bluuebunny/crossref_metadata_2025_split huggingface dataset:
The yield of durum wheats released in Mexico between 1960 and 1984
Authors: Waddington S. R. , Osmanzai M. , Yoshida M. , Ransom J. K. 
Published: March 2009

SummaryTwo trials designed to measure progress in the yield of durum wheat cultivars released in Mexico by the Institute Nacional de Investigaciones Agrícolas over the period 1960–84 were grown in the Yaqui Valley, Sonora, Mexico, during the 1983–4 and 1984–5 cropping seasons. The trials compared grain yield, above-ground biomass, harvest index (ratio of dry grain yield to dry above-ground biomass), yield components, grain-growth rates and phenological characters for eight key cultivars and the modern advanced line, Carcomun ‘S’, when grown at a high level of agronomic inputs and management.The grain yield of durum wheat was estimated to have risen for 25 years of breeding from 3·70 to 8·40 t/ha. The estimated average annual rates of increase in grain yield for the periods 1960–71 and 1971–85 were 251 and 121 kg/ha respectively. Grain yield improvements were based on a linear increase in the number of grains/m2 over the 25-year period, the result of more grains per spikelet. An improved above-ground biomass at maturity was a feature of the two modern genotypes, Altar 84 and Carcomun ‘S’. Harvest index increased with each new cultivar up to the release of Mexicali 75 in 1975, but thereafter the higher grain yields achieved with the modern genotypes were not associated with a higher harvest index. Thousand-grain weight remained steady for the released cultivars but fell slightly for the advanced line Carcomun ‘S’. Improvements in yield were not associated with a longer cropping cycle.It is concluded that a breeding strategy combining selection for morphological characters thought to confer high yield potential, such as a more erect leaf posture and high number of grains per spikelet, with selection for grain yield per se has been successful in improving the grain yield of durum wheats adapted to north-west Mexico. Improvements have come not only in the size of the grain sink and the efficiency of assimilate partition to grain but also in the biomass produced above ground.
Studies of resource use and yield of mustard and chickpea grown in intercropping systems
Authors: Kushwaha B. L. , De R. 
Published: March 2009

SummaryA study was made under rainfed (unirrigated) conditions in a subtropical and semi-arid region of northern India during the winter (October–March) seasons of 1980–1 and 1981–2 to evaluate the growth, resource use and seed yield performance of four intercropping systems, namely mustard alone, ⅔ mustard +⅓ chickpea, ⅓ mustard + ⅔ chickpea and chickpea alone grown at 7·5, 15·0, 22·5 and 30·0 plants/m2.The total economic productivity of intercrop systems was greater than that of either component grown alone. The components of seed yield (number of primary and secondary branches, number of pods, seed weight per plant and weight of seed) increased in mustard where intercropped but the opposite occurred in chickpea. These growth attributes were decreased with an increase in plant population density. The two crop species needed an individual density less than their sole crop optima to form an optimum density when intercropped. A mixture of ⅓ mustard + ⅔ chickpea appeared to be the best system for the rainfed conditions in which these experiments were made and produced greatest yield advantage.Chickpea grown in ⅓ mustard + ⅔ chickpea combination had greater nodulation with higher dry weight per nodule. A greater leaf area index (LAI) for both the crop species was noted in ⅓ mustard + ⅔ chickpea mixture than were found in other systems. The maximum LAI of mustard and chickpea was attained at 60 and 120 days after sowing respectively and this may be why a lower proportion of mustard plants in the intercrop was more advantageous.A combination of ⅓ mustard + ⅔ chickpea removed more nitrogen from the soil, had better water use efficiency and comparatively less soil moisture depletion than the sole crop. Soil nitrogen utilization and soil moisture depletion were less at higher densities.
Thyroxine concentration in maternal and foetal plasma during pregnancy in Australian feral goats
Authors: McDonald B. J. , Stocks D. C. , Connell J. A. , Hoey W. A. 
Published: March 2009

SummaryGestational age-related changes in plasma free thyroxine (FT4) concentration in maternal and foetal goats were determined for 65–140 days of pregnancy. The placental permeability to maternal thyroxine (T4) and iodine (I) during the last trimester of pregnancy was evaluated.The presence of T4in foetal circulation at 65 days' gestation, the absence of a significant correlation between maternal and foetal levels and the absence of any transplacental diffusion of125I–T4showed autonomous foetal thyroid function during pregnancy in goats. Significantly low maternal FT4was measured at 95 and 110 days' gestation (32·7 and 31·5 pmol/1 respectively). Plasma concentration increased to 48·6 pmol/1 at day 125 then fell before parturition to a level similar to that of non-pregnant goats (41·9 pmol/1). In contrast, foetal FT4increased with gestational age to 110 and 125 days when levels of 64·0 and 59·1 pmol/1 respectively were greater than those at all other ages, suggesting that the foetal hypothalamic-pituitary-thyroid is functioning at a higher rate than the maternal system around this time. This was supported by increased foetal thyroid affinity for I when compared with the maternal thyroid at 110–140 days' gestation.A significant cubic relationship between foetal FT4and gestational age was established.
Influence of particle size and surface area onin vitrorates of gas production, lipolysis of triacylglycerol and hydrogenation of linoleic acid by sheep rumen digesta orRuminococcus flavefaciens
Authors: Gerson T. , King A. S. D. , Kelly Kathleen E. , Kelly W. J. 
Published: March 2009

SummaryParticulate fractions prepared from meadow hay, ranging in size from 0·1 to 2 mm, were incubated with rumen digesta from four cannulated Romney sheep fed the same hay. The rates of gas production, lipolysis of corn oil and hydrogenation of linoleic acid were measured.The rate of gas production per g fermentable particles (FP) was approximately 30% lower with 1–2 mm than with the 0·1–0·4 mm particles. However, per m2surface area the rate for the larger particles was found to be approximately 600% greater.The rates of lipolysis of triacylglycerols and hydrogenation of linoleic acid were respectively 25 and 60% higher per g FP and 1100 and 1200% higher per m2FP surface area with the 1–2 mm particulate fraction.The same hay particulate fractions were incubated with pure cultures ofRuminococcus flavefaciens, since this organism is active in both lipid metabolism and cellulose fermentation. The rate of gas production and the number of organisms adhering to the particles were determined.The effects of particle size on gas production were similar to those found when incubations were carried out with rumen digesta. Per g FP the rate was 40% lower with 1–2 mm than with 0·1–0·4 mm particles. However, per m2surface area the rate was found to be approximately 450% greater with the former.It was further found that although the density of the bacterial population on 1–2 mm particles was 600% higher than on the 0·1–0·4 mm particles, the rate of gas production per 109bacteria remained unchanged.We conclude that per m2surface area fermentation, lipolysis and hydrogenation were more rapid with particles ranging from 1 to 2 than from 0·1 to 0·4 mm in size. This was due, at least in part, to microbial population density.
Manganese-resistant mutants ofAzospirillum brasilense: their response of associative nitrogen fixation, dry-matter production and nitrogen content of cheena (Panicum miliaceumL.) to different amounts of applied nitrogen in acid soil
Authors: Rai R. 
Published: March 2009

SummarySix nitrosoguanidine-induced manganese-resistant mutants ofAzospirillum brasilensewere isolated and used for associative N2fixation studies with cheena (Panicum miliaceumL.) in acid soil. Three mutants showed cross-resistance to aluminium and neomycin, but of these three only one showed cross-resistance to streptomycin. Inoculation of cheena withA. brasilenseand its mutants at different rates of applied nitrogen led to a significant increase in associative N2fixation, N content, dry-matter production and grain yield in acid soil. A saving of about 20 kg N/ha could be achieved by inoculating seeds of cheena with these mutant strains in acid soil.
Effects of nitrogen supply and drought on early development of winter wheat in the field in Eastern England
Authors: Thorne G. N. , Wood D. W. , Stevenson H. J. 
Published: March 2009

SummaryDevelopment was studied in winter wheat sown after rape or after oats in September 1984, 1985 and 1986, and in October 1985. N03-N residues from rape in October exceeded those from oats by 60, 50 and 40 kg N/ha respectively in the 3 years. Previous crops affected development only in the 1984–5 season. The first 12 apical primordia were initiated faster after rape; thereafter rates were similar, wheat after rape having two more primordia than wheat after oats. Final numbers of leaves and spikelets were each increased by one. The first five leaves appeared faster after rape so that from December onwards the number of emerged leaves was one more after rape than after oats. The double ridge and terminal spikelet stages occurred 8 and 4 days respectively earlier after rape than after oats. Development was unaffected by N fertilizer applied in November or at various times from February onwards, although growth and N uptake were increased. Drought during autumn 1985 delayed emergence of the September-sown wheat and slowed the rates of initiation of the first ten primordia and appearance of the first four leaves. Consequently the number of shoots per plant in December was only about three cf. six in the other 2 years.
The fate of carbon in dying tillers of winter wheat
Authors: Thorne Gillian N. , Wood D. W. 
Published: March 2009

SummaryChanges in dry weight and14C contents of categories of shoots that did and did not survive to produce ears were examined in winter wheat grown in micro-plots in 1982–4. The weight of a group of tillers when dead was similar to their maximum dry weight when living. By anthesis dead shoots exceeded living ones in number but contributed less than 10% of total shoot dry weight.14CO2was supplied, near the time that number of shoots was maximal, to tillers in axils of first (T1) and third (T3) main stem leaves; T1usually survived and T3usually died. The percentage of14C in the plant retained in T1was 78–94%. That retained in T3ranged from 9 to 81%. Little14C moved from dying shoots into the rest of the plant in two experiments. In another, perhaps 70% of the14C in living tillers was transferred as they died but this represented only a small proportion of total plant weight.14C not retained in tillers to which it had been given was found in all parts of the plant, including about 7% in grain.
Influence of dates of sowing on Brassica species under semi-arid rainfed conditions of north-west India
Authors: Saran G. , Giri G. 
Published: March 2009

SummaryField experiments conducted during the winter seasons of 1982–3 and 1983–4 in semi-arid rainfed conditions of north-west India indicated that sowing of Brassica species at the right time can considerably increase productivity. Sowing in the middle of October with daily mean temperatures around 26 °C produced 1·5 t/ha against 0·9 t/ha obtained from the crops sown 1 month later with daily mean temperatures around 20 °C. Under such conditions Brassica juncea cv. Pusa Bold (medium in stature and duration and bold seeded) gave the highest (1·66 t/ha) yield. Eruca sativa could withstand sowing at still lower temperature (19 °C). Increasing temperatures in the second fortnight of February adversely affected the productivity of a late-sown crop by reducing the reproductive phase.
Comparison of the effects of spring applications of ammonium chloride and other nitrogen fertilizers on take-all in winter wheat
Authors: Gutteridge R. J. , Bateman G. L. , Hornby D. 
Published: March 2009

SummaryField experiments made in 1984 and 1985 compared the effects of ammonium chloride with those of other nitrogen fertilizers applied to winter wheat in spring. The dressing was divided, 40 kg N/ha in March and 160 kg N/ha in April. In both years take-all in July was at levels which usually decrease yield, and take-all ratings were greatest in plots treated with ‘Nitro-Chalk’ (calcium ammonium nitrate) and least in plots treated with ammonium sulphate, but the differences were not statistically significant. Ammonium chloride and the other treatments, urea and ‘Nitro-Chalk’ with potassium chloride, had intermediate effects and the ranking of treatments according to disease was consistent in both years. In 1984 the mean yield was 8·27 t/ha, range 7·92 t/ha (with ammonium chloride) to 859 t/ha (with ‘Nitro-Chalk’) and in 1985, 821 t/ha, range 7·;42 t/ha (with ‘Nitro-Chalk’) to 8·55 t/ha (with ammonium sulphate). In both years treatments had no significant effects on yields and the relationship between yield and disease was obscured in 1985 because of highly correlated disease and block effects.Whereas applying spring nitrogen all in the ammonium form seemed to decrease take-all slightly, the effects on yields of winter wheat were inconsistent. There is no evidence of extra benefit to be gained from applying the ammonium as ammonium chloride to crops at risk from take-all in this country, but there may be some benefit in applying KCl with ‘Nitro-Chalk’ top-dressings in the spring.
Long-term effects of improvement methods on Molinia caerulea dominant rough grazing on wet hill land. 1. Pasture production, quality and botanical composition
Authors: Davies D. A. 
Published: March 2009

SummaryFifteen treatments were applied in 1966 to Molinia caerulea dominant rough grazing on wet hill land at 305 m in mid-Wales. Improvement methods varied from controlled sheep grazing, application of lime, basic slag and nitrogen to the introduction of grasses and white clover with and without cultivations. Pasture productivity, feed quality and botanical composition were studied in the 4th, 9th, 14th and 18th harvest years. Controlled grazing increased D.M. production from 1·1 t/ha on the native vegetation to 3 t/ha in the 18th year. Application of lime, basic slag and 75 kg N/ha gave mean pasture production of 4·5 t D.M./ha which increased to 6·3 t D.M./ha on application of 290 kg N/ha per year. The quickest and greatest improvement was achieved by the introduction of grasses and clover following rotary cultivation or ploughing. At the lower N input these swards produced on average 6·3 t D.M./ha. Reseeds also showed the best response to 290 kg N with mean production on S. 23 perennial ryegrass (Lolium perenne L.) swards of 9·0 t D.M./ha. In vitro digestibility, crude protein and water-soluble carbohydrates were also highest on the reseeded swards.Increased grazing eliminated Molinia before the 4th year and it was replaced by Nardus stricta and Festuca ovina. Subsequently, Agrostis tenuis replaced Nardus. On the swards given fertilizer the rate of botanical change was accelerated with the ingress of Poa spp., Holcus lanatus and Festuca rubra. The proportion of sown grass remained high on the seeded plots throughout the duration of the experiment but the white clover content was lower than expected and it virtually disappeared from most of the swards before the 18th year.The results show the potential improvement possible on wet hill land. Given good fertilizer and grazing management, this improvement can be maintained for several years.
Long-term effects of improvement methods on Molinia caerulea dominant rough grazing on wet hill land. 2. Mineral composition of herbage and soil physical, chemical and biological characteristics
Authors: Davies D. A. 
Published: March 2009

SummaryThe effects of controlled grazing, application of N, P, K, Ca, and Mg and the introduction of grasses and white clover, with and without cultivations, on Molinia caerulea dominant rough hill grazing were studied over 19 years in mid-Wales. Nutrient concentration in, and uptake by, the herbage and changes in soil physical, chemical and biological characteristics were monitored periodically. Concentrations and uptake of N, P, K, Ca, Mg and Na were highest on the reseeded pastures. Nutrient balance sheets showed that the nutrients applied were most efficiently utilized on reseeded swards. They also highlighted the considerable losses of applied Ca and Mg that occurred.Implications of the results are discussed in relation to both future agricultural use of such areas in the hills and the effects on the environment.
The effect of height of pasture and concentrate composition on dairy cows grazed on continuously stocked pastures
Authors: Kibon A. , Holmes W. 
Published: March 2009

SummaryThe effects of pasture height and of a cereal-based concentrate or a sugar-beet pulp supplement were studied with 30 spring-calving cows on continuously stocked, perennial ryegrass dominant pasture in a 3 × 3 latin-square design with periods of 4 weeks. Pastures were maintained at heights of about 5·0 cm (short) or 6·5 cm (control). On the short pasture, the two supplements had similar effects and were additive but on the control pasture, compared with sugar-beet pulp, the cereal concentrate depressed herbage intake. Average fat-corrected milk yields were 26·3 and 28·1 kg/day on short and control areas respectively. Both supplements increased milk yields by about 0·7 kg per kg OM supplied. Cows on the short pasture tended to lose weight. Supplements slightly increased live weight and sugar-beet pulp tended to increase body condition score. In observations continued after the conclusion of the main experiment the short pasture was more productive and of slightly higher nutritive value. Cows receiving the concentrate supplements increased total intake but this was reflected only in live weight. The total utilized metabolizable energy for the whole season was about 130 GJ/ha.
Carcass, soft tissue and bone composition of early and late maturing steers fed two diets in two housing types and serially slaughtered over a wide weight range
Authors: Nour A. Y. M. , Thonney M. L. 
Published: March 2009

SummarySeventy-one small-framed Angus and seventy-four Holstein steers were chosen to represent small and large mature types in a study designed to provide quantitative information on the effect of breed, diet and housing type on composition of carcasses from cattle slaughtered serially over a wide weight range. Within breed, steers were individually fedad libitumeither a maize-grain or a maize-silage diet and assigned randomly to one of two housing types. The effects of treatments on response variables with increasing carcass weight were tested by covariance analysis.The rate of change of soft tissue chemical composition with increasing carcass weight was not influenced by diet, breed mature size or housing type except for ash which decreased at a faster rate in Angus than in Holstein steers. Percentages of water, protein and ash decreased while lipid increased with increasing carcass weight. At any carcass weight, Angus had more lipid and less water in soft tissue. Percentages of soft tissue protein and ash were affected by diet within breed. The energy content of soft tissue increased with weight and was affected only by breed. Angus soft tissue had more energy than that of Holsteins. Similar results were obtained when the entire carcass was analysed.Cattle fed grain had slightly more water and less ash in bone than cattle fed silage. Angus steers had more protein and ash in bone than Holsteins. Although there was a diet × breed × housing type interaction for lipid content of bone, Holstein bone had higher lipid content than Angus bone for either diet or type of housing. All percentages of chemical components in bone, except water, increased with increasing carcass weight.The experiment showed that large mature-size breeds have the ability to transform a high-energy diet into protein for human consumption. The percentage changes in ash, protein and lipid with increasing carcass weight appeared to follow a pattern of development similar to bone, muscle and fat, respectively, suggesting that Hammond's theory of differential growth holds also for chemical components of bovine carcasses. Bone chemical components, however, had a slightly different developmental pattern. The quantitative information on bone presented herein could be used to exploit bone as a source of human food, dietary supplements and products for bone remodelling surgery.
Effects of sex, age and body weight on selected organs of indigenous Nigerian pigs: liver, kidney, heart, lung-and-trachea
Authors: Essien A. I. , Fetuga B. L. 
Published: March 2009

SummaryThe absolute and relative growth of the liver, kidney, heart and lung-and-trachea were studied for 64 female, 64 castrated male and 64 intact male indigenous Nigerian pigs between birth and 672 days of age. Highly significant (P< 0·001) sex and age influences were obtained for the absolute and relative weights of the liver, kidney and heart. At 280 days of age, the four organs on average weighed 28 times their birth values; the terminal weights averaged 1·31 times their values at 280 days. Organ growth became stabilized after 280 days.The allometric equation:Y=aXb, transformed to its linear form logY= loga+blogX, was employed to examine the relationship between organ weight and body weight. The growth coefficients 6 obtained ranged from 0·787 for kidney to 0·850 for lung-and-trachea and were similar to values reported in the literature. The accompanying highly significantR2values strongly indicate that the functions of these organs are related to overall metabolism, which in turn is strongly dependent on body size.
Effect of amount consumed and diet composition on the apparent digestibility of feed in cattle and sheep
Authors: Bines J. A. , Broster W. H. , Sutton J. D. , Broster Valerie J. , Napper D. J. , Smith T. , Siviter J. W. 
Published: March 2009

SummaryDigestibility trials were conducted at two stages of lactation with each of 107 Friesian cows using three diets (60:40, 75:25, 90:10 proportions of compound feed to medium quality hay fed long). Each cow received throughout lactation fixed daily allowances of one of these diets at either 2·26 or 2·63 times average maintenance requirements (MM), or was fed ad libitum, average intake equalling 3·07 MM. The digestibilities of the diets were also measured on immature cattle at 0·76 and 1·33 MM and sheep at 0·65 and 1·27 MM.For all classes of stock the digestibility of dry matter increased linearly and that of fibre decreased curvilinearly with increasing proportion of compound in the diet. There was no interaction of effects of diet composition and amount consumed on digestibility of feed. The digestibility of both dietary components declined for the young cattle and sheep with increased intake. The digestibilities for lactating cows were lower than for other stock but did not change with amount consumed or milk yield. Digestibility was slightly higher for first and second calf cows than for adult cows; and was higher for organic matter in mid lactation compared with early lactation for adult cows.These results for dairy cows conflict with the generally accepted interpretation that a linear decline in digestibility occurs from once to five times maintenance intake, embracing all classes of stock.