Are composts from shredded leafy branches of fast-growing forest species suitable as nursery growing media in arid regions?

The morpho-physiological quality of seedlings is negatively affected by the wide scale use of forest soils as substrates in developing countries. With the objective of finding long-term sustainable supply of growing media, compost was produced from shredded branches of three fast growing species (Acacia cyanophylla (AA), Acacia cyclops (AS) and Eucalyptus gomphocephala (EG). The composting process covered three different periods over the course of a year. Pile temperatures were monitored daily and the composts were routinely sampled and analyzed for 19 chemical variables. Although composting is feasible year-round in arid climates, compost produced in the humid cool conditions of autumn, winter and early spring reaches the maturation phase more quickly than compost produced under hot, dry summer conditions. It also requires less turning and water. The evolution of the composting process and quality of the final product can be assessed using three chemical variables (C/N, pH, EC). Seed germination rates in the three types of compost were similar to that in a peat:vermiculite substrate and vigorous high quality seedlings were produced in the two acacia composts. However, compost-grown seedlings had significantly smaller shoots and root systems than those produced in peat substrate. Principal components analyses showed that the quality of a compost-based substrate is reproducible and that its final chemical composition can be predicted from its raw organic materials. The EG composts had higher pH than the acacia composts, whereas the AA and EG composts were higher in mineral salts than the AS.     

Molecular characterization of pathogenic Escherichia coli isolated from diarrheic and in-contact cattle and buffalo calves

Tropical Animal Health and Production - Escherichia coli field isolates from calves were characterized and categorized into the most significant diarrheagenic pathotypes using polymerase chain...     

Use of some plant extracts to control Biomphalaria alexandrina snails with emphasis on some biological effects

The present work was carried out to evaluate, the molluscicidal activity of cold water, boiled water, methanol, ethanol, acetone and chloroform extracts of some plant species against Biomphalaria alexandrina snails. Preliminary screening tests on 10 plant species showed that the highest molluscicidal potency was recorded for Euphorbia splendens, Atriplex stylosa and Guayacum officinalis. Exposure of B. alexandrina snails to plant’s methanol extracts led to a significant reduction in their survival and growth rates. In addition, newly hatched snails were susceptible to plant’s methanol extracts than elder ones. LC₂₅ of methanol extract from these plants caused a considerable reduction in the infectivity of Schistosoma mansoni miracidia to the snails. It caused a reduction in number of cercariae per snail during the patent period and in the period of cercarial shedding. The results, also, revealed that the glucose concentration in treated snails was increased in haemolymph, while soft tissue glycogen decreased. The activities of glycogen phosphorylase, succinate dehydrogenase (SDH), glucose-6-phosphatase and acetylcholinesterase (AchE) in homogenate of snail’s tissues were reduced (P < 0.001) in response to treatment with plants methanol extract, while glucose-6-phosphate dehydrogenase (G-6-PD) activity increased (P < 0.001). It was concluded that the application of LC₂₅ of methanol extracts of E. splendens, A. stylosa and G. officinalis may be helpful in snail control as it interferes with the snails’ biology and physiology.     

Changes in the physical properties of two Acacia compost-based growing media and their effects on carob (Ceratonia siliqua L.) seedling development

In arid zones, the use of compost for plant production in forest nurseries is hindered by a lack of water. The main objectives of this study were (1) to evaluate the physical stability of composts produced from shredded branches of Acacia cyanophylla and A. cyclops subjected to a repeated drying and wetting cycles, similar to those used at the operational scale in nurseries in arid regions and to compare these composts with a standard peat-vermiculite (PV) substrate; (2) to identify the relevant substrate physical variables that correlate with seedling growth. Carob (Ceratonia siliqua L.) was cultivated during a production cycle of 27 weeks in a completely randomized block experiment. Substrate physical variables were measured at the beginning, middle and end of the experiment. Seedling growth variables were evaluated over the course of the production cycle, while gas exchange and water-relation variables were measured during a wetting and drying cycle at the end of the experiment. All three substrates produced vigorous seedlings with well-developed root systems that colonized the entire root plug. The growth of seedlings produced in the PV substrate was better than those grown in the compost-based substrates. No significant differences in gas exchange capacities and water relation variables were observed among the three substrates at the end of experiment with the exception of net photosynthesis, which was higher for the PV substrate at high substrate matric potential. Excessive drainage was negatively correlated with growth variables while water availability in the early growth phase and air porosity towards the end of experiment were positively correlated. Performance of the two composts could be increased by improving their initial structure and stability and by adjusting the irrigation regime.     

Ploidy determination of some yam species (Dioscorea spp.) by flow cytometry and conventional chromosomes counting

Chromosomes counting and flow cytometry were used for assessing the ploidy level of various yam accessions of the INRA collection located in Guadeloupe. About 85 different clones were evaluated in the D. alata and D. cayenensis-rotundata and four other wild species related to D. cayenensis-rotundata. All the studied clones fitted in 4x, 6x and 8x ploidy levels. No diploid clone was found. Chromosomes counts and flow cytometry data led to the same results. The flow cytometry histograms for D. cayenensis-rotundata were not separated from those of its related wild species. Polyploidisation by fusion of 2n+n gamets was found to be unlikely for the two species D. cayenensis-rotundata and D. alata. Moreover, these results lead to the conclusion that the D. cayenensis-rotundata cultigens and the wild species analysed in this study may belong to the same gene pool.     

Biological and biochemical responses of Biomphalaria alexandrina to some extracts of the plants Solanum siniacum and Artemisia judaica L.

The molluscicidal activity of cold water, boiled water, methanol, ethanol, acetone and chloroform extracts of Solanum siniacum and Artemisia judaica L. plants against Biomphalaria alexandrina snails was carried out. The tests revealed plant’s ethanol extract was more toxic to the snails than the other tested extracts. Therefore, it was tested against snails’ fecundity (M_x), reproduction rate (R₀) and their infection with Schistosoma mansoni miracidia. In addition, biochemical parameters and the activities of some enzymes in tissues of snails treated with the two tested plants were determined. As well, glucose concentration in snails’ hemolymph was evaluated. Exposure of B. alexandrina snails to plant’s ethanol extract led to a significant reduction in their survival and snails’ fecundity, reproduction rate. In addition, it caused a considerable reduction in the infectivity of S. mansoni miracidia to the snails. Also, it caused a reduction in number of cercariae per snail during the patent period and in the period of cercarial shedding. The results revealed that the glucose concentration in hemolymph and Lactate level in soft tissues of treated snails were increased (P < 0.001) while glycogen, total protein, the lipid content and the pyruvate level in snail’s tissues decreased (P < 0.001). The activities of lactic dehydrogenase (LDH), pyruvatekinase (PK) and cytochrome oxidase (CY) enzymes in homogenate of snail’s tissues were reduced (P < 0.001) in response to treatment with the two tested plants while protease (PR) activity increased (P < 0.001). It is concluded that the application of LC₂₅ of ethanol extract of S. siniacum and A. judaica L. may be helpful in snail control as it interferes with the snails’ biology and physiology.     

The improvement of hydraulic efficiency of irrigation systems with particular reference to biological control method

This paper represents a research study of the conveyance efficiencies for one main vegetated canal with particular reference to biological agent, using grass carp (Ctenopharyngodon idella Val.). The canal and the stocking procedure are briefly described and water measurements techniques utilized are analyzed. The results showed that an increasing of irrigation efficiency along the vegetated canal was achieved, in which the flow resistance in terms of Manning's n is decreased. The successive use of biological method in comparison to other methods, are that it combines relatively low cost and a minimum of side effect. However, advantage of conserving water and controlling weed infestation, makes its use of such method, is necessary as water is becoming a scarce commodity.     

Regime behavior for alluvial stable Egyptian canals

The design of stable alluvial canals in Egypt is based on regime formulas. These formulas are valid for conditions prevailing before the construction of the High Aswan Dam (HAD), in which the solid suspension was more than 3500 p.p.m. As the regime of Egyptian canals has changed after the construction of HAD (Suspension solid became less than 100 p.p.m.), the design adopted by old regime equations is not satisfactory and a new design concept for the new regime is necessary.In 1982, investigations were carried out in Egypt based on field study on a group of stable alluvial irrigation channels and other collected data from Irrigation Districts and others, from which a series of design formulas for stable canals has been deduced.In this paper a continuation of regime studies have been emphasized by analyzing currently the available field data measurements on thirty alluvial stable channels in Egypt. A more useful relationships have been achieved which may give an approach for a better solution in the scope of stable canal design in Egypt.An investigation of regime theory verifies that the regime formulas of Egyptian Canals are only valid for the limited range of conditions upon which they are based.     

Biological, biochemical, and molecular parameters of Helisoma duryi snails exposed to the pesticides Malathion and Deltamethrin

Aquatic environments get contaminated with pesticides residues that result from the application of pesticides in agricultural practices. The present study aimed to evaluate the pesticides Malathion and Deltamethrin on biological and biochemical parameters of Helisoma duryi snails. The results showed that LC₁₀ of the two pesticides caused considerable reduction in survival rates and egg production of treated snails. Glucose concentration in hemolymph of the exposed snails showed a significant increase. On the other hand, albumin in hemolymph and glycogen contents as well as the activities of enzymes in tissues of snails including lactate dehydrogenase (LDH), succinate dehydrogenase (SDH), arginase, and ornithine aminotransferase (OAT) were significantly inhibited. Meanwhile, the activity of AMP deaminase of the exposed snails was significantly increased in the hemolymph in response to treatment. The electrophoretic pattern of total protein showed differences in number and molecular weights of protein bands. DNA concentration was investigated by measuring the intensity of the genomic bands and its showed its increase in the treated snails. It was concluded that the residues of Malathion and Deltamethrin pesticides in aquatic environments have toxic effects on non-target organism, e.g. H. duryi snails.     

The effects of GA3, CCC and B-9 upon growth,development and organic compounds in Primula obconica

GA₃ induced stem elongation and had no effect on leaf area, whereas CCC and B-9 reduced those characteristics. All 3 growth substances increased leaf formation. GA₃ and CCC accelerated the beginning and duration of blooming, but B-9 exhibited the opposite trend. Inflorescence formation was promoted by CCC and B-9 and decreased by GA₃. Stalk length of inflorescences was elongated only by GA₃ and dwarfed by CCC and B-9. Carbohydrate fractions and content of anthocyanin in flowers were promoted by CCC and B-9.