bluuebunny/crossref_metadata_2025_split huggingface dataset:
The mechanism of cellulose digestion in the ruminant organism: IV. Further observations fromin vitrostudies of the behaviour of rumen bacteria and their bearing on the problem of the nutritive value of cellulose
Authors: Woodman H. E. , Evans R. E. 
Published: March 2009

Further studies of the behaviour of cellulose-splitting bacteria in artificial media have been made in an attempt to account for the manner in which cellulose is utilized for fat production in the ruminant. The behaviour of thermophilic bacteria, with an optimum temperature of fermentation in the neighbourhood of 65°C, has been compared with that of the micro-organisms capable of fermenting at 37°C. In both cases the cultures were obtained from the rumen contents of sheep.By the addition of toluene at the “head” stage of fermentation, it was possible to demonstrate, both at 37 and 65°C., the production of small amounts of glucose during subsequent incubation. Glucose is clearly a primary breakdown product in the bacterial fermentation of cellulose.An investigation has been made of the nature of the volatile fatty acids produced by bacterial decomposition of shredded filter paper. No consistent differences from this standpoint were noted between the reactions as carried out at 37 and 65°C., but the nature and proportions of the acids varied considerably from culture to culture. In some cases acetic acid was produced almost exclusively, whilst in others the fatty acids consisted of butyric and formic acids, with but traces of acetic acid. The findings in this regard apparently afford no clue to the manner in which cellulose is used for fat production, since propionic acid, the only recognized fat-former among the lower normal fatty acids, was not detected.
Observations on the proteins of pasturage. Phosphorus and protoplasm
Authors: Foreman F. W. 
Published: March 2009

1. Studies lead to the conclusion that Chibnall-preparations of pasturage proteins, in spite of their small amounts of carbohydrate impurity, may yet yield, on hydrolysis by mineral acids, practically the right amounts even of most of those amino-acids which are adversely affected by carbohydrates to some extent when tested singly under the conditions.2. Preparations made in another way after treating the pasturage with ether as in the original Chibnall-method showed features of interest in the problem of attaining very pure proteins now much needed for purposes of comparison.3. A new method is introduced by which it is possible to compare what may be extracted from the protoplasm of fresh unpulverized pasturages with the composition of the natural saps on a unit weight basis.4. Production and breakdown of protoplasmic protein in perennial rye-grass during growth consistently appeared related to variations in the content of “nitrogen” and phosphates in the saps and the supplies of “nitrogen” and phosphates from the soil.
The effect of nitrogenous fertilizers on the calcium status of soil
Authors: Lewis A. H. 
Published: March 2009

The results of an experiment, conducted over one cycle of a four-course rotation to study the effects of nine nitrogenous fertilizers on crops and soil, are described.All the crops gave fairly good responses to nitrogen but in no case was there a significant difference between the effects of the various nitrogenous fertilizers. The “recovery” of added nitrogen was about 40–50 % with all the fertilizers.Figures are given for the changes in exchangeable CaO content of the soil. The results confirm Crowther and Basu's deduction that “the loss of calcium exceeds that for equivalent nitrogen added as nitrate by an amount equivalent to the excess of anions over the cations in the added fertilizer, all added nitrogen being regarded as nitrate and all carbon and phosphates being ignored”.The fact that phosphate should be ignored is shown by results for mono- and diammonium phosphates. Precipitation of phosphates in the soil almost certainly involves removal of calcium from the exchange complex but the calcium in such precipitated phosphates is exchangeable.Since phosphate has no effect on calcium status, it is clear that fertilizers based on ammonium phosphates remove less calcium from the soil than do mixtures based on ammonium sulphate and superphosphate.
An attempted fractionation of the soil phosphorus
Authors: Dean L. A. 
Published: March 2009

1. Extractions of soils with sodium hydroxide, followed by an acid, have been used in an attempt to fractionate the soil phosphorus.2. Colorimetric methods for the estimation of the organic and inorganic phosphorus in alkali soil extracts have been suggested.3. The amount of soil phosphorus soluble in sodium hydroxide is affected by the active soil calcium. It is suggested that sodium-saturated soils be used when studying the alkali-soluble phosphorus.4. The acid-soluble phosphorus remaining in soil after extraction with sodium hydroxide was determined. This fraction appears by analogy to be similar to the apatites.5. The largest fraction of the total soil phosphorus was not dissolved by the sodium hydroxide and acid extractions. This fraction was not increased by the long-continued use of phosphatic fertilizers at Rothamsted and Woburn.6. Relatively large amounts of organic phosphorus were found in soils and the amounts were closely related to the carbon contents.
Excretion of nitrogen by leguminous plants
Authors: Wilson P. W. , Burton J. C. 
Published: March 2009

The literature which deals with the question of excretion of nitrogen by leguminous plants is reviewed especially with reference to accounts of experiments in which no excretion was obtained.Experiments made at the Wisconsin experiment station prior to 1936, primarily concerned with the associated growth of pea and oat mixtures, were uniformly negative with respect to benefit to the oat plants through the association.Experiments carried out at the Biochemical Institute in Helsinki, Finland, with a pea and barley mixture were in general positive, although poor development of the plants because of unfavourable weather were accompanied by little or no excretion.On duplicating the Helsinki experiments at Wisconsin, once more both positive and negative results were obtained, although the development of the plants was excellent.The occurrence of excretion appears to depend on many complicated circumstances some of which have been defined, while others are at present unknown. Factors which insure a uniform development of the plant cultures and especially a not too rapid growth of the leguminous plant appear to be important; as yet no universally successful method of achieving this type of development has been determined. It is concluded that although there can be no doubt with, regard to the existence of excretion, knowledge of the factors concerned is still insufficient to allow duplication of the results consistently at all experiment stations. Until such knowledge becomes available, application to practical agriculture can remain only an attractive possibility and not an established fact.
Some observations on the normal variations in composition of Light Sussex cockerels
Authors: Halnan E. T. 
Published: March 2009

Individual analyses of forty Light Sussex cockerels of twenty-two weeks of age yielded the following results:1. There is a highly negative correlation between the fat percentage of the carcass and the moisture percentage.2. Owing to the large variability in the fat content of individuals, live-weight increases are unreliable as a measure of energy storage.3. Comparison of the fat content of the bones with that of the flesh and offal leads to the conclusion that the bones as well as the flesh and offal play a significant role in the general fat metabolism of the body.4. There exists a strongly positive correlation between the ash content of the bones and that of the flesh and offal.5. The protein ash ratio of both the Light Sussex breed and the White Leghorn breed is practically constant for all individuals after the age of seven weeks, indicating that the growth of the skeletal and the muscular tissues are closely correlated and controlled by the same growth impulse.6. The individual variation in energy content is shown to be ± 11.42% of the total energy content.
Relation of ear survival to the nitrogen content of certain varieties of barley: With a statistical study
Authors: Hunter H. , Hartley H. O. 
Published: March 2009

1. The high grain-yielding capacity and low total nitrogen content of predominant British varieties of barley, in conjunction with high ear survival at harvest, are discussed.2. The results of a series of quantitative comparisons in which increased tillering was promoted by the application of nitrate of soda at various phases of plant development, and similarly when tillers were removed at various stages, were examined.3. It was shown that the effect of nitrogen on the yield and quality of the grain depends upon the time in relation to the stage of plant development at which it was applied; the early applications enhanced the yield without detriment to the quality of the grain, whilst the later applications did not increase the yield but increased the total nitrogen content, and consequently reduced the malting quality of the grain.4. The increase in yield was obtained primarily by an increase in the number of surviving tillers and to a less extent by an increase in yield of grain per ear; the latter was in some cases accompanied by an increase in 1000-grain weight. High ear survival in varieties such as those under examination may consequently be regarded as an index of high yield of grain and of low total nitrogen content.5. The removal of tillers resulted in increased total nitrogen content and increased 1000-grain weight in the grain of the main stem; the former was not affected by the stage of development of the plant at which abscission was made, but the highest value of the latter was obtained when the abscission was made before flowering.6. The relation of 1000-grain weight and nitrogen content was discussed, and it was shown that high 1000-grain weight may exist with both high and low total nitrogen. Although the 1000-grain weight is an hereditary attribute it is subject to considerable fluctuation and cannot by itself be usefully employed as an index of nitrogen content, and consequently of malting quality, in either an inter- or intra-varietal sense.
The indirect determination of the “wilting coefficient” by the freezing-point method, and the influence of the salts upon the pF at that critical moisture content
Authors: da Costa J. V. Botelho 
Published: March 2009

The results obtained in the preliminary investigation were entirely confirmed, the pF at the “wilting coefficient”, as measured by the modified freezing-point method, varied from 4·0 to 4·4 (round figures), with an average of 4·2.The variation observed bears no relation to the soil texture, neither can it be explained by uncertainties in the freezing-point determinations which have proved to be accurately reproducible. Freezing-point measurements after leaching, conductivity measurements and freezing-point determinations in saturated soil and at the moisture equivalent proved that part of the variation is due to the presence of soluble salts, the more saline soils having a higher pF at the “wilting coefficient”. When the salt content does not exceed about 500 p.p.m. the influence of the salts is hardly detectable, and the pF at the “wilting coefficient” lies between 4·0 and 4·3. Besides unavoidable errors in the wilting experiments several other factors may account for this variation. They are all the factors that have any role in the “history” of the soil. In view of these uncontrollable sources of error a variation of 0·3 pF units can be considered very small.It can therefore be confidently concluded that in ordinary agricultural soils with a salt content of less than about 500 p.p.m. permanent wilting occurs when a critical pF value (lying between 4·0 and 4·3) is reached.
Experiments on the spacing of sugar beet: II. Results based on weights of individual plants
Authors: Garner F. H. , Sanders H. G. 
Published: March 2009

1. Yields of plots estimated from the known weights of “perfect” beet (i.e. plants with no gaps in the ring immediately surrounding them) showed 18 × 9 in. to be the optimum spacing.2. Sugar analyses performed on individual “perfect” beet showed that very diminutive roots were low in sugar, but that in general sugar percentage decreased with increasing weight of root; the decrease was, however, slight and only amounted to unity for an increase of 1000 g. in weight of root.3. In a dry year the roots immediately surrounding a gap compensated to the extent of 80–89% for the missing plant: the allocation to the individual neighbours was approximately inversely proportional to the square of their distance from the site of the gap. In a wet year compensation was less complete, amounting to from 41 to 84% under various spacing treatments. In both years compensation was less complete in the case of tops than in the case of roots.4. Within classes of beet similar in regard to spacing treatment and gappiness there still remained considerable variation due to soil and to genetic heterogeneity.5. The genetic variability of commercial seed appears to be large, so that in sugar beet experiments it is very desirable that each plot should carry a considerable number of plants: in these experiments, assuming that all variations within ultimate classes were of genetic origin, 400 plants would have been necessary to reduce the plot error due to genetic variability to 2% of the mean.
The estimation of leaf area in field crops
Authors: Watson D. J. 
Published: March 2009

1. It is shown that the leaf area: leaf weight ratio decreases with increasing leaf weight.2. The relation between the leaf area: leaf weight ratio and leaf weight is well fitted by a linear regression equation.3. A method of estimating the mean leaf area per leaf or per plant of a field crop by means of this regression is described. The mean weight per leaf is determined by a large sampling, and the leaf area: leaf weight ratio and its regression on leaf weight are estimated on a small subsidiary sample.4. Alternative methods of estimation from the mean leaf weight and either the unweighted or the weighted mean leaf area: leaf weight ratio are shown to give positively biased estimates of mean leaf area.5. It is emphasized that the small sample, from which the leaf area: leaf weight ratio and its regression on leaf weight are determined, must be a strictly random selection from the whole population.
Analytical yield investigations on New Zealand wheat: IV. Blending varieties of wheat
Authors: Frankel O. H. 
Published: March 2009

1. An endeavour was made to obtain a blend of Tuscan wheat with a high quality line which would yield as much as Tuscan, at the same time possessing a superior baking quality. Of the eleven lines which were blended with Tuscan, nine blends returned yields corresponding to the expectation calculated from the pure varieties, and two blends yielded more than the expectation; these increases were not statistically significant.2. Tuscan, three lines and their blends were submitted to yield analytical treatment. The yield characters of the components of blends were compared with their yield characters when grown by themselves. Whilst the yields per plot of the blends corresponded to the expectation, the yield analyses revealed that the component varieties exerted a modifying influence on each other, which was different in each of the three trials. Tuscan demonstrated its aggressiveness by depressing in every case the yield characters of the lines with which it was blended.
Genetic variability and inter-relationship of some quantitative characters in safflower
Authors: Khidir M. O. 
Published: March 2009

SUMMARYEighteen varieties of safflower were studied in a randomized block design with five replications. Data on fourteen quantitative characters were recorded. Appreciable variability was displayed by all characters, especially yield and number of heads/plant. The heritability estimates ranged between 65 and 98%.Seed (achene) yield gave a significant positive genotypic correlation with number of seeds/head, head width, bract width and oil content. The 100-seed weight was significantly negatively correlated with the number of seeds/head and plant height at maturity. The genotypic correlations between yield/plant and four other traits were partitioned into direct and indirect effects. The highest direct positive contribution to yield was given by plant height, which had also a positive indirect effect via number of heads. The direct effect of the number of heads/plant was negative and the indirect effect via head width was positive.
Photosynthesis in the ear of barley, and the movement of nitrogen into the ear
Authors: Watson D. J. , Norman A. G. 
Published: March 2009

Experiments were made in 1936 and 1937 on barley plants grown in pot culture, to determine the effect of shading the ear or the shoot after ear emergence on dry weight and nitrogen content.It was found that after ear emergence the ear and the shoot (leaves and stem) make approximately equal contributions to the assimilation of the whole plant. In the 1936 experiment 28% of the final dry weight of the ear was accounted for by assimilation in the ear itself, and in the 1937 experiment, 19%. These are minimum estimates, for assimilation must have been proceeding in the ears during emergence, before the shading treatments were applied. The results agree well with similar estimates of the extent of assimilation in the ear made on wheat by other workers.The effects of shading on the amount of nitrogen present in the plant at harvest were somewhat variable, but they were always small compared with the effects on dry weight. Shading tended to reduce the amount of nitrogen in the ear, but as the dry weight of the ear was reduced to a much greater extent, - nitrogen as percentage of dry matter in the ear was increased. It is concluded from this result that translocation of nitrogen compounds to the ear is not closely dependent on the amount of the concurrent increase in dry weight of the ear. It appears that the approximate constancy of nitrogen percentage in the ear and the grain throughout development is a consequence of the particular conditions prevailing during normal growth in the field.The experiments showed that 20–30 % of the dry weight of the whole plant was added after ear emergence, suggesting that climatic conditions during this late stage of growth is of considerable importance in determining the final yield.The authors wish to thank Miss J. Hellyer for carrying out many of the determinations of nitrogen content, and Mr S. A. W. French for assistance with the statistical computation.
Field experiments on the effect of applying a nitrogenous fertilizer to wheat at different stages of growth
Authors: Watson D. J. 
Published: March 2009

An account is given of the results of two series of field experiments carried out at Rothamsted and Woburn in the years 1926 to 1936 on the effect of nitrogenous fertilizers on wheat. In the first series a comparison was made of the effects of early (March) and late (May) top-dressings, and in the second series a range of times of application from sowing to the end of May were tested.At Rothamsted, the increases of yield of grain produced by the nitrogenous fertilizer were small and rarely significant, but they were greater at Woburn. On the average of all experiments, the effect of the fertilizer on yield of grain was independent of the time of application. In individual years, variation in effectiveness between times of application was found, and this was correlated with the amount of rain falling in a short period after the time of application. At Woburn, the effectiveness of the fertilizer decreased with increase in the amount of rain falling immediately after the application of the fertilizer, but at Rothamsted the effects were less clear and appeared to be in the opposite direction.The effects on straw yield were relatively greater, and more consistent, than those on grain yield. A greater increase of straw yield was produced by early top-dressing (January–March) than by application at the time of sowing, and the increase declined steadily the later the time of topdressing. Shoot height was increased by the nitrogenous fertilizer, and varied with time of application in a similar manner to straw yield.
Experimental methods with cotton: II. A study of the effects of seed rate and time of thinning on the development and yield of cotton plants in hand-planted cotton trials
Authors: MacDonald D. , Fielding W. L. , Ruston D. F. 
Published: March 2009

The object of this experiment was, in the first place, to see whether, with cotton experiments, there was an advantage in planting a larger number of seeds per hill than the customary number of three; and, in the second place, to see the effect of the interaction of time of thinning with varying numbers of seeds per hill.In cotton breeding work, where trials of new strains have to be carried out as soon as sufficient seed is available, it is important to conserve seed in all possible ways. At the same time it is necessary to plant sufficient seed to give a full and even stand for all strains.In experiments carried out in 1936–7 and 1937–8 stand counts, made soon after germination, showed the advantage of the higher seed rates in obtaining a quick and full stand. Later counts and final counts at harvest showed a considerable evening up, although the two-seed treatment proved unreliable, giving the lowest stand in both seasons.Plant height and weight records, made during both seasons, showed that plants from the larger hills were drawn up much more rapidly than plants from the smaller hills. This rapid elongation in stem height proved, from weight figures, to be at the expense of lateral development, weak and leggy plants being produced in these hills. The ten-seed treatment showed up particularly badly in this respect, the yield figures showing that the plants never recovered from this early deleterious effect.The six-seed treatment, whilst giving a quick and excellent stand suffered to a certain extent from the same defects as the ten-seed treatment. If thinned early they tended to fill out and become more comparable with plants from the three-seed treatment, but when thinning was delayed they never caught up and final yield suffered adversely.
Field crops and variety comparison between Imperial Valley, California and Kufra Oasis, Libya
Authors: Worker G. F. 
Published: March 2009

SUMMARYA study was conducted to compare field crops and varieties grown at the Kufra Agricultural Project, Libya, and the Imperial Valley Field Station, El Centro, California. Lucerne (Medicago sativa L.), barley (Hordeum vulgare L.), wheat (Triticum octivum L.), sudangrass (Sorghum bicolor Moench) were grown at both locations in 1969–70.Yield studies at Kufra, Libya, and the Imperial Valley Field Station indicated that the crop performances were equally well adapted at both locations. Lucerne yields were higher at Kufra, which may have been due to more moderate temperatures and less salt in soil and water at Kufra. Low yields in some of the other crops at Kufra such as wheat may be due to inexperience and inadequate fertilizers. Newly developed varieties for Imperial Valley should be adapted to the Kufra area.