ABSTRACT
Mycorrhizal symbiosis represents a valuable tool for increasing plant nutrient uptake, affecting system biodiversity, ecosystem services and productivity. Introduction of agroecological service crops (ASCs) in cropping systems may determine changes in weed community, that can affect the development of the mycorrhizal mycelial network in the rhizosphere, favoring or depressing the cash crop mycorrhization. Two no-till Mediterranean organic horticultural systems were considered: one located in central Italy, where organic melon was transplanted on four winter-cereals mulches (rye, spelt, barley, wheat), one located in southern Italy (Sicily), where barley (as catch crop) was intercropped in an organic young orange orchard, with the no tilled, unweeded systems taken as controls. Weed "Supporting Arbuscular Mycorrhiza" (SAM) trait, weed density and biodiversity indexes, mycorrhization of coexistent plants in the field, the external mycelial network on roots were analyzed by scanning electron microscopy, crop P uptake, yield and quality were evaluated. We verified that cereals, used as green mulches or intercropped, may drive the weed selection in favor of the SAM species, and promote the mycelial network, thus significantly increasing the mycorrhization, the P uptake, the yield and quality traits of the cash crop. This is a relevant economic factor when introducing sustainable cropping practices and assessing the overall functionality of the agroecosystem.
ABSTRACT
The article presents the results of research consisting of the application of deficit irrigation (DI) criteria, combined with the adoption of micro-irrigation methods, on orange orchards (Citrus sinensis (L.) Osbeck) in Sicily (Italy) during the irrigation season of 2015. Regulated deficit irrigation (RDI, T3) and partial root-zone drying (PRD, T4) strategies were compared with full irrigation (T1) and sustained deficit irrigation (SDI, T2) treatments in terms of physiological, biochemical, and productive crop response. A geophysical survey (electrical resistivity tomography, ERT) was carried out to identify a link between the percentages of drying soil volume in T4 with leaves abscisic acid (ABA) signal. Results highlight that the orange trees physiological response to water stress conditions did not show particular differences among the different irrigation treatments, not inducing detrimental effects on crop production features. ABA levels in leaves were rather constant in all the treatments, except in T4 during late irrigation season. ERT technique identified that prolonged drying cycles during alternate PRD exposed more roots to severe soil drying, thus increasing leaf ABA accumulation.
ABSTRACT
BACKGROUND: A glass-matrix fertiliser (GMF), a by-product from ceramic industries, releases nutrients only in the presence of complexing solutions, similar to those exuded by plant roots. This ensures a slow release of nutrients over time, limiting the risk of their loss in the environment. With the aim to improve fertiliser performance, GMF was mixed with vine vinasse (DVV), pastazzo (a by-product of the citrus processing industry, PAS) or green compost (COMP) and nutrient release was evaluated by citric and chloridric acid extraction, at different concentrations. RESULTS: Theoretical and actual nutrients release were compared to evaluate possible synergistic effects due to the organic component added to the mineral fertiliser: phosphorus (+7.1%), K (+4.8%), Fe (+8.5%) and Zn (+5.5%) were released more efficiently by 2% citric acid from GMF + DVV, while Ca availability was increased (+5.3%) by 2% citric acid from GMF + PAS mixture. Both DVV and COMP increased by 12-18% the Fe release from GFM matrix. CONCLUSION: Organic biomasses added to GMF increased the release of some macro and micronutrients through an 'activation effect', which suggests the employment of these organo-mineral fertilisers also in short-cycle crops production. Moreover, the re-use of some agro-industrial organic residues gives another 'adding value' to this novel organo-mineral fertilfertilisers.
