Improving performance of olive trees by the enhancement of key physiological parameters of olive leaves in response to foliar fertilization

Most of the studies investigated the effects of nutrient-based fertilizers on olive fruits and oil quality; few studies have been interested in the modification of the chemical composition of olive leaves in response to fertilization. Thus, the current study aims to examine the effects of foliar fertilization on the mineral profile of olive leaves as well as the concentrations of chlorophyll, antioxidants (phenolic compounds) and carbohydrates. Experimentation consists of the annual application of six treatments during two successive growing seasons (2009–2010): TC (untreated trees), P1 (nitrogen-based fertilizer), P2 (contains boron, magnesium and manganese), P3 (phosphorus and potassium based fertilizer), P4 (rich in calcium and phosphorus), T5 (P1 and P2 application) and T6 (P1, P2, P3 and P4 application). At the end of the experiment, mineral analysis of olive leaves showed an increase in the concentrations of most nutrients which induced changes in biochemical composition: an increase of chlorophyll content, a reduction of total phenols and oleuropein concentrations coupled with an increase of hydroxytyrosol level. Moreover, an increase of total sugar content and most individual sugars, principally translocated forms of sugars (mannitol, sucrose and raffinose), was also observed. The accumulation of these key physiological parameters by foliar fertilization suggests an improvement of physiological performance and photosynthetic capacity of olive trees. Moreover, from a biological point of view, the results of the study revealed the possibility to improve plants of medicinal interest by enhancing the accumulation of some bio-active compounds, such as hydroxytyrosol and mannitol, via foliar nutrient supply.     

Risk factors for total joint arthroplasty infection in patients receiving tumor necrosis factor α-blockers: a case-control study

Introduction

The objective of this study was to assess natural microbial agents, history and risk factors for total joint arthroplasty (TJA) infections in patients receiving tumor necrosis factor (TNF)α-blockers, through the French RATIO registry and a case-control study.

Methods

Cases were TJA infections during TNFα-blocker treatments. Each case was compared to two controls (with TJA and TNFα-blocker therapy, but without TJA infection) matched on age (±15 years), TJA localization, type of rheumatic disorder and disease duration (±15 years). Statistical analyses included univariate and multivariate analyses with conditional logistic regression.

Results

In the 20 cases (18 rheumatoid arthritis), TJA infection concerned principally the knee (n = 12, 60%) and the hip (n = 5, 25%). Staphylococcus was the more frequent microorganism involved (n = 15, 75%). Four patients (20%) were hospitalized in an intensive care unit and two died from infection. Eight cases (40%) versus 5 controls (13%) had undergone primary TJA or TJA revision for the joint subsequently infected during the last year (P = 0.03). Of these procedures, 5 cases versus 1 control were performed without withdrawing TNFα-blockers (P = 0.08). In multivariate analysis, predictors of infection were primary TJA or TJA revision for the joint subsequently infected within the last year (odds ratio, OR = 88.3; 95%CI 1.1-7,071.6; P = 0.04) and increased daily steroid intake (OR = 5.0 per 5 mg/d increase; 1.1-21.6; P = 0.03). Case-control comparisons showed similar distribution between TNFα-blockers (P = 0.70).

Conclusions

In patients receiving TNFα-blockers, TJA infection is rare but potentially severe. Important risk factors are primary TJA or TJA revision within the last year, particularly when TNFα-blockers are not interrupted before surgery, and the daily steroid intake.     

In vitro toxicity and genotoxic activity of aqueous leaf and fruit extracts of <Emphasis Type="Italic">Ruscus hypophyllum</Emphasis> L.

Ruscus hypophyllum L. is a rare Mediterranean plant which is used in the traditional medicine. We studied its phenolic content and in vitro toxicity and genotoxicity using the neutral red uptake (NRU) test, the bacterial Vitotox test, and the comet assay in human C3A hepatic cells. Aqueous leaf and fruit extracts were investigated. Antigenotoxicity against 4-nitroquinoline-oxide (4NQO, 0.4 µg/mL) and Benzo(α)pyrene (BaP, 800 µg/mL) was also investigated with the Vitotox test. The extracts appeared to be genotoxic only at high exposure levels in the comet assay. There was no indication of a genotoxic activity in the Vitotox test and also no indication of antigenotoxicity. The moderate polyphenol content may provide an explanation for the absence of antigenotoxicity.     

Effects of mycorrhizal fungi inoculation and soil amendment with hydrogel on leaf anatomy,growth and physiology performance of olive plantlets under two contrasting water regimes

Abiotic stresses present a real environmental problem in agriculture field. In our paper, we examine the significance of arbuscular mycorrhizal fungi (AMF) and soil amendment with water retaining superpolymers (hydrogel) on growth and physiology performance of olive plantlets. Our experiment was carried out in nursery conditions, to test the impact of hydrogel (TH) and mycorrhizal fungi (TM), used individually or combined (THM), and compare them with non inoculated plants (TC), to understand and reduce the water stress damage in olive plantlets (cv. Chemlali). We also evaluate interactions between hydrogel, mycorrhizal treatments and water regimes. Results of mycorrhization (M%) show that roots colonized by Rhizophagus irregularis of well-watered plants were about 40.87%. In combined treatment (THM), M% was about 32.14%. Compared to TC treatment, TM treatment enhances significantly the dry weights of the whole plant under the two water regimes. The TM treatment had the highest relative water content (66.50%) and Chl (a?+?b) (0.83 mg g^??1) in stressed conditions. We found also that under water stress, the maximal quantum efficiency of the photosystem II measurements in leaves were significantly improved by 50.70% in TH treatment compared to control. For phenolic contents, TH treatment decreased significantly total phenols by 50.10% compared to TC. Our study gives evidence that the use of AMF and the hydrogel separately or in combination may enhance the capacity to avoid drought damages of olive plantlets and improve olive performances.     

Seasonal changes in the testicular morphology and interstitial tissue histomorphometry of Sahraoui camel under Algerian extreme arid conditions

The seasonal testicular morphology and the morphometry of the interstitial tissue were studied in 62 camels at Algerian extreme arid region. The maximal testicular size was recorded during the rutting season. In this period, the interstitial tissue occupied high area and volume with significant increase of the intertubular constituent’s volume, hypertrophy of the Leydig cell, and maximal number of Leydig cells per testes. Therefore, the highest ratios of seminiferous tubules to interstitial tissue area and volume and the highest fraction of intertubular empty space were recorded during the non-rutting. The greater Leydig cell nucleus size was observed during the post-rutting season. Finally, the numerical density of Leydig cells did not significantly change over the year. These results provide information on the relationship between seasonal changes of camel testicular morphology and the histomorphometry of the testicular endocrine compartment in camels at the arid livestock conditions of the southeastern Algerian desert.     

Differences in abscisic acid concentration in roots and leaves of two young Olive (<Emphasis Type="Italic">Olea europaea</Emphasis> L.) cultivars in response to water deficit

Differences in abscisic acid (ABA) accumulation between two olive cultivars were studied by enzyme-linked immunosorbent assay in roots and leaves, leaf water potential (Ψ_l), stomatal conductance (g _s) as well as photosynthetic rate (A) were also determined in well-watered (WW) and water-stressed (WS) plants of two olive cultivars ‘Chemlali’ and ‘Chetoui’. ‘Chemlali’ was able to maintain higher leaf CO₂ assimilation rate and leaf stomatal conductance throughout the drought cycle when compared with ‘Chetoui’. Furthermore, leaf water potential of ‘Chemlali’ decreased in lower extent than in Chetoui in response to water deficit. Interestingly, significant differences in water-stress-induced ABA accumulation were observed between the two olive cultivars and reflect the degree of stress experienced. Chemlali, a drought tolerant cultivar, accumulated lower levels of ABA in their leaves to regulate stomatal control in response to water stress compared to the drought sensitive olive cultivar ‘Chetoui’ which accumulated ABA in large amount.     

Effects of the planting density on water relations and production of ‘Chemlali’ olive trees (Olea europaea L.)

Water relations are a key factor limiting olive production. In this study, effects of plating density on physiological aspects and productivity of ‘Chemlali’ olive trees were analyzed under rain-fed conditions in four planting densities (156, 100, 69 and 51 trees ha⁻¹), in an experimental olive orchard located in the center of Tunisia. Seasonal changes in leaf relative water content (RWC), leaf water potential, stomatal conductance (g _s), CO₂ assimilation rate and tree production were studied. Accompanying the changes in leaf water status, all the monitored trees reduced leaf stomatal conductance (g _s) and photosynthetic rate (A) throughout the summer drought, mirroring the increase in soil moisture deficit and vapor pressure deficit. However, the decrease in gas exchange was much more pronounced in high planting densities than in low ones. Our results confirm that the increase of tree-to-tree water competition with planting density was significant in the dry climate of Tunisia. Thus, planting density is critical when planting new olive orchards in arid regions.     

Changes in lipid composition, water relations and gas exchange in leaves of two young ‘Chemlali’ and ‘Chetoui’ olive trees in response to water stress

The comparative responses of two young olive trees (Olea europaea L. ‘Chemlali’ and ‘Chetoui’) to drought stress were investigated during 1 month. Three-month-old own-rooted plants were subjected to two irrigation treatments: WW (well watered plants that were irrigated with fresh water to maintain a soil water content close to field capacity), and WS (water stressed plants by withholding water). Leaf water potential, gas exchange and leaf lipid composition were studied. ‘Chemlali’ was able to maintain higher leaf CO₂ assimilation rate and leaf stomatal conductance throughout the drought cycle compared to ‘Chetoui’. Water stress induced a larger decrease in the total lipid content in ‘Chetoui’ than in ‘Chemlali’. Interestingly, the constitution of different lipid classes was highly altered in ‘Chetoui’. Lipid changes in Chemlali, a drought tolerant cultivar, revealed more stability of its cellular membranes to drought stress as compared to the drought susceptible olive cultivar, Chétoui. Furthermore, in comparison to the controls, drought stressed plants showed an increase in the degree of unsaturation of leaf lipids in the two olive cultivars. Moreover, the results observed in Chemlali showed that besides changes in lipids composition this cultivar may have an efficient defence strategy which can be related on antioxidative production against oxidative stress.