Competitive and allelopathic interference between soybean crop and annual wormwood (Artemisia annua L.) under field conditions

Annual wormwood interference on soybean crop growth and yield may result from competition and allelopathy, which are modulated by crop management. Allelochemicals released by annual wormwood (e.g. artemisinin) may affect the crop directly or indirectly through the effect on the nitrogen fixing symbiont, Bradyrhizobium japonicum. The objectives were (i) to quantify the crop response (i.e. biomass production, nodulation and yield) to weed interference and (ii) to determinate the relative change of competition and allelopathy interferences, when a sublethal dose of herbicide is applied. Two split plot field experiments with three replications were used. The experiment involved a factorial combination of five weed–crop density (soybean/annual wormwood, plants m^?2) levels: D1, pure soybean, 40/0 plants m^?2; D2, 40/2 plants m^?2; D3, 40/4 plants m^?2 and D4, 40/8 plants m^?2, and D5, pure annual wormwood, 0/8 plants m^?2, two activated carbon (allelopathy) levels: C?, with activated carbon (reduced allelopathy) and C+, non activated carbon applied (with allelopathy) and two herbicide levels: H?, untreated and H+, treated with a sub-lethal dose of glyphosate. Activated carbon to adsorb allelochemicals (with and without activated carbon) and glyphosate application (with and no herbicide) were assigned to sub-plots. Increasing weed density did not affect crop biomass at flowering, but changed nodule number and soybean yield with a different pattern depending on carbon and herbicide treatment. Relative crop yield decreased with increasing relative weed biomass. This decrease was particularly drastic when allelopathy was reduced by activated carbon and without herbicide application. The maximum yield losses of 33% in 2006 and 17% in 2007 were observed with the highest weed density (8 plants m^?2). In contrast, without carbon (high allelopathy level), soybean yield remained stable within the explored range of annual wormwood biomass, despite the fact that weed biomass at high densities (D4) was high enough to generate competition. The lack of response to increasing weed density could be related to the indirect effect of allelochemicals interacting with soil microorganisms (i.e. B. japonicum) that positively affected the nodulation (e.g. larger nodules in 2006 and increased nodules biomass due to higher number of roots in 2007 at high densities). With herbicide application, soybean yield of both carbon treatments remained stable when biomass of annual wormwood increased. This research provided strong evidence in support of the existence of positive effect of allelopathic and competitive interactions between annual wormwood and soybean crop under field conditions that may be overridden under herbicide application.     

Inhibition of telomerase in canine cancer cells following telomestatin treatment

Telomere shortening in normal somatic cells has been proposed as a major barrier to unlimited cellular proliferation. Telomerase is an enzyme capable of maintaining telomere length, and thus bypassing this barrier. In human beings, telomerase activity is restricted to cancer cells and cells of stem or germ cell lineages. Dogs represent a potentially useful clinical model for the development of telomerase‐based therapies because telomerase activity is also restricted to cancer cells and stem cells in this species. We examined the ability of telomestatin to inhibit telomerase activity in telomerase‐positive D17 and CMT7 canine cancer cell lines. At a concentration of 2 μM, telomestatin treatment resulted in a decrease in telomerase activity, telomere shortening, growth inhibition and apoptosis in telomerase‐positive cancer cells. These effects were not seen in telomerase‐negative skin fibroblasts or negative controls. These results confirm that telomestatin specifically inhibits telomerase activity in canine cancer cells and strengthens the usefulness of dogs as a model for testing telomerase‐based therapies.     

Sources of resistance in wheat to speckled leaf blotch caused by Septoria tritici

Summary Seven and a half thousand wheat varieties, including over 2,000 durums, were screened for resistance to Septoria tritici under conditions of artificial inoculation in the field. From this screening, 460 varieties were selected on the basis of resistance and earliness and were subject to more detailed observation.Selected varieties were tested in the field with two replications under both natural and artificial epidemic conditions. The agreement between varietal scores in the two replications and under the two conditions was good; 91–94% of varieties showing consistent disease scores. The correlation coefficient between varietal scores for the natural epidemic and the artificial epidemic conditions was 0.63^***.A number of the very early maturing varieties of T. aestivum showed good resistance as measured by pycnidial production but exhibited extensive leaf necrosis. This reaction was not observed in later varieties and in accessions of T. durum.Varieties of Triticum durum were typically more resistant than varieties of T. aestivum. Thirty-four varieties of T. aestivum and 266 varieties of t. durum showed a consistent expression of resistance. A list of these 34 accessions of T. aestivum and selected accessions of T. durum is provided, along with agronomic data.     

Tuta absoluta,a South American pest of tomato now in the EPPO region: biology,distribution and damage

Tuta absoluta (Meyrick) is an invasive pest of tomato native to South America, where it is responsible for extensive damage. It rapidly spread into several European countries, becoming a key pest. Knowledge of its main biological traits can be used to develop effective plant protection management strategies. It is a multivoltine species with a homodynamous behaviour, and the length of its life cycle depends on environmental conditions, particularly temperature. The larvae feed and develop inside tomato leaves, stems and fruits throughout the entire growing cycle. The adults have crepuscular habits, and in Mediterranean conditions they can be easily detected throughout the year. Damage is directly related to the reduction of plants' photosynthetic capacity and of production levels in both protected and open‐field tomato crops; indirect damage can be also caused by secondary infections, with pathogens developing on the infested plant and fruit tissues.     

Factors affecting the variability in cracked and dirty eggs and egg production profitability on an integrated poultry operation

1. A number of factors causing variability in the percentages of cracked, and dirty eggs and weekly standard margin (WSM) of returns from eggs over production costs were examined on an integrated commercial poultry plant in Scotland.

2. As the bird aged, the percentage of cracked eggs increased (P <0.01) and the percentage of grade A eggs and WSM decreased (P <0.01). Cracks in dirty eggs (10.1%) were more than double those in all eggs laid (4.9%).

3. Seasonal effects on percentage cracked eggs and percentage grade A eggs were one‐third the magnitude of those due to age but were significant (P <0.05).

4. Variability in percentage cracked eggs, dirty eggs and WSM accounted for by the factors measured, were 72, 64 and 92% respectively.

5. The variability in WSM was significantly affected by percentage lay, food consumption and age but not by percentage cracked eggs, originally dirty and grade A eggs.

6. Flock management and climate inside the laying house each increased the amount of variability accounted for in the percentage cracked eggs and dirty eggs by at least 10%.     

Renal concentrating mechanism: possible role for sodium-potassium activated adenosine triphosphatase

Sodium-potassium activated adenosine triphosphatase activity was found to be almost twice as high in renal medulla as in cortex. Infusion of digoxin, a specific inhibitor of the enzyme, into one renal artery of the dog resulted in unilateral natriuresis, impaired concentrating capacity, and reduction of the enzyme activity in both cortex and medulla. It is suggested that the sodium-potassium adenosine triphosphatase plays an important role in urine concentration mechanisms.     

From alley cropping to rotational fallow: Farmers' involvement in the development of fallow management techniques in the humid forest zone of Cameroon

Alley cropping was introduced in the humid forest zone of Cameroon to increase soil fertility in 1987, but until 1992 the adoption rate had remained low. To better understand the reasons behind this, three types of on farm trials were established from fully researcher controlled to fully farmer controlled. During the evaluation of the technology with farmers a number of modifications were registered (1) Pruning height and frequency: Because of the difficulties to consistently cut back at 30 cm, farmers decided to slash at ground level as they normally do while slashing the natural fallow vegetation. This equally allowed for more flexibility in time of pruning. (2) Cropping intensity and pattern: Initially, alleys were cropped each year. This however had several shortcomings. Having observed the positive impact of incidental fallow period in a farmer's field, it was decided to introduce a fallow phase of at least one year. During the fallow period the plot can be used for fodder production, bee farming and production of stakes. (3) Residue management: Fire went incidentally in a farmer's tree plot after slashing, and the trees were not affected. This gave farmers an alternative way to manage the residue, by controlling the fire, before bringing in other crops such as groundnut and cassava. (4) Agroforestry species: Because Leucaena leucocephala, in spite of it soil fertility restoration potential, rapidly became a noxious weed, farmers have asked for a less invasive species. Calliandra calothyrsus was introduced for this purpose and became a good bee forage. With these modifications, the original alley cropping system has evolved into a rotational tree fallow with higher adoption potential. From about 15 farmers who were testing the technology in 1992, the number increased to 52 in 1996, 120 in 1997 and 236 in 1998. This revised version was published online in June 2006 with corrections to the Cover Date.