bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of cultural practices on reducing field infestation of potato tuber moth (Phthorimaea operculella) and greening of tubers in the Sudan
Authors: Ali M. A.
Published: March 2009

The population dynamics of the potato tuber moth (PTM) Phthorimaea operculella (Zeller) and the influence of potato cultivar, planting date, planting depth, hilling-up, irrigation intervals and mulching on insect infestation and on the greening of tubers in the field were studied at Shambat, Khartoum North, Sudan in the 1987/88 and 1988/89 winter seasons.

The insect population initially increased slowly, then more rapidly after crop establishment and throughout the harvest period, after which it declined sharply. Tuber shape and skin characteristics had no effect on the degree of PTM infestation. Planting in the second week of November resulted in less insect damage and a significantly greater total yield compared with crops planted 3 weeks later. Greater depth of planting and more frequent hilling-up significantly lowered infestation levels and reduced the greening of tubers; for example, insect damage in early planted crops ranged from 3·3% (planting 10 cm deep and hilling-up thrice) to 16% (planting at 5 cm depth and hilling-up once).

Irrigation and mulching both significantly reduced PTM damage and the greening of tubers.

Light irrigation every 4 days and mulching with neem (Azadirachta indica) leaves during the last 4 weeks before harvest were the most effective treatments.

Significant reductions in losses inflicted by PTM and by the greening of tubers were therefore achieved by the manipulation of crop husbandry practices.
Screening of groundnut germplasm collection and selection of genotypes tolerant of lime-induced iron chlorosis
Authors: Singh A. L. , Chaudhari V.
Published: March 2009

Erect type groundnut germplasm belonging to the Valencia and Spanish botanical groups was examined in the field for five consecutive cropping seasons (wet 1988, 1989 and 1990 and dry 1989 and 1990) at Junagadh, India, in order to identify groundnut genotypes with the ability to grow in calcareous soil and tolerate iron deficiency (lime-induced iron chlorosis). On the basis of the visual chlorotic rating scores of their leaves, 17 and 19 genotypes of the Valencia and Spanish groups, respectively, which showed the least or no chlorosis were classified as tolerant (iron-efficient) to iron chlorosis. These genotypes may now be used as donor parents in groundnut breeding programmes for the development of iron chlorosis-tolerant varieties.

Almost all the iron-efficient groundnut genotypes had higher pod and seed (kernel) yields and Harvest Index (HI) than the susceptible types. The seed yield of 12 iron-efficient groundnut genotypes was either equal to or higher than a commercial cultivar which showed tolerance to iron chlorosis and, hence, these genotypes could profitably be grown in those areas where chlorosis due to iron deficiency is a major problem.
Use of a long-term rumen simulation technique (Rusitec) to provide micro-organisms forin vitrodigestibility assays
Authors: Owen E. , Jayasuriya M. C. N. , Hamilton R. , Lalenta M.
Published: March 2009

Four experiments involving the two-stagein vitrodigestibility technique of Tilley & Terry (1963) were undertaken to investigate whether cow rumen liquor could be replaced with effluent or extract from feed residue containing micro-organisms derived from the long-term rumen simulation technique (Rusitec) of Czerkawski & Breckenridge (1977).

In Expts 1 and 2, the dry matter digestibility (DMD) of hay was determined using either cow rumen liquor or Rusitec liquid effluent or extract from feed after 48 h of digestion in a Rusitec apparatus using various volumes of liquor and artificial saliva. Digestibilities determined with rumen liquor werec.70% (c.v. 1·2%) while those determined with Rusitec effluent or extract werec.62% (c.v. 1·8%). In treatments common to Expts 1 and 2, Rusitec effluent digestibilities were more repeatable than extract or rumen liquor digestibilities.

In Expts 3 and 4, Rusitec effluent was compared with cow rumen liquor for determining DMD of seven forages with DMD ranging from 33 to 70%. For a given feed there was good agreement between experiments in DMD values determined with Rusitec effluent, and for ten paired values there was a high correlation (r2= 0·976) between DMD determined by the two methods. DMD determined using rumen liquor (y) was accurately predicted by Rusitec liquid effluent digestibility (x) from the equationy= 2·663 + 1·06477.x; R.S.D. 2·433.

The results show that Rusitec liquid effluent can be used instead of rumen liquor as a source of micro-organisms for the two-stagein vitrodigestibility method. Routine use of Rusitec would obviate the need for using fistulated animals.
Micrometeorological studies of ammonia emission from sheep grazed swards
Authors: Jarvis S. C. , Hatch D. J. , Orr R. J. , Reynolds S. E.
Published: March 2009

Losses of ammonia (NH3) through volatilization from the excretal returns from sheep grazing a range of swards in S.E. England were determined over two seasons. Four swards were examined: grass + 420 or 0 kg N/ha per year, grass/white clover and clover monoculture. These were grazed continuously to sustain a constant sward height of 6 cm. The patterns of NH3-N concentration above the sward changed with treatment and throughout the season: there were, on occasion, irregularities in the concentration profiles which may have been due to differential behaviour of paniculate and gaseous forms. Significant losses of NH3 occurred on all treatments, although on some occasions the low input systems appeared to be acting as sinks rather than sources of NH3. There were trends for the losses to be greater during the middle of the grazing season. In contrast to previous studies there was little relationship between seasonal N losses and changes/differences in dietary N content. The overall losses, whether on a per unit area or per animal basis, were generally in the order, clover > grass + 420 kg N > grass+ 0 N > grass/clover. Mean annual losses from grass + 420kg N and grass/clover were 94 and 1·2 kg N/ha, respectively. For a comparable fertilizer N treatment, losses were lower than previously found with swards which were rotationally grazed by cattle. The present losses, although dependent upon level of N input, whether from fertilizer or from biological fixation, were relatively small, ranging from 05 to 11·2 kg N/ha per year, and represented small proportions of either the N input to the system or the excretal returns from the animals.
The relationship between total yield, number of tubers and yield of large tubers in potato crops
Authors: Burstall Lindsay , Thomas M. N. , Allen E. J.
Published: March 2009

Experiments were made over 2 years at two sites using three varieties to investigate the relationship between total yield, number of tubers > 1 cm and the yield of tubers in the 60–80 mmsize range. Regressionanalysisrevealed that yield of tubers in the 60–80 mm size range was a linear function of total yield and number of tubers > 1 cm. The effect of changes in tuber shape on this relationship is discussed.
Growth and chemical composition of carrots as influenced by the time of sowing and harvest
Authors: Nilsson T.
Published: March 2009

The effects of the time of sowing on growth and chemical composition of carrots grown from May to November were studied during 3 years.

Delaying sowing for 1 or 2 months after the beginning of May resulted in a reduction in the growth of both roots and foliage and gave roots with lower dry-matter content and glucose/fructose ratio but higher amounts of hexoses, total nitrogen and amino nitrogen in root dry matter. Sowing date had no influence on the concentration of sucrose, phosphorus, potassium, calcium and magnesium in root dry matter up to 137 days from sowing. Carotene decreased only after the last sowing. Sucrose concentration of the roots increased throughout the periods studied irrespective of the time of sowing. The longer the growing period the higher was the sucrose concentration. The concentration of hexoses decreased from the first harvest at 70 days to reach a constant level at about 130 days from sowing.

The results did not indicate the presence of a well-defined stage of biochemical maturity in the autumn when carrot roots are expected as most suitable for harvest and subsequent long-term storage.
Effect of nitrogen fertilizer on yield and nitrogen concentration in grain and straw of rice under semi-deepwater conditions (51–100 cm)
Authors: Reddy M. D. , Panda M. M. , Ghosh B. C. , Reddy B. B.
Published: March 2009

Under conditions of semi-deep water (51–100 cm) rice varieties with greater plant height produced more dry matter and grain yield as N fertilizer was increased from 0 to 20 and 40 kg/ha. The varieties which performed better in a situation of slow rise in water level to a depth of 120 cm could not survive a quick rise in water level owing to their lesser plant height and elongation ability. The loss of dry matter (dead and dried leaves) was also greater in varieties susceptible to deep water than varieties tolerant of deep water.

With the increase in N fertilizer, there was increase in plant height, number of tillers, dry-matter production and grain yield. The loss of dry matter was less in crops given N fertilizer than in those not given N fertilizer. The varieties capable of producing higher grain yield in response to N fertilizer under semi-deep water did not improve their grain yield under intermediate deep water (15–50 cm). With increase in application of N fertilizer from 0 to 40 kg/ha the N concentration in grain increased. N concentration did not vary in straw under intermediate deep water, there was no definite trend in semi-deep water, and it was higher under conditions of semi-deep than intermediate deep water.
Performance of carrot seeds possessing different germination rates within a seed lot
Authors: Finch-Savage W. E. , McQuistan C. I.
Published: March 2009

The relationship between germination rate within a carrot seed lot and subsequent seedling performance was studied in four seed lots of different viability. Seedling performance was assessed using slope tests conducted under controlled conditions and in the field following fluid drilling under a range of environmental conditions. Germination rate within a seed lot was positively related to vigour measured by slope tests, percentage emergence and seedling weight, and was negatively related to the spread of emergence times (In variance days) and the coefficient of variation (c.v.) of seedling weights. Sowing seeds selected as fast germinating resulted in greater seedling emergence percentages over a range of environmental conditions than when sowing seeds selected as slowly germinating.
The chromosomal locations in wheat of genes conferring differential response to the wild oat herbicide, difenzoquat
Authors: Snape J. W. , Angus W. J. , Parker Beryl , Leckie Debra
Published: March 2009

F2, monosomic analysis involving crosses between the monosomic series of a resistant wheat variety, Chinese Spring, and a susceptible variety, Sicco, has located a major gene locus, designated Dfql, on chromosome 2B of wheat which determines the differential response of these varieties to treatment with the wild oat herbicide, difenzoquat. The allele from Chinese Spring conferring resistance is dominant and studies of the responses of Chinese Spring single chromosome substitution lines and nullisomic–tetrasomic lines for chromosome 2B indicate that this allele actively promotes resistance to the herbicide. It is suggested that this gene may prevent inhibition of DNA synthesis in the apical meristem, which is the site of action of the herbicide (Pallett & Caseley, 1980).

Other chromosomes were also implicated as carrying ‘modifier genes’ which affect the ratio of resistant: susceptible plants in F2 monosomic families, namely 1D, 2D, 3A, 3B, 5B and 5D. These chromosomes may affect the retention and translocation of the herbicide to the target site and hence the threshold of response.

The simple inheritance of difenzoquat resistance indicates that it should be easy by conventional breeding techniques to transfer the resistance into susceptible varieties.
Potassium requirement of groundnut (Arachis hypogeae) in the lowland tropics
Authors: Kayode G. O.
Published: March 2009

A 2-year field study to investigate the potassium nutrition of groundnut in the lowland tropics showed that a low rate of K is beneficial to the crop. Applied K significantly increased leaf N, seed S, seed P, seed Fe, seed oil and protein content of groundnut. Leaf Ca significantly decreased with increased K application but K treatments significantly increased the seed and shell Ca. Potassium and Ca concentrations were highest in the leaf and lowest in the shell and seed respectively. The significant increases in shell P, shell Ca and shell Fe with increased K application would greatly improve the groundnut shell quality as an animal feed component. The relationship between seed oil and protein content was positive and significant.
Linkage between brown planthopper resistance and morphological characters in rice
Authors: Prasad G. S. V. , Sastry M. V. S. , Srinivasan T. E. , Kalode M. B.
Published: March 2009

Linkage was detected between brown planthopper resistance and anthocyanin or nonanthocyanin pigmentation in rice cultivars. The crossover values were: 21·9–37% for leaf sheath, 31% for junctura, 41% for auricle, 12·5–40% for ligule, 14·32–1% for leaf tip and margin, 19·7–37% for stigma, 19·7–36% for apiculus and 46·7% for pericarp colour. Genes governing resistance and black hull colour or glabrousness of leaf blade assorted independently. The genes identified and designated for brown planthopper resistance and pigmentation have been tentatively proposed to linkage groups II, IV and V.
Effect of cotton genotypes on numbers of adult lady beetles (Coleoptera: Coccinellidae)
Authors: Bhardwaj H. L. , Weaver J. B.
Published: March 2009

Predatory arthropods can play an important role in the natural control of cotton pests, including bollworms (Heliothis zea Boddie and H. virescens F.). Smith & Fontenot (1942) reported that widespread use of calcium arsenate in cotton fields reduced the number of coccinellids, which resulted in increased damage by pests. Ewing & Ivy (1943) confined several predacious insects collected from cotton (individually in jelly glasses fitted with slightly moistened blotting paper) and supplied them daily with eggs deposited by insectary-reared bollworm moths. The maximum number of eggs destroyed in a day by a single adult of the convergent lady beetle (Hippodama convergent Guerin-Meneville) was 275. Adults of another species of lady beetle (Coleomegilla fuscilabris Muls.) frequently consumed all the eggs given them, an adult on average consuming 22 eggs per day. All the 12 species of predacious insects found in cotton fields survived on bollworm eggs. Whitcomb & Bell (1964) showed that the three most common lady beetles in cotton fields in Arkansas were: (1) spotted lady beetles (Coleomegilla maculata De Geer), (2) convergent lady beetles, and (3) ninespotted lady beetles (Ciccinella novemnotata Herbst). They recorded 24 species of lady beetles, all feeding on lepidopterous eggs including those of bollworms. Many of these predators were captured while feeding on small bollworm larvae. Van den Bosch & Kagen (1966) proposed guidelines for the mass releases of convergent lady beetle adults as a pest control measure in cotton. Lingren, Ridgway & Jones (1968) reported from small-container experiments that adult females of convergent lady beetles consumed an average of 129·9 bollworm eggs per day.
Growth, yield and crop quality performance of sugarcane cultivar Co 957 under different rates of application of nitrogen and potassium fertilizers
Authors: Abayomi A. Y.
Published: March 2009

Screen house and field experiments at the Sugar Research Institute, University of Ilorin, Nigeria were carried out to evaluate the effects of various amounts of nitrogen and potassium fertilizers singly and in combinations on growth, yield and crop quality of sugarcane cultivar Co 957. Growth rate, number of green leaves per mother shoot, leaf area, plant height, stalk length and tiller density were significantly affected by nitrogen application but were not significantly affected by potassium. Similarly, cane tonnage was significantly affected by nitrogen but not by potassium. In the screen house trial, responses to N were linear from 0 to 160 kg N/ha. However, in the field, while the measured variables also increased linearly with N application from 0 to 160 kg N/ha, they decreased at 200 kg N/ha.

Cane quality decreased with increased nitrogen and potassium. However, these reductions were significant only at the highest level of nitrogen and potassium. There were no significant nitrogen and potassium interactions on any of the variables studied.
Effects of night enclosure and extensive walking on the productivity of zebu cattle
Authors: Nicholson M. J.
Published: March 2009

The effects of night enclosure and walking 3000 km on growing and breeding cattle were examined over an 8-month period. Walking consisted of an 8 h walk of 40 km every 3rd day and experimental cattle were enclosed each night for 11 h. In addition, all cattle were allowed water once every 3 days. In cattle which both walked and were enclosed, a reduction of nearly 40% in grazing time was recorded. This was associated with a depression of dry-matter intake of only 12%, suggesting an intensification of eating in response to a restriction of grazing time. The overall effects of walking and enclosing on productivity, as determined by adult weight loss, calf and weaner growth, calving percentage and birth weight, were negligible and masked by the greater effects of poor nutrition during the dry season which affected all the animals. It is concluded that the additional energetic requirements for walking are small and this is attributed to adaptation, fitness and a possible depression of metabolic rate. These factors may explain why the observed costs of walking were lower than those reported in the literature.
Reflexion and absorption of solar radiation by flowering canopies of oil-seed rape (Brassica napus L.)
Authors: Yates D. J. , Steven M. D.
Published: March 2009

Flowers were present over a period of approximately 6 weeks in 12 varieties of oil-seed rape. A linear relationship was found between flower cover (maximum 74%) and photon reflectivity (400–700 nm) which increased from around 0·047 during vegetative growth to 0·195 for a canopy in full flower. Reflexion and absorption of photons by flowers reduced light available to the leaf canopy and immature pods. Spectral measurements indicate that flowering canopies reflect substantially more radiation and absorb less than vegetative canopies between 500 and 700 nm but reflect less and absorb slightly more between 400 and 500 nm.

Seed yield was not strongly correlated with estimates of the radiation absorbed by the leaf canopy under the flower layer. It appears that whilst increased flower density in a canopy might be expected to contribute to increased seed yield, increased reflectivity by petals may have a negative effect on yield. Breeding for reduced petal size or for apetalous lines may result in improved yields by producing more efficient light distribution within the canopy.
Factors affecting growth and yield of short-duration pigeonpea and its potential for multiple harvests
Authors: Chauhan Y. S. , Venkataratnam N. , Sheldrake A. R.
Published: March 2009

Environmental and cultural factors that may limit the yield of short-duration pigeonpea were investigated over three seasons. Plants in the peninsular Indian environment at Patancheru grew less and produced less dry matter by first-flush maturity than at Hisar, a location in northern India where the environment is considered favourable for the growth of short-duration pigeonpea. However, with a similar sowing date in June, the mean seed yields of three genotypes, ICPL 4, ICPL 81 and ICPL 87, were very similar, at about 2·3 t/ha, in both environments. This was mainly due to the higher ratio of grain to above-ground dry matter at Patancheru. In addition to the first harvest, all genotypes showed a potential for two more harvests owing to the warm winters at Patancheru. The potential for multiple harvests was particularly high in ICPL 87, which yielded 5·2 t/ha from three harvests in 1982–3, 3·6 t/ha from two harvests in 1983–4, and 4·l t/ha from three harvests in 1984–5. The optimum plant population density at Patancheru was 25–35 plants/m2 for ICPL 87, but was higher for the other two genotypes.

At Patancheru, the total dry-matter and seed yield of first and subsequent harvests were significantly reduced by delaying sowing beyond June. Generally, the second- and the third-harvest yields were lower on vertisol than on alfisol under both irrigated and unirrigated conditions.

The total yield of ICPL 87 from two harvests was far higher than that of a well-adapted medium-duration genotype BDN 1, grown over a similar period. The yield advantage was greater on the alfisol because of the better multiple harvest potential of this soil. The results of this study demonstrate that properly managed short-duration genotypes of pigeonpea may have considerable potential for increased yield from multiple harvests in environments where winters are warm enough to permit continued growth.
Relationships of brown planthopper resistance to tungro virus and grain characteristics in rice
Authors: Prasad G. S. V. , Sastry M. V. S. , Rao J. R. K. , Ghosh A. , Rao Y. Kondala
Published: March 2009

Brown planthopper, Nilaparvata lugens (Stal), is one of the most serious insect pests of rice (Oryza sativa L.) throughout Asia. Introduction of resistant varieties could be an effective means of minimizing losses from the pest. Several hundred rice cultivars resistant to the pest have been identified and the genetics of resistance has been analysed. Studies have shown that the genes for resistance to brown planthopper, bph-4, and to green leafhopper, Glh-3, are linked (Sidhu & Khush, 1979). Ideka & Kaneda (1983) reported that bph-2 for brown planthopper resistance was linked with the gene d2 for dwarfness. The present study sought to ascertain relationships between resistance to brown planthopper and tungro virus and grain characteristics.
Genotypic variation in the responses of Brassica species to water deficit
Authors: Kumar A. , Singh D. P. , Singh P.
Published: March 2009

The problem of drought presents a challenge to plant breeders as breeding is a major method by which yield improvement can be obtained in drought-prone areas. The plant responses to drought and the nature of drought resistance have received the attention of several workers (Kozlowski, 1968; Kramer, 1969; Levitt, 1972). There are reports in the literature which show that yield and drought resistance are controlled by separate genetic entities. Breeding thus requires identification of definite drought resistance attributes and their transfer to high-yielding and agronomically acceptable cultivars.
Seasonal yield changes in white clover varieties and ecotypes in Nova Scotia
Authors: Fraser Joanna
Published: March 2009

Two ecotypes and three varieties of white clover (Trifolium repens) of contrasting morphology were established in monoculture field plots in Truro, Nova Scotia (45° N) in July 1985. Destructive measurements were taken at monthly intervals from August to November 1985 and April to August 1986. The seasonal distribution of number of active stolons/m2, number of leaves, number of leaves per stolon, and lamina weight together with dry weights of leaves-I-petioles, stolons and flowers + peduncles were recorded. Number of leaves was inversely proportional to leaf weight, smaller-leaved varieties and ecotypes having higher leaf densities than large-leaved white clovers. Leaf and petiole dry-matter yields were related to leaf and number of active stolons in 1985 and to leaf weight increments in 1986. The two naturalized ecotypes exhibited considerably less leaf loss than the three varieties in a winter where mean minimum air temperatures drop to as low as – 13°C. There were considerable differences between ecotypes and between varieties in the seasonal distribution of leaves and petioles, stolon and flower dry weights over the limited time period of this study.
Effect of improved management of legumes in a legume-cereal rotation on field estimates of crop nitrogen uptake and symbiotic nitrogen fixation in northern Syria
Authors: Keatinge J. D. H. , Chapanian N. , Saxena M. C.
Published: March 2009

Improved management compared with traditional practices common in northern Syria for growing field bean (Vicia faba L.), chickpea (Cicer arietinum), lentil (Lens culinaris), peas (Pisum sativum) and vetch (Vicia sativa) was shown to increase significantly (P < 0·001) the crop nitrogen (N) uptake and subsequent protein yields in either hay, grain or straw. This intervention more than doubled N uptake in 1982–3 when averaged over crops and locations increasing from 31·8 kg N/ha under traditional management to 68·7 kg N/ha under improved management. Improved management also increased the proportion of nitrogen uptake that was derived from symbiotic nitrogen fixation by the crop from 55 to 69%. The treatments which gave improved crop N uptake were application of phosphate fertilizer, reduced row spacing and control of weeds. Seed inoculation with rhizobia had little or no effect on N uptake or on the proportion of N that was fixed biologically by the crop. Environmental effects on productivity, as expressed by seasonal and locational differences, were as, or more, important than management-imposed effects.

Differences in N uptake by barley, following either a legume crop or barley, indicated that the residual effects of the legume crop amounted to approximately 10 kg N/ha. This represents a substantial contribution to the N nutrition of a barley crop in the dry areas of northern Syria.
Effect of sodicity and zinc on soil solution chemistry of manganese under submerged conditions
Authors: Sadana U. S. , Takkar P. N.
Published: March 2009

In a greenhouse experiment, the effect of soil sodicity (exchangeable Na percentage 3, 10, 20, 40 and 60) and Zn (0 and 10 mg Zn/kg soil) on soil solution chemistry of Mn was investigated under submerged conditions. Calculated amounts of NaHCO3 were added to Typic Ustifluvent sandy loam soil to obtain required sodicity levels. The soil solutions collected under the atmosphere of N2 gas by gravity were analysed for pH, pE, EC and Mn. Soil submergence decreased pH and pE, and increased Mn concentrations in all the treatments. Maximum Mn concentration was obtained at 14-day submergence. Increasing sodicity levels increased soil solution pH and decreased Mn concentrations. A significant negative correlation (r = -0·74**) was observed between soil solution Mn and pH. Despite large variations in pH, pE, ionic strength and Mn concentration in soil solution, the values of expressions: pH+½log Mn2+ + ½log Pco2 and pMn+2pOH were fairly constant and close to the theoretical values of 4·4 and 17·2 respectively, indicating that the MnCO3-Mn2+ system regulated the solubility of Mn2+ in the sodic soils. Addition of ZnSO4 did not have appreciable effects on the soil solution pH, Mn and solid phases of Mn.
Effect of different combinations of light and dark regimes on the performance of egg lay events, fertility and plasma steroid hormones, during the ovulatory cycle in Peking ducks
Authors: Abdelrazik M. A. , El Sayiad Gh. A. , Marai I. F. M. , Soliman M. M.
Published: March 2009

Different photoperiodic treatments within 2 types of light dark cycles ranging from 24 to 30 h were applied to Peking ducks. The first consisted of constant photoperiods (1, 8L: 16D; 2, 14 L: 10D; 3, 18L:6D; 4, 14L: 13D; 5, 14L: 16D and 6, continuous light) and the second of intermittent cycles (1, 6L:2D:2L:14p; 2, 6L:4D:2L:12D; 3, 6L:6D:2L:10D; 4, 6L:8D:2L:8D and 5, 14L:½D:3½L:6D). The traits studied varied in response according to the photoperiodic regimes used. Rate of lay and eggs laid in the modal 8 h period increased with the duration of the light period in the cycle. Sequence lengths of 1–3 eggs were most frequent under all photoperiodic regimes (constant and intermittent). Length of intra-sequence interval (h) showed an inverse relationship with length of inter-sequence interval. A pause length of 2–4 days was the most frequent for all the different light-dark cycles. Egg weight was heavier in the second season than in the first when the light period of the photoperiodic regime was long. Weights of albumin and yolk showed similar trends to egg weight. The latter differences were significant, while shell weight differences were not significant. Plasma progesterone lvels were lowest in non-laying ducks. The highest values in laying ducks were before ovulation. The highest level of cortisol was shown during the last hours of the dark period. Differences from ovulatory cycle to another were observed.
An evaluation of tree legumes on an acid ultisol in South Sumatra, Indonesia
Authors: Blair G. J. , Panjaitan Mas'ud , Ivory D. A. , Palmer B. , Sudjadi M.
Published: March 2009

Seventeen tree species (16 legumes and Eucalyptus saligna) were grown for 4 years on an Ultisol of pH 4·5 at Nakau, South Sumatra, Indonesia. Leaf and wood yields were recorded seven times during the 4-year period and mineral and plant quality measurements were made on leaf samples from the first harvest taken 2 years after transplanting. At this time, leaf and wood yields were highest from Acacia mangium but the yield of this species declined over time. Highest leaf production was recorded for Cassia siamea over the 4-year period.

Mineral analyses of leaf indicated N, K, Ca and Mg to be adequate for animal production in all species. P was below the critical level for animals in all species and Na levels were adequate only in Acacia mangium and Acacia auriculiformis.

Plant quality measures (ADF, NDF, lignin) suggest marked differences could be expected in potential feed value between species through differences in voluntary intake and digestibility.
The effects of nitrogen, potassium and sodium fertilizers on sugar beet
Authors: Tinker P. B. H.
Published: March 2009

A series of forty-two factorial field trials in 1959–62 tested the effects of 0·6 and 1·2 ewt./acre of N; 0, 1·2 and 2·4 cwt./acre of K2O; and 0, 2 and 4 cwt./acre of salt on sugar beet. Extra plots received 0 and 1·8 cwt./acre of N.

On average, 0·6 cwt./acre of N was more profitable than 1·2 cwt./acre. There was a positive interaction between N and Na, and a lesser one between N and K; in presence of the heavy salt dressing, or the light salt dressing and potassium the optimum rate of nitrogen was 1·0 cwt./acre.
Some aspects of the utilization of tropical forages. I. Green elephant grass at various stages of growth
Authors: Butterworth M. H.
Published: March 2009

1. Cuts of elephant grass (Pennisetum purpureum were made at 40–60 (trial 1), 30 (trial 2), 50 (trial 3) and 70 (trial 4) days of age. Determinations of voluntary intake, digestibility coefficients, rate of passage through the gut, time spent eating and ruminating, number of boluses, rate of chewing, production of volatile fatty acids (both total and individual) were determined using individually housed sheep.

2. Digestibility coefficients of crude protein declined with the level of crude protein in the forage; digestion of the crude fibre fraction declined with advancing maturity. The digestibility of N.F.E. increased with increasing maturity resulting in similar values for T.D.N. among the four cuts. Digestibility of dry matter of the grass in trial 2 was significantly higher than that for the other three trials.
Density ofTrifolium repensplants in mixed swards under intensive grazing by sheep
Authors: Hay M. J. M. , Brock J. L. , Thomas V. J.
Published: March 2009

Densities of physiologically independent plants of white clover were studied in New Zealand in pastures stocked at 22·5 ewes plus lambs/ha by set stocking, rotational grazing or a combination of both systems. Plants were sampled once a month for 1 year (1984/85) by taking turves and washing out the plants. Numbers of growing points and stolon dry weight per plant were obtained. At each sampling fifty, 50 mm diameter pasture plugs were taken from each sward and growing point density and stolon mass/m2of white clover were measured. The density of white clover plants in the swards was estimated on the basis of both stolon dry weight and number of growing points.

The two estimates gave similar results. There was a trend of lowest densities in set-stocked pastures (334/m2), intermediate densities in combination management pastures (431/m2) and highest densities in the rotationally grazed pastures (553/m2). The overall mean density of white clover plants was 439/m2and the range was 193–811/m2.

The structure of swards under the three systems of grazing differed and this was considered to contribute towards the variation in density of white clover plants in the various swards.
The effects of diets deficient in phosphorus, phosphorus and vitamin D, or calcium, on the skeleton and teeth of the growing sheep. II. Malocclusion of the teeth
Authors: McRoberts M. R. , Hill R. , Dalgarno A. C.
Published: March 2009

1. In growing sheep fed on a low-calcium diet for 12 months and for a similar period on a diet of adequate mineral content, a tendency for the incisor teeth to protrude beyond the maxillary pad (prognathism) was observed. This arose primarily during the repair period, and was apparently caused by poorer repair of the upper skull than of the mandible. This was not observed in animals fed on a control diet or one deficient in phosphorus and vitamin D.

2. A malocclusion of molar teeth associated with poorly mineralized and extremely weak mandibles, which prevented the incisor teeth from meeting the dental pad, occurred in growing sheep fed for 12 months on a diet deficient in phosphorus and vitamin D. This defect was not observed in similar animals fed on a control diet nor in those fed on a diet of low calcium content. Treatment effects on the shape of the mandible that were apparently related to this malocclusion are described.
The effect of diet on glucose utilization by sheep
Authors: Ford E. J. H.
Published: March 2009

Using the continuous infusion isotope dilution technique, the glucose utilization rate has been compared in three groups of sheep on different diets. Glucose was utilized at the mean rate of 1·8 mg./kg./min. on a daily ration containing 126 g. crude protein, at the mean rate of 2·8 mg./kg./min. on a daily ration containing 197 g. crude protein, and at the mean rate of 4·3 mg./kg./min. on a daily ration containing 460 g. crude protein. The mean percentage of expired carbon dioxide that was derived from glucose was 3·5, 6·5 and 8·9 respectively on the three diets.
Experiments comparing concentrated and dilute NPK fertilizers and four nitrogen fertilizers on a range of crops
Authors: Widdowson F. V. , Penny A. , Williams R. J. B.
Published: March 2009

1. In 1959 a concentrated granular fertilizer (15% N, 10% P2O5, 20% K2O) was compared with an equivalent mixture of ammonium sulphate, superphosphate and muriate of potash (each supplying 0·75 or 1·50 cwt. N/acre) for potatoes. At Rothamsted (on heavy soil) the two fertilizers gave similar yields, but at Woburn (on light soil) the larger dressing of the concentrated fertilizer gave about 1 ton/acre more potatoes. In similar barley experiments a concentrated granular fertilizer (20% N, 10% P2O5, 10% K2O) was compared with a dilute granular fertilizer (12% N, 6% P2O5, 6% K2O); each was combine-drilled to supply 0·3 or 0·6 cwt. N/acre. At Rothamsted the two fertilizers gave identical yields, but at Woburn the concentrated fertilizer (at the double rate) gave significantly more grain.
Selection criteria in grass breeding. IV. Effect of nitrogen and spacing on yield and its components
Authors: Lazenby Alec , Rogers H. H.
Published: March 2009

1. The effects of applied nitrogen (0, 200, 400, 600, and 800 lb. per acre per annum) and spacing (widely spaced plants and simulated monoculture swards) on average yields and yield components of eight clones of Lolium perenne are reported for four harvests taken each year during 1962 and 1963.

2. During both years, higher yields per unit area were obtained from swards than from spaced plants; the degree of difference varied from harvest to harvest.

3. A greater effect of nitrogen on yield was detected in 1963 than in 1962, an effect especially marked in swards at lower rates of nitrogen application. A highly significant nitrogen x spacing interaction on yield was detected in 1963.
Crop yields from lucerne (Medicago sativa) cultivars displaying gradations in resistance to wilt (Verticillium albo-atrum)
Authors: Dixon G. R. , Kershaw C. D. , Hunter E. A.
Published: March 2009

Yields from lucerne cultivars grown on land infested with Verticillium albo-atrum, a cause of wilt disease, were studied over the period 1969–77. Field experiments established in 1969, 1971, 1972 and 1973 were maintained for periods of 4–6 years. Reactions by cvs Europe and Vertus were of principal interest. Europe is considered to be moderately susceptible, initially producing yields exceeding those of resistant types on uninfested land. In comparison cv. Vertus has considerable resistance derived from a polygenic system. In the first 2 cropping years on infested land, Europe yielded similarly to Vertus with only slight symptom expression. In year 3, Europe maintained comparable yields to Vertus but with increasing disease expression. During succeeding years Europe was badly affected by discase and yields were below those achieved by Vertus. Data from other cultivars indicated a positive correlation between symptoms in years 4 and 5, a negative correlation between dry-matter yield in year 5 and symptom severity in year 4, and a negative correlation between symptom severity and yield in year 5. Symptom expression and pathogen build-up appear to occur at similar rates in the latter years of a lucerne crop. Disease development in one season has a considerable effect on future productivity. These findings are discussed in terms of the primary (extra-vascular) and secondary (intra-vascular) determinants of resistance to wilt pathogens. It is suggested that the apparent moderate susceptibility of cv. Europe in seasons two and three relates to a rapid growth rate.
Development of shape in turkey carcasses
Authors: Swatland H. J.
Published: March 2009

Forty-four turkeys including both sexes of two genetic strains were drawn at mean weight-for-age at 2 week intervals from a flock of 380 birds from hatching to 20 weeks post-hatching. Birds were dissected and linear measurements of skeletal units and breast dimensions were compared with keel length using the logarithmic form of Huxley's allometric growth equation. Live weights and weights of selected muscles were similarly compared with breast muscle weight. Wing bones and the biceps brachii muscle grew at approximately the same rate as keel length and breast muscle, respectively. However, leg bones and semitendinosus and gastrocnemius muscles exhibited slower growth than the breast region. Growth of maximum breast length and width was closely matched to keel length but growth in keel depth was much slower. The desirable convexity in breast shape lateral to the keel was considered to be directly proportional to maximum meat depth over the sternum and inversely proportional to keel depth. Maximum meat depth increased at a faster rate than either keel length or depth.
Game domestication for animal production in Kenya: field studies of the body-water turnover of game and livestock
Authors: King J. M.
Published: March 2009

Field studies were made of tritiated water turnover, drinking water and dietary water intake throughout the year, in 212 animals of the following species: African buffalo, dromedary camel, zebu cow, eland, small East African goat, fringe-eared oryx, and Dorper sheep.

There were significant differences (P< 0·005) in the water drunk and water turnover between species and between seasons. Furthermore the species (or season) differences were also significantly different (P< 0·005) for each season (or species). The lowest turnover rates were found in oryx, then camel, sheep, goat, eland, cow and buffalo, when expressed in ml/l0·82/day, which was the appropriate metabolic unit for these species.

The restraints imposed by traditional African animal husbandry have drastically reduced the natural ability of eland to conserve body water but had much less effect on buffalo and oryx. The reason appears to be that eland is behaviourally adapted to a semi-arid environment, whereas a species like oryx is more physiologically adapted.
Primordium initiation at the shoot apex in four contrasting varieties of spring wheat in response to sowing date
Authors: Stern W. R. , Kirby E. J. M.
Published: March 2009

The spring wheat varieties Kolibri, a typical north temperate variety, Pitic 62, a Mexican variety known to respond to vernalization and two selections from the Institute's breeding programme TW 161 and TJB 155 were sown early (2–5 March), during the normal sowing period (27 March) and late (17 April). Primordium initiation was observed until the time of terminal spikelet initiation and the number of leaves and the number of spikelets were analysed in terms of rate and duration of leaf and spikelet primordium initiation. The rate of leaf initiation was affected by time of sowing but not in a systematic way and there were differences between varieties in the way in which the number of leaves changed in response to sowing time. The rate of spikelet initiation increased and the duration decreased with later sowing. There were strong variety × time of sowing interactions. For almost all characters measured, Pitic 62 responded least to time of sowing. Varieties differed in the way in which the number of spikelets per ear responded to time of sowing but in all cases the changes were only small. This waa because the change in the rate of spikelet initiation was almost exactly compensated for by a change in the duration of spikelet initiation. In each variety, the period from terminal spikelet initiation to ear emergence was similar in all sowing treatments and was of similar duration in the main shoot and in the ear-bearing tillers.

The number of leaves per shoot on the tillers was less than the number of leaves on the main shoot and the rate of spikelet primordium initiation of the tillers was faster than in the main shoot. These changes tended to synchronize the time of terminal spikelet initiation. Because of the changes in the number of leaves per shoot and the rate of spikelet initiation the number of spikelets borne on the main shoot and the tillers were similar although the growth period of the tillers was shorter than that of the main shoot.
Oestrous cycle synchronization and oestrus induction in indigenous and European cattle in Tanzania
Authors: Schmidt H. , Jöchle W. , Smidt D.
Published: March 2009

From 1969 to 1971, 743 animals (indigenous Zebu and European dairy cattle, lactating or dry cows and heifers) received oestrous cycle synchronization treatments at government-owned and private ranches and farms in the Tanzanian highlands (West Kilimanjaro); 445 matching animals served as controls. Treatment schedules consisted of chlormadinone acetate (CAP) given daily for 14 days (10 mg/day) orally; or a single CAP injection (50 mg) followed by 4 or 5 days of oral treatment (10 mg/day) 9–12 or 11–15 days later. In addition, some groups received either estradiol valerate (5 mg) together with the CAP injection, or 10 mg/day mestranol from day 11 to 15, together with CAP; one treatment group received 1000 i.u. of HCG after the last CAP medication and were inseminated 12 and 24 h thereafter. Animals were either inseminated or bred naturally. With all treatment schedules, good synchronization, unimpaired fertility and consistently a significant reduction of anoestrus was achieved. Oestrogen treatments had no effects; treatment with 1000 i.u. of HCG was unsuccessful. Management factors, food supply and phase of reproductive life had significant impacts on treatment success and fertility. Synchronization can be used successfully under a wide range of management conditions to unfold existing potentials of artificial insemination in Bos indicus and Bos taurus in the tropics.
Regional body surface area of sheep
Authors: Bennett J. W.
Published: March 2009

Twenty-three shorn, adult Merino sheep weighing 22·6–63·1 kg were killed and total skin surface area and eight regional skin surface areas measured after skinning. Bodyfat content (1·9–43·6% of body weight) was estimated from the tritiated-water space and body dimensions were recorded before slaughter.

Body weight was the best single measure for predicting total area and regional areas, and little advantage was gained by using multiple regressions incorporating body weight, fat content and body dimensions. Proportional surface areas of all regions except the neck were significantly related to body weight; positively for the trunk, and negatively for the ear, lower leg, upper leg and head. Equations relating regional surface area (% total area) to body weight are presented.
Variation in pod length in spring rape (Brassica napus) and its effect on seed yield and yield components
Authors: Chay P. , Thurling N.
Published: March 2009

Ten selections from the cultivar China A, with widely different pod lengths, were compared in a single environment in Perth in 1983. Pod length was correlated positively with seed weight per pod but negatively with number of pods per plant. As a result, there was no significant relationship between pod length and seed yield, although the highest- and lowest-yielding lines were, respectively, longand short-podded.

Two lines differing markedly in pod length were compared in a second experiment in 1984 in which sowing date and plant population density within a sowing date were varied. Although pod length was relatively stable, seed yield and some of its components were greatly affected by sowing date and plant density. Again, the long-podded line produced fewer pods with a greater weight of seed per pod than the short-podded line in most conditions. Compensation for greater seed weight per pod by a reduction in number of pods per plant was primarily responsible for the absence of significant differences in yield between lines in any treatment.

Although long pods generally produced a greater weight of seeds per pod than short pods, the advantage in seed number and/or the weights of individual seeds was less than that expected pro rata for the much greater pod length. Indeed, short pods produced more seeds per unit length of pod than long pods. This suggested a less efficient distribution of assimilates within the longer pods, a greater amount being required to support the growth of pod walls than in short pods.

Alternative approaches to using pod length as a criterion of selection for high yield are discussed.