Influence of different soil moisture levels on boron behavior in sunflower nutrition

The effect of different soil water regimes on the behaviour of boron on the nutrition of sunflower has been studied on a calcareous soil and a noncalcareous soil in a greenhouse pot experiment. The results obtained showed that the different parts of sunflower (leaves, steam, head, roots) were affected by the decrease of water availability. The reductions observed vary from 2.5 to 50.3%, 4.8 to 31.7% and 4.8 to 65.3%, for dry matter, boron concentration and boron uptake respectively. The different parts of sunflower reacted with the same intensity. The mean reductions observed in the dry matter were 21.7%, 23.1%, 23.9% and 23.9% for the leaves, the steam, the head and the roots respectively. Those observed in boron uptake were 32.8%, 34.9%, 32.5% and 36.1% for the leaves, the steam, the head and the roots respectively. This decrease was more important for the calcareous soil compared to the non-calcareous soil. Boron translocation from roots to shoots varied from 45.4 to 57.0%, 17.3 to 21.1% and 17.0 to 22.2% for the leaves, the steam and the head respectively

The various forms of soil boron: importance, effect of soil characteristics and plant availability

The study has been carried out on eleven soils using both soil analysis and a greenhouse pot experiment. Soil boron has been determined according to the hot water method and fractioned in five distinct fractions. The greenhouse experiment was carried out according to the Neubauer technic using barley as the plant test. Hot water boron represents 0.81% of total boron. The > and > fractions are negligible and represent together 1.18% of total boron. The residual fraction constitutes the most important fraction and represents 78.75%. Intermediate fractions represent together 20.08%, of which 8.04% is bound to oxydes and 12.04% is bound to organic matter. The soil characteristics that most influenced the different forms of soil boron are cation exchange capacity, texture, organic matter and pH. Highly significant correlations have been observed between these soil characteristics and some forms of soil boron. Boron uptake by barley was higher than the quantities of boron corresponding to the > and > fractions. This means that other forms, including organic matter bound-form and probably also oxydes bound-form, participated in boron nutrition of the plants

Adsorption et désorption du bore sur les sols et influence des apports de fumier

Boron adsorption-desorption processes were invistigated in 11 soils and composted manure according to the Langmuir and Freundlich isotherms. The data obtained showed that these processes have been well described by these isotherms (r ranging from 0.902*** to 0.999***). Adsorption capacities of soils varied from 23.98 to 102.04 mug B/g soil. Significant relationships were observed between these adsorption capacities and some of the soil characteristics, mainly clay content (r = 0.730**), organic matter content (r = 0.615**) and cation exchange capacity (r = 0.852***). The adsorption capacity of composted manure was 312.50 mug B/g manure and represents 3 to 13 times that of the studied soils. Incorporation of manure to soils increased their adsorption capacities. Comparison of desorption to adsorption isotherms showed that there was a hysteretic effect for all the substrats studied. However, this effect was more important for the soils than for the composted manure. The desorption index for the composted manure was 1.5183, a value not far from 1, which indicates the reversibility of the adsorption process. The mean desorption indices observed varied from 1.9771 to 4.7639 for soils. Significant relationships were observed between these indices and some of the soil characteristics, of which organic matter content (r = -0.787**) and cation exchange capacity (r = -0.709**). The incorporation of composted manure to soils caused an important decrease of their desorption indices

Clinical and Molecular Epidemiology of Extended-Spectrum Beta-Lactamase-Producing Klebsiella spp.: A Systematic Review and Meta-Analyses

Healthcare-related infections caused by extended-spectrum beta-lactamase (ESBL)-producing Klebsiella spp. are of major concern. To control transmission, deep understanding of the transmission mechanisms is needed. This systematic review aimed to identify risk factors and sources, clonal relatedness using molecular techniques, and the most effective control strategies for ESBL-producing Klebsiella spp. A systematic search of PubMed, Embase, and Outbreak Database was performed. We identified 2771 articles from November 25th, 1960 until April 7th, 2014 of which 148 were included in the systematic review and 23 in a random-effects meta-analysis study. The random-effects meta-analyses showed that underlying disease or condition (odds ratio [OR] = 6.25; 95% confidence interval [CI] = 2.85 to 13.66) generated the highest pooled estimate. ESBL-producing Klebsiella spp. were spread through person-to-person contact and via sources in the environment; we identified both monoclonal and polyclonal presence. Multi-faceted interventions are needed to prevent transmission of ESBL-producing Klebsiella spp