Biodegradation of olive washing wastewater pollutants by highly efficient phenol-degrading strains selected from adapted bacterial community

The bacterial community of an olive washing water (OWW) storage basin was characterized, by both cultivation and cultivation-independent methods. PCR-TGGE fingerprints analysis of different samples, taken along the olive harvesting season, revealed important variations of the bacterial community structure showing rapid establishment of prevalent bacterial populations. Several bacteria, isolated from OWW, were cultivated, in media containing increasing amounts of polyphenols, in order to select high phenol-degrading strains for the effluent pollutants reduction. Strains PM3 and PM15, affiliated to Raoultella terrigena and Pantoea agglomerans by 16S rRNA gene sequencing, were selected and used for OWW biological treatment under batch conditions in shake flasks cultures. The OWW content of phenols, BOD5, COD and colour, was reduced by 93, 91, 89 and 62%, respectively, permitting effluent disposal and/or reuse with no additional treatments.This research was supported by European project Algatec (FP7/SME/2008/1/232331)

Efficient urea-N and KNO3-N uptake by vegetable plants using fertigation

Vegetable production demands high nitrogen inputs. Fertigation is a means to increase fertilizer-N use by plants. However, the effect of different N sources and doses, and how they relate to the total available N in soils are poorly known. In this study we applied 15N-labeled fertilizers to green pepper in the field using a drip irrigation system during the dry summer. KNO3-N and urea-N were applied at a total of 6, 12 and 18 g plant−1. Our results show that urea was as effective as KNO3 as a N source. The fertilizer-N utilization efficiency was dramatically reduced at higher N doses, from 48% for the 6 g N plant−1 dose to 36% and 26% for the 12 and 18 g N plant−1 doses, respectively. However, the N in plants derived from fertilizer consistently exceeded 60%, indicating high availability of fertilizer-N even at the lowest dose. Negative added nitrogen interactions – the effect of added N on the fate of soil-N – were observed, particularly at high fertilizer-N doses. The fertilizer-N utilization efficiency calculated by the difference method was lower compared with the 15N enrichment method. This clearly indicates luxury N applications and excess N availability brought about by precise localized placement of fertilizer-N that leads to limited uptake of the available soil-N. N leaching risks in the following rain period should therefore be based on both the residual fertilizer-N and the increased amounts of residual soil mineral-N

Towards a paradigm for the convergence of production, marketing and environmental protection in the field of the organic olive oil production chain- Conclusions from the BIOLMED project

The majority of innovations pioneered within/for the organic olive oil production (OOOP) chain may, and are, increasingly becoming, adopted by the conventional olive oil production chain, especially regarding cultivation, inputs related to plant/ecosystem protection and trade/promotion of specialized high quality products. Therefore the OOOP-chain may become a pioneering paradigm, for the implementation and convergence of agricultural production, marketing, sustainable rural development and environmental/biodiversity protection EU policies in the Mediterranean. Moreover, it appears that OOOP systems are increasingly becoming model systems for developing, applying and evaluating innovations that may have far more general applicability for Mediterranean agriculture. There is little divergence between conventional and organic production regarding water consumption and waste production, but the OOOP-chain has a lower impact as regards to soil erosion, desertification, pollution due chemicals and fertilizers (minimal), and effects on wildelife/vegetation biodiversity. Regarding pest and disease control, Bactrocera oleae is the most common pest problem, but effective means of control are available. On the contrary, Verticillium wilt is constantly expanding and, although not still a widespread problem, it is difficult to manage. Bottom-up demand for innovations, however, tends to underrate the need for innovations on common marketing priorities, trade policies, infrastructure and joint promotion strategies. Regarding “biopesticides” and “natural products”, approval protocols and legislation regarding synthetic inputs should also be fully applied to these products, to assure safe development of the OOOP sector. By working on innovations, differentiations, measures, policies and strategies regarding the organic olive oil production chain in the Mediterranean (OOOP) we realized that OOOP may have a much wider impact. By merging all major attributes of environmentally safe, sustainable agriculture, and becoming a key parameter of integrated rural development in the Mediterranean OOOP may serve as paradigm that may be tailored to apply to a much wider range of agricultural and agro-industrial activities. Features of OOPC in line with this view are discussed belo

Nitrogen turnover during decomposition of recalcitrant plant residues in acid soils

SIGLEAvailable from British Library Document Supply Centre-DSC:DXN017700 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Efficient urea-N and KNO

Vegetable production demands high nitrogen inputs. Fertigation is a means to increase fertilizer-N use by plants. However, the effect of different N sources and doses, and how they relate to the total available N in soils are poorly known. In this study we applied 15N-labeled fertilizers to green pepper in the field using a drip irrigation system during the dry summer. KNO3-N and urea-N were applied at a total of 6, 12 and 18 g plant−1. Our results show that urea was as effective as KNO3 as a N source. The fertilizer-N utilization efficiency was dramatically reduced at higher N doses, from 48% for the 6 g N plant−1 dose to 36% and 26% for the 12 and 18 g N plant−1 doses, respectively. However, the N in plants derived from fertilizer consistently exceeded 60%, indicating high availability of fertilizer-N even at the lowest dose. Negative added nitrogen interactions – the effect of added N on the fate of soil-N – were observed, particularly at high fertilizer-N doses. The fertilizer-N utilization efficiency calculated by the difference method was lower compared with the 15N enrichment method. This clearly indicates luxury N applications and excess N availability brought about by precise localized placement of fertilizer-N that leads to limited uptake of the available soil-N. N leaching risks in the following rain period should therefore be based on both the residual fertilizer-N and the increased amounts of residual soil mineral-N

Multi-species relationships in legume roots: From pairwise legume-symbiont interactions to the plant - Microbiome - soil continuum

Mutualistic relationships of legume plants with, either bacteria (like rhizobia) or fungi (like arbuscular mycorrhizal fungi), have been investigated intensively, usually as bi-partite interactions. However, diverse symbiotic interactions take place simultaneously or sequentially under field conditions. Their collective, but not additive, contribution to plant growth and performance remains hard to predict, and appears to be furthermore affected by crop species and genotype, non-symbiotic microbial interactions and environmental variables. The challenge is: (i) to unravel the complex overlapping mechanisms that operate between the microbial symbionts as well as between them, their hosts and the rhizosphere (ii) to understand the dynamics of the respective mechanisms in evolutionary and ecological terms. The target for agriculture, food security and the environment, is to use this insight as a solid basis for developing new integrated technologies, practices and strategies for the efficient use of beneficial microbes in legumes and other plants. We review recent advances in our understanding of the symbiotic interactions in legumes roots brought about with the aid of molecular and bioinformatics tools. We go through single symbiont-host interactions, proceed to tripartite symbiont-host interactions, appraise interactions of symbiotic and associative microbiomes with plants in the root-rhizoplane-soil continuum of habitats and end up by examining attempts to validate community ecology principles in the legume-microbe-soil biosystem. © 2021 The Author(s) 2020

Tolerance of tomato plants to water stress is improved by the root endophyte Fusarium solani FsK

The endophyte Fusarium solani strain FsK may colonize the roots of tomato plants and protect them against fungal pathogens. Here we show that the fungus can alleviate the strong negative effects of water stress on the development and growth of tomato seedlings that were co-cultivated with FsK under in vitro conditions. In a succeeding pot experiment, the presence of FsK ameliorated physiological stress in plants grown in peat under water deficit irrigation conditions: plants practically restored levels of net photosynthesis rate (PN), maximal potential yield of PSII (Fv/Fm) and relative water content (% RWC) and displayed a 4-fold increase in stomatal conductivity (gs) and a 7-fold decrease in proline levels compared to mock-inoculated plants. These changes indicate a shift towards an anisohydric type response to water stress, aided by mechanisms maintaining efficient water absorption by roots and high-water conductance in planta. Effects on the accumulation of reactive oxygen species and relevant antioxidant enzymes were less dramatic. Our data indicate that the endophyte may reduce stomatal closure response to water stress, and potentially improve water acquisition by roots and/or water conductance in planta, thus preventing reduction in photosynthesis rates and minimizing water loss; this, results in increased tolerance of tomato plants to water deprivation, conferred by the endophyte. © 2018 Elsevier B.V