Identifying candidates for the phytoremediation of copper in viticultural soils: a systematic review

For many years, copper-based fungicides have been used in viticulture and have contributed to increasing concentrations in soils. Today, it is not uncommon to find vineyard soils with total copper topsoil concentrations above 100 mg kg−1, which may have consequences for both the environment and human health. Phytoremediation, the use of plants to remove heavy metals from soils, is a promising and environmentally-friendly method to extract copper from soils. The objectives of this study were to review and synthesise the current knowledge on copper phytoremediation in vineyard soils and identify future applications. A systematic literature search in Web of Science was conducted on 19 July 2022 and resulted in twenty-seven papers meeting the inclusion criteria. Approximately one third of the papers were from Brazil and most of the experiments had been carried out in pots. In some studies, the addition of bacteria or chelators was also evaluated. Some species, such as Plantago lanceolata L. or Ricinus communis L., can accumulate copper in their tissues at concentrations above 1000 mg kg−1. Addition of bacteria and chelators to the soil can also increase the copper uptake capacity by plants. However, most of the species evaluated accumulate copper in the roots, rather than in the shoots, thus limiting the implementation of this method in practice. Further studies are thus needed to find other hyperaccumulator plants. Future research should focus primarily on the ability of plants to accumulate copper in their aerial parts, their ability to transfer copper from roots to shoots, and their biomass production under high soil copper concentrations. Longer-term experiments and more in situ testing are also needed to evaluate the potential for development and use of copper phytoremediation in vineyards. To conclude, species of the Poaceae and Lamiaceae families are the most promising so far for phytoremediation. Identifying plants able to translocate copper from the roots to the aerial parts will be an important factor in the success of this method

Biological Control of the Raspberry Eriophyoid Mite Phyllocoptes gracilis Using Entomopathogenic Fungi

There is an urgent need to develop biological control methods against the eriophyoid mite, Phyllocoptes gracilis, which causes significant losses in organic raspberry production in Europe. The use of entomopathogenic fungi (EF) is a sustainable alternative to conventional chemical pesticides, reducing the risks of pesticide resistance and other negative environmental impacts of agriculture. The objective of this study was to assess the pathogenicity of three strains of EF, two of Beauveria bassiana and one of Metarhizium anisopliae, on P. gracilis under laboratory conditions. Fungal spore suspensions (1 × 107 spores per mL) were sprayed on detached leaves infested with P. gracilis. Treated mites were kept under controlled conditions (25 ± 3 °C, 72 ± 10% relative humidity and photoperiod of 16:8 (light/dark)) and mite mortality was assessed three, five and seven days after inoculation. At all three measurement points (days after inoculation), the mortality of P. gracilis was highest for B. bassiana strain BB 1.1 and M. anisopliae strain MA 10.1. Our data demonstrate that EFs are promising candidates for the development of biological control agents against P. gracilis in raspberry crops

Improving plantain ( Musa spp. AAB) yields on smallholder farms in West and Central Africa

Plantain is an important staple in West and Central Africa, where it is predominantly grown by smallholder farmers. On-farm data are rare but yields are considered to be low. We collated actual yields in the region, reviewed regional plantain research published from 1976 to 2013, then estimated what yields would be attainable on smallholder farms if the proven, best-fit innovations were adopted. Mean actual yields reported ranged from 2.9 to 8.9Mgha−1 with a mean of 5.7Mgha−1 for False horn plantain and 4.5 to 10.2Mgha−1 with a mean of 7.8Mgha−1 for French plantain. Experiments found dealt with: cultural practices, particularly intercropping; abiotic factors such as fertiliser, mulch application and irrigation; biotic factors, predominantly sucker sanitation methods, but including three controlled yield loss studies on nematodes and black sigatoka; landrace comparisons and the introduction of improved cultivars, predominantly those exhibiting black sigatoka-tolerance. We conclude that intercropping should be retained according to farmer preference as there was no evidence of yield reductions for plantain. Boiling water treatment of suckers should be universally recommended. Inputs, whether mulch or K fertiliser up to 300kgha−1, should be applied as both reduced plant losses and increased bunch mass. With the highest yielding local landrace type, on-farm yields could be increased from 7.8Mgha−1 to 35.5Mgha−1 with purchased inputs or to 23.7 Mg ha−1 without purchased inputs

Can jatropha curcas contribute to climate change mitigation?

Climate change mitigation is one of the key arguments for promoting biofuels. It has been claimed that cultivating jatropha increases the carbon stock when grown on marginal land, and additional GHG reductions are possible by replacing fossil diesel with biofuels. We have shown that bioenergy from jatropha can generate GHG savings of more than 40% compared with fossil fuels. However, jatropha can also create a carbon debt, delaying net savings for more than 50 years. The potential for climate change mitigation depends on where and how the value chain is established and is particularly sensitive to the initial soil and vegetation carbon stocks, land preparation, crop management and use of by-products

Entomopathogens and Parasitoids Allied in Biocontrol: A Systematic Review

Biological pest control is an environmentally friendly alternative to synthetic pesticides, using organisms such as viruses, bacteria, fungi, and parasitoids. However, efficacy is variable and combining different biocontrol agents could improve success rates. We conducted a systematic review of studies combining a parasitoid with an entomopathogenic microorganism, the first of its kind. We searched in Web of Science and extracted data from 49 publications matching the pre-defined inclusion criteria. Combinations of 36 hymenopteran parasitoids with 17 entomopathogenic microorganisms used to control 31 target pests were found. Trichogramma pretiosum and Encarsia formosa were the most frequently studied parasitoids, while Beauveria bassiana, Metarhizium anisopliae, Lecanicillium muscarium, Bacillus thuringiensis var. kurstaki, the Spodoptera exigua multiple nucleopolyhedrovirus, and the Spodoptera frugiperda multiple nucleopolyhedrovirus were the main microbial agents assessed. Out of 49 parasitoid–microorganism combinations assessed in the laboratory experiments, thirty-eight were reported as compatible and six as incompatible. Timing and dosage of biopesticides played a crucial role, with later application and appropriate dosage minimizing adverse effects on parasitoid development. More research is needed to assess compatibility and efficacy under real-world conditions. Our review provides valuable insights for researchers and practitioners to optimize the combined use of micro- and macroorganisms for effective pest control

Response of selected indigenous dryland agroforestry tree species to salinity and implications for soil fertility management

Salt tolerant plants are known to remove excess soluble salts from the soil and thus may be used in land reclamation. We studied the responses of the trees, Balinites aegyptiaca L. (Zygophyllaceae), as well as the Fabaceae, Acacia tortilis (Forssk) Hayne, and Tamarindus indica L. to salinity. Three experiments were conducted on: germination, in the laboratory; seedling performance in a lath house; and, the impact of the tree species on soil productivity in the field in Afar regional state along the Awash river, eastern Ethiopia. Mixtures of salts, composed of chlorides and sulfates were tested at different concentrations in both germination and lath house experiments in randomized complete block designs. Seedling root collar diameter and height were measured every two weeks. Soil samples were collected from randomly selected pots to examine the effect of salinity on soil properties. The effects of trees on in situ soil productivity was studied by collecting 72 soil samples at different distances from the tree and different soil depths. The soil productivity index was calculated. The study revealed that germination percentage and rate decreased significantly with increasing salt concentrations. The effects of the three tree species on soil properties were significantly different at 12.2 dS m -1 salinity level compared to the control. A. tortilis was the least salt-sensitive. Balancing the key requirements of adequate germination and growth and the ability to reduce the salt concentration of the soil solution, B. aegyptiaca is the species with the most potential. Therefore, the study suggests to use B. aegyptiaca as agroforestry trees in the form of parkland in arid and semi-arid areas where salinity problems are prominent

Organic Farming Practices and Shade Trees Reduce Pest Infestations in Robusta Coffee Systems in Amazonia

Coffee agroforestry systems could reconcile agricultural and environmental objectives. While pests and diseases can reduce yield, their interactions with shade and nutrition have been rarely researched, and are particularly lacking in perennial systems. We hypothesized that intermediate shade levels could reduce coffee pests while excess shade could favor fungal diseases. We hypothesized that organic rather than mineral fertilization would better synchronize with nutrient uptake and higher nutrient inputs would be associated with reduced pest and disease damage due to higher plant vigor, yet effects would be less obvious in shaded plots as coffee growth would be light-limited. Using three-year-old trees of Coffea canephora var. Robusta (robusta coffee) in the Ecuadorian Amazon, we compared a full-sun system with four shading methods creating different shade levels: (1) Myroxylon balsamum; (2) Inga edulis; (3) Erythrina spp.; or, (4) Erythrina spp. plus Myroxylon balsamum. Conventional farming at either (1) moderate or (2) intensified input and organic farming at (3) low or (4) intensified input were compared in a split-plot design with shade as the main plot factor and farming practice as the sub-plot factor. The infestation of the following pests and disease incidences were evaluated monthly during the dry season: brown twig beetle (Xylosandrus morigerus), coffee leaf miner (Leucoptera coffeella), coffee berry borer (Hypothenemus hampei), anthracnose disease (Colletotrichum spp.), thread blight (Pellicularia koleroga), and cercospora leaf spot (Cercospora coffeicola). Coffee berry borer and brown twig beetle infestation were both reduced by 7% in intensified organic treatments compared to intensified conventional treatments. Colonization of coffee berry borer holes in coffee berries by the entomopathogenic fungus Beauveria bassiana was also assessed. Brown twig beetle infestation was significantly higher under full sun than under Inga edulis, yet no other shade effects were detected. We demonstrate for the first time how intensified input use might promote pest populations and thus ultimately lead to robusta coffee yield losse

Arbuscular mycorrhizal fungi improve nutrient status of Commiphora myrrha seedlings under drought

In dryland ecosystems, tree and shrub seedling establishment, growth and survival are limited by access to water and nutrients. Arbuscular mycorrhizal fungi (AMF) increase seedling establishment and survival by enhancing nutrient and water acquisition. We executed a fully-factorial greenhouse experiment to determine the interactive effect of AMF (with and without), water deficit (four levels), and soil layer (topsoil and subsoil) on the biomass, growth, nutrient concentrations, and mycorrhizal root colonization of seedlings of Commiphora myrrha, a tree species that dominates large areas of dry forest and woodland in the Horn of Africa. Mycorrhizal seedlings had higher root and shoot biomass than non-mycorrhizal seedlings. They also had higher nutrient concentrations in root and shoot. Plant biomass was higher when plants were grown in topsoil at lower soil moisture levels. Mycorrhizal responsiveness was highest at lower soil moisture. The drought response index was higher for mycorrhizal than for non-mycorrhizal plants, indicating enhanced mycorrhizal benefits at lower water supply. Seedlings grew better in topsoil than in subsoil. Mycorrhizal colonization of roots of C. myrrha seedlings was higher with lower moisture and higher in topsoil than in subsoil. The increased performance of mycorrhizal C. myrrha indicates that mycorrhization is a major component of the adaptive strategy of seedlings of this species, similar to other species in these dryland deciduous ecosystems. We conclude that for restoration purposes with this species, nursery seedlings should be mycorrhized because of their enhanced growth performance

Effects of Forest Composition and Disturbance on Arbuscular Mycorrhizae Spore Density, Arbuscular Mycorrhizae Root Colonization and Soil Carbon Stocks in a Dry Afromontane Forest in Northern Ethiopia

We investigated arbuscular mycorrhizal fungi (AMF) spore density and root colonization in three distinct dry Afromontane forest plant communities, representing differing levels of disturbance and soil properties. Soil and root samples were collected from sixty-five 50 × 50-m plots from four plant communities. We collected data for AMF spore density, AMF root colonization and soil organic carbon stocks in 0–25 and 25–50 cm soil depth ranges. AMF spore density, and root colonization differed significantly among plant communities. The least disturbed Juniperus procera–Maytenus senegalensis (Jupr-Mase) plant community, which contained high tree and shrub density, had the highest AMF spore density, root colonization and soil carbon stocks. The most disturbed Cadia purpurea–Opuntia ficus-indica (Capu-Opfi) community which contained the lowest tree and shrub density supported the lowest AMF spore density, root colonization and soil carbon stocks. There was no significant difference in spore density between the two soil depths, but AMF root colonization was significantly higher in the upper soil than in the subsoil (p < 0.001). The difference in soil properties was not uniform between plant communities. Conserving remnant dry Afromontane forests and restoring the degraded forests are critical to improve and maintain forest ecosystem functioning and sustain ecosystem services