The roles of non-structural carbohydrates in fruiting: a review focusing on mango (Mangifera indica).

Reproductive development of fruiting trees, including mango (Mangifera indica L.), is limited by non-structural carbohydrates. Competition for sugars increases with cropping, and consequently, vegetative growth and replenishment of starch reserves may reduce with high yields, resulting in interannual production variability. While the effect of crop load on photosynthesis and the distribution of starch within the mango tree has been studied, the contribution of starch and sugars to different phases of reproductive development requires attention. This review focuses on mango and examines the roles of non-structural carbohydrates in fruiting trees to clarify the repercussions of crop load on reproductive development. Starch buffers the plant's carbon availability to regulate supply with demand, while sugars provide a direct resource for carbon translocation. Sugar signalling and interactions with phytohormones play a crucial role in flowering, fruit set, growth, ripening and retention, as well as regulating starch, sugar and secondary metabolites in fruit. The balance between the leaf and fruit biomass affects the availability and contributions of starch and sugars to fruiting. Crop load impacts photosynthesis and interactions between sources and sinks. As a result, the onset and rate of reproductive processes are affected, with repercussions for fruit size, composition, and the inter-annual bearing pattern.

Outcomes and Hospital Service Use Among Patients With COPD in a Nurse- and Allied Health-Led Clinic.

Importance: Multidisciplinary disease management efforts enable the improvement in lung function among patients with chronic obstructive pulmonary disease (COPD), but there is little evidence of its association with risks of adverse health outcomes and health care service use. Objective: To examine the association between the use of a nurse- and allied health-led primary care clinic for respiratory patients, namely the Nurse and Allied Health Clinic-Respiratory Care (NAHC-Respiratory), and their risks of mortality and morbidity and health care service use. Design, Setting, and Participants: This territory-wide, population-based, propensity-matched, retrospective cohort study used data from the electronic health records of all patients who used public health care services in Hong Kong, China, from January 1, 2010, to December 31, 2019. All patients with COPD treated in public outpatient clinics between January 1, 2010, and December 31, 2014, were included. Patients who attended NAHC-Respiratory and usual care only were propensity score-matched at a 1:2 ratio. Data analyses were conducted between August 2023 and April 2024. Exposure: Attendance at NAHC-Respiratory. Main Outcomes and Measures: All-cause and cause-specific mortality, incidence of COPD complications, and use of emergency department and inpatient services until the end of 2019 were compared between the NAHC-Respiratory and usual care participants using Cox proportional hazard regression, Poisson regression, and log-link gamma regression models after matching. Results: This study included 9048 eligible patients after matching, including 3093 in the exposure group (2814 [91.0%] men; mean [SD] age, 69.8 [9.5] years) and 5955 in the reference group (5431 [91.2%] men; mean [SD] age, 69.5 [11.7] years). Compared with patients in the usual care-only group (reference), patients in the exposure group had lower risks of all-cause mortality (hazard ratio [HR], 0.84; 95% CI, 0.78-0.90) as well as pneumonia-caused (HR, 0.85; 95% CI, 0.74-0.97), respiratory-caused (HR, 0.86; 95% CI, 0.77-0.96), and cardiovascular-caused (HR, 0.74; 95% CI, 0.59-0.93) mortality. Exposure was associated with reduced rates of emergency department visits (incidence rate ratio [IRR], 0.92; 95% CI, 0.86-0.98) and hospitalization through emergency department (IRR, 0.89; 95% CI, 0.83-0.95). Conclusions: In this cohort study, the use of a nurse- and allied health-led clinic in primary care settings was associated with reduced risks of mortality and use of hospital services among patients with COPD. These findings emphasize the important role of health care workers other than physicians in disease management in the primary care setting. The NAHC-Respiratory model and service components can be used to help improve primary care programs to benefit more patients with COPD.

Nitrogen fertilizer rate but not form affects the severity of Fusarium wilt in banana.

Nitrogen (N) fertilizers are routinely applied to bananas (Musa spp.) to increase production but may exacerbate plant diseases like Fusarium wilt of banana (FWB), which is the most economically important disease. Here, we characterized the effects of N rate and form on banana plant growth, root proteome, bacterial and fungal diversity in the rhizosphere, the concentration of Fusarium oxysporum f.sp. cubense (Foc) in the soil, and the FWB severity. Banana plants (Musa subgroup ABB) were grown under greenhouse conditions in soil with ammonium or nitrate supplemented at five N rates, and with or without inoculation with Foc. The growth of non-inoculated plants was positively correlated with the N rate. In bananas inoculated with Foc, disease severity increased with the N rate, resulting in the Foc-inoculated plant growth being greatest at intermediate N rates. The abundance of Foc in the soil was weakly related to the treatment conditions and was a poor predictor of disease severity. Fungal diversity was consistently affected by Foc inoculation, while bacterial diversity was associated with changes in soil pH resulting from N addition, in particular ammonium. N rate altered the expression of host metabolic pathways associated with carbon fixation, energy usage, amino acid metabolism, and importantly stress response signaling, irrespective of inoculation or N form. Furthermore, in diseased plants, Pathogenesis-related protein 1, a key endpoint for biotic stress response and the salicylic acid defense response to biotrophic pathogens, was negatively correlated with the rate of ammonium fertilizer but not nitrate. As expected, inoculation with Foc altered the expression of a wide range of processes in the banana plant including those of defense and growth. In summary, our results indicate that the severity of FWB was negatively associated with host defenses, which was influenced by N application (particularly ammonium), and shifts in microbial communities associated with ammonium-induced acidification.

Extraction of metals from mildly acidic tropical soils: Interactions between chelating ligand, pH and soil type.

Naturally occurring and synthetic chelating ligands can act as suppressants for fungal pathogens, nematodes and weeds, based on their ability to alter micronutrient bioavailability in soil, particularly iron. Chelators are also used as detergents, for remediation of heavy metal contamination and for supplying metals as fertiliser. The aim of this work was to test the ability of chelators to solubilise metals, in particular iron, in tropical soils over an environmentally relevant pH range. Six topsoils from farms in North Queensland, Australia were adjusted to pH 5, 6 and 7 and then extracted with CaCl2, EDTA, DTPA, EDDHA and mimosine. The extracts were analysed for concentrations of aluminium, copper, iron, magnesium, manganese, potassium, strontium and zinc. EDDHA solubilised iron effectively under all of the conditions tested, indicating its likely suitability for pest suppression. The concentration of aluminium in EDDHA extracts was positively correlated with pH, and at pH 7 the concentration of aluminium was far greater than that of iron. An increase in the mobility of aluminium from EDDHA application to soil may lead to aluminium toxicity in plants, which should be considered further in any practical application of EDDHA. Mimosine, which is also a strong chelator, was a poor extractor of all metals, possibly due to adsorption to the soil.

Sorption behaviour of per- and polyfluoroalkyl substances (PFASs) in tropical soils.

The sorption behaviour of three perfluoroalkyl substances (PFASs), namely perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA) and perfluorohexane sulfonic acid (PFHxS), was determined on 28 tropical soils. Tropical soils are often highly weathered, richer in sesquioxides than temperate soils and may contain variable charge minerals. There are little data on sorption of PFASs in tropical soils. The highest Kd values were found for PFOS with mean values ranging from 0 to 31.6 L/kg. The Kd values for PFOA and PFHxS ranged from 0 to 4.9 L/kg and from 0 to 5.6 L/kg, respectively. While these values are in the range of literature sorption data, the average Kd values for PFOS and PFOA from the literature were 3.7 times and 3.6 times higher, respectively, than those measured in this study. Stepwise regression analysis did explain some of the variance, but with different explanatory variables for the different PFASs. The main soil properties explaining sorption for PFOS and PFOA were oxalate-extractable Al and pH, and for PFHxS was pH.

The role of surface charge and pH changes in tropical soils on sorption behaviour of per- and polyfluoroalkyl substances (PFASs).

This study investigated the effect of surface charge on the sorption of perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA) and perfluorohexane sulfonic acid (PFHxS) onto 7 tropical soils as a function of pH. The net surface charge became less negative with decreasing pH (from 7.5 to 3.5) in all soils. The rate of change in net surface charge varied from -0.6 to -2.8 (cmol/kg)/pH unit. The effect on sorption behaviour of PFASs was variable among soils. For two soils, the average sorption increased 54- and 45-fold for PFOS, 33- and 9-fold for PFOA, and 39- and 400-fold for PFHxS, across the pH range 7.5 to 3.5. Sorption in another sandier soil showed negligible change with decreasing pH. Sorption in the other soils did not change significantly until the pH decreased to approximately 5.5. The soils with high contents of sesquioxides (Fe and Al oxides) showed the most marked increase in sorption with decreasing pH. This study demonstrated that in addition to hydrophobic interactions with OC and other processes, electrostatic interactions are also important in the sorption process for these chemicals in soils. In acidic, variably charged tropical soils there is the possibility that any PFOS, PFOA or PFHxS sorbed to the soils may become desorbed if management practices (e.g. liming) raised soil pH.