Phytotoxicity of Several Iron Fertilizers and Their Effects on Fe, Mn, Zn, Cu, and P content of African Marigolds and Zonal Geraniums

Abstract

<jats:p>Zonal geraniums (<jats:italic>Pelargonium</jats:italic> ×<jats:italic>hortorum)</jats:italic> from seed and african marigolds (<jats:italic>Tagetes erecta</jats:italic>), which are known to be highly susceptible to Fe toxicity problems, were grown with I, 2, 4, or 6 m<jats:sc>m</jats:sc> Fe from ferrous sulfate, ferric citrate, FeEDTA, FeDTPA, FeEDDHA, ferric glucoheptonate, or ferrous ammonium sulfate in the subirrigation solution. FeEDTA and FeDTPA were highly toxic to both species, even at the 1 m<jats:sc>m</jats:sc> rate. Ferrous sulfate and ferrous ammonium sulfate caused no visible toxicity symptoms on marigolds, but did reduce dry weights with increasing Fe concentrations. Both materials were slightly to moderately toxic on zonal geraniums. FeEDDHA was only mildly toxic at the 1 m<jats:sc>m</jats:sc> concentration on both species, but was moderately toxic at the 2 and 4 m<jats:sc>m</jats:sc> concentrations. Substrate pH was generally negatively correlated with geranium dry weight and visible phytotoxicity ratings, with the least toxic materials, ferrous sulfate and ferrous ammonium sulfate, resulting in the lowest substrate pHs and the chelates FeEDTA, FeDTPA, and FeEDDHA the highest pH. The ionic Fe sources, ferrous sulfate and ferrous ammonium sulfate, suppressed P uptake in both species, whereas the Fe chelates did not. Fe EDDHA should be considered as an effective and less toxic alternative for the widely used FeEDTA and FeDTPA in the production of these crops.</jats:p>

The Influence of Biochar and Solid Digestate on Rose-Scented Geranium (Pelargonium graveolens L’Hér.) Productivity and Essential Oil Quality

“…This physiopathy is particularly frequent in geranium due to the pH status of the growth media. The pH level can indeed affect the capability of plants to uptake nutrients, thus leading to nutrient deficiency or toxicity [57][58][59][60][61][62]. An analysis of the nutrient contents in the leaves of the symptomatic plants (Table 3) indicated a high concentration of Fe and Mn, as compared to those that are found in the leaves cultivated using SDS and CS.…”

“…This condition can result in leaf discoloration that, by reducing the photosynthetic efficiency, indirectly affects crop growth [63]. Several studies reported that the toxicity can be due to an overload of Fe in different forms: ferrous sulfate, ferrous ammonium sulfate, ferric glucoheptonate, and ferric citrate are recognized to be moderately toxic to zonal geraniums at high application rates [61], while Fe chelates showed high toxicity when applied in liquid fertilizers [59]. Monteiro and Winterbourn [64] indicated that an excess of iron absorption might induce the production of free radicals that can oxidize the chlorophyll, which thus causes a decrease in the chlorophyll content.…”

Influence of FeEDDS, FeEDTA, FeDTPA, FeEDDHA, and FeSO4 on Marigold Growth and Nutrition, and Substrate and Runoff Chemistry

“…Iron chelates are used to prevent or correct Fe deficiency and have been reported to be more effective than other non-APCA sources of Fe, including Fe citrate, Fe glucoheptonate, and Fe sulfate (Broschat, 2003). Iron chelates, however, have also been found to contribute, possibly in association with substrate pH, to Fe toxicity in certain bedding plants, including marigolds and geraniums (Pelargonium • hortorum) (Albano et al, 1996;Broschat and Moore, 2004;Wik et al, 2006).…”

Effect of Integrated Nutrient Management on Growth, Yield and Quality of Gladiolus (Gladiolus grandifloru L.) Cv. Psittacinus Hybrid

“…They reported iron toxicity in cranberry and plant death at treatments of 50 ppm over five weeks, but they noted that plant death could be attributed to interactions with the chelate rather than a direct consequence of iron concentration [10]. Experiments conducted using different iron sources such as ferrous sulfate instead of chelated forms [11] have demonstrated that Fe is not particularly toxic in several plant species previously deemed highly susceptible [12,13]. In the present study, field iron tissue ranged from 143 to 881 ppm among 15 Wisconsin cultivated marshes with no apparent iron adverse reaction (Table 3).…”