Paloma Nadal

Evaluation of Fe-N,N′-Bis(2-hydroxybenzyl)ethylenediamine-N,N′-diacetate (HBED/Fe3+) as Fe carrier for soybean (Glycine max) plants grown in calcareous soil

AimsThe efficacy of N,N′-bis(2-hydroxybenzyl)ethylenediamine-N,N′-diacetic acid (HBED) as an Fe source in plant nutrition for soybean (Glycine max) plants grown in calcareous soil under controlled conditions was studied.MethodsThe ability of ethylenediamine-N,N′-bis(o-hydroxyphenylacetic) acid (o,oEDDHA/57Fe3+) and HBED/57Fe3+ at increasing concentrations and the long lasting effect were evaluated. In addition, iron nutrition was studied considering the Fe uptake from the chelates prepared with the isotope 57Fe. Further, the SPAD index, total Fe and 57Fe content in plant were analyzed and soluble and available 57Fe fractions in soil were determined over time.ResultsDoses experiment indicated that a higher concentration of HBED/57Fe3+ as compared to o,oEDDHA/57Fe3+ is necessary for obtaining the same 57Fe absorption by the plant; however, these differences were found to be lower in the second sampling time as compared to the first one. This long lasting effect of HBED/Fe3+ was corroborated in the long term experiment. Moreover, it was found that the load of Fe in the pods was higher when using HBED/57Fe3+ than when o,oEDDHA/57Fe3+ was used. The soil extract analysis for each sampling time indicated that HBED/57Fe3+ presented a higher stability in soil than o,oEDDHA/57Fe3+ over time.ConclusionThe HBED/Fe3+ could be a long lasting alternative to EDDHA/Fe3+ for correcting the iron chlorosis of dicotyledonous plants grown on calcareous soils.

Root iron uptake efficiency of Ulmus laevis and U. minor and their distribution in soils of the Iberian Peninsula.

The calcifuge and calcicole character of wild plants has been related to nutrient availability shortages, including iron (Fe)-deficiency. Surprisingly, just a few studies examined the relation between root Fe uptake and plant distribution in different soil types. We assessed the root Fe acquisition efficiency of two Ulmus species with calcareous (Ulmus minor) and siliceous (U. laevis) soil distribution patterns in the Iberian Peninsula. Seedlings of both elm species were grown hydroponically with different Fe concentrations during 6 weeks. Plant physiological responses to Fe-limiting conditions were evaluated as were the ferric reductase activity and proton (H+) extrusion capacity of the roots. Iron deprived elm seedlings of both species were stunted and suffered severe Fe-chlorosis symptoms. After Fe re-supply leaf chlorophyll concentrations rose according to species-dependent patterns. While U. minor leaves and seedlings re-greened evenly, U. laevis did so along the nerves of new growing leaves. U. minor had a higher root ferric reductase activity and H+-extrusion capability than U. laevis and maintained a better nutrient balance when grown under Fe-limiting conditions. The two elm species were found to have different Fe acquisition efficiencies which may be related to their natural distribution in calcareous and siliceous soils of the Iberian Peninsula.

Reactivity and effectiveness of traditional and novel ligands for multi-micronutrient fertilization in a calcareous soil

This study compares the effectiveness of multi-micronutrient formulations containing iron (Fe), manganese (Mn), and zinc (Zn) with traditional (EDTA, DTPA, HEEDTA, and EDDHAm) or novel chelates (o,p-EDDHA, S,S-EDDS, and IDHA) and natural complexing agents (gluconate and lignosulfonate). The stability and reactivity of the formulations were studied on batch experiments with calcareous soil and by speciation modeling. Formulations containing traditional ligands maintained higher Mn but lower Zn concentration in soil solution than the novel ligands. The gluconate and lignosulfonate maintained low concentrations of both Mn and Zn in soil solution. Selected formulations were applied into calcareous soil and their efficacy was evaluated in a pot experiment with soybean. The formulation containing DTPA led to the highest Zn concentration in plants, as well as the formulation containing S,S-EDDS in the short-term, which correlated with its biodegradability. The application of traditional or novel ligands in formulations did not result in sufficient plant Mn concentrations, which was related to the low Mn stability observed for all formulations under moderate oxidation conditions. The results highlight the need to consider the effect of metals and ligands interactions in multi-nutrient fertilization and the potential of S,S-EDDS to be used for Zn fertilization. Furthermore, it is necessary to explore new sources of Mn fertilization for calcareous soils that have greater stability and efficiency, or instead to use foliar fertilization.

Efficacy of Micronutrient Chelate Treatments in Commercial Crop of Strawberry on Sand Culture

Strawberry production is usually carried out in Spain on sand substrate under fertigation. Micronutrient chelates are frequently applied as ethylenediaminetetraacetic acid (EDTA) chelates; EDTA is a recalcitrant chelating agent so the concern about the environmental fate of EDTA applied in agriculture has risen. In this work, the efficacy of iron, manganese, zinc, and copper in two alternative chelating agents has been evaluated: the biodegradable N-(1,2-dicarboxyethyl)-D,L-aspartic acid (IDHA) and a combination of the regioisomers ethylenediamine-N,N´-bis(2-hydroxyphenylacetic) acid (o,o-EDDHA) and ethylenediamine-N-(2-hydroxyphenylacetic)-N´-(4-hydroxyphenylacetic) acid (o,p-EDDHA) (called EDDHA mix). Doses were split according to the stability of the chelates in three or six weekly applications. Experiment started 2 January 2010. Leaf samples were taken 6, 12, and 17 weeks after the first application. Foliar analysis, in comparison with chlorophyll indices based on Soil Plant Analysis Development (SPAD) measurement, was used to evaluate chelate efficacy. No differences between treatments were found for the SPAD index, but the SPAD increment was greater for the IDHA treatment during the whole assay. However, foliar analysis was the most adequate method for evaluating differences among the three chelates. The treatment based on EDDHA mix and the IDHA chelates showed greater Fe content in leaves in the first and last periods respectively. The EDDHA mix and EDTA were better alternatives for Zn nutrition than IDHA. Manganese content in leaf was sufficient and not affected by the treatment used. Copper content in leaf showed similar results for all treatments. The Fe/Mn molar ratio showed results similar to those obtained for Fe contents in leaf. The IDHA and EDDHA mix treatments produced similar quality parameters in fruits as EDTA. As conclusion, IDHA and EDDHA mix could be good alternatives for recalcitrant EDTA to apply micronutrient chelates in strawberry plants in fertigation.

Comparison of Different Nutritional Diagnostic Methods for Peach Trees Treated with Iron Chelates

Synthetic chelates such as ethylenediamine-N,N′-bis(2-hydroxyphenylacetic acid) (EDDHA) have shown their efficacy in correcting iron (Fe) chlorosis on crops grown on calcareous soils. Several parameters, such as Fe concentration, soil and plant analyzer development (SPAD) index, yield, and fruit size, have been previously described to evaluate their efficacy. However, the relationships among them and the method variability are little known. The aim of this study was to examine both relative standard deviations and coefficients of correlation when several nutritional status indexes are compared. Three Fe chelates plus additional treatment without any exogenous Fe source were applied on a commercial nectarine grove during two consecutive growing cycles. Data from 12 nutritional status indexes were compared (related to Fe concentrations in leaf and flower, SPAD index, Fe / manganese (Mn) ratio, yield, and size of fruit). Relative standard deviations (RSD) (as dimensionless parameter) were statistically compared. Additionally, Pearsons correlation coefficient was analyzed by comparing mean values from all pairs of nutritional status indexes. Statistical analyses, analysis of variance, and Pearsons correlation coefficient were performed. Because several methods are used for nutritional status assessment, statistical methodology is necessary to know their dispersion and the relationships between these methodologies. In this experiment, relative standard deviations of all nutritional status indexes were less than 30%, which is associated with acceptable experimental variability. In conclusion, SPAD index in fruit-bearing branches seems to be one of the most adequate nutritional evaluation method because low RSD and no variation throughout sampling time and growing cycle were found. However, Fe content in leaves at 77 DAFB (days after full bloom) was correlated with yield and quality fruit parameters having relevant significance as prognosis parameters. In addition, Fe contents in leaves show low relative standard deviations.

Fertilizer properties of DCHA/Fe3+

AimsThe suitability of the non-symmetrical chelating agent DCHA (2-{2-[(2-hydroxybenzyl)amino]ethylamino}-2-{2-hydroxyphenyl}acetic) to improve Fe nutrition in plants is investigated in order to confirm the good results deriving from its chemical reactivity in agronomic systems achieved by analytical and modeling studies. Moreover, the factors affecting the efficacy of this new Fe chelate, that it is predicted to combine a good stability in nutrient solution and calcareous soils, are explored.MethodsThe role of DCHA/Fe3+ as substrate for the Fe chelate reductase (FCR) activity in cucumber (Cucumis sativus L. cv. Ashley) plants and its efficacy to provide Fe to chlorotic soybean (Glycine max L. cv. Stine 0408) plants in both hydroponic and soil culture were determined.ResultsThe chelate DCHA/Fe3+ presented an intermediate behavior between o,oEDDHA/Fe3+ and o,pEDDHA/Fe3+ as substrate of the FCR. In the hydroponic experiment, nutritional indexes indicated a faster and higher re-greening of the plants treated with DCHA/Fe3+ and o,pEDDHA/Fe3+ than with o,oEDDHA/Fe3+. In the soil experiment, plants treated with o,oEDDHA/57Fe3+ showed the highest 57Fe concentration in leaves and no differences were observed between o,pEDDHA/57Fe3+ and DCHA/57Fe3+.ConclusionsThe chelate DCHA/Fe3+ has adequate fertilizer properties since it is able to correct the Fe chlorosis and to maintain good nutritional status of plants over time both in hydroponic and soil cultures. This is related to its ability to serve as substrate for the FCR and its good stability in solution and in soil conditions observed in this and previous studies.