Gisela Díaz

Selection of Plant Species–Organic Amendment Combinations to Assure Plant Establishment and Soil Microbial Function Recovery in the Phytostabilization of a Metal-Contaminated Soil

A mesocosm experiment was established to evaluate the effect of two organic wastes: fermented sugar beet residue (SBR) and urban waste compost on the stimulation of plant growth, phytoaccumulation of heavy metals (HM) and soil biological quality and their possible use in phytostabilization tasks with native (Piptatherum miliaceum, Retama sphaerocarpa, Bituminaria bituminosa, Coronilla juncea and Anthyllis cytisoides) and non-native (Lolium perenne) plants in a heavy metal-contaminated semiarid soil. Except R. sphaerocarpa, SBR increased the contents of shoot N, P and K and shoot biomass of all plants. The percentage of mycorrhizal colonization was not affected by the organic amendments. The highest increase in dehydrogenase and β-glucosidase activities was recorded in SBR-amended P. miliaceum. SBR decreased toxic levels of HM in shoot of P. miliaceum, mainly decreasing Fe and Pb uptake to plants. This study pointed out that the SBR was the most effective amendment for enhancing the plant performance and for improving soil quality. The combination of SBR and P. miliaceum can be regarded the most effective strategy for being employed in phytostabilization projects of this contaminated site.

The combination of compost addition and arbuscular mycorrhizal inoculation produced positive and synergistic effects on the phytomanagement of a semiarid mine tailing

A field experiment was carried out to assess the effectiveness of combining mycorrhizal inoculation with a native AM fungus (Glomus sp.) and the addition of an urban organic waste compost (OWC) applied at two rates (0.5 and 2.0% (w:w)), with regard to promoting the establishment of Anthyllis cytisoides L. seedlings in a heavy metal polluted mine tailing, as well as stimulating soil microbial functions. The results showed that the combined use of the highest dose of OWC and AM inoculation significantly increased shoot biomass - by 64% - compared to the control value. However, the separate use of each treatment had no effect on the shoot biomass of this shrub species. At the 2% rate, OWC enhanced root colonisation by the introduced fungus as well as soil nutrient content and soil dehydrogenase and ß-glucosidase activities. The combined treatment increased the uptake of Zn and Mn in shoots, although only Zn reached excessive or potentially toxic levels. This study demonstrates that the combination of organic amendment and an AM fungus is a suitable tool for the phytomanagement of degraded mine tailings, although its effectiveness is dependent on the dose of the amendment.

Mycorrhizal synthesis of Lactarius indigo (Schw.) Fr. with five Neotropical pine species

This paper describes for the first time the ectomycorrhiza synthesized between two Guatemalan strains of Lactarius indigo (Schw.) Fr. and the Neotropical species Pinus ayacahuite var. ayacahuite Ehren, P. hartwegii Lindl., P. oocarpa Schiede ex Schltdl. var oocarpa, P. pseudostrobus Lindl. and P. rudis Endl. The synthesis was carried out in a controlled growth chamber using plastic containers with peat moss-vermiculite substrate and mycelial inoculum. Mycorrhiza were obtained 25 days after inoculation. A description of the morphology, appearance and structure of mantle and Hartig net is given for each combination. Mycorrhiza were saffron to cinnamon greenish with age, with a net of saffron laticifers visible through outer mantle; orange latex secreted when injured. Cystidia-like emanating hyphae were observed on the mantle surface of young mycorrhiza. Plectenchymatous mantle with abundant interhyphal gelatinous material.

Date Palm Status and Perspective in Spain

The date palm (Phoenix dactylifera L.) is an archaeophyte in Spain and is the iconic species of an introduced mixed irrigated agricultural system of food crops, animal feed, grasses, and livestock. Traditionally, date palms are propagated from seed and grown for their fruits, as well as for products derived from the leaves and stem wood. The seedling date palm populations in Spain represent a diverse pool of genetic resources with potential to improve the crop in general. Depending on the local microclimate, 20–50 % of date fruits in Spain do not fully ripen on the tree because of cooler temperatures late in the growing season. Artificial ripening techniques have been devised to deal with this situation. Local genotypes are under study for the best fruit types for expanded marketing, as a gourmet fresh fruit product in Europe, to enhance farmer income and to sustain the traditional production system. Tissue culture of selected genotypes is contributing to sustainability of the palm groves. New commercial date products are under study to broaden economic possibilities. The exotic red palm weevil pest represents the main threat to the palm grove and control measures are being pursued. Historic palm groves persist in Spain, especially in Elche and Orihuela, as well as presumably naturalized feral palms exhibiting distinctive morphological characteristics described as P. iberica. Phoenix palms are protected and continue to provide commercial fruits and palm leaves for religious ceremonies and to enhance the local landscape. Elche, the largest palm grove, is a World Heritage Site and a major tourist attraction.