. 9 t/ha with the larger dose of paraquat. Differences in chemical composition reflected much larger clover contents in 1988 than in 1987. Yields of N and water-soluble carbohydrate were at least as large or larger with moderate paraquat than for the clover-free plots. Grain yields ranged from 5·6 to 6·9 t/ha for the three cereal cultivars without clover but were negligible to very small in the unchecked and band-sprayed treatments, and were 3·4 and 2·0 t/ha for oats and barley, respectively, with the larger dose of paraquat. Residual stolon weights, 70–80 days after whole-crop harvest, greatly exceeded initial values in all treatments. They were smallest following the larger dose of paraquat, and larger in Digger than in Dandy, which in turn was larger than in Emrys.It is concluded that the concept of growing cereals in a clover base shows potential as a low input–moderate output system of cereal production. However, further longer term work is needed on regulation of the cereal–clover balance, on the release and uptake of N and the environmental effects of the technique.

Description: SUMMARYField experiments were conducted at Fagu and Shimla in India in 1983 and 1984 to study the effect of thiourea (0 and 5 kg/ha) on tuber yield of potatoes and uptake of P with different rates of fertilizer P (0, 22, 33, 44 and 66 kg/ha). Application of phosphorus and thiourea, both alone and in combination, increased tuber yield and uptake of P significantly at both the locations in both years.

Description: SUMMARYIn a 2-year field experiment at Hohenheim in 1987–88, with an intact or partly deflowered indeterminate cultivar and a determinate cultivar, light interception and dry matter production were highest in crops grown in isometric stands (equal distances between plants), lowest in double rows and intermediate in single rows. Dry matter production was greater at high than at low population density and in the wetter and cooler weather of 1987. Population density had a greater effect on DM production than on light interception. The greater leaf canopies under high density and in 1987 (Stützel & Aufhammer 1991) reduced light extinction coefficients. In the determinate cultivar, light extinction coefficients were consistently higher and light use efficiencies were consistently lower than in the indeterminate cultivar. Deflowering the indeterminate genotype and different planting designs did not change light use efficiencies and light extinction coefficients. In general, differences in light use efficiencies were inversely related to differences in light extinction coefficients.

Description: SUMMARYIn studies of two indeterminate cultivars in field experiments in 1985 and 1986 at Hohenheim University, the hierarchy within the reproductive storage system of field bean plants was manipulated by removal of inflorescences at various growth stages and nodes. Shading reduced pod set and seed weight mainly at basal nodes. Increasing plant population density reduced seed yield traits at all nodes. Removal of basal inflorescences increased pod set and seed weight at the remaining nodes, especially the lower ones. The favourable effects were greater under high light intensities and in sparse stands. The growth stages at which the basal inflorescences were removed and the removal of apical inflorescences were of minor importance.

Description: SUMMARYA collection of 168 accessions belonging to 62 species and subspecies was evaluated in Cordoba, Spain, in 1985 for fatty acid composition of the seed oil. Linoleic acid content of seed produced in Cordoba (mean temperature during seed formation 27·9 °C) was compared with that of seed obtained under much cooler environmental conditions in Montpellier, France, (mean temperature 19·5 °C). Linoleic acid content ranged from 27·3 to 83·7% in the warm environment and from 45·9 to 88·7% in the cool environment with average values of 64·3% and 75·0%, respectively. Twenty-three species with linoleic acid values of 〉 70% in both environments were evaluated again, in 1989 in Cordoba (mean temperature 31 °C). Twelve wild species showed consistently high and more stable linoleic acid contents than the cultivated control and could be readily used in breeding programmes to improve oil quality.

Description: SUMMARYField experiments in 1987 and 1988 on peaty-loam, Mn-deficient soils of the Adventurers series in Cambridgeshire, UK, tested the response of sugarbeet to three forms of manganese fertilizer supplied as foliar sprays. The influence of a wetter and an adjuvant on manganese absorption and growth was also investigated.Cutonic and chelated forms of Mn, when applied at standard rates, were inefficient at increasing Mn concentrations in plants and alleviating deficiency symptoms during early summer. Mn concentrations in foliage increased rapidly after spraying with manganese sulphate, and most of the deficiency symptoms disappeared. These benefits were usually enhanced when manganese sulphate sprays were used with an adjuvant.Averaged over both years, yield without Mn was 8·83 t sugar/ha; the largest yield, 9·56 t/ha, was obtained with manganese sulphate plus adjuvant. Smaller benefits were obtained with the other forms of Mn. The adjuvant, when used with chelated Mn, appeared to depress sugar yields in both years. The likelihood of reducing the number of sprays required to control Mn deficiency on Fen soils was improved by using an adjuvant with manganous sulphate sprays.

Description: SUMMARYThe minirhizotron technique was evaluated for estimating root length density in potatoes (Solanum tuberosum ‘Record’) by comparing observations in angled 45° glass tubes with corresponding root length densities obtained by (a) destructive core sampling, and from (b) counts of root tips on the soil face of excavated trenches. Measurements were made in a field experiment in Bedfordshire, UK, in 1985, with shallow and deep cultivation as variables, and in a glasshouse trial.Only at depths below 0·3 m did root lengths observed with minirhizotrons reflect at all closely those estimated from core sampling and even then there was a tendency to overestimate root density. In the surface cultivated layers, where 80–90% of the total root length was present, results from minirhizotrons were unreliable, probably because of poor soil–tube contact and, in soils which shrink on drying, preferential root growth at the interface between the soil and the glass.Minirhizotrons can provide a realistic estimate of the rate of root growth of potatoes with depth over time when compared with maximum depths of water extraction, but appear to be unreliable for providing a quantitative measure of total root length density.

Description: SUMMARYGrain sorghum (Sorghum bicolor L. Moench) was grown in Texas in 1985 at a constant population density of c. 6·6 plants/m2 in rows 0·5, 1·0 and 1·5 m apart and with the soil profile at field capacity at planting time. Dry matter production and yield were least at the widest spacing, principally because of a reduction in number of tillers. Dry matter accumulation was in direct proportion to the amount of light intercepted and largely independent of spacing between rows, with a conversion coefficient of 1·71 g dry matter/MJ energy intercepted. The most widely spaced crop used less water but not in proportion to the extent that ground cover was reduced. Water use efficiency was also less in the most widely spaced crop, probably because of heat advection from the bare soil between rows.

Description: SUMMARYComponents of the N cycle were studied at Hurley, UK, in 1985–87. In grass-clover (Lolium perenne and Trifolium repens) swards, grazed at three intensities, low total inputs of N were associated with low outputs and losses of N. Nevertheless, the flows (intake and excretion) of N through animals were substantial and gave rise, at the higher intensities of grazing, to an acceptably high agricultural output per hectare. This was considered evidence of a fast and efficient recycling of N between plants, animals and soil. The release of N to the environment (as nitrogenous gases and nitrate) was substantially less from the grass–clover swards than from a grass sward fertilized with 420 kg N/ha, and this was at the expense of only 20% loss in production. The mechanisms which might account for the high efficiency of utilization and recycling of N in grass–clover swards are discussed in the context of the balance of the supply of C and N to plant and soil biomasses under grazing. The results confirm that optimizing agricultural output in grass–clover swards has little adverse effect on the environment, but the importance to this end of sustaining a large proportion of N-deficient grass in grass-clover swards is emphasized.

Description: SUMMARYThree rates of phosphate (0, 25, and 60 kg/ha P2O5) were applied to phosphorus-deficient native grassland at Tel Hadya, in northern Syria, and biomass productivity, botanical composition and number of legume seeds in the soil were monitored for five seasons (1984/85–1988/89). The experiment was grazed at low (0·8 sheep/ha per year) and high (1·7 sheep/ha per year) stocking rates from the second to the fourth seasons of the experiment; in the fifth season, the low and high stocking rates were increased to 1·1 and 2·3 sheep/ha per year, respectively. The experimental site was typical of native grassland within the cereal zone of west Asia, where cropping is not possible because of shallow, stony soils and steep slopes.The results showed that annual applications of phosphorus, even as low as 25 kg P2O5/ha, alleviated the deficiency in soil P and resulted in improved pasture production, even in dry years. Legume production showed the greatest response to P, increasing by 0·3–3 times the production of the control treatments. By the fifth season, legume seed mass had increased threefold and number of seeds sixfold in the P-treated plots, compared with the first season, while in the control plots there was little change. Rain-use efficiency on the P-treated plots was more than double that of the controls by the fourth and fifth seasons.Practical application of the results depends on whether (i) legumes are as frequent in native grasslands, as a whole, as they are at Tel Hadya, (ii) the P deficiency observed at Tel Hadya is widespread, and (iii) grazing of communally owned grasslands can be controlled. It is suggested that all three criteria will often be fulfilled and, therefore, that grassland productivity in west Asia could be substantially increased. Furthermore, the results suggest that above-ground cover and soil organic matter will also increase after P application, both of which will help to reduce soil erosion and thereby increase the sustainability of livestock production in west Asia.

Description: SUMMARYThe effects of deep tillage and no-tillage on soil physical properties and wheat yield following rice were compared with conventional tillage at three irrigation rates (irrigation water:open pan evaporation ratios of 0·6, 0·9 and 1·2) in 1982–85 at the experimental station of the Punjab Agricultural University, Ludhiana. Deep tillage decreased soil bulk density and penetrometer resistance, and increased depth of rooting, profile water use and wheat yield. No-tillage adversely affected all these variables. The tillage effects varied with amount and distribution of rain during the cropping season.

Description: SUMMARYIn laboratory studies, the amount of N mineralized under waterlogged conditions during 14 days at 30°C was significantly correlated (P 〈 0·001) with the activities of amidase, glutaminase and asparaginase in soil when these enzymes were assayed by either a nonbuffer or a buffer method using appropriate substrates. N mineralization under waterlogged conditions was also significantly positively correlated with N mineralization under aerobic conditions, especially at 25 and 35 °C (P 〈 0·001). Generally, the results indicate that the use of amidase, glutaminase and asparaginase activities in predicting plant-available N in soils deserves more attention.

Description: SUMMARYAcid and neutral invertase activities in the stem of an early (CoJ 64) and a late cultivar (Col 148) of sugarcane were estimated by incubating stem slices in buffered sucrose solution and measuring the production of reducing sugars. High enzyme activity occurred in young tissue but the activity of both enzymes was considerably lower in the mature internodes. Acid and neutral invertase activity was highest in the midinternode position, corresponding to the region of cell expansion.

Description: SUMMARYShading treatments of 50% of the incident radiation were applied to the semidwarf wheat cultivar Leones INTA before and after anthesis in two field experiments in Argentina in 1987 and 1988. The treatments reduced biological (above-ground dry matter) yield, grain yield and number of grains/m2. Number of grains/m2 was closely and linearly correlated with ear dry weight at anthesis and with the photothermal quotient, calculated from 20 days before to 10 days after anthesis. Grain yield was sink limited, and the shading treatments reduced sink strength. The contribution of preanthesis assimilates to grain yield was smaller in the shaded crops than in the unshaded controls; in unshaded crops, almost 40% of grain yield was contributed by preanthesis assimilates whilst in preanthesis shaded crops this contribution was negligible. The proportion of preanthesis assimilates contributed to the grain was closely related to the decrease in stem dry weight during grain filling. The effects of shading on main stems and tillers were the same.

Description: SUMMARYOne hundred and fifty-four, March-born, lowland ewe lambs, on the Lyons Estate farm, were allocated to a 2×2 factorial experiment. In September 1987, half were shorn and 1 month later the lambs were treated with intravaginal sponges, containing either 60 mg medroxyprogesterone acetate or 40 mg fluorogestone acetate, for 12 days. Following sponge removal, ewes were mated to fertile rams at a ram: ewe ratio of 1:6. There was no significant difference in reproductive performance between the two progestagen treatments (P 〉 0·05). Premating shearing increased (P 〈 0·01) conception rate and reduced the percentage of barren ewes (P 〈 0·01) but there was no effect on litter size. Time of gestation following shearing was increased (P 〈 0·01) by 1·24 days. Lamb growth rate up to weaning was not affected by the shearing treatment. The results of this trial indicate positive advantages of premating shearing of ewe lambs.

Description: SUMMARYTwo experiments were carried out in Scotland 1984 to study the efficiency of energy utilization by Suffolk × Blackface lambs. In the first experiment, a digestibility trial, the lambs were fed three diets: roughage (R) consisting of chopped dried grass; concentrate (C) containing 700 g whole barley, 225 g ground barley and 75 g fishmeal/kg dry matter (DM); and a mixed diet (M) containing 500 g of roughage and 500 g of concentrate/kg DM. The DM and organic matter digestibility coefficients of diet M were lower than the ‘expected’ values calculated by summation of the separately determined digestibility coefficients of the component feeds. Similarly, the metabolizable energy (ME) value was 4·0% lower than expected.In the second experiment, 40 lambs of c. 20 kg live weight (LW) were offered 50 kg roughage DM (ME 9·74 MJ/kg DM) and 50 kg concentrate DM (ME 12·21 MJ/kg DM) either as a mixture (treatment M) or sequentially (treatment S). Lambs on treatment S took 33 days longer to consume their allocation of food than those on treatment M, but achieved a similar final empty body weight and empty body composition. This contrasts with results predicted by a feeding standards model for lambs of a similar LW offered diets of the same ME content. The longer feeding period, and hence greater overall maintenance requirement, of lambs on treatment S was partly offset by associated effects causing a reduction in the total ME available to lambs on treatment M, and partly to improved efficiency of energy utilization for gain and/or a lower daily maintenance requirement of lambs on treatment S. Allowing for associated effects and the adoption of a variable maintenance requirement in current feeding standards would result in a more accurate prediction of animal performance.

Description: SUMMARYA total of 52 individually penned pigs (mean initial and final live weights (LW) of 31·7 and 81·5 kg, respectively) was used in a randomized block experiment at the Agricultural Research Institute of Northern Ireland, Hillsborough, in 1984. The treatments were based on dietary regimes which comprised a control diet in which meal was offered at 86 g dry matter/k W0·75 per day or diets in which silage effluent was substituted for part of the allowance of meal of the control diet at 125, 175, 225 and 275 g/kg on a dry matter basis to give 0·125, 0·175, 0·225 and 0·275 effluent diets. There was also a negative control diet in which meal was offered at 850 g/kg of the rate of feeding of the control diet. Each of these dietary treatments included water available ad libitum. In a further treatment, effluent was substituted for 225 g/kg of the meal allowance of the control treatment on a dry matter basis, but additional water was not offered. The treatment based on the 0·275 effluent diet was omitted from the first four replicates.Some refusals of diet occurred at the higher rates of effluent feeding, with mean refusals of 7, 11 and 21 g/kg, respectively, for the 0·175, 0·225 and 0·275 effluent diets on a dry matter basis. Significant linear and quadratic contrasts (P