bluuebunny/crossref_metadata_2025_split huggingface dataset:
Biodegradability of mature grass cell walls in relation to chemical composition and rumen microbial activity
Authors: Ford C. W. , Elliott R. 
Published: March 2009

SummaryCell walls from mature stems of three tropical grass species (Digitaria decumbens(pangola),Setaria anceps(cv. Kazangula) and sugar cane), and temperate barley straw, were analysed for lignin, carbohydrate, and the maj or acyl groups ferulate, ρ-coumarate and acetate. Samples were incubated in nylon bags in the rumen of sheep in a 4 x 4 latin-square design, and rates of disappearance of cellulose, hemicellulose, xylose, arabinose, ferulate, ρ-coumarate and acetate were determined during 60 h incubation. Interspecies differences in cell-wall chemistry appeared largely in the variable degree of acylation with p-coumaric acid (1·0–3·3%) and acetate (0·5–3·6%), and the high glucose concentration in the hemicellulose from pangola (17%) andSetaria(9%). Barley had much lower concentrations of these components than the tropical species. After 24 h incubation, losses of cellulose and acyl groups were greatest from pangola, whereas hemicellulose and its major components xylose and arabinose were degraded to the greatest degree from barley straw.Setariacell-wall components were generally more resistant to degradation than the other species. No relationship was found between the concentration of any cell-wall constituent and degradability measurements. Nor were changes in microbial population, indicated by measuring the accumulation of cystine on the fibres, related to the rate or degree of degradation of any of the measured cell-wall constituents. Lignin was fractionated with alkali into insoluble and soluble fractions. The latter (25–50% of original lignin) gave high interspecies correlations with the degradability of total hemicellulose and its component monosaccharides. It was concluded that variability in the biodegradability of the cell walls was more likely due toin situstructural features, such as cross-linking between polymers, than to the concentration of any particular cell-wall constituent.
The relative importance of cluster size, sowing depth, time of seedling emergence and between-plant spacing on variation in plant size in red beet (Beta vulgaris L.) crops
Authors: Benjamin L. R. 
Published: March 2009

SummaryBeets with a coefficient of variation (c.v.) of weight of only 36–46% were produced by reducing the variation in cluster size, sowing depth, time of seedling emergence, proximity and size of neighbours to as low a value as practicable. The relative importance of these different sources of variation in plant size was examined in two experiments sown in contrasting conditions.Variation in time of seedling emergence was a major source of variation in plant size and was partially caused by variation in the environment around the clusters. Variation in true seed size and between-plant spacing was achieved by use of clusters of different sizes, but these factors were associated with only a negligible variation in root size. Similarly, local interactions between plants, brought about by variation in plant-to-plant spacing, accounted for only a small proportion of the variation in root weight.
Selection for height of nectar in the corolla tube of English singlecut Red Clover
Authors: Hawkins R. P. 
Published: March 2009

SUMMARYPollination of red clover by honey bees would be expected to increase if varieties could be produced in which the nectar is within 7 mm of the mouth of the corolla tube and so within the bee's reach.Pollination by honey bees in a small glasshouse increased the height of nectar in the resulting stock of red clover but when this was again pollinated by honey bees there was no further increase.Selection of plants with above average nectar height ultimately produced a stock in which the nectar height was 0·76 mm higher than in the original; a difference which was significant. There was also a considerable and significant increase in the proportion of florets with nectar within 7 mm of the mouth of the corolla tube.It was concluded that the height of nectar can be increased by selection; this would be of particular value for the pollination of red clover varieties with long corolla tubes grown for seed where there are insufficient numbers of bumble bees.
Plant population and shading studies in barley
Authors: Willey R. W. , Holliday R. 
Published: March 2009

SUMMARYTwo barley experiments are described in which a range of plant populations were shaded during different periods of development. Shading during the ear development period caused considerable reductions in grain yield, largely by reducing the number of grains per ear. Shading during the grain-filling period caused no reduction in grain yield. It is suggested that under conditions of these experiments there was probably a potential surplus of carbohydrate available for grain filling and that grain yield was largely determined by the storage capacity of the ears. The importance of the number of grains per ear as an indicator of individual ear capacity is emphasized.The effects of plant population on grain yield and its components are also examined. It is concluded that the number of grains per ear is the component having greatest influence on the decrease in grain yield at above-optimum populations and attention is again drawn to the possible importance of ear capacity. It is argued that on an area basis the number of grains per unit area may give a good indication of ear capacity. Examination of this parameter shows a close relationship with grain yield per unit area for both the shading and population treatments. It is particularly evident that a decrease in grain yield at high populations was associated with a comparable decrease in the number of grains per unit area. It is suggested that this decrease in grain number may be due to a lower production of total dry matter during ear development rather than an unfavourable partitioning of this dry matter between the ear and the rest of the plant. This lower production of total dry matter is attributed to the crop growth rates of the higher populations having reached their peak and then having declined before the end of the ear development period. This crop growth rate pattern, through its effect on grain number per unit area, is put forward as the basic reason why, in the final crop, grain yield per unit area decreases at above-optimum populations.
Plant population, shading and thinning studies in wheat
Authors: Willey R. W. , Holliday R. 
Published: March 2009

SUMMARYThree wheat experiments are described in which a range of plant populations were shaded during different periods of development; in two of the experiments plant thinning was also carried out at a number of growth stages. Shading during the period of ear development caused an appreciable decrease in grain yield by decreasing the number of grains per ear. Shading during the grain filling period also reduced grain yield, this being brought about by decreased grain size. Thus in contrast to the barley experiments reported earlier (Willey & Holhday, 1971), these particular results gave no indication of a potential surplus of carbohydrate for grain filling and an associated limited ear capacity. However, when plant thinning was carried out at anthesis to make more carbohydrate available for grain filling in the remaining ears, grain yield per ear did not increase. It is argued, therefore, that grain yield probably was determined at least partly by a limited ear capacity. Plant thinning at earlier stages showed how the development of competition during the ear development period progressively reduced the potential capacity of the ear; the greater competition of higher plant populations accelerated this reduction in ear potential.From an examination of the effects of plant population, it is suggested that the number of grains per ear is the component having greatest influence on the decline in grain yield at above-optimum populations. The possible importance of the number of grains per unit area as an indicator of ear capacity on an area basis, and as a determinant of grain yield per unit area, is emphasized. A close relationship between grain yield per unit area and number of grains per unit area is illustrated for a number of plant-population response curves, and it is suggested that the decrease in grain yield at high populations is probably determined by a decrease in the number of grains per unit area. Evidence is presented to substantiate the idea put forward in the barley paper that this decrease in the number of grains per unit area may be attributable more to a lower production of total dry matter by the high populations during the later stages of ear development, than to an unfavourable partitioning of such dry matter between the ear and the rest of the plant.
Inter-varietal competion and its possible consequences for the production of F1 hybrid wheat
Authors: Sage G. C. M. 
Published: March 2009

SUMMARYThe graphical and statistical analyses of competition diallels devised by Durrant were applied to an experiment investigating competition between four spring-wheat varieties. The results indicated that at low seed rates mixtures between varieties having a wide phenotypic difference between them in competitive characters, such as height and early maturity, could significantly outyield pure-stands of the component varieties. However, the results of a second experiment, in which these mixtures were grown at a range of seed rates, indicated that the yield advantage of mixtures over pure-stands was unlikely to occur at normal seed rates.It is suggested that, at the low seed rates likely to be used in growing F1 hybrid wheat crops, mixtures of F1 hybrids and male parental lines might achieve very nearly the same yield as the pure F1 hybrid variety with a seed bulk that was cheaper to produce.
The voluntary intake of silage by sheep:I. Interrelationships between silage composition and intake
Authors: Wilkins R. J. , Hutchinson K. J. , Wilson R. F. , Harris C. E. 
Published: March 2009

SUMMARYThe voluntary intake by sheep of seventy silages was measured in experiments in several years. Linear and multiple regression analyses were made between these voluntary intakes and the contents of dry matter, various acids and nitrogen and the digestibility value determined in vivo. There were some differences in these relationships for silages made from different groups of species, particularly those made from legumes. Voluntary intake was positively correlated with the contents of dry matter, nitrogen, lactic acid as a percentage of total acids and with the Flieg index. Voluntary intake was negatively correlated with the contents of acetic acid and ammonia as a percentage of total N. Although pH alone did not account for a significant part of the variation in intake, multiple regressions in which pH and one of the measurements of fermentation quality were included were significant, with pH positively related to intake. When all silages were considered, the correlation between voluntary intake and the apparent digestibility of dry matter was not significant. However, for legumes this correlation was significant and positive and for grasses other than ryegrass the correlation was significant and negative.
The voluntary intake of silage by sheep:III. The effects of post-ruminal infusions of casein on the intake and nitrogen retention of sheep given silage ad libitum
Authors: Hutchinson K. J. , Wilkins R. J. , Osbourn D. F. 
Published: March 2009

SUMMARYIsocaloric quantities of casein, and glucose were infused into the abomasum and duodenum of sheep given perennial ryegrass silage ad libitum. Casein infusion significantly increased nitrogen retention but failed to affect silage consumption, suggesting that the positive relationship found between silage intake and silage nitrogen content is unlikely to be due to a low nitrogen status in sheep fed all-silage rations.
Controlling soil pH with different N-fertilizers in experiments with ryegrass in pots
Authors: Bolton J. 
Published: March 2009

SUMMARYThe pH of soil cropped with ryegrass increased with calcium nitrate as a fertilizer and decreased with ammonium nitrate, especially in the mid-range of pH. Changes above pH 7·2 and below pH 4·5 were small.Yields of 4 cuts of grass given either N-fertilizer were similar over a pH range (in 0·01M-CaCl2) from 4·3 to 7·4. However, the composition of the grass and nutrient uptakes were affected by both soil pH and form of N-fertilizer.
Cation-anion relationships in crop nutrition
Authors: Cunningham R. K. , Karim A. 
Published: March 2009

Italian rye-grass was grown in the greenhouse in clay loam soil in winter 1962 with several rates of a nutrient solution containing NO3-N and P, K, Ca and Mg to see whether the grass had maximum values for sums of the cations and anions (σ cations, σ anions). Two other experiments were done in summer 1962 with a similar nutrient solution containing either NO3-N alone or NO3-N plus NH4-N.At the same level of added nutrients summer yields of grass were about twice those in winter and there was little difference when nutrient mixtures with NO3-N+NH4-N or with NO3-N alone were used. The sum of the cations (m-equiv./lOO g. dry matter) in the grass was positively correlated
The grazing feed intake of Hereford and Brahman cross cattle in a cool temperate environment
Authors: Moran J. B. 
Published: March 2009

SUMMARYThe grazing feed intake of four ¾ Brahman and four purebred Hereford steers was measured on four occasions during 12 months while they grazed improved pastures in a cool temperate environment. When pen fed roughage diets, the excretion pattern of chromic oxide and faecal nitrogen–digestibility relationships were also investigated in these animals.There were no breed differences in the relative recovery of Cr2O3 in the faeces when bulking 10.00 and 17.00 h samples nor were there breed differences in the faecal nitrogen–digestibility regression obtained. However, although there were large discrepancies between feed intake and live-weight change when measured in different seasons, the Herefords had the higher feed intake on each occasion while breed differences in live-weight change were non-significant.
Effect of harvesting stage on cereal and legume forage production in low rainfall regions
Authors: Hadjichristodoulou A. 
Published: March 2009

SUMMARYThe effect of stage of harvesting on dry-matter (D.M.) yield and chemical composition of barley, wheat and the legumes common vetch (F. sativa), woollypod vetch (F. dasycarpa) and fodder peas (P. sativum) were studied in Cyprus under low rainfall conditions in a series of trials sown in four successive years. Cereals were harvested at the beginning of heading, 50% heading and the milk stage of grain, and legumes at three stages from preflowering to full pod formation, D.M., protein and digestible D.M. yields and percentage D.M. content increased with age, whereas percentage protein content and D.M. digestibility declined. Under moisture stress conditions before and during the harvesting period D.M. yields did not increase significantly with age. Protein content of cereals under low rainfall conditions was higher than that of cereals grown in the U.K. under higher N fertilization levels. Rainfall conditions affected drastically the performance of both cereals and legumes. However, average yields were satisfactory; the barley variety 628 gave 8·98 t/ha, the highest D.M. yield among all cereal and legume varieties.
Evaluation of the performance of sweet potato genotypes by joint regression analysis
Authors: Ngeve J. M. 
Published: March 2009

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.
Comparative studies of upland and swamp rice varieties (Oryza sativaL. ). I. Effect of soil moisture on growth and nutrient uptake
Authors: Enyi B. A. C. 
Published: March 2009

SummaryGrowth and nutrient uptake by an upland rice variety, Agbede and a swamp rice variety, BG 79, were studied under four different soil moisture regimes (60, 80, 100% soil moisture saturation and flooding).BG 79 (Swamp rice) ultimately attained greater mean total dry weight than Agbede (Upland rice), except in the flooding treatment, where the reverse applied. For both, 100% soil moisture saturation gave the greatest total dry weight increase, whereas the driest soil depressed dry-matter production: plants grown on soil maintained at 80% moisture saturation ultimately attained greater mean total dry weight than those grown on flooded soil. Flooded plants of the swamp rice outyielded plants grown on soil maintained at 80% moisture saturation, but the reverse applied to the upland rice.Total leaf numbers were usually greater in BG 79 than in Agbede during the tillering and mid-vegetative stages. Increase in the soil moisture up to complete saturation increased the total leaf number in both varieties.Mean leaf area was greater in Agbede than in BG 79 during the tillering and midvegetative stages. During these two periods of growth the 100% saturation treatment produced plants with the greatest leaf area, whereas 60% soil moisture saturation produced plants with the smallest leaf area in both varieties.BG 79 had more shoots than Agbede. During tillering saturated and flooded soil encouraged the production of shoots in both varieties, but the driest soil prolonged the tillering period, especially in BG 79. Final shoot number tended to decrease with decreasing soil moisture. The percentage shoot mortality in Agbede was not significantly affected by soil moisture regimes, but BG 79 plants grown on the driest and saturated soil had significantly greater percentages of shoot mortality than flooded plants. In both varieties, plants grown on the driest soil had significantly greater percentage shoot mortality than those grown on soil maintained at 80% moisture saturation.Mean Relative Leaf Growth Rate and Net Assimilation Rate were significantly faster in BG 79 than in Agbede variety, but the reverse applied with regard to Leaf Weight Ratio.In both varieties flooded plants had the lowest concentration of manganese, especially during tillering. The small adsorption of Mn with flooding is attributed to a probable antagonism between iron and manganese.
Variation in the host-parasite relationship of a crop disease
Authors: Arnold M. H. , Brown S. J. 
Published: March 2009

SummaryVariations in the host–parasite relationship of bacterial blight of cotton, caused by Xanthomonas malvacearum, E. F. Smith (Dowson), axe elucidated in terms of the three main components of variation, namely, genetic variation in the host, genetic variation in the parasite and variations in environment.Although the relative resistance shown by host varieties differed both with the culture of the pathogen used for inoculation and with the environmental conditions, over-riding patterns of host resistance could be detected, showing that certain varieties maintained their resistance over a wide range of conditions.It was found that phage type in X. malvacearum was not related to virulence. Moreover, none of the cultures of the pathogen which had been isolated from different sources, could be shown to be identical when inoculated into a range of host varieties under a range of environmental conditions. It was concluded that the pathogen showed continuous variation in virulence and that it would be difficult and of little value to attempt to define races.Some success was achieved in relating observed variations in the host–parasite relationship to easily measured components of the environment, by using multiple regression analyses. It is suggested that this might provide a means of characterizing the complex variations observed and that the host–parasite relationship could be regarded as a dynamic system, in which disease expression is a function of the interactions of environmental factors and two polygenic systems, that of the host and that of the parasite.Intrapopulation variances were also studied in the host varieties. A population which showed little variation for resistance under one set of conditions might show considerable variation in a different environment or when inoculated with a different culture. It is suggested that selection for resistance under conditions which favour the expression of variation can lead, by repeated selection and inbreeding, to the production of resistant populations which retain their resistance under conditions in which the parental stocks showed no worthwhile resistance. These conclusions are discussed in relation to problems in resistance breeding and genetics.
Serum protein concentrations in 2-day-old Finnish Landrace, Scottish Blackface, Merino and Merino × Cheviot lambs
Authors: Halliday R. 
Published: March 2009

SummaryThe micro-Kjeldahl technique and paper electrophoresis were used to measure the total protein and γ-globulin concentrations in the sera of 423 2-day-old Finnish Landrace, Scottish Blackface, Merino and Merino × Cheviot lambs, and the total protein concentrations in the sera and colostra of their mothers. The concentrations were higher in Finnish lambs than in lambs of other breeds. The interbreed variations between single lambs were not significant, but the variations between lambs from larger litters were highly significant, because the concentrations in Finnish twins and triplets were as high as in single lambs, whereas the concentrations in Blackface and Merino × Cheviot lambs were negatively correlated with litter size. The differences between the breeds were attributable to the particularly high protein concentrations in the colostra from the Finnish ewes, to the small size of their lambs, and, probably, to a higher rate of production of colostrum by Finnish than by other ewes. There was some evidence of a positive correlation between the lengths of the gestation periods and the γ-globulin concentrations of the lambs.