bluuebunny/crossref_metadata_2025 huggingface dataset:
The artificial rearing of calves and their growth on grass diets:III. The effect of length of period of feeding cold milk Substitute to calves given dride grass in different physical forms
Authors: Lonsdale C. R. , Tayler J. C.
Published: March 2009

An experiment was conducted with 63 July-born Friesian heifer calves, purchased at an average age of 10 days and fed cold reconstituted milk substitute for 4, 6 or 8 weeks. The sole ‘solid’ feed was dried grass, chopped and fed loose (a), milled through a 6 mm screen and pelleted (b) or milled through a 3 mm screen and pelleted (c). The experiment was of 3 x 3 factorial design.

Calves fed milk for 4, 6 or 8 weeks consumed mean amounts of 20, 42 and 63 kg milk D.M. respectively. During the first 10 weeks the mean daily intake of grass b was significantly greater than that of grasses a or c (0.77, 1.09 and 0.89 kg D.M. for grasses a, b and c respectively) and during weeks 11 to 21 the mean intake of grasses b and c was greater than that of a (3.1, 4.1, 3.7 kg D.M. for grasses a, b and c respectively). Also during weeks 11 to 21 the previous milk feeding had a small but significant effect on the mean daily intake of grass (3.4, 3.7, 3.8 kg D.M./head/day for 4, 6 and 8 weeks of milk feeding respectively).

Increasing the period of milk feeding significantly increased the rate of live-weight gain during the first 10 weeks, but subsequently had no effect. During the first 10 weeks and during weeks 11–21, feeding grass b or c significantly increased the rate of liveweight gain compared with grass a but had no effect during a period of uniform feeding, weeks 23–34.

During the first 21 weeks feed conversion efficiency was positively related to duration of milk feeding, and was greater for calves given grass b or c than, for thoso given grass a.

During weeks 23–34, 36 calves (4 from each original treatment) were fed another uniformly milled and pelleted dried grass. There were no significant differences in voluntary intake, live-weight gain or efficiency of food conversion between the groups of calves during this period. Hence the results of this experiment support previous observations, that when only forage diets are fed the effect of level of early nutrition is still evident in live weights of calves at 6 months of age.
Phosphorus and calcium metabolism in growing calves with special emphasis on phosphorus homoeostasis. 4. Studies on milk-fed calves given different amounts of dietary phosphorus but a constant intake of calcium
Authors: Challa J. , Braithwaite G. D.
Published: March 2009

Friesian bull calves, 2 weeks old, were given an experimental diet of cow's milk supplemented with phosphorus to provide three rates of P intake: adequate, high, and very high. After 1 week's preliminary feeding, studies of absorption, endogenous secretion, urinary excretion, serum concentration, retention and kinetics of Ca and P metabolism were made by a balance and dualradioisotope technique with 32P and 45Ca.

The efficiency of P absorption decreased significantly as the P intake increased and the highest absorption efficiency was 96% on the unsupplemented milk diet. Endogenous faecal excretion of P was low on all treatments. Urinary P excretion was substantial even on the milk-only diet and increased further with supplementation of P. The efficiency of absorption of Ca remained constant, and urinary Ca excretion was low in all the groups. Serum P and Ca concentrations did not vary significantly but there was a significant decrease in the retention of P and Ca as the P intake increased.

Although urinary excretion appears to be the main process responsible for P homoeostasis in preruminant milk-fed calves, some regulation of the efficiency of absorption of P according to the P intake may also occur.
Breed and sex differences in skeletal dimensions of sheep in the first year of life
Authors: Searle T. W. , Graham N. McC. , Donnelly J. B. , Margan D. E.
Published: March 2009

Various measures of skeletal size were made on five or six occasions on 30 Dorset Horn and 30 Corriedale sheep (10 entire males, 10 females and 10 castrated males) commencing at 1 month of age (live weight 10 kg) and then at increments of 10 kg until 55 kg. After weaning at 6–7 weeks, they were fed ad libitumon a high-quality diet. The data sets for each sheep were analysed separately and, where appropriate, pooled equations for sex and breed were generated. Within both breeds, males had the widest shoulders at any given age and, within the Corriedales, males had the deepest chests. Dorset Horns grew faster than Corriedales and, except for leg length, were larger and heavier at corresponding ages.

At any given live weight, there was no difference between sexes within breeds and the breeds had similar chest depths. The Corriedales had longer legs and smaller shoulders than the Dorset Horns at all weights and, when heavier than 30 kg, were also larger in other body dimensions.
Influence of planting date on plant losses and yield responses of geranium (Pelargonium graveolens) to root rot and wilt
Authors: Kalra A. , Parameswaran T. N. , Ravindra N. S.
Published: March 2009

Different geranium (Pelargonium graveolens L. Herit) clones differed in susceptibility to root rot and wilt caused by Rhizoctonia solani Kuhn. Reactions were consistent when assessed either by standardized laboratory tests or by pot experiments using 60-day-old well-rooted plants. Plants of an Algerian-type clone (Kd) had a lower survival rate and higher root rot index values than those of a Reunion type (Lo) and an Egyptian type (Eg). Field studies conducted in naturally-infected plots in southern India from 1987 to 1990 showed that summer planting resulted in higher plant losses of all clones than winter planting. As in the laboratory and pot experiments, the Lo and Eg clones sustained less plant loss and produced higher herbage and oil yields than the Kd clones in both field experiments.
Effects of active immunization against LHRH and melatonin on growth and plasma hormone concentrations in red deer stags during their second year
Authors: Ataja A. M. , Barry T. N. , Hoskinson R. M. , Wilson P. R.
Published: March 2009

The effects of immunization against luteinizing hormone releasing hormone (LHRH) and melatonin were studied during autumn and winter 1989 in yearling red deer stags initially aged 14 months and weighing 90–96 kg. Four out of five stags immunized against LHRH and six out of eight stags immunized against melatonin developed detectable levels of antibody titre. Immunization against LHRH reduced plasma LH concentration and both delayed and reduced weight loss associated with the rut (autumn); however, it had no effect upon carcass weight and dressing-out percentage was slightly lowered, showing that non-carcass components had been affected. Immunization against melatonin had no effect either on weight loss during the rut or on the rate of liveweight gain during winter and spring. Plasma concentrations of LH and testosterone were not affected by melatonin immunization; however, plasma prolactin concentration was consistently, but non-significantly, higher in immunized than control animals.
No-tillage and dry ploughing compared with puddling for wet-season rice on an alluvial sandy clay–loam in eastern India
Authors: Mahata K. R. , Sen H. S. , Pradhan S. K. , Mandal L. N.
Published: March 2009

No-tillage and dry ploughing were compared with puddling under identical cultivation conditions for their effect on growth and yield of wet-season rice. The experiment was conducted on an alluvial sandy clay–loam soil over 5 years (1978–82) at Cuttack, India. In the preceding dry season, each plot was split into two halves for growing dry-season crops, with and without tillage. Growth of rice seedlings without applying N to the seed bed was faster and more vigorous after puddling, as shown by greater shoot and root weight per hill and a higher shoot:root ratio, and remained so until maturity. This was reflected in earlier flowering and maturity, followed by greater grain and straw yields. These results are attributed to the ability of the roots to obtain more N from the puddled soil.

Under high water table conditions, extractable and soluble N in the root zone were not much influenced by tillage treatments. Grain and straw yields after no-tillage were similar to those produced by dry ploughing but smaller than those produced by puddling, although the differences were not significant in some years.

Soil strength measured at the end of the rice-growing season in 1980 and 1981 was significantly greater after continuous no-tillage. The decreasing trend in grain and straw yield and number of panicle-bearing tillers/m2 from 1980 onwards after continuous no-tillage, was associated with increasing soil strength. The results suggest that, where percolation losses of water and nutrients are small, puddling, which is capital intensive and detrimental to soil structure, could be replaced by notillage accompanied by suitable N and weed management. However, continuous no-tillage is not recommended for a soil with a lower clay content because the soil will gradually harden with time.
Sowing sugar beet in autumn in England
Authors: Wood D. W. , Scott R. K.
Published: March 2009

Experiments in England from 1970 to 1973 investigated the possibility of extending the growing season and increasing yields of bolting resistant sugar beet by sowing in autumn rather than in spring. September-sown plants grew rapidly in spring and achieved a complete leaf cover by mid-June by which time they had intercepted 40 % of radiation incident since mid-April compared with 28 and 9% for crops sown on 13 October and 13 April respectively. By early June autumn-sown plants were 20 fold heavier than spring sown but this advantage was progressively lost with the onset of bolting. Root growth slowed as assimilates were diverted to stem and inflorescence growth. Delaying autumn sowing from late September until mid-October delayed and reduced the frequency of bolting, probably because of a shortening of the period when plants were sufficiently large to respond to cold. Cutting down bolting inflorescences at frequent intervals improved root growth of both bolters and non-bolters. However, yields from autumn sowing never exceeded those from spring sowing, the best yield from an autumn-sown crop was 6·1 t/ha of sugar which was similar to that of the spring-sown crop. To try to prevent bolting of overwintered plants the growth regulator ethephon was applied at 10000 mg a.i./l water sufficient to wet the foliage in mid-April. Growth was severely checked and 55 % of plants died. Of the remainder 25–30% fewer than in the untreated crop bolted but yields were 26–42 % less. Less concentrated doses of ethephon did not affect bolting.
Transmission of Helminthosporium solani from potato seed tubers and effects of soil conditions, seed inoculum and seed physiology on silver scurf disease
Authors: Firman D. M. , Allen E. J.
Published: March 2009

The transmission of silver scurf (Helminthosporium solani) disease of potatoes was examined in field experiments at Cambridge University Farm in 1988–90. Treatment factors examined were seed size, seed age, seed incubation, soil moisture regime and planting date. A laboratory experiment investigated the viability of conidia of Helminthosporium in soil stored under different conditions.

Incubation of seed at high humidity before planting increased sporulation of Helminthosporium on seed tubers after planting and fewer conidia were produced from small seed than from larger seed. Delay in planting caused more rapid growth of Helminthosporium on seed tubers after planting.

Early planting and late harvesting increased the severity of silver scurf on progeny tubers. Severity of silver scurf was also increased by ageing seed and by incubating seed. Weight loss of potato tubers during storage tended to be greater from treatments with most severe silver scurf in all years but a significant linear regression of weight loss on silver scurf severity was found in only one year out of three from a late harvest. The viability of conidia added to soil was found to decrease rapidly so that by 10 weeks after addition, < 1% of conidia were apparently viable.
Availability to subsequent crops and leaching of nitrogen in 15N-labelled sugarbeet tops and oilseed rape residues
Authors: Thomsen I. K. , Christensen B. T.
Published: March 2009

In autumn 1991, sugarbeet tops (Beta vulgaris L.) and different components of oilseed rape residues (Brassica napus L.), both labelled with 15N, were incorporated into the soil under field conditions at Askov Experimental Station, Denmark, using stainless steel cylinders to contain the treatments. The availability of this labelled N to a subsequent crop was measured, using as test crops autumn-sown rye (Secale cereale L.), wheat (Triticum aestivum L.) and spring barley (Hordeum vulgare L.). In spring 1992, cylinders with 15 N-residues received NH4NO3 and those without 15NH415NO3. In a parallel experiment, 15N-labelled beet tops were incorporated in lysimeters. A four-course rotation of sugarbeet, spring barley (undersown with perennial ryegrass Lolium perenne L.), perennial ryegrass and winter wheat at two rates of calcium ammonium nitrate (CAN) or animal slurry was grown in these lysimeters. Leaching and the availability of beet top N to successive crops were followed for 2 years. The soil in the cylinders and lysimeters was a light sandy loam (˜ 10% clay).

Of the 7·10 g N/m2 added in beet tops, 10–15% was harvested in two subsequent crops of barley and ryegrass and 13–19% was lost by nitrate leaching. Beet top N accounted for 3–7% of the total N offtake in 1992. In 1993 < 1·5% of the total N offtake in ryegrass was from the beet tops applied in 1991. Combining results from mineral fertilized treatments, it was found that 9% of the beet top N was removed in the first cereal crop, 9% was lost by nitrate leaching and 68% remained in the 0–20 cm soil layer (including roots), suggesting that the denitrification loss was < 15%.

Incorporation of oilseed rape stubble (1·35 g N/m2), two rates of pods (6·25 and 18·75 g N/m2) or mixed residues (12·25 g N/m2) contributed 0·5, 2·3, 7·4 and 4·6%, respectively, to the total N harvested in the following crop of winter wheat. The percentage of the added labelled N taken up by the wheat ranged from 4·9 to 6·1%, with 60–79% remaining in the 0–20 cm layer after harvest.

For beet tops it was calculated that 100 kg N/ha in residues incorporated in the autumn could replace 18 kg N/ha given in the following spring as mineral fertilizer. For oilseed residues, the corresponding average value was 9 kg N/ha.

In fertilized cropping systems, oilseed rape residues had minor effects on the subsequent crop, so that an uneven return of residues, as often occurs with combined crops, would do little harm. A considerable proportion of the N applied in sugarbeet tops was lost by leaching and the residual value of the sugarbeet tops to subsequent crops was low.
Influence of nitrogen on the development of Septoria epidemics in winter wheat
Authors: Leitch M. H. , Jenkins P. D.
Published: March 2009

Field experiments were undertaken at the University of Wales, Aberystwyth over two seasons to investigate the effects of N fertilizer rate and timing on the development of Septoria diseases (principally Septoria tritici) in winter wheat and its subsequent effect on crop growth. Rates of 100, 200 and 300 kg/ha N were applied at GS23, GS30, or split (GS23/30/38) in 1985/86 and 100 and 250 kg/ha N at GS23, GS30, GS23/30, or GS23/30/37 in 1987/88. Foliar diseases were allowed to develop or were controlled with fungicide. Early disease levels were temporarily enhanced soon after N application and were greater at the higher rates of N. In April and June a significant correlation between disease infection and concentration of N in leaf tissue was shown. Despite differences in the level of early infection, dry matter production up to and including anthesis was unaffected by disease. Infection during grain filling caused premature senescence of the flag leaf which significantly reduced grain yield, primarily through a reduction in grain size. Loss of yield was directly related to severity of disease on the flag leaf in early July, with a yield loss of 0·45% for every 1% increase in disease infection. The severity of Septoria post-anthesis increased with increasing rate of fertilizer N by an average of 11·1% per 100 kg/ha N (translating to a potential yield loss of 5% for each 100 kg/ha N given as fertilizer), but was unaffected by its timing of application.
Barley development as affected by rate of change of photoperiod
Authors: Kernich G. C. , Slafer G. A. , Halloran G. M.
Published: March 2009

The rate of leaf appearance of barley varies substantially with time of sowing. This variation has been related to both the length and the rate of change of photoperiod at the time of plant emergence. An outdoor pot experiment was conducted to test if rate of change of photoperiod directly affects phasic development and rate of leaf emergence of spring barley. Two photoperiod-sensitive cultivars (Bandulla and Galleon) were subjected to five photoperiod regimes: two constant photoperiods, of 14 and 15·5 h, and three different rates of change of photoperiod ofc. 2, 9 and 13 min/day from seedling emergence to awn initiation.

Photoperiod treatments significantly affected the duration from seedling emergence to awn initiation in both cultivars. Rate of change of photoperiod did not affect the rate of development towards awn initiation independently of the absolute daylength it produced. Although Bandulla had a longer duration than Galleon at any photoperiod regime, the cultivars did not vary in their sensitivity to photoperiod. When this phase was divided into the leaf initiation (LI) and spikelet initiation (SI) phases, it was evident that the sensitivity to photoperiod was not constant, being in general higher during the SI than during the LI phase. However, the magnitude of the change in sensitivity was cultivar-dependent, indicating that sensitivity to photoperiod during the different phases could be under independent genetic control.

Final numbers of primordia (leaves together with maximum spikelet number) were negatively affected by increasing photoperiods, but once again, there was no evidence of any effect of the rate of change of photoperiod which was independent of the average photoperiod. Both cultivars showed similar sensitivities for final leaf number but maximum spikelet number was more sensitive to photoperiod in Galleon than in Bandulla.

Highly significant linear relationships between leaf number and thermal time were found for all combinations of cultivars and photoperiod regimes (r2> 0·98). The rate of leaf appearance (RLA) was similar for both cultivars (c. 0·0185 leaves/°Cd) and did not alter during plant development or in response to the change in photoperiod at awn initiation. The range in RLA was greater for Galleon (0·0170–0·0205 leaves/°Cd) than for Bandulla (0·0173–0·0186 leaves/°Cd). Neither of these cultivars exhibited a significant relationship between rate of leaf emergence and photoperiod or rate of change of photoperiod. The lack of significant relationships between RLA and length or rate of change of photoperiod is in contrast with previous reports using time of sowing as a main treatment.
The response of plants to temperature change
Authors: Pollock C. J.
Published: March 2009

In general, the form and function of living plants reflect a requirement to maximize their interaction with the environment in order to harvest more effectively the energy and materials they require (Corner 1964). Thus, fluctuations in the aerial environment exert a considerable effect upon the physiology of the plant and lead to initiation of a range of responses. Changes in temperature are known to exert a pronounced effect on the growth of plants, and hence upon their productivity (Ong & Baker 1985). Most temperate species spend the majority of their life at mean temperatures below the optimum for their growth, and there are marked genetic differences between plant species in their ability to tolerate nonoptimal temperatures (Pollock & Eagles 1988). This review summarizes some of the ways in which plants are known to sense and respond to temperature change and discusses the potential for improving growth and performance at nonoptimal temperatures. Discussion concentrates upon temperate grasses and cereals because of their suitability as experimental material and because of their economic importance. Consequently, this review is largely concerned with responses to low temperatures, but some responses of tropical cereals to high temperatures are also described.
Growth, development and yield of bambara groundnut (Vigna subterranea) in response to soil moisture
Authors: Collinson S. T. , Azam-Ali S. N. , Chavula K. M. , Hodson D. A.
Published: March 2009

Stands of bambara groundnut (Vigna subterranea (L.) Verde.) were grown in five controlledenvironment glasshouses at the Tropical Crops Research Unit, University of Nottingham, Sutton Bonington Campus, in 1990. Five soil moisture regimes were imposed (one per house), from fully irrigated each week (treatment A), to no irrigation after crop establishment at 35 days after sowing (DAS) (treatment E). Decreasing the amount of water applied resulted in a decline in total dry matter production and harvest index, and a reduction in pod yield from 412 (treatment B) to 0·041 ha-1 (treatment E) at 125 DAS. A maximum leaf area index of 5–4 was achieved by treatments B and C at 90 DAS, resulting in a fractional interception of c. 0·8 of incoming radiation. Total accumulated radiation interception values were 749, 693, 688, 618 and 554 MJ m-2 for treatments A, B, C, D and E, respectively. The efficiency of conversion of the radiation intercepted into dry matter was reduced from 1·41 to 0·50 g MJ-1 by drought.
Pre- and post-natal wool follicle development and density in sheep of five genotypes
Authors: Edwards J. E. Hocking , Birtles M. J. , Harris P. M. , Parry A. L. , Paterson E. , Wickham G. A. , McCutcheon S. N.
Published: March 2009

The pre-natal and post-natal development of wool follicles in sheep of five genotypes with contrasting wool types was examined to provide data on which to base studies of physiological factors affecting wool type via follicle development. This study was conducted following Autumn mating in 1992 at Palmerston North, New Zealand (40° S, 176° E). The rate and timing of follicle development in midside skin samples from Romney, Merino, Merino × Romney (M × R), Drysdale and Wiltshire foetuses and lambs collected at weekly intervals from days 76 to 143 of gestation and 1, 3, 7, 12 and 32 weeks after birth were examined.

Primary (P) follicle density had a similar pattern of development in each of the genotypes, although the Merino had a significantly greater density of P follicles than the other genotypes. There was a difference in the rate of P follicle maturation between genotypes with the Drysdale, Wiltshire and M × R completing P follicle maturation before the other two genotypes. However, the majority of P follicles in all genotypes were producing fibres by 111 days of gestation. It was concluded that the small differences in the density and time of development of the P follicles could not cause the differences in wool type between genotypes.

The pattern of development of the secondary (S) follicle population was examined by comparing S: P ratios. The initiation of S follicles began at similar ages in the five genotypes, but initiation was completed earlier in the Romney, Drysdale and Wiltshire than in the Merino and M × R, as indicated by a significant genotype by age interaction (P < 0·001). There was no difference between genotypes in S:P ratio from 90 to 104 days of gestation. The S:P ratio of the Romney, Drysdale and Wiltshire did not change significantly from 104 days of gestation until the end of the study, indicating that few S follicles were initiated in these genotypes after 104 days of gestation. The M × R data showed a significant increase in S:P ratio until 119 days of gestation and the Merino S:P ratio increased until 126 days of gestation.

The period between days 90 and 125 of gestation was identified as being the critical period for the development of different follicle populations in Merino and non-Merino genotypes and it is this period which should be the focus for studies to determine physiological factors controlling secondary follicle development.
Pollination requirements of linseed (Linum usitatissimum)
Authors: Williams I. H. , Martin A. P. , Clark S. J.
Published: March 2009

The phenology of anthesis, anther dehiscence, fertilization and petal fall in the linseed cultivar Antares and its response to supplementary pollination when grown in a glasshouse were investigated. Anthesis commenced 15–30 min after the onset of the photophase and was complete within 2 h. Anthers dehisced when buds were in the tube stage of opening and produced a mean of c. 4·5 × 103 pollen grains per flower. Most ovules were fertilized within 6 h of the onset of the photophase. Flowers self pollinated naturally and, although supplementary pollination increased the percentage of flowers that produced capsules and the number of seeds per capsule, it decreased flower production and individual seed weight and conferred no increase in seed yield. Flowers retained their petals for at least 2 h after the onset of the photophase but, by 10 h, 97% of hand-pollinated flowers had shed their petals; those naturally self pollinated or shaken retained their petals for longer.
Response of eight winter crops to zinc fertilizer on a Typic Ustochrept soil
Authors: Tiwari K. N. , Dwivedi B. S.
Published: March 2009

The responses to Zn fertilizer of wheat, barley, oats, lentil, chickpea, pea, mustard and linseed were studied on a Typic Ustochrept soil in Pura, India in winter 1982/83 and 1983/84. Application of Zn significantly increased the grain or seed and total biomass yield of all the crops and enhanced Zn concentration and uptake. The response was greatest in lentil, followed by chickpea, pea, wheat, linseed, mustard, barley and oats. Cereals accumulated the most Zn, followed by the pulses and oilseeds. The pulses were more sensitive to Zn deficiency than the other crops.
Effect of monensin on in vitro fermentation of maize starch by hindgut contents of cattle
Authors: Marounek M. , Petr O. , Machañová L.
Published: March 2009

Contents of the caecum and the colon of four steers and four cows fed concentrate-plus-roughage diets were obtained at an abattoir, transferred to the laboratory and incubated anaerobically with maize starch in the presence (10mg/l) or absence of monensin. Samples taken at the end of incubation were assayed for fermentation acids and methane production.

Monensin significantly increased the molar percentage of propionate and decreased that of butyrate. Acetate percentage was not significantly influence by the addition of monensin. There was no consistent effect of monensin on total volatile fatty acid concentrations. Monensin decreased methanogenesis in all incubations. The production of methane was small, only 1 mmol/13–50 mmol of volatile fatty acid.
Effect of drought stress during grain filling in near-isogenic tall and dwarf hybrids of pearl millet (Pennisetum glaucum)
Authors: Mahalakshmi V. , Bidinger F. R. , Raju D. S.
Published: March 2009

The susceptibility to drought stress during flowering and grain filling of dwarf hybrids of pearl millet carrying the dwarfing gene d2 was investigated in 1987 at Patancheru, India, under field conditions during the dry season and, in the rainy season, under a rain shelter, using four pairs of near-isogenic tall and dwarf hybrids. Drought stress during grain filling reduced the number of grains per unit area and individual grain mass. Grain yields of the dwarf hybrids were lower than those of the corresponding tall hybrids in the unstressed control and under drought stress and were associated with a lower individual grain mass in the dwarf lines. In the dwarf hybrids, harvest index was similar to or better than that of the tall versions but a reduced biomass resulted in lower grain yields. Dwarf hybrids were not more adversely affected by water stress, however, than their tall counterparts, indicating that susceptibility to drought stress would not be likely to limit acceptance of new dwarf varieties.
Effects of windrowing, irrigation and defoliation of potatoes on silver scurf (Helminthosporium solani) disease
Authors: Firman D. M. , Allen E. J.
Published: March 2009

Field 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

Gaseous 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

Crops 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

Potato 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

A 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

The 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

Experiments 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

The 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

Dietary 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

The 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

Two 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

The 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

Two 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.