FE-polyphosphate formulations as replacement for fe-chelates in nutrient solutions: preliminary experiments with cucumber (cucumis sativus l.) in hydroponics
Voogt, W. ; IJdo, M.L. - \ 2014
In: Proceedings of the IS on Growing Media and Soilless Cultivation. - Leuven : ISHS - ISBN 9789462610217 - p. 583 - 589.
One of the critical success factors for soilless culture is the sequestration of FeIII-ions, making Fe available for plant roots. Chelates are used primarily, but other compounds, like polyphosphates are also able to bind Fe-ions. A new group of Fe-polyphosphates have recently been developed by Prayon chemical company. Two experiments were conducted to evaluate the utility of these products in nutrients solutions for soilless systems using cucumber as test crop. Three different poly-phosphate formulations were compared with Fe-DTPA as reference, at two pH levels: low pH (5.2-5.6) and high pH (6.4-6.8). The plants were grown in substrate-free nutrient solution for six weeks, starting from the seedling stage. The first test was conducted in spring with 25 µmol Fe l-1 and the second test in summer with 15 µmol Fe l-1. In the first experiment, no differences in biomass production were found. Light chlorosis symptoms appeared throughout the growing season at all treatments, tending to be less at the reference treatment with high pH. Fe contents in plant tissue were lower at the high pH treatments for both the reference and the polyphosphate treatments, whilst the Fe contents were significantly higher at low pH with the polyphosphate treatments. In the second experiment the biomass production for all treatments was significantly lower at the high pH, the lowest for the polyphosphate treatments. Chlorosis was closely related with the biomass production and was most severe in the polyphosphate treatments at high pH. Fe contents in the tissue were not different among treatments at low pH, but at high pH these were clearly lower for the polyphosphate treatments compared to the reference. Interestingly, tip-burn symptoms, commonly ascribed to Ca deficiency, were observed and were significantly more severe in the reference treatments than at the polyphosphate treatments. Polyphosphates can be used as complexer agent for the delivery of Fe3+ ions to plant roots grown in nutrient solutions. However, the combination of high pH and low Fe supply concentrations should be avoided. Further investigation with this type of fertilisers is necessary to evaluate the applicability in commercial practice
Relation between soil health, wave-like fluctuations in microbial populations, and soil-borne plant disease management
Bruggen, A.H.C. van; Semenov, A.M. ; Diepeningen, A.D. van; Vos, O.J. de; Blok, W.J. - \ 2006
European Journal of Plant Pathology 115 (2006)1. - ISSN 0929-1873 - p. 105 - 122.
combining biocontrol agents - organic farming systems - biological-control - bacterial-populations - damping-off - root-rot - species composition - conventional farms - mycorrhizal fungi - wheat roots
A healthy soil is often defined as a stable soil system with high levels of biological diversity and activity, internal nutrient cycling, and resilience to disturbance. This implies that microbial fluctuations after a disturbance would dampen more quickly in a healthy than in a chronically damaged and biologically impoverished soil. Soil could be disturbed by various processes, for example addition of a nutrient source, tillage, or drying-rewetting. As a result of any disturbance, the numbers of heterotrophic bacteria and of individual species start to oscillate, both in time and space. The oscillations appear as moving waves along the path of a moving nutrient source such as a root tip. The phase and period for different trophic groups and species of bacteria may be shifted indicating that succession occurs. DGGE, Biolog and FAME analysis of subsequent populations in oscillation have confirmed that there is a cyclic succession in microbial communities. Microbial diversity oscillates in opposite direction from oscillations in microbial populations. In a healthy soil, the amplitudes of these oscillations will be small, but the background levels of microbial diversity and activity are high, so that soil-borne diseases will face more competitors and antagonists. However, soil-borne pathogens and antagonists alike will fluctuate in time and space as a result of growing plant roots and other disturbances, and the periods and phases of the oscillations may vary. As a consequence, biological control by members of a single trophic group or species may never be complete, as pathogens will encounter varying populations of the biocontrol agent on the root surface. A mixture of different trophic groups may provide more complete biological control because peaks of different trophic groups occur at subsequent locations along a root. Alternatively, regular addition of soil organic matter may increase background levels of microbial activity, increase nutrient cycling, lower the concentrations of easily available nutrient sources, increase microbial diversity, and enhance natural disease suppression.
Literatuurstudie ten behoeve van de methodeontwikkeling voor de analyse van residuen van polaire en/of thermisch instabiele bestrijdingsmiddelen in vegetatie, voedingsmiddelen en daaraan gerelateerde matrices op laag niveau
Blok-Tip, L. - \ 2001
Wageningen : RIKILT (Rapport / RIKILT 2001.013) - 30
pesticidenresiduen - hplc - vloeistofchromatografie - massaspectrometrie - literatuuroverzichten - analytische scheikunde - pesticide residues - hplc - liquid chromatography - mass spectrometry - literature reviews - analytical chemistry
Onderzoek naar residuen van bestrijdingsmiddelen in nederwiet
Traag, W.A. ; Gercek, H. ; Kloet, D. ; Wychgel, H.D. ; Faasen, I.S. ; Kerssemaker, R.P. - \ 2001
Wageningen : RIKILT - 19
pesticidenresiduen - furalaxyl - propamocarb - abamectine - parathion - drugsmisbruik - nederland - risicoschatting - pesticide residues - furalaxyl - propamocarb - abamectin - parathion - drug abuse - netherlands - risk assessment - propamocarp
|Literatuurstudie ten behoeve van de methodeontwikkeling voor de analyse van residuen van polaire en/of thermisch instabiele bestrijdingsmiddelen in vegetatie, voedingsmiddelen en daaraaan gerelateerde matrices op laag niveau
Blok-Tip, L. - \ 2001
Wageningen : Rijks-Kwaliteitsinstituut voor land- en tuinbouwproducten (RIKILT) (Rapport RIKILT 2001.013) - 30 p.
residuen pesticiden - HPLC
|Differences in fragmentation behaviour between a- and b-linked derivatized xylobiosedes: explanation in terms of sigma conjugation.
Kerk, S.M. van der; Blok-Tip, L. ; Kerk-van Hoof, A. van der; Heerma, W. ; Haverkamp, J. - \ 1994
International journal of mass spectrometry and ion processes 134 (1994). - p. 41 - 54.