bluuebunny/crossref_metadata_2025_split huggingface dataset:
Simulating winter wheat shoot apex phenology
Authors: McMaster G. S. , Wilhelm W. W. , Morgan J. A. 
Published: March 2009

SummarySimulation models are heuristic tools for integrating diverse processes and help to increase our understanding of complex processes and systems. Models that predict crop development can serve as decision-support tools in crop management. This paper describes a phenology simulation model for the winter wheat shoot apex and reports validation and sensitivity analysis results.The complete developmental sequence of the winter wheat shoot apex is quantitatively outlined and correlated with commonly recognised phenological growth stages. The phyllochron is used to measure the thermal time between most phenological growth stages, thereby increasing the flexibility over the growing degree-day (GDD) and photothermal approaches. Nineteen site-years covering a range of climatic conditions, cultural practices and cultivars across the Central Great Plains, USA, are used to validate the model.Validation results show that the predicted phyllochron (108 GDD) agrees well with the observed phyllochron (107 GDD) for ten cultivars. Mean seedling emergence is predicted to within 2 days in almost all of the 19 site-years. The ability of the model to predict growth stages accurately increased successively from jointing to heading to maturity. Maturity is generally predicted to within 5 days of the observed day.After validation, recalibration of the phyllochron estimates between growth stages are provided, and corrections for mesic and xeric conditions are suggested. Further validation of the entire developmental sequence of the shoot apex is recommended.
Effects of sowing winter barley on different dates in autumn on the severity of take-all (Gaeumannomyces graminis var. tritici) in those and the subsequent crops
Authors: Jenkyn J. F. , Gutteridge R. J. , Todd A. D. 
Published: March 2009

SummaryExperiments on winter barley at Rothamsted, testing different sowing dates, were sampled in 1987–89 to measure effects on take-all caused by the fungus Gaeumannomyces graminis var. tritici. The experiments used the same plots in each year, and in 1988 and 1989 the randomization was restricted so that sowing dates were balanced for sowing dates in the previous year.The site had been used to grow barley since at least 1979 (spring barley from 1979 until 1985), and take-all was much more severe than expected. It was usually most severe in the earliest-sown plots and decreased almost linearly as sowing was delayed. There was also evidence that the sowing dates of the preceding crop had a continuing, residual effect. In the two years that the effects of previous sowing dates were tested, there was usually least take-all in plots where the crop followed one sown very early or very late in the previous year, and most where it followed one sown at the end of September or in early October. These effects probably reflect differences in amounts of inoculum and in the rate of development of take-all decline.
Determination of optimum tuber planting density in the potato varieties Pentland Squire, Cara, Estima, Maris Piper and King Edward
Authors: Wurr D. C. E. , Fellows J. R. , Allen E. J. 
Published: March 2009

SummaryThirty-two experiments examining the effects of the weight and within-row spacing of potato seed tubers on graded tuber yields of five varieties were conducted on eight sites from 1980 to 1985. A complex analysis technique was used to combine these data and estimate the optimum tuber planting densities for different ratios of seed cost to small (40–60 mm) and large (60–80 mm) ware value. The same technique could be applied to any other combination of seed cost, ware size and ware value.The optimum tuber planting density decreased with increasing seed-tuber weight. Differences in optimum planting density between varieties were much greater with small (35 g) than with large (105 g) seed tubers and decreased as the cost of seed increased relative to the value of ware. As large ware became worth more than small ware the influence of increasing seed cost on the optimum density was reduced. As the value of large ware increased, net returns increased and the effect of seed cost on net returns was reduced. Mean tuber size decreased with increasing stem density at harvest and at the same stem density was lower in varieties producing more daughter tubers/stem. Changes of mean tuber size (μ) and the spread of yield across size grades (σ) with time were well described by parallel curves in different varieties. It is suggested that in future it may not be necessary to determine optimum tuber planting densities by complex experiments involving several seed-tuber weights and spacings. Instead μ and σ could be estimated from simple experiments and tuber spacings determined by comparison with control varieties.
Nutrient cycling and losses based on a mass-balance model in grazed pastures receiving long-term superphosphate applications in New Zealand: 1. Phosphorus
Authors: Nguyen M. L. , Goh K. M. 
Published: March 2009

SummaryPhosphorus (P) cycling and losses in irrigated, sheep-grazed pastures receiving superphosphate (SP) applications for 35 years at annual rates of 0, 188 and 376 kg/ha were studied using a massbalance approach which accounted both for P inputs to and outputs from the soil-plant-animal system. Total recoveries of applied P in the soil-plant-animal systems in the 188 and 376 kg SP/ha treatments were 94 and 83% respectively. Approximately 52–53% of the applied P was recovered in the soil within the major plant rooting zone (0–300 mm soil depth). These data suggest that P leaching losses from SP fertilizer, plant litter, root residue and sheep faeces were unlikely to occur beyond the major plant rooting zone. However, the transfer of excretal P to stock camps and the transport of P from SP fertilizer, plant litter and sheep faeces via the irrigation water along the border from the top to the bottom of the irrigated border strip accounted for less than 6% of the applied P. Superphosphate applications resulted in the accumulation of both soil inorganic and organic P fractions to a depth of 225 mm. The accumulation of soil inorganic P was most pronounced when SP was applied annually at the rate of 376 kg/ha, which was in excess of pasture P requirements.
Effects of plant density and fertilization on the yield and quality of flue-cured tobacco in the Kenana area of the Sudan
Authors: Farah S. M. 
Published: March 2009

SUMMARYIn one experiment, variety Kutsaga 51 was grown at inter- and intra-row spacings of 60, 80 and 100 cm. Both yield and quality of leaf were improved as plant density per unit area increased. The greatest yield and highest quality were obtained from the 60 x 60 and 80 x 60 cm spacings while the lowest yield and quality were obtained from the 100 x 100 and 100 x 80 cm spacings.In a second experiment the same variety was subjected to three levels of N and four levels of K. Higher doses of N or K were not necessarily effective in increasing the yield or improving the quality of leaf; on the contrary rates higher than 42/ha reduced both yield and quality of the leaf. Progressively higher doses of K did not offset the ill effects of excessive N.Yield of leaf was primarily a function of leaves per unit area in the plant density experiment and number of leaves per plant in the fertilizer experiment.
Influence of growth temperature on anatomy andin vitrodigestibility of maize tissues
Authors: Cone J. W. , Engels F. M. 
Published: March 2009

SUMMARYTissues of maize grown under different temperature regimes showed remarkable differences in anatomical and chemical properties andin vitrodigestibility. A high temperature regime (12 h at 30 °C and 12 h at 24 °C) resulted in decreased cell wall thickness, cell diameter and cell wall yield, doubled lignin content and decreasedin vitrodigestibility, compared with plants grown under a low temperature regime (12 h at 18 °C and 12 h at 12 °C). A reduction in intensity of staining for lignin was observed in plants grown at 30/24 °C. Cell wall digestibility was thought to be limited by an indigestible cell wall layer between the secondary walls of adjacent cells. The use of lignin staining was of limited value for predicting cell wall digestibility. High temperatures probably affect physiological processes leading to lignin formation and deposition.
Excretion of purine derivatives by ruminants. Effect of microbial nucleic acid infusion on purine derivative excretion by steers
Authors: Verbic J. , Chen X. B. , MacLeod N. A. , Ørskov E. R. 
Published: March 2009

SUMMARYTwo steers totally nourished by intragastric infusion of volatile fatty acids and casein were given an abomasal infusion of a microbial protein preparation (Pruteen) at eight rates with a purine input ranging from 0 to 170 mmol/day over 11 successive 5-day periods. The urinary excretion of purine derivatives relative to the purine input was measured. Negligible amounts of xanthine plus hypoxanthine were present in the urine. The relative contributions of allantoin and uric acid to the total excretion were not affected by the rate of purine infusion. Total purine derivative excretion (uric acid and allantoin) was linearly correlated with purine input. Recovery in the urine of the infused purines was 0·77. It is suggested that utilization of exogenous purines may only occur in the intestinal mucosa and that the remaining purines may be completely converted, before entering the liver, to uric acid and allantoin, which are subsequently eliminated by the renal and extrarenal routes. The differences between cattle and sheep in excretion of purine derivatives, and the implications of these differences for the use of purine excretion values in order to estimate microbial protein supply to the ruminant, are discussed.
Solubility of mineral elements present in ruminant feeds
Authors: Ibrahim M. N. M. , Van Der Kamp A. , Zemmelink G. , Tamminga S. 
Published: March 2009

SUMMARYEight feeds were treated with seven solvents and the proportion of seven mineral elements (Ca, Mg, P, Na, K, Cu, Zn) released was assessed. Six of the feeds were from Sri Lanka (Panicum maximum ecotype Guinea A, Glyricidia maculata, Artocarpus heterophyllus, untreated and urea-treated rice straw, and rice bran) and two from the Netherlands (maize silage and wheat straw). The solvents were water, tris buffer, rumen fluid from a cow deprived of (RF -) or fed (RF +) mineral supplements, neutral detergent solution with (NDS +) or without (NDS -) EDTA, and acid detergent solution (ADS).Both the type of feed and the solvent significantly influenced (P < 0·01) the amount of dry matter loss and the proportion of minerals released. Maize silage released over 80% of its minerals, except Cu, in water and tris buffer, probably because of the low pH (3·7) during ensiling. The other feeds differed widely in their ability to release minerals. In general, P, Na and K. were more soluble in water than Ca, Mg and Zn.Mineral concentration in RF influenced not only the amount of minerals released, but also the extent of sorption by the feed. The latter effect was more pronounced in feeds with low mineral concentration, maize silage being no exception.Treatment with NDS+ and ADS removed all minerals except Cu. With all feeds, 12–34% and 5–34% of the Cu remained in the ND and AD residues, respectively, indicating its association with the cell wall. Results of the NDS- treatment showed that some of the Ca and Mg may be associated with the cell wall.Comparison of the feeds across the different solvents tested indicated that, in terms of absolute quantity of mineral released, G. maculata could be a good source of Ca, Mg, K and Cu, and that rice bran is a good source of P and Zn. The variety of rice straw tested released high amounts of Na. A. heterophyllus is rich in available Ca.
Recovery and germination rates of seeds of Mediterranean medics and clovers offered to sheep at a single meal or continuously
Authors: Thomson E. F. , Rihawi S. , Cocks P. S. , Osman A. E. , Russi L. 
Published: March 2009

SUMMARYMeasurements were made of the recovery and germination rates of seed of eight species of annual medic (Medicago spp.) and three of clover (Trifolium spp.) after ingestion by sheep. Recovery of medic seed was measured as the number of seeds collected from faeces after feeding, in addition to a basal diet, either (i) 200 g of pods at a single meal, or (ii) a quantity of pods estimated to contain 30000 seeds at a single meal or (iii) 200 g of pods daily for 21 days. Only the first method was applied to the clovers.There were large differences (P < 0·001) in seed recovery between species, from < 2% to nearly 20% in medics, and up to 59% in T. campestre, which has low single-seed mass. Although there was a curvilinear decrease in seed recovery as single-seed mass increased (r2 = 0·80), the high recovery of M. rotata, a fairly large-seeded species, suggests that there are important differences between species, irrespective of seed size.When 200 g of medic pods was offered to sheep at a single meal, mean seed recovery was slightly lower than when 200 g of medic pods was offered daily for 21 days. Seed recovery of medics was much higher (P < 0·001) when 30000 seeds were offered at one meal.Germination rate before ingestion was 1·9–6·5% (P < 0·001) for hard-seeded medics and 2·7–9·7% (P < 0·001) for clovers with low single-seed mass; passage through the digestive tract increased (P < 0·001) germination rate in both medics and clovers.
Effect of hedgerow species in alley cropping systems on surface soil physical properties of an Oxic Paleustalf in south-western Nigeria
Authors: Hulugalle N. R. , Kang B. T. 
Published: March 2009

SUMMARYEffects of hedgerow species on surface soil physical properties were studied in an on-going trial established since 1981 on an Oxic Paleustalf in southwestern Nigeria. The experimental treatments wereLeucaena leucocephala, Gliricidia sepium, Alchornea cordifoliaandAcioa barteriihedgerows planted at 4 m interhedgerow spacings and a control (no hedgerows). Plots were sequentia-ly cropped with maize (Zea mays) and cowpea (Vigna unguiculata). Soil physical properties, i.e. particle size distribution, bulk density, apparent pore size distribution and water infiltration, were monitored during the dry season in January and the main growing season in June 1989. Soil temperature was monitored at approximately monthly intervals from February to June 1989. Soil properties of alleycropped plots were superior to those of the control. Soil compaction was highest in the control and lowest withL. leucocephala. Between the hedgerow species, within-season increases in soil compaction were largest withA. cordifolia. Lowest soil temperatures were observed withL. leucocephalaandA. barterii. Frequency, quantity and quality of prunings produced by the hedgerow species appeared to have a major beneficial effect on soil physical properties.
Growth, yield and water use of lentils (Lens culinaris) in Canterbury, New Zealand
Authors: McKenzie B. A. , Hill G. D. 
Published: March 2009

SUMMARYLentils (Lens culinaris Medik.) were sown on eight sowing dates from April to November in two seasons in Canterbury, New Zealand. In 1984/85, six sowing dates were combined with two lentil cultivars (Olympic and Titore) and two irrigation treatments. In 1985/86, Titore was sown on two dates, with four irrigation treatments. An additional experiment grown under rain shelters examined the response of Titore to four irrigation regimes. The 1984/85 season was dry and rainfall was only 70% of the long-term mean. In this season, seed yield was high, 3·3 t/ha from the May sowing. The 1985/86 season was wetter than average and seed yields were lower, ranging from 0·6 to 1·5 t/ha. Under rain shelters, seed yield ranged from the equivalent of 0·32 to 2·5 t/ha.Sowing date had the most marked effect on seed yield. In the 1984/85 season, all autumn and winter sowings yielded 2·4–3·3 t/ha, whereas the spring sowings yielded 0·5–1·5 t/ha. In 1985/86, unirrigated plots from the May sowing yielded 1·5 t/ha, whereas all other plots yielded c. 0·8 t/ha.Generally, the small-seeded cultivar Titore outyielded Olympic. Dry matter (DM) accumulation followed similar trends to seed yield. Seasonal DM accumulation followed a sigmoidal curve. Functional growth analysis indicated that plants from autumn/winter sowings had a weighted mean absolute growth rate of 110–171 kg/ha per day, whereas spring-sown plants grew at 96–137 kg/ha per day. The maximum crop growth rate was 230 kg/ha per day in the July 1984 sowing.There was little positive response to irrigation in both seasons. Under rain shelters, there was a linear increase in both dry matter and seed production with increased total water. Fully irrigated plants produced 1·27 g DM and 0·72 g seed/m2 per mm of water received.In the field experiments there was no relationship between maximum potential soil moisture deficit (D) and yield. Under rain shelters, however, there was a linear relationship which indicated a limiting deficit of c. 130 mm. The relationship showed that, for each millimetre increase in D above D1, 0·39% of the maximum yield was lost.Under the rain shelters, there was a strong relationship between yield and actual evapotranspiration (ET). Water-use efficiency (WUE) ranged from 2·81 g DM/m2 per mm ET in unirrigated plots to 0·69 g seed/m2 per mm ET.The results showed that lentil growers in Canterbury, and presumably in similar environments, are unlikely to benefit from irrigating their crops. In such environments, lentils appear to be an ideal dryland crop.
Effect of water stress on potato growth, yield and water use in a hot and a cool tropical climate
Authors: Trebejo I. , Midmore D. J. 
Published: March 2009

SUMMARYIrrigation experiments are described in which three cultivars were subjected to varying degrees of drought in the cool and hot seasons in Lima, Peru. The most severely draughted plots received, on average, 20% and 35% less water than the well-watered control plots, resulting in 20% and 52% yield reduction in the cool and hot seasons, respectively. Average fresh tuber yields ranged, according to cultivar, from 1370 to 2450 g/m2in the summer and from 2800 to 4450 g/m2in the winter, with tuber dry-matter percentages ofc. 17% and 20%, respectively. The production of total dry matter per unit intercepted solar radiation (the conversion coefficient, estimated from the slope of the regression, in g/MJ) was markedly less during the hot season but, regressed on a photo thermal quotient ∑((MJ/m2)/(°C > 4·5°C)), a common relationship across seasons was achieved. The conversion coefficient was less in draughted than in well-watered plots, more so in the hot season.Crop transpirational and evapotranspirational water use efficiencies (WUE) were less in the hot season largely because of the greater saturation vapour-pressure deficit. However, because of greater harvest index (HI) and more-efficient interception of solar radiation per unit of applied water by draughted than by well-watered plots in the summer, and despite a lower conversion coefficient, draughted plots showed greater WUE. Based on total water applied and final fresh tuber yields, WUE was, on average, 3·9 and 12·4 kg/m3in the hot and cool seasons, respectively, values close to the extremes of the range of published values. Low HI in the summer was, to some extent, responsible for this seasonal difference.
Response of Egyptian cotton (Gossypium barbadense) yield to 1,1-dimethyl piperidinium chloride (Pix)
Authors: Sawan Z. M. , Sakr R. A. 
Published: March 2009

SUMMARYTwo field experiments were conducted in Egypt in 1985 and 1986 to examine the responses of yield and its components and fibre quality in the Egyptian cotton cultivar Giza 75 to the spray application of 0, 10, 20, 40, 60, 80, and 100 mg of 1,1-dimethyl piperidinium chloride (Pix)/litre at 90 days or at 90 and 110 days after sowing. Number of opened bolls/plant, boll weight, seed and lint index, seed cotton yield/plant, seed cotton and lint yield/ha and yield earliness increased, but lint percentage decreased after Pix application. The number of opened bolls/plant increased after one application, but there was no effect from a further application. There were no effects of concentration or number of applications of Pix on any fibre property.
Modelling the effects of sowing date and plant density on the yield and timing of development of Brussels sprouts (Brassica oleracea)
Authors: Hamer P. J. C. 
Published: March 2009

SUMMARYThe effect of sowing date and plant density are modelled in relation to three variables: Ym, the maximum yield the crop can produce; τ, the interval from sowing to Yb/Ym = 0·5 where Yb is the yield of Brussels sprout buttons and Nb, the number of buttons on a plant stem. Ym is well related to the quantity of solar energy which the crop intercepts during the main period of growth. The fraction of radiation intercepted by the crop canopy is related to leaf area index (L) and sub-models relate L to sowing date and plant density. An empirically derived parameter relates the value of τ to thermal time and photoperiod time. The time course of Nb is modelled relative to the number of buttons at the end of the growing season. To overcome influence of site, variety and season, a generalized equation relates Nb, to plant density and a ‘known’ number of buttons at a specified planting density. The yield of buttons in specific size ranges (required for marketing) is described by a normal distribution with the standard deviation (σ) representing the spread of button diameter. There were no obvious effects of sowing date and plant density on σ. The model enables the effects of sowing date and plant density to be simulated using only simple and easily understood parameters. A sample simulation is presented.
An induced mutant with extended vegetative phase in stem nodulating Sesbania rostrata
Authors: Joshua D. C. , Ramani S. 
Published: March 2009

SUMMARYThe flowering response of a late-flowering mutant of Sesbania rostrata was compared with that of the parent plants by sowing it on ten different dates, from December 1990 to September 1991, in India. Flowering response was also studied following exposure to an 8-h photoperiod at four different stages of growth. The parent flowered at different times of the year depending on the time of sowing, while the mutant flowered only during October–November irrespective of sowing date. The parent was sensitive to a short-day photoperiod as early as 15 days after sowing, but the mutant became sensitive to the critical photoperiod only after 60 days of vegetative growth. The mutant, by virtue of its longer vegetative phase, had the potential to produce adequate phytomass irrespective of the time of sowing.
Use of prolonged-release bovine somatotropin for milk production in British Friesian dairy cows. 2. Effect on health and reproduction in two consecutive lactations of treatment
Authors: Weller R. F. , Phipps R. H. , Craven N. , Peel C. J. 
Published: March 2009

SUMMARYThere were 45 cows in each of the control and treated groups in the first lactation of the study and, of these, 30 cows in each group received the same treatment for a second lactation. The study was conducted during the winters of 1985/86 and 1986/87. Injections of either bovine somatotropin (BST) or a placebo were started at day 60±3 post partum and repeated at fortnightly intervals for the remainder of each lactation.Body temperature and heart and respiration rates were unaffected by the administration of BST. Minor abnormalities were noted in individual animals in both groups, hygromata of the tarsus or carpus being most common. However, no health problems could be related to treatment. There was no evidence that the administration of BST increased the incidence of metabolic disorders. Ketosis was not observed in either lactation.