1,721,029 research outputs found
I substrati di coltivazione : aspetti teorici ed applicativi di un fattore chiave delle produzioni in contenitore
No full textFitoestrazione dei metalli: aspetti relativi alla biodisponibilità dei metalli nei suoli agrari
No full textMolti sono i fattori che nel suolo controllano la biodisponibilità dei metalli pesanti e che quindi possono influenzare il buon esito di un processo di fitoestrazione. Nel capitolo viene illustrato il comportamento dei metalli nel suolo, con particolare riferimento alla rizosfera, quale luogo di interazione suolo-pianta-microrganismi. Possibili interventi al suolo atti a modificare la biodiponibilità dei metalli, incrementando in tal modo l’efficacia della fitoestrazione, vengono esaminati e per alcuni di essi si riportano risultati sperimentali
Potential for the use of rhizobacteria in th sustainable management of contaminated soils
No full textEffects of Cr on proton extrusion,potassium uptake and transmembrane electric potential in maize root segments
No full textAbstract Proton extrusion of maize root Zea mays segments, was inhibited by the presence of Cr (o.n. + 6; present in solution as CrO42‐, Cr2O72‐) in the incubation medium: the minimum inhibiting concentration was 2 × 10−3 mol m−3 and the inhibition progressively increased with Cr concentration. Cr inhibited proton extrusion. Also, when this activity was stimulated by the presence of K+ or fusicoccin (FC) in the incubation medium, the K+ and FC stimulating effect was still present when proton extrusion was inhibited by Cr. In addition, Cr inhibited K+ uptake. This inhibition was higher (50%) at K+ concentrations up to 1 mol m−3 lower (15%) at higher K+ concentrations. This result indicates that the system responsible for K+ uptake operating at low K+ concentrations is more sensitive to Cr inhibition. Cr had no effect on transmembrane electric potential (PD). The depolarizing and hyper‐polarizing effect of K+ and FC, respectively, were not affected by Cr; but Cr enhances the depolarizing effect of the uncoupler carbonylcyanide m‐chlorophenylhydrazone (CCP). These results indicate that Cr inhibited the proton translocating mechanism coupled with K+ uptake, but did not change the net transport of charges through the plasmalemma. The Cr effect is discussed, taking into account the possibility of a direct effect of Cr at the membrane level or, alternatively, of an effect on some metabolic processes controlling membrane function
Impiego dei biosaggi vegetali nella caratterizzazione dei substrati di coltivazione
No full textL’introduzione dei biosaggi vegetali tra le determinazioni utili alla valutazione della qualità dei substrati di coltivazione risponde ad esigenze di conoscenza dei materiali che le analisi chimiche o fisiche routinarie non sono in grado di soddisfare. In questa ottica si propone l’applicazione dei biosaggi in senso positivo e innovativo, quindi non per evidenziare
aspetti legati alla fitotossicità, ma per fornire una risposta rapida e predittiva sull’attitudine di un prodotto a sostenere
lo sviluppo delle piante nel breve e nel lungo periodo. Tale capacità è strettamente legata alle caratteristiche fisico-
idrologiche dei materiali e per quanto riguarda il lungo periodo, alla loro stabilità nel tempo. L’esperienza maturata
dal DI.PRO.VE. di Milano su alcuni biosaggi descritti da metodiche ufficiali nazionali ed internazionali (germinazione,
allungamento radicale, accrescimento), sviluppati per la valutazione della qualità di suoli, acque, biomasse, e della tossicità
di xenobiotici e non, ha messo in luce le specificità di ciascun test. In particolare, il test di allungamento radicale ha
dimostrato una particolare attitudine a rilevare gli effetti correlabili a specifiche caratteristiche fisiche dei materiali. Per
questo motivo il test di allungamento radicale ISO 11269-1 è stato testato su 19 diversi campioni di substrati di coltivazione
a base di torba, dimostrando di essere in grado di fornire risultati compresi in un ampio range di risposte (da valori
di allungamento inferiori al 70% fino a valori superiori al 90% rispetto al testimone). Lo stesso test è stato applicato ad
otto campioni pretrattati per ottenere un “invecchiamento” fisico in grado di simulare gli effetti della coltivazione (cicli
alterni di essiccazione e reumidificazione). I primi risultati sembrano essere promettenti e meritano una prosecuzione
della sperimentazione che coinvolga anche verifiche di serra e correlazioni con i dati analitici
Biological mobilization of arsenic in a pyrite cinders polluted soil
No full textBioavailability of arsenic (As) in soil is governed by chemical and biological factors, in particular the redox condition. The objective of this research was to study (1) the effect of plant material decomposition on arsenic mobilization in a contaminated soil under flooded and not flooded conditions; (2) arsenic uptake and translocation in willows (Salix purpurea L). The experimental soil was a mixture (1:1 w/w) of a unpolluted soil and pyrite cinders, contaminated by several metals and As.
1-year old cutlings of willow were transplanted in pots containing 1 kg of experimental soil amended with dry alfalfa. During two months of growth two environmental conditions were tested by maintaining soil in submersion or at 70% of the water holding capacity.
Samples of soil solution were weekly collected by Rhyzon syringes and pH, redox potential, Fe, and As were determined. Leaves of salix were sampled at day 0 and day 56 and As and Fe concentrations were determined. The reductive conditions induced by organic matter decomposition in submersion resulted in a fast arsenic mobilization
Utilization of the solid fraction of digestate from anaerobic digestion as container media substrate
No full textThe solid fraction of two digestates (D1 and D2) pure and diluted with Sphagnum peat (25%, 50% vol. digestate) was investigated in order to replace totally or partially peat in growing media. They were analyzed for pH, EC, water soluble Ca,Mg, K, NH4-N, NO3-N, physical properties and submitted to germination (cress), root elongation (barley), plant growth (lettuce) tests for phytotoxicity and quality evaluation. Both digestates showed high pH and electrical conductivity and induced negative effects on cress germination; D1 had scarce amount of easy available water, high shrinkage rate and induced a decrease of barley root elongation. Mixing of digestates and peat strongly ameliorated chemical characteristics, and balanced bioavailable plant nutrients; consequently plant tests gave positive results. On the basis of our results it can be concluded that digestate can partially substitute peat, decreasing the high cost of peat based growing media
Effect of Controlled-Release Fertilizers on Chemical Parameters of Two Growing Media during 12 Months Storage
No full textA one year long incubation experiment was carried out using a peat-based growing media (GM) and a peat and pumice GM (80% and 20% v/v), in combination with two controlled-release fertilizers (CRFs) and stored in two conditions. Samples with 60% water content were kept at 21°C throughout the experiment (correct storage condition) or at 40°C for 15 days and then at 21°C until the end of the experiment (improper storage condition). Three replicates of each treatment were analyzed monthly for pH, EC, water soluble potassium, phosphorus and mineral N (1:5 vol/vol extraction method). The strong acidification induced by CRFs reduced pH of the peat based growing media below the permitted tolerance of pH (± 1 unit of the declared value) after 60 days, and peat-pumice GM after 30 days correct storage. Soluble salts buildup during two month storage led both GM to exceed admitted tolerance (25% of the declared value) for Italy. Biological oxidation of ammonium was more efficient in the most aerated substrate (peat-pumice GM) based on measured ammonium versus nitrate in the soil solution. Potassium concentrations were lower in peat-pumice based GM for possible interaction between potassium and pumice. No changes in phosphorus extracted by water were detected. The intensity and pattern of nutrient release from CRFs were influenced both by storage conditions and by GM type. During the first 3 months of incubation improper storage increased ammonium build up in both GM
Behaviour of hoof and horn during the storage of peat-based and peat/pumice-based growing media
No full textHoof and horn is one of the most widely used organic fertilizers by the Italian substrate manufacturers and it is frequently used for substrates devoted to organic production. Together with chemical fertilizers, it is used for long lasting conventional production. A recent national law (Leg. Decree n.75, 2010) set up a series of rules in substrate production and set tolerance degrees for pH and EC. At present there is little information regarding the influence of organic fertilizers on pH and electrical conductivity (EC) during the storage of growing media. An experiment has been carried out in order to investigate the behaviour of hoof and horn added to two growing media (a peat based media and a mixture of peat 80% and pumice 20% v/v). These media were stored for 12 months at a constant temperature of 21°C or kept at 40°C for 15 days and then at 21°C until the end of the trials. In all treatments pH decreased exceeding dramatically the degree of tolerance. The more aerated substrate promoted the fastest and widest pH reduction. The heat treatment reduced the acidification of media maintaining the final pH slightly higher than in samples non heated. The substrate containing pumice induced an early increase in EC values while both the heated media showed the highest differences between initials and final values. In both growing media EC values exceeded the admitted tolerance. Results showed a dramatic effect of temperature treatment and marked differences between the studied growing media
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