bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of windrowing, irrigation and defoliation of potatoes on silver scurf (Helminthosporium solani) disease
Authors: Firman D. M. , Allen E. J. 
Published: March 2009

SUMMARYField experiments with the potato variety Desiree at Cambridge, UK, in 1988–90 examined the effects of windrowing on the development of blemishing diseases during storage on tubers from crops grown with differing irrigation regimes and dates of defoliation and harvest. Irrigation reduced levels of silver scurf (Helminthosporium solani) at harvest in all three years and increased black dot (Colletotrichum coccodes) in one year. Early crop defoliation slightly increased silver scurf at harvest in one year only. Silver scurf developed less during storage at 3 °C than at 7 °C and disease levels on tubers after storage were related to levels present at harvest. The effects of leaving tubers for up to 6 h in a windrow at harvest on silver scurf after storage were small and inconsistent between years despite similar drying conditions. The results suggest that windrowing may be of little practical use in controlling silver scurf during storage.
Ammonia volatilization during storage of cattle and pig slurry: effect of surface cover
Authors: Sommer S. G. , Christensen B. T. , Nielsen N. E. , Schjφrring J. K. 
Published: March 2009

SUMMARYGaseous NH3 losses from pig and cattle slurry stored in eight storage tanks were measured simultaneously using wind-tunnels. The slurry was either stirred weekly (uncovered), or was allowed to develop a natural surface crust. Oil, peat, chopped cereal straw, PVC foil, leca® (pebbles of burned montmorillonitic clay) and a lid were tested as additional covers. Convective transport of ammonium to the surface layers caused NH3 volatilization losses of 3–5 g NH3-N/m2 per day from the stirred, uncovered tanks. The loss of NH3 from the stirred slurry was related to air temperature. The development of a natural surface crust reduced NH3 losses to 20% of those from stirred slurry. NH3 losses from slurry not developing a natural surface crust layer and left undisturbed were similar to the losses from stirred slurry. A 15 cm layer of straw was as effective as a surface crust layer in reducing NH3 losses. In one experiment, cracks developed in the oil cover and losses were therefore only reduced to 50% of those of uncovered slurry. Apart from this experiment, NH3 losses from slurry covered with oil, leca®, peat and foil were small.
Growth and yield of winter wheat (Triticum aestivum) crops in response to CO2and temperature
Authors: Wheeler T. R. , Batts G. R. , Ellis R. H. , Hadley P. , Morison J. I. L. 
Published: March 2009

SUMMARYCrops of winter wheat (Triticum aestivumL. cv. Hereward) were grown within temperature gradient tunnels at a range of temperatures at eitherc.350 or 700 μmol mol−1CO2in 1991/92 and 1992/93 at Reading, UK. At terminal spikelet stage, leaf area was 45% greater at elevated CO2in the first year due to more tillers, and was 30% greater in the second year due to larger leaf areas on the primary tillers. At harvest maturity, total crop biomass was negatively related to mean seasonal temperature within each year and CO2treatment, due principally to shorter crop durations at the warmer temperatures. Biomass was 6–31% greater at elevated compared with normal CO2and was also affected by a positive interaction between temperature and CO2in the first year only. Seed yield per unit area was greater at cooler temperatures and at elevated CO2concentrations. A 7–44% greater seed dry weight at elevated CO2in the first year was due to more ears per unit area and heavier grains. In the following year, mean seed dry weight was increased by > 72% at elevated CO2, because grain numbers per ear did not decline with an increase in temperature at elevated CO2. Grain numbers were reduced by temperatures > 31 °C immediately before anthesis at normal atmospheric CO2in 1992/93, and at both CO2concentrations in 1991/92. To quantify the impact of future climates of elevated CO2concentrations and warmer temperatures on wheat yields, consideration of both interactions between CO2and mean seasonal temperature, and possible effects of instantaneous temperatures on yield components at different CO2concentrations are required. Nevertheless, the results obtained suggest that the benefits to winter wheat grain yield from CO2doubling are offset by an increase in mean seasonal temperature of only 1·0 °C to 1·8 °C in the UK.
Planting materials for warm tropic potato production: production and field performance of nursery-produced tubers
Authors: Benz J. S. , Keller E. R. , Midmore D. J. 
Published: March 2009

SUMMARYPotato production in the lowland tropics is constrained by lack of affordable supplies of planting material. Therefore, the potential to producein situtuber seed from true potato seed (TPS) seedlings and rooted stem cuttings under nursery conditions in the warm tropics was studied, and their yields were compared with those of the same materials obtained under cool conditions. Subsequently, their field performance in the warm tropics was evaluated.Tuber yield from TPS seedlings and rooted cuttings transplanted in nursery beds under warm conditions ranged from 50% to < 20% of that obtained in cool conditions, but reductions in tuber numbers were less marked under warm conditions. Survival of seedlings was less than that of stem cuttings, but tuber numbers of seedlings exceeded those of rooted cuttings by a factor of two or more (e.g. 700 m−2for seedlingsv.224 m−2for rooted cuttings). Low tuber number is physiologically inherent in cuttings, as is high tuber number in seedlings. Total tuber yields varied significantly amongst clones grown in the warm climate from rooted cuttings, not always in proportion to the number of tubers produced. Differences in tuber yield and tuber number were less marked between the two TPS progenies studied.The field comparisons highlighted the 30–40% lower yield potential for warm-climate-produced nursery seed materials. Slower emergence and fewer stems apparently were in part responsible for this effect; however, neither tuber number harvested nor the proportion of marketable tubers was affected by site of production of seed materials. Cutting medium-sized warm-produced tubers (mean 23 g), the use of larger sized whole tubers (10–20 gv.5–10 g) or increasing the planting density of 5 g tubers from 8·8 to 15·5 plants m-2significantly increased yields by 4·9, 2·25 and 3·5 t ha-1, respectively, but yields were not increased further by 20–40 g tubers nor by 22·2 plants m-2. Small seedling tubers (≤ 5 g) can potentially lead to high stem numbers per unit weight of tubers, but their success in plant establishment was hampered in warm climates, especially in the presence of soil pathogens. Cool-climate-produced seedling tubers and tubers from cuttings can compete physiologically with field-produced seed tubers when used as planting materials in the warm tropics. However, with few exceptions, no crop from tubers produced under warm conditions could match the performance of crops from similar cool-produced tubers when planted out in the warm tropics.
Simulation of digestion in cattle fed sugarcane: model development
Authors: Dijkstra J. , France J. , Neal H. D. St. C. , Assis A. G. , Aroeira L. J. M. , Campos O. F. 
Published: March 2009

SUMMARYA dynamic model of digestion and absorption of nutrients in cattle fed sugarcane-based diets is described. There are 11 rumen state variables, and four zero pools representing absorbed nutrients. The rumen state variables represent nitrogen, carbohydrate, long chain fatty acid, microbial and volatile fatty acid pools. The zero pools relate to absorbed amino acids, glucose, long chain fatty acids, and volatile fatty acids. The flux equations are described by mass-action and Michaelis-Menten forms. Wherever possible, data derived from trials with cattle fed sugarcane-based diets were used to parameterize the model. Sensitivity analyses revealed that stability and behaviour of the model was generally satisfactory. The model was most sensitive to changes in fractional passage and substratehydrolysis rates and to the microbial maintenance requirement. Within the limited information available for comparison, the simulations agreed with observations of fibre flows and ammonia and volatile fatty acid concentrations in rumen fluid. Duodenal non-ammonia nitrogen flow was consistently underpredicted and reasons for this underprediction are suggested.
Effect of nitrogen rates on rice growth and biological nitrogen fixation
Authors: Carreres R. , Tomé R. González , Sendra J. , Ballesteros R. , Valiente E. Fernández , Quesada A. , Nieva M. , Leganés F. 
Published: March 2009

SUMMARYThe effect of different rates (0–140 kg/ha) of nitrogen fertilizers on soil cyanobacteria and rice crop performance were studied in a rice-cropping system on an alkaline Fluvent soil at Valencia, Spain, during three consecutive crop seasons (1990–92). The results showed that the rice fields of Valencia favour the development of N2-fixing cyanobacteria. Nitrogen fixation varied during the cultivation cycle, reaching its highest values at the maximum tillering stage, 5–6 weeks after sowing, and showed a positive correlation with the abundance of cyanobacteria and a negative correlation with the amount of N fertilizers used. Grain yield increased with increasing amounts of N fertilizers up to 70 kg N/ha. N rates appeared to affect grain yield by causing variations in the number of panicles/m2. Leaf chlorophyll readings at the end of the tillering stage were positively correlated with the number of panicles/m2, suggesting that it could be a useful parameter for predicting productivity. There was a significant increase in the N uptake of the rice but a decrease in the apparent N recovery and Nuse efficiency of applied fertilizer N, with the application of increasing rates of N fertilizer. In all instances, except in plots fertilized with 140 kg N/ha, the amount of N removed by plants was significantly higher than that applied as N fertilizer. The differences were positively correlated with the values for N fixation, suggesting a significant contribution by N fixation to rice production. These results show that a rational use of biological N fixation, in combination with inorganic N fertilization, would permit the input of N fertilizers to be reduced by c. 50% without any significant loss of productivity and with an ecological benefit for the whole ecosystem.
Effect of nitrogen fertilization on rice spikelet differentiation and survival
Authors: Senanayake N. , Naylor R. E. L. , De Datta S. K. 
Published: March 2009

SUMMARYExperiments were conducted in glasshouses at the Agronomy Department, International Rice Research Institute (IRRI), Philippines, in 1987 and 1988 to test the effects of small amounts of additional N applied at different times during the vegetative and reproductive phases of growth on rice yield components and on spikelet differentiation and survival.The results showed that an additional 10 kg/ha of N fertilizer had the largest effect on maximum spikelet number when applied at growth stage (GS) 1·9 but was too low to sustain the survival of the differentiated spikelets. Applications after panicle initiation did not lead to an increased survival of spikelets. Foliar N application at GS 5·5 did increase spikelet survival.The results confirm the role of limited N supply in restricting yields of rice. Altering the timing of N inputs seems unlikely to improve spikelet survival.
Nitrogenase activity, nodulation and seed production inVicia fabaas affected by methabenzthiazuron
Authors: Martínez J. , Vidal D. , Simón E. 
Published: March 2009

SUMMARYThe effects of recommended application rates of the herbicide methabenzthiazuron (MBT) (2·5 and 4 kg ha-1) on vegetative growth, nodulation and N2fixation in faba bean plants were studied in the field at Barcelona during 1990 and 1991. Nodulation, specific nitrogenase activity (SNA) of excised nodules, dry weight of plants and seed nitrogen content at harvest were compared in MBT-treated, hand-weeded (HW) and control plants. In 1990 the higher MBT application (4 kg ha-1) caused a decrease in nodulation and acetylene reduction activity (ARA) per plant during the mid-period of pod-fill, and also in vegetative growth, seed production and N content of seeds, whereas the lower rate (2·5 kg ha-1) did not have a significant effect on any of these factors. However, in 1991, growth and herbicide effects were different from those in the previous year. No inhibitory effect of MBT on nodulation, SNA or ARA per plant was observed and vegetative growth, seed production and N content of seeds were not significantly different from those of plants from HW plots. In 1991, both 4 kg ha-1of MBT and the HW treatment caused a stimulatory effect on seed N recovery and yield compared to control plants. Rates of ARA per plant at late pod-fill were positively related to N recovery by seeds. These differences could have been due to the low rainfall in 1990, which may have permitted MBT to remain in the soil for a longer period and to inhibit N fixation and plant growth in theVicia fabacrop.
Influence of manufacturing conditions on the bioavailability of magnesium in calcined magnesites measured in vivo and in vitro
Authors: Adam C. L. , Hemingway R. G. , Ritchie N. S. 
Published: March 2009

SUMMARYDietary calcined magnesite supplements of different particle sizes and temperatures of calcination were examined at Glasgow University Veterinary School in 1981. Balance experiments with wether sheep revealed that particle sizes < 75, 75–150, 150–250 and 500–1000 μm diameter of a feed-grade calcined magnesite all increased urinary output of magnesium to a similar extent but the apparent magnesium availability coefficient for the 500–1000 μm diameter fraction (0·03) was significantly less than for fractions of smaller diameter (0·17–0·23) (P < 0·01). A 1000–2000 μm fraction of fertilizer-grade material had an apparent availability of 0·18 but had the least effect on urinary magnesium output. Calcination temperatures of 800, 900 and 1100 °C significantly increased apparent availability (c. 0·46)compared with that for temperatures of 500 and 650 °C (c. 0·12) (P < 0·01), and significantly increased urinary output of magnesium. Losses of magnesium from these supplements incubated in the rumen of cows at grass in 24 μm mesh nylon bags showed some correlations with their apparent availability and urinary magnesium output. Solubility in molar ammonium nitrate showed some good correlations with urinary magnesium output but not with magnesium availability. Supplementation of a low magnesium diet given to lactating ewes with fine particle (< 75μm) calcined magnesite resulted in significantly greater increases in plasma magnesium concentration than when coarse particle material (500–1000 μm) was given (P < 0·05), but magnesites calcined at 650 and 800 °C induced similar changes in plasma magnesium.
The phenology of the emergence of brassica pod midge (Dasineura brassicae Winn.) and its infestation of winter oil-seed rape (Brasica napus L.)
Authors: Williams Ingrid H. , Martin A. P. , Kelm Maria 
Published: March 2009

SummaryThe phenology of the emergence of brassica pod midge from overwintering sites and its subsequent infestation of winter oil-seed rape crops on a farm in southern England was studied over 3 years. Two generations occurred each year. The first generation of adults emerged from mid-May or early June until early July from overwintering cocoons in soil at sites where oil-seed rape had been grown in the previous year or years. Many females and a few males migrated to flowering winter rape crops where eggs were laid in the pods. Mature larvae dropped daily from the pods from early or mid-June until late July or early August, and formed cocoons in the soil. The second generation of adults emerged from late June until mid-July or early August to lay further eggs in the crop. Larvae from these eggs dropped to the soil to diapause within cocoons for up to 3 years.
Inheritance of pod and seed resistance to the cow-pea seed beetle (Callosobruchus maculatus Fabr.)
Authors: Rusoke D. G. , Fatunla T. 
Published: March 2009

SummaryTwo seed-resistant land races were crossed to a seed-susceptible cultivar to produce Fl, F2, BC1; and BC2 generations. It was observed that seed resistance was conditioned by two unlinked recessive genes and cytoplasmic factors. Similarly, generations derived from a pod-resistant, seed-susceptible cultivar with a seed-resistant, pod-susceptible land race demonstrated that seed and pod resistance are independently inherited.
The phenology of the emergence of brassica pod midge (Dasineura brassicae Winn.) and its infestation of spring oil-seed rape (Brassica napus L.)
Authors: Williams Ingrid H. , Martin A. P. , Kelm Maria 
Published: March 2009

SummaryThe phenology of the emergence of brassica pod midge from overwintering sites previously sown with spring oil-seed rape and its subsequent infestation of spring rape crops was studied over 3 years. Adults emerged from the overwintering sites from mid-May until early July, but infestation of spring rape did not begin until late June. Two generations occurred on spring rape. Mature larvae dropped from the pods almost daily from early to mid-July until mid-August to early September to form cocoons in the soil. A small proportion of these larvae developed into pupae and emerged as a second generation of adults to lay further eggs in the crops. Larvae from these eggs dropped to the soil to diapause within cocoons.
Factors affecting yield and quality in irrigated wheat
Authors: Barber J. S. , Jessop R. S. 
Published: March 2009

SummaryTwo field experiments examined the effects of nitrogen fertilizer, irrigation frequency and three wheat varieties on the yield and quality of irrigated wheat on a heavy clay soil. In the first experiment, with irrigation supplied to all plots at mid-tillering and close to ear emergence, there were negative effects of nitrogen fertilizer on grain yield with the reverse occurring with grain protein. The variety Songlen had one of the highest grain yields combined with higher milling yields and flour protein. In the second experiment, yield was maximized with at least two irrigations, whilst increasing irrigation frequency reduced flour protein and dough development time. While WW15 gave the highest yields irrespective of nitrogen or irrigation treatments, this variety had the lowest flour protein. With only one irrigation or without irrigation, nitrogen fertilizer increased grain protein; more frequent irrigation reduced mean flour protein.
Influence of plane of nutrition and diet composition on rumen fermentation and energy utilization by dairy cows
Authors: Sutton J. D. , Broster W. H. , Schuller E. , Napper D. J. , Broster Valerie J. , Bines J. A. 
Published: March 2009

SummaryMean digestible energy (DE) intakes of 147 cows of three parities receiving three levels of DE including one ad libitum (about 2·2, 2·6 and 3·3 multiples of maintenance (MM)) drawn from three mixed diets containing hay and 60, 75 or 90% compound were calculated.Rumen samples were taken from three-quarters of the cows at monthly intervals throughout the experiment. Molar proportions of volatile fatty acids (VFA) in the rumen were not affected by stage of lactation over the 36 weeks of the experiment. The proportion of acetic acid decreased and that of propionic acid increased with greater intakes and with higher proportions of compound in the diet. The proportion of n-butyric acid was little affected by level of intake but decreased with increasing proportions of compound. In young, non-lactating cattle given the same diets but at lower levels of intake, VFA proportions were unaffected by diet composition at intakes of about 0·7 MM but at intakes of about 1·3 MM the proportion of acetate decreased and that of propionate increased when the proportion of compound was increased from 75 to 90%.The efficiency of milk energy production in relation to DE or metabolizable energy (ME) above maintenance decreased with increasing level of intake but was little affected by the proportion of compound. Partition towards live weight increased with level of intake in early lactation but not in late lactation. It also increased with higher proportions of compound in mid and late lactation but not in early lactation.Estimates of the ME requirement for live-weight change (LWC) were in reasonable agreement with recently published standards in early lactation when live weight was decreasing, but later in lactation when live-weight gain was occurring, a much higher value was calculated which is difficult to reconcile with these standards.Rumen VFA proportions were related to dietary fibre concentration and level of intake additively. The relationship to VFA proportions was close for milk fat concentration, but less so for energy partition towards live weight and none was apparent for the efficiency of ME utilization for milk energy production. It is suggested that both the reduction in milk fat concentration and the increase in milk yield in response to reductions in the fibre content of diets may be independently related to the increase in the proportion of propionate in the rumen VFA.It is concluded that further progress in studies of the dietary factors affecting the efficiency of milk production will require measurements of nutrient uptake from the digestive tract and description of milk production and LWC in terms of their chemical composition rather than energy alone.
A study of the process of making clamp silage
Authors: Amos Arthur , Woodman Herbert Ernest 
Published: March 2009

An account has been given of an investigation into the changes which occur during the preservation of the oat and tare crop in the clamp silo.The material obtained from the clamp was divisible into three types: (1) An uppermost thick layer of mouldy material. (2) “Sweet” silage from the middle layers. (3) Wet “sour” silage from the bottom layer. The spoilt material in the top layer represented approximately 19 per cent. of the whole of the crop contained in the clamp, and in addition to this, the silage was extensively spoilt round the sides of the clamp to an average depth of 12 inches. In comparing the processes of ensilage in the tower and in the clamp, it should be remembered that spoiling of this type only affects the top few inches of the material in the tower silo.The loss of dry matter in the “sour” silage layer, arising from fermentation and drainage away of juice, amounted to more than one-fifth of the dry matter of the crop originally present in the layer. This represents a much bigger loss than any previously recorded at Cambridge in similar work with tower silos. An exceptionally heavy destruction of carbohydrates further characterised the production of the “sour” silage in the clamp.The loss of dry matter in the “sweet” silage layer was much smaller and was comparable in magnitude with that occurring during the production of “green fruity” silage in tower silos.The chemical characteristics of the “sour” silage samples were investigated and were found to conform with results discussed in a previous communication, namely, the samples contained a high proportion of volatile bases to amino acids, and the volatile acids were present in appreciable excess of the non-volatile organic acids.