Duration from vine emergence to flowering suggests a long-day or rate of change of photoperiod response in white yam (Dioscorea rotundata Poir.)

The objective of this study was to quantify the effect of photoperiod on the duration from vine (shoot) emergence to flowering in white or Guinea yam (Dioscorea rotundata). The duration from vine emergence to flowering in two clonal varieties of yam (TDr 131 and TDr 99-9) was recorded at 10 different sowing dates/locations in Nigeria. Durations to flowering varied from 40 to > 88 days. Mean daily temperature and photoperiod between vine emergence and flowering varied from 25 to 27 degrees C and 13.1 to 13.4 h day(-1), respectively. Both clones had similar responses to temperature, with base and optimum temperatures of 12 and 25-27 degrees C, respectively. Thermal durations to flowering were strongly related (r(2) > 0.75-0.83) to absolute photoperiod (h) at vine emergence as well as to rate of change of photoperiod (s day(-1)) at vine emergence. The response to absolute photoperiod suggests that white yams are quantitative LDPs, flowering sooner in long than short days. Yams also flowered earlier when the rate of change of photoperiod was positive but small, or was negative. It is suggested that yams may use a combination of photoperiod and rate of change in order to fine tune flowering time. (c) 2006 Elsevier B.V. All rights reserved.

Immigration, species radiation and extinction in a highly diverse songbird lineage: white-eyes on Indian Ocean islands

Molecular phylogenetic hypotheses of species-rich lineages in regions where geological history can be reliably inferred may provide insights into the scale of processes driving diversification. Here we sample all extant or recently extinct white-eye (Zosterops) taxa of the southwest Indian Ocean, combined with samples from all principal continental lineages. Results support a high dispersal capability, with at least two independent continental sources for white-eyes of the region. An early (within 1.8 million years ago) expansion into the Indian Ocean may have originated either from Asia or Africa; the three resulting lineages show a disparate distribution consistent with considerable extinction following their arrival. Africa is supported as the origin of a later expansion into the region (within 1.2 million years ago). On two islands, a pair of Zosterops species derived from independent immigrations into the Indian Ocean co-occur or may have formerly co-occurred, providing strong support for their origin by double-island colonization rather than within-island (sympatric or microallopatric) speciation. On Mauritius and La Reunion, phylogenetic placement of sympatric white-eyes allow us to rule out a scenario in which independent within-island speciation occurred on both islands; one of the species pairs must have arisen by double colonization, while the other pair is likely to have arisen by the same mechanism. Long-distance immigration therefore appears to be responsible for much of the region's white-eye diversity. Independent immigrations into the region have resulted in lineages with mutually exclusive distributions and it seems likely that competition with congeneric species, rather than arrival frequency, may limit present-day diversity.

The effect of carrier substrate, dose rate and time of application on biocontrol efficacy of fungal antagonists against Armillaria root rot of strawberry plants.

In a glasshouse experiment using potted strawberry plants (cv. Cambridge Favourite) as hosts, the effect of selected fungal antagonists grown on 25 or 50 g of mushroom compost containing autoclaved mycelia of Agaricus bisporus, or wheat bran was evaluated against Armillaria mellea. Another glasshouse experiment tested the effect of application time of the antagonists in relation to inoculations with the pathogen. A significant interaction was found between the antagonists, substrates and dose rates. All the plants treated with Chaetomium olivaceum isolate Co on 50 g wheat bran survived until the end of the experiment which lasted 482 days, while none of them survived when this antagonist was added to the roots of the plants on 25 g wheat bran or 25 or 50 g mushroom compost. Dactylium dendroides isolate SP had a similar effect, although with a lower host survival rate of 33.3%. Trichoderma hamatum isolate Tham 1 and T. harzianum isolate Th23 protected 33.3% of the plants when added on 50 g and none when added on 25 g of either substrate, while 66.7% of the plants treated with T. harzianum isolate Th2 on 25 g, or T viride isolate TO on 50 g wheat bran, survived. Application of the antagonists on mushroom compost initially resulted in development of more leaves and healthier plants, but this effect was not sustained. Eventually, plants treated with the antagonists on wheat bran had significantly more leaves and higher health scores. The plants treated with isolate Th2 and inoculated with Armillaria at the same time had a survival rate of 66.7% for the duration of the experiment (475 days), while none of them survived that long when the antagonist and pathogen were applied with an interval of 85 days in either sequence. C. olivaceum isolate Co showed a protective effect only, as 66.7% of the plants survived when they were treated with the antagonist 85 days before inoculation with the pathogen, while none of them survived when the antagonist and pathogen were applied together or the infection preceded protection.

Cultural techniques for improvement in biocontrol potential of fungal antagonists for biological control of Armillaria root rot of strawberry plants under glasshouse conditions

Several in vitro and in vivo experiments were conducted to develop an effective technique for culturing potential fungal antagonists (isolates of Trichoderma harzianum, Dactylium dendroides, Chaetomium olivaceum and one unidentified fungus) selected for activity against Armillaria mellea. The antagonists were inoculated onto (1) live spawn of the oyster mu shroom (Pleurotus ostreatus), (2) extra-moistened or sucrose-enriched mushroom composts containing living or autoclaved mycelia of P. ostreatus or Agaricus bisporus (button mushroom), (3) pasteurized compost with or without A. bisporus mycelium, wheat bran, wheat germ and (4) spent mushroom composts with living mycelia of A. bisporus, P. ostreatus or Lentinus edodes (the Shiitake mushroom). In one experiment, a representative antagonist (isolate Th2 of T. harzianum) was grown together with the A. bisporus mycelium, while in another one, the antagonist was first grown on wheat germ or wheat bran and then on mushroom compost with living mycelium of A. bisporus. Some of the carrier substrates were then added to the roots of potted strawberry plants in the glasshouse to evaluate their effectiveness against the disease. The antagonists failed to grow on the spawn of P. ostreatus even after reinoculations and prolonged incubation. Providing extra moisture or sucrose enrichment also did not improve the growth of Th2 on mushroom composts in the presence of living mycelia of A. bisporus or P. ostreatus. The antagonist, however, grew rapidly and extensively on mushroom compost with autoclaved mycelia, and also on wheat germ and wheat bran. Colonization of the substrates by the antagonist was positively correlated with its effectiveness in the glasshouse studies. Whereas only 33.3% of the inoculated control plants survived in one experiment monitored for 560 days, 100% survival was achieved when Th2 was applied on wheat germ or wheat bran. Growth of the antagonist alone on pasteurized or sterilized compost (without A. bisporus mycelia) and simultaneous growth of the antagonist and mushroom on pasteurized compost did not improve survival over the inoculated controls, but growth over mushroom compost with the living mycelium resulted in 50% survival rate. C. olivaceum isolate Co was the most effective, resulting in overall survival rate of 83.3% compared with only 8.3% for the inoculated and 100% for the uninoculated (healthy) controls. This antagonist gave the highest survival rate of 100% on spent mushroom compost with L. edodes. T harzianum isolate Th23, with 75% survival rate, was the most effective on spent mushroom compost with P. ostreatus, while D. dendroides isolate SP resulted in equal survival rates of 50% on all the three mushroom composts.

Distribution of nutrients in the root zone affects yield, quality and blossom end rot of tomato fruits

Tomato plants (Lycopersicon esculentum Mill. 'DRK') were grown hydroponically in two experiments to determine the effects of nutrient concentration and distribution in the root zone on yield, quality and blossom end rot (BER). The plants were grown in rockwool with their root systems divided into two portions. Each portion was irrigated with nutrient solutions with either the same or different electrical conductivity (EC) in the range 0 to 6 dS m(-1). In both experiments, fruit yields decreased as EC increased from moderate to high when solutions of equal concentration were applied to both portions of the root system. However, higher yields were obtained when a solution with high EC was applied to one portion of the root system and a solution of low EC to the other portion. For example, the fresh weight of mature fruits in the 6/6 treatment was only 20% that of the 3/3 treatment but the 6/0 treatment had a yield that was 40% higher. The reduction in yield in the high EC treatments was due to an increase in the number of fruits with BER and smaller fruit size. BER increased from 12% to 88% of total fruits as EC increased from 6/0 to 6/6 and fruit length decreased from 67 mm to 52 mm. Fruit quality (expressed as titratable acidity and soluble solids) increased as EC increased. In summary, high yields of high quality tomatoes with minimal incidence of BER were obtained when one portion of the root system was supplied with a solution of high EC and the other portion with a solution of moderate or zero EC.

Uneven distribution of nutrients in the root zone affects the incidence of blossom end rot and concentration of calcium and potassium in fruits of tomato

Tomato plants ( Lycopersicon esculentum Mill. var. DRK) were grown hydroponically to determine the effect of an uneven distribution of nutrients in the root zone on blossomend rot (BER) and Ca and K concentrations in the fruits. The plants were grown in rockwool with their root system divided into two portions. Each portion was irrigated with nutrient solutions with either the same or the different electrical conductivity (EC) in the range 0 to 6 dS m(-1). Solutions with high EC supplied to both sides of the root system significantly increased the incidence of BER. However, when only water or a solution of low EC was supplied to one portion, BER was reduced by 80%. Fruit yields were significantly higher ( P < 0.01) for plants that received solutions of the uneven EC treatments (6/0 or 4.5/0 EC treatment). Plants supplied with solutions of uneven EC generally had higher leaf and fruit concentrations of Ca but lower concentrations of K than those supplied with solutions of high EC. There was no difference in Ca concentration at the distal end of young fruits of the uneven EC treatment but it was reduced in the high EC treatments. The concentration of K in the mature fruits of the uneven EC treatments was lower than that of the high EC treatments and higher or similar that of the 3/3 or 2.5/2.5 EC treatments ( controls). A clear relationship was found between the incidence of BER and the exudation rate. High rate of xylem exudation was observed in the uneven EC treatments. Reduction of BER in the uneven EC treatments is most likely to be the effect of high exudation rate on Ca status in the young fruits. It was concluded that high EC of solution had positive effects on Ca concentration and incidence of BER provided that nutrient solution with low EC or water is supplied to the one portion of the root system.

Managing Armillaria root rot

Controlling Armillaria infections by physical and chemical methods alone is at present inadequate, ineffective, or impractical. Effective biological control either alone or in integration with another control strategy appears necessary. Biological control agents of Armillaria function by the antagonists inhibiting or preventing its rhizomorphic and mycelial development, by limiting it to substrate already occupied, by actively pre-empting the substrate, or by eliminating the pathogen from substrate it has already occupied. Among the most thoroughly investigated antagonists of Armillaria are Trichoderma species. Depending on the particular isolate of a Trichoderma species, control may be achieved by competition, production of antibiotics, or by mycoparasitism. The level of control is also influenced by the growth and carrier substrate of the antagonist, time of application in relation to the occurrence of the disease, and several environmental conditions. Among a range of the other antagonists are several cord-forming fungi and an isolate of Dactylium dendroides. Integrating biological methods with an appropriate method of chemical could control the disease more effectively. However it is essential to determine whether the antagonist or the fungicide should be applied first, and the time interval between.

Optimization of protoplast production in white lupin

The influence, was investigated, of abiotic parameters on the isolation of protoplasts from in vitro seedling cotyledons of white lupin. The protoplasts were found to be competent in withstanding a wide range of osmotic potentials of the enzyme medium, however, −2.25 MPa (0.5 M mannitol), resulted in the highest yield of protoplasts. The pH of the isolation medium also had a profound effect on protoplast production. Vacuum infiltration of the enzyme solution into the cotyledon tissue resulted in a progressive drop in the yield of protoplasts. The speed and duration of orbital agitation of the cotyledon tissue played a significant role in the release of protoplasts and a two step (stationary-gyratory) regime was found to be better than the gyratory-only system.

Comparison of white metal and resin socket terminations for wire ropes

Previously the authors have presented both theoretical and experimental work discussing the operating mechanism of a wire rope held in a tapered socket by means of a cast resin cone. The work reported here extends the investigation to address the question of whether the same socket fabricated with white metal operates in the same manner. To date, previous investigations have compared the operational efficiency of resin and white metal in terms of both strength and/or fatigue endurance. Some other work has analysed the operation of resin sockets or specific cast metal terminations. This paper seeks to draw the results from this work together, and, in addition to a theoretical analysis, presents experimental data obtained from a direct comparison of the operation mechanism for the same sockets filled with resin or white metal. Results show that white metal terminations have a very different distribution of stresses along the length of the socket basket from resin terminations, and a smaller but still significant amount of socket draw. For both types of termination the socket draw develops high frictional gripping forces which can transfer the load from the rope to the socket. The different stress distributions mean that the consequences of termination fabrication defects may not be the same for resin and white metal terminations.

Testing white line strength in the dairy cow

The tensile strength of 576 pieces of white line horn collected over 6 mo from 14 dairy cows restricted to parity 1 or 2 was tested. None of the cows had ever been lame. Seven cows were randomly assigned to receive 20 mg/d biotin supplementation, and 7 were not supplemented. Hoof horn samples were taken from zones 2 and 3 (the more proximal and distal sites of the abaxial white line) of the medial and lateral claws of both hind feet on d 1 and on 5 further occasions over 6 mo. The samples were analyzed at 100% water saturation. Hoof slivers were notched to ensure that tensile strength was measured specifically across the white line region. The tensile stress at failure was measured in MPa and was adjusted for the cross-sectional area of the notch site. Data were analyzed in a multilevel model, which accounted for the repeated measures within cows. All other variables were entered as fixed effects. In the final model, there was considerable variation in strength over time. Tensile strength was significantly higher in medial compared with lateral claws, and zone 2 was significantly stronger than zone 3. Where the white line was visibly damaged the tensile strength was low. Biotin supplementation did not affect the tensile strength of the white line. Results of this study indicate that damage to the white line impairs its tensile strength and that in horn with no visible abnormality the white line is weaker in the lateral hind claw than the medial and in zone 3 compared with zone 2. The biomechanical strength was lowest at zone 3 of the lateral hind claw, which is the most common site of white line disease lameness in cattle.

Responsiveness to change by standard-form contract drafters: A case study of the FIDIC White Book

Purpose – The purpose of this paper is to focus on the Fédération Internationale des Ingénieurs-Conseils (FIDIC) White Book standard form of building contract. It tracks the changes to this contract over its four editions, and seeks to identify their underlying causes. Design/methodology/approach – The changes made to the White Book are quantified using a specific type of quantitative content analysis. The amended clauses are then examined to understand the nature of the changes made. Findings – The length of the contract increased by 34 per cent between 1990 and 2006. A large proportion of the overall increase can be attributed to the clauses dealing with “conflict of interest/corruption” and “dispute resolution”. In both instances, the FIDIC drafting committees have responded to international developments to discourage corruption, and to encourage the use of alternative dispute resolution. Between 1998 and 2006, the average length of the sentences increased slightly, raising the question of whether long sentences are easily understood by users of contracts. Research limitations/implications – Quantification of text appears to be particularly useful for the analysis of documents which are regularly updated because changes can be clearly identified and the length of sentences can be determined, leading to conclusions about the readability of the text. However, caution is needed because changes of great relevance can be made to contract clauses without actually affecting their length. Practical implications – The paper will be instructive for contract drafters and informative for users of FIDIC's White Book. Originality/value – Quantifying text has been rarely used regarding standard-form contracts in the field of construction.

Textural and microstructural properties of urfa cheese (a white-brined Turkish cheese)

The texture and microstructure of white-brined cheeses similar to urfa (a traditional Turkish cheese) were studied. One batch of cheeses was made in the traditional manner and one batch was made from ultrafiltered (UF) milk. Samples from each batch were either ripened in brine after production or scalded in whey for 3 min at 90degreesC prior to ripening. The results showed only marginal differences in the ripening profiles of both batches of unscalded cheeses, but scalding slowed down the extent of proteolysis in both batches. The scalded cheeses had a firmer texture than the unscalded ones, and the unscalded UF cheese had a more 'springy' body than the unscalded traditional cheese. Overall, scalding resulted in a more homogeneous structure, but the unscalded UF cheese had a close texture that resembled the scalded samples. It was concluded that, with respect to texture and structure, cheeses made with UF milk do not need to be scalded after production.

Effect of chymosin reduction and salt substitution on the properties of white salted cheese

A whey salts mixture was used as a partial substitute for sodium chloride to provide a modified Na:K ratio (1:3.4) in the manufacture of white salted cheese using ultrafiltration. Reduction of chymosin addition from 20 to 8 mu L kg(-1) of cheese was also investigated. Variation of salt and chymosin levels did not result in any significant differences in composition and physicochemical properties. The rates of proteolysis in terms of water-soluble nitrogen (WSN) and nitrogen soluble in 12% trichloroacetic acid (TCA-SN) were affected by chymosin levels but not by salt treatment. Urea-PAGE electrophoretic analysis of caseins from the cheeses manufactured using three levels of chymosin and two salt types showed that the hydrolysis of alpha(s1)-casein was higher than for beta-caseins but the differences between the cheeses were not significant (P > 0.05). The chymosin level did not have a significant effect (P > 0.05) on hardness and fracturability, suggesting that any variation in hardness due to the initial hydrolysis was being confounded by other variables. Cheeses including the whey salts product were harder and more fracturable (P < 0.01) than the cheese treated with NaCl only. Both hardness and fracturability values decreased (P < 0.05) over the maturation period. The scores for bitterness were low; neither the effects of salt nor chymosin levels were significant (P > 0.05). (c) 2005 Elsevier Ltd. All rights reserved.