bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of nitrogen fertilizer rate on soil nitrate nitrogen content after harvesting winter wheat
Authors: Chaney K. 
Published: March 2009

SUMMARYThe nitrate nitrogen content of the soil (0–90 cm) was measured immediately after the harvest of winter wheat at eight sites in central and eastern England in 1987 and 1988. On average, 50% of the total nitrate detected was in the 0–30 cm, 30% in the 30–60 cm and 20% in the 60–90 cm soil horizon. Although soil nitrate N increased with the amount of N fertilizer applied, it was not a linear relationship. There were small nonsignificant increases in soil nitrate up to the optimum fertilizer rate for yield but, once the optimum was reached, further addition of fertilizer increased nitrate contents significantly.Therefore, applying the correct quantity of N for high grain yield did not significantly increase soil nitrate residues after harvest compared with the no-fertilizer treatment. This emphasizes the importance of applying the appropriate rate of N for each crop, because applying too much is not only uneconomic but also significantly increases the amount of mineral N which could be subsequently leached over the winter.
Variation among wheat cultivars in the response of leaf gas exchange to light
Authors: Blum A. 
Published: March 2009

SUMMARYThis research was done in order to explore genetic variation in carbon exchange rate (CER) of spring wheat (Triticum aestivum) leaves in response to variable photosynthetically active radiation (PAR) and to compare old and new Israeli cultivarsin this respect. Leaf gas exchange was measured in detached turgid leaves of 17 cultivars inan open system at 25 °C when PAR was reduced from c. 1200 to 200 μmol/m2 per s. Linear regressions of CER, stomatal conductance, transpirationand leaf internal CO2 concentration (Ci) on log PAR were fitted for each leaf(regression r2 was never <0·79) and the regressions were compared among cultivars by analysis of variance.Genotypes differed significantly for the slope (b) but not the intercept (a) of the regression of CER on log PAR, indicating that genotypic differences for CER increased with increasing PAR. Photosynthetic capacity, as expressed by the ratio of CER/Ci, differed significantly among cultivars only at high PAR. Stomatal conductanceand transpiration increased in a linear or a nonlinear fashion with log PAR and differences among cultivars for both were greatest at medium to low PAR. Photosynthetic water–use efficiency (WUE) and its variation among cultivars were greatest at the highest PAR. Genotypic variation in CER athigh PAR was confirmed by repeated results for 11 cultivars intwo independent experiments.The recently developed high-yielding cultivar V652 had a higher maximum CER, higher photosynthetic capacity and greater WUE at high PAR than older and lower-yielding cultivars. The results suggest an upward genetic shift in photosynthetic capacity andin CER at high PAR when selection for yield was performed under the high-irradiation conditions of Israel.
The effects of weather, seed rate and cultivar on lodging and yield in winter wheat
Authors: Easson D. L. , White E. M. , Pickles S. J. 
Published: March 2009

SUMMARYWinter wheat cultivars Apollo, Hornet, Longbow and Norman were each sown at 50, 100, 200, 400, 800 and 1600 seeds/m2in a field experiment conducted in Northern Ireland over the 1989/90 crop year. No growth regulators were applied and the wheat received 178 kgN/ha top-dressing in the spring. Hourly rainfall, windspeed and wind direction data were recorded and lodging was visually assessed from the end of May to harvest. Lodging first occurred in the 1600 seed-rate plots as the ears were emerging in early June and then progressively increased in the 800, 400 and 200 plots during June, July and August. Lodging did not occur suddenly but took several hours, with the stems first lying at an angle before lodging completely. Stem buckling or breakage did not appear to be the principal form of structural failure. The longest strawed cultivar, Longbow, lodged most severely. The shorter-strawed Norman also lodged badly in contrast with Hornet which had a similar straw length. Apollo, which was taller than Norman and Hornet and produced more ears per square metre than the other cultivars, lodged least but tended to lean atc.30° from the vertical. Lodging occurred during or within 24 h of periods of rainfall which, in many cases, coincided with windspeeds at crop height averaging > 25 km/h and occasionally > 50 km/h. Lodging also occurred following rainfall when the windspeed did not exceed 16 km/h. The grain yield was negatively correlated with the average lodging from ear emergence to harvest, there being a 1 t/ha decline in yield for each 10% increase in average area lodged. The 50 and 100 seed-rate plots yielded 10 t/ha and had little or no lodging. The decline in yield with increased lodging and seed rate was attributed to the effect of lodging rather than to seed rate and was associated with a fall in the number of grains/ear and 1000-grain weight from 56 and 53·5 g at the lowest seed rate to 15 and 42·7 g at the highest, respectively. A comparison of the plants from lodged and unlodged plots of the 1600 and 800 seed rates, and subsequently of the 800 and 400 seed rates, indicated that at the higher seed rate, lodged plots had less fresh weight per unit area, basal internodes with smaller diameters, fewer support roots per stem, and a lower root dry weight per stem.
Amide nitrogen transformation in waterlogged soil
Authors: Magid H. M. Abdel , Tabatabai M. A. 
Published: March 2009

SUMMARYIn laboratory studies, the amount of N mineralized under waterlogged conditions during 14 days at 30°C was significantly correlated (P< 0·001) with the activities of amidase, glutaminase and asparaginase in soil when these enzymes were assayed by either a nonbuffer or a buffer method using appropriate substrates. N mineralization under waterlogged conditions was also significantly positively correlated with N mineralization under aerobic conditions, especially at 25 and 35 °C (P< 0·001). Generally, the results indicate that the use of amidase, glutaminase and asparaginase activities in predicting plant-available N in soils deserves more attention.
Effect of nitrogen, phosphorus and potassium application on yield of potato tubers (Solatium tuberosum L.)
Authors: Sharma U. C. , Arora B. R. 
Published: March 2009

SummarySix field experiments, three each during 1982–3 and 1983–4, were conducted on a sandy loam soil to study the effect of varying levels of nitrogen, phosphorus and potassium, in the absence and presence of farmyard manure (FYM) (30 t/ha), on the number of tubers and yield of potato in three grades. Increase in nitrogen, phosphorus and potassium application, in the absence or presence of FYM, did not significantly affect the total number of tubers/m2 but did affect the number of tubers in different grades. An increase in nitrogen and potassium significantly decreased the number of tubers/m2 in small (< 25 g) and increased in medium (25–75 g) and large (> 75 g) grades at 45, 60, 75 and 90 days after planting. Increase in the application of phosphorus increased the number of tubers/m2 in the small grade and decreased it in the large grade but did not affect the number in the medium grade. Increase in nitrogen and potassium application decreased the tuber yield in the small grade and increased it in the medium and large grades. Applied phosphorus increased the yield in the small and medium grades and decreased it in the large grade. The increase in the yield of tubers with increase in nitrogen and potassium application was found to be caused by an increase in the number of tubers in the medium and large grades at the expense of the small grade; however, with applied phosphorus the increase in yield was due to increase in the weight of individual tubers within the small and medium grades. FYM application decreased the number of tubers in the small grade and increased it in the medium and large grades. The response of potato to nitrogen increased and to phosphorus and potassium decreased with the application of FYM.
Effect of the duration of the vegetative phase on crop growth, development and yield in two contrasting pearl millet hybrids
Authors: Craufurd P. Q. , Bidinger F. R. 
Published: March 2009

SummaryThe phenotype of medium duration pearl millet varieties grown in West Africa differs from that of the shorter duration millets grown in India. African varieties are usually much taller, have longer panicles, fewer productive tillers, and a lower ratio of grain to above-ground dry-matter (harvest index). The effect of crop duration on plant phenotype was investigated in two hybrids using extended daylengths to increase the duration of the vegetative phase (GSl: sowing to panicle initiation). The two hybrids, 841A × J104 and 81A × Souna B, were considered to represent the Indian and African phenotype, respectively. Tiller production and survival, leaf area, and dry-matter accumulation and partition, were monitored over the season. Grain yield and its components were determined at maturity.The two hybrids responded similarly to the short and long daylength treatments. The duration of GSl was increased from 20 to 30 days, resulting in increased number of leaves, leaf area, and stem and total dry-matter accumulation; there was no effect on tiller production and survival, or on panicle growth rate. Grain yield was, therefore, the same in both GSl treatments, and harvest index (HI) was much reduced in the long GSl treatment owing to the increased stem growth. One evident effect of a longer GSl was on dry-matter partitioning between shoots; partitioning to the main stem (MS) was increased, whereas partitioning to the tillers was reduced.There was no difference in crop development, growth or yield between the two hybrids in either GSl treatment. The only significant differences were in the efficiency with which intercepted radiation was converted to dry matter, which was greater in 841A × J104 than in 81A × Souna B, and in the balance between MS and tillers; the grain yield of the MS was significantly greater in 81A x Souna B than in 841A × J104, but at the expense of number of productive tillers.The results demonstrate that both African and Indian phenotypes are equally productive under good agronomic conditions. The lower HI in longer duration African millets is a consequence of a much extended stem growth phase and therefore increased competition between stem and panicle during grain filling. Possible ways to increase grain yield in the medium duration African millets are considered.
Effects of acute heat stress on changes in the rate of liquid flow from the rumen and turnover of body water of swamp buffalo
Authors: Chaiyabutr N. , Buranakarl C. , Muangcharoen V. , Loypetjra P. , Pichaicharnarong A. 
Published: March 2009

SummaryDuring 5 h of acute heat exposure (41 °C), there were increases in the heart rate from 43±2 (S.E.) to 51 ± 1 beats/min, respiratory rate from 26±4 to 86± 16 breaths/min and rectal temperature from 38·5 ± 0·1 °C to 39·7 ± 0·2 °C. The flow rate of liquid from the rumen and body water turnover significantly increased while biological half life of chromium-51 ethylenediaminetetra-acetate in the rumen and tritiated water decreased from 12·9 ± 2·5 and 87·7 ± 6·8 h to 9·3 ± 2·0 and 49·2 ± 5·7 h respectively. An increase in blood volume during acute heat stress occurred with an increase of both plasma and cell volume. An elevation of plasma water coincided with an increase in plasma protein and glucose. There is evidence that the increase in plasma water during heat exposure came from extravascular tissue space and/or from the digestive tract.
Nitrogen fixation as influenced by pesticides and rice straw in paddy soils
Authors: Jena P. K. , Rao V. Rajaramamohan 
Published: March 2009

SummaryThe effect of three herbicides and an insecticide combination on nitrogen fixation in three paddy soils was investigated in a laboratory incubation study. The influence of pesticide combination on N2 fixation was evaluated in the presence and absence of rice straw under flooded and non-flooded conditions. In a non-flooded alluvial soil single or combined application of butachlor and carbofuran significantly stimulated N2 fixation. There was no effect on N2 fixation when thiobencarb was applied alone; but with thiobencarb in combination with carbofuran higher N2 fixation occurred. Both oxadiazone and thiobencarb had no effect on N2 fixation under flooded conditions, but in combination with carbofuran the N2 fixation was high. In acid sulphate saline Pokkali soil, rice straw application stimulated N2 fixation; the stimulatory effect of carbofuran either alone or in combination became more pronounced under flooded conditions. N2 fixation was low in a laterite Sukinda soil and the effect of pesticides was not changed by rice straw amendment. A uniform stimulation of N2 fixation occurred in soils when carbofuran was applied either singly or in combination with other herbicides tested. Results indicate that the effect of pesticides on N2 fixation varied with the rice straw application and water regime.
Metabolic adaptation during pregnancy in winter-shorn sheep
Authors: Symonds M. E. , Bryant M. J. , Lomax M. A. 
Published: March 2009

SummaryThe effects of winter shearing on ewe live weight, body condition score (BCS) and the concentrations of glucose, non-esterified fatty acids (NEFA), 3-hydroxybutyrate, growth hormone (GH), cortisol, insulin and the thyroid hormones in plasma plus that of oxygen and carbon dioxide in jugular vein blood and packed cell volume (PCV) were measured at weekly intervals over the final 7 weeks of pregnancy in two groups of multiple-bearing shorn and unshorn pregnant ewes.Shorn ewes lost 47% more live weight than unshorn controls over the period from the day of being shorn to immediately after lambing. There was a significant decrease in BCS in both groups between 45 and 9 days before lambing. Three days after shearing the plasma NEFA concentration was higher in the shorn group but there were no other significant differences between shorn and unshorn groups in the plasma concentrations of NEFA, cortisol or insulin over the remaining 7 weeks of pregnancy. Both the PCV and concentration of carbon dioxide in blood were higher in shorn sheep throughout the final 6 weeks of pregnancy indicating they were making metabolic adaptations to long-term cold exposure. This response may have been mediated via an increase in thyroid hormone concentrations which were higher throughout the 7-week sampling period in shorn animals compared with unshorn controls. A decrease in ambient temperature was associated with a significant increase in the plasma concentration of GH and glucose in shorn animals. At 2 weeks before lambing there was a decrease in the plasma glucose concentration and an increase in 3-hydroxybutyrate concentration in the unshorn ewes, but these changes were not observed in the shorn animals. It is concluded that winter shearing of the pregnant ewe results in an increased loss of maternal body tissues and metabolic adaptations to long-term cold exposure without any of the changes associated with an increase in energy expenditure during the final third of pregnancy.
Response of lactating goats to low phosphorus intake 2. Nitrogen transfer from rumen ammonia to rumen microbes and proportion of milk protein derived from microbial amino acids
Authors: Petri A. , Müschen H. , Breves G. , Richter O. , Pfeffer E. 
Published: March 2009

SummaryFive rumen-cannulated dairy goats were fed diets supplying 2·8 g P/day plus 1·4 g P/kg milk (adequate P) for weeks 1–6 of lactation. Two goats then continued to receive this adequate P supply while three goats were fed deficient diets supplying only 0·8 g P/day plus 0·4 g P/kg milk. Solutions containing CrEDTA and (15NH4)2SO4 were infused into the rumen continuously for 96 h during weeks 5–6 and 11–12, respectively. At intervals following the intraruminal infusion, 15N enrichments of rumen ammonia-N, rumen bacteria-N and milk protein-N were determined. Cr concentration was measured in particle-free rumen fluid.P deficiency did not significantly affect rumen fluid kinetics. It caused a significant increase in pH and reduced the size of the rumen ammonia pool and its outflow rate. Digestibility of organic matter as well as efficiency of microbial protein synthesis were decreased significantly and thus net microbial yield was reduced from 34·1 to 13·7 g N/day. The transfer of N of microbial origin to milk protein decreased from 5·3 to 2·7 g/day, whereas secretion of N in milk protein not originating from rumen microbes remained unchanged at 5·6–5·8 g/day.
Effect of pod removal and plant growth regulators on the growth, development and carbon assimilate distribution in oilseed rape (Brassica napusL.)
Authors: Keiller D. R. , Morgan D. G. 
Published: March 2009

SummaryRemoval of basally positioned pods on the terminal inflorescence at anthesis and 6 days thereafter increased the duration of flowering and resulted in the formation of a larger number of smaller pods.Removal at 12 days after anthesis did not affect flower production but increased the number of flowers setting pods. Application of benzyladenine to the apices of intact plants from 8 days but not 14 days after anthesis greatly extended flower but not pod production. Liquid scintillation counting showed that the benzyladenine treatment led to more14C-labelled assimilates moving to the apices.
Plasma profiles of progesterone and total oestrogens in buffaloes (Bubalus bubalis) around parturition
Authors: El-Belely M. S. , Zaki K. , Grunert E. 
Published: March 2009

SummaryBlood samples were collected three times weekly for 21 days before and after calving (day 0) from 29 buffalo cows and 22 buffalo heifers. Plasma concentrations of progesterone and total oestrogens were quantified by validated radioimmunoassays. Ovarian activity and uterine involution were monitored by rectal palpation at the sampling times and extended up to 60 days postpartum. The concentration of plasma progesterone in cows declined from 3·0 ± 0·2 ng/ml (mean ± S.E.) during days 21–17 before calving to 2·1 ± 0·1 ng/ml at day −3, followed by a rapid fall during the last 3 days of gestation, reaching 1·2 ± 0·3 ng/ml at the day of parturition. In heifers, plasma progesterone values increased slightly from 2·9 ± 0·2 ng/ml at days 21–19 before parturition to 3·4 ± 0·3 ng/ml by day −1 and then fell sharply to 2·1 ± 0·1 ng/ml at calving time. During the postpartum period, plasma progesterone decreased gradually and reached baseline values after day 15 postpartum, when the residual corpus luteum of pregnancy had completely regressed in all the animals studied. The plasma concentrations of total oestrogens started to increase at day −15 in cows and day −5 in heifers from below 40 pg/ml to 122·5 ± 51 pg/ml for cows and 100·7 ± 3·4 pg/ml for heifers by day −1. This was followed by a sharp increase to 251·2 ± 17·3 and 240·5 ± 10·1 pg/ml in these animals at the day of calving. Immediately after parturition, total oestrogens dropped abruptly to the lowest values and remained below 30 pg/ml in all cows and heifers until the end of the sampling period. We concluded that female foetuses significantly (P< 0·05) increased the maternal total oestrogens. Moreover, animals having postpartum disorders had significantly higher values for progesterone (P< 0·05) and lower values for total oestrogens (P< 0·01) than those having normal puerperal periods, but the magnitude of this difference varied in samplings between cows and heifers.
Interactions between plots in experiments with the splash-dispersed pathogenRhynchosporium secalison winter barley
Authors: Jenkyn J. F. , Dyke G. V. , Stedman O. J. , Todd A. D. 
Published: March 2009

SummaryExperiments of balanced design in harvest years 1981 and 1982 were used to measure interactions between plots of winter barley with different amounts of leaf blotch, caused by the splash-dispersed pathogenRhynchosporium secalis. On the appropriate transform scales (logarithms of counts and logits of percentages), the effects of extreme treatments on neighbouring plots were up to 30% of the effects of the same treatments on the plots to which they were applied. Powdery mildew (Erysiphe graminisf.sp.hordei) was commonly least severe in plots with most leaf blotch except soon after fungicide sprays had been applied which, although chosen to decrease leaf blotch, also had short-lived effects on mildew. Consequently, contrasts in mildew between differently treated plots changed sign during the season. The effects of the same treatments on neighbouring plots similarly changed with time but not necessarily in phase with their direct effects. Analyses of the rhynchosporium data that recognized the effects of neighbouring treatments typically had much smaller residual mean squares than analyses that ignored neighbour effects but assumed randomized block designs.Treatments had mostly small effects on grain yield but these data from two of the experiments showed marked positional variation. Individual plots yields from one of these experiments, testing five treatments, are quoted in the appendix so that they are available to others with an interest in alternative methods, such as nearest-neighbour models, to adjust for local correlations between plots.
Stocking density of cattle and herbage production on Mediterranean grassland
Authors: Seligman N. G. , Gutman M. , Holzer Z. , Meir I. Noy , Baram H. 
Published: March 2009

SUMMARYA Mediterranean grassland was grazed with beef cattle at 0·5, 0·67 and 0·83 cows/ha, all the year round for 5 years. Range forage became increasingly scarce during the dry season, especially at high stocking density, and more supplementation was needed to maintain the animals. Herbage consumption was calculated from standard requirements for recorded body weight and performance. Maintenance requirements were multiplied by a grazing activity factor of 1·6.Mean annual herbage dry matter production was estimated atc.3·06 ± 0·137 t/ha. Most of the variation between years was due to a particularly productive year in 1978. Contrary to expectation, stocking density had a small effect on total herbage production, despite significant differences in animal performance. It appears that herbage production of the seasonally temperate herbaceous range, typical of the basaltic hills in eastern Galilee in Israel, is not limited by total annual rainfall. Alternative limiting factors are nutrient deficiency and restricted rooting zone, or a combination of both.