Roberto Baigorri

• Ph.D.
• Senior Researcher at Fertinagro Biotech

The water‐insoluble phases of phosphate fertilisers have traditionally been considered an agronomic concern because of their phosphorus bioavailability. However, this chemical behaviour with respect to its solubility in soil could be an advantage from the point of view of environmental sustainability, since these phosphates are more stable in soil...

Many studies have shown the capacity of soil humic substances (HS) to improve plant growth in natural ecosystems. This effect involves the activation of different processes within the plant at different coordinated molecular, biochemical, and physiological levels. However, the first event triggered by plant root-HS interaction remains unclear. Some...

Soil organic matter is considered by soil scientists as the interlayer that connect alive with mineral sides of the soil. In addition, microorganisms have in soil organic matter a source of carbon as well as a source of energy. We can observe a duality that can be analyzed from a biological, physicochemical, or even thermodynamic sense. From this l...

Many studies have shown the close relationship between the beneficial action of soil and sedimentary humic acids on the growth of plants cultivated in calcareous soils and their ability to improve Fe plant nutrition. These results have been ascribed to the humic acid (HA) capability to improve Fe solubility and bioavailability. However, other effec...

Salinization as an initial degradation soil step causes soil structural damage, normally by dissolution of organic and mineral colloids, humic substances and clay materials respectively. At the beginning of the process, sodium and/or chloride start to accumulate, firstly displacing Ca, Mg, Fe and Al, and then sulphates and phosphates respectively....

Some studies have reported that the capacity of humic substances to improve plant growth is dependent on their ability to increase root hydraulic conductivity. It was proposed that this effect is directly related to the structural conformation in solution of these substances. To study this hypothesis, the effects on root hydraulic conductivity and...

Humification is a process that plant and microbiota residues experiment in natural or agronomic soils under microorganisms action and environmental conditions. Under this process natural biomolecules - such as protein, carbohydrates or lignin – experience secondary biochemical and chemical reactions yielding to the formation of new organic biomolec...

Because of the low consistency of the results obtained in the field, the use of biochar as a soil amendment is controversial. Thus, in general, in acidic soils, results are positive, while in alkaline soils, they are non-significant or even negative. The results regarding biochar action in acidic soils have been related to a lime-like effect due to...

Due to the low consistency of the results obtained in field, the use of biochar as soil amendment is controversial. Thus, in general in acidic soils results are positive while in alkaline soils they are non-significant or even negative. The results regarding biochar action in acidic soils have been related to a lime-like effect due to its alkaline...

The role of soil humus in soil fertility and crop production has been well established by many studies and practical farming experience. This role is related to the presence of a family of organic substances, known as humic substances, with the capacity to increase the pool of plant-available nutrients in soil for root uptake. The improvement in pl...

Nitrogen (N) is probably the most important macronutrient and its scarcity limits plant growth, development and fitness. N starvation response has been largely studied by transcriptomic analyses, but little is known about the role of alternative polyadenylation (APA) in such response. In this work, we show that N starvation modifies poly(A) usage i...

Although the ability of humic (HA) and fulvic acids (FA) to improve plant growth has been demonstrated, knowledge about the mechanisms responsible for the direct effects of HA and FA on the promotion of plant growth is scarce and fragmentary. Our study investigated the causal role of both root PM H+‐ATPase activity and ABA in the SHA‐promoting acti...

Phosphate-metal-humic complexes are very relevant in nature due to their crucial role in phosphate availability for plants and microorganisms. Synthetic phosphate-calcium-humic acid (HA) complexes have proven to be efficient sources of available phosphorus for crops. However, the current knowledge about their structure and molecular features is ver...

Phosphate (Pi) is an essential nutrient for all organisms. Roots are underground organs, but the majority of the root biology studies have been done on root systems growing in the presence of light. Root illumination alters the Pi starvation response (PSR) at different intensities. Thus, we have analyzed morphological, transcriptional and physiolog...

Root development and its response to environmental changes is crucial for whole plant adaptation. These responses include changes in transcript levels. Here we show that the alternative polyadenylation (APA) of mRNA is important for root development and responses. Mutations in FIP1, a component of polyadenylation machinery, affects plant developmen...

Availability of fresh water for crop irrigation is becoming scarce and rather expensive. In this context, the research about the potential reutilization of non-conventional water sources becomes highly relevant, principally in arid and semi-arid areas. On many occasions these new water resources involve water with a moderate concentration of salt,...

Background: The release of phytosiderephores (PS) to the rhizosphere is the main root response to iron (Fe) deficiency in graminaceous plants. We have investigated the role of the Fe status in the shoot as well as of the signaling pathways controlled by three relevant phytoregulators - indolacetic acid (IAA), ethylene and nitric oxide (NO) - in th...

This study describes the efficiency of a new coating material for preparing granulated potassium-fertilizers with a potassium release to the soil solution sensitive to rainfall intensity. The composite is prepared by reaction of an alkyd-resin with cement in the absence of water. The complementary use of diverse analytical techniques showed that th...

Purpose The traditional method to determine humic content (humic and fulvic acids) in commercial fertilizers, biostimulants, and organic materials is based on the oxidation of the organic carbon contained in the basic-soluble but acid-insoluble fraction (humic acids) and the basic-acid soluble fraction (fulvic acids) of their alkaline water extract...

Plant roots have the potential capacity to grow almost indefinitely if meristematic and lateral branching is sustained. In a genetic screen we identified an Arabidopsis mutant showing limited root growth (lrg1) due to defects in cell division and elongation in the root meristem. Positional cloning determined that lrg1 affects an alpha-1,2-mannosylt...

It has been very well stablished that plant nitrogen (N) use efficiency is severely impaired by sulfur (S) deficiency. However the mechanisms behind this fact are not very well known yet. Several works have demonstrated that the shoot growth promoting action of nitrate is closely linked to the root to shoot translocation of active cytokinins (Saka...

The ability of rhizospheric humic substances to improve plant growth has been well established by many studies carried out using diverse plant species cultivated under many different conditions. These beneficial effects of humic substances on plant development are expressed in both root and shoot. However, the mechanisms responsible for this action...

Natural Organic Matter (NOM) and the NOM fraction present in soil solution (dissolved organic matter: DOM) are currently considered as fundamental actors in soil fertility and crop mineral nutrition. This role of NOM (and DOM) seems to be associated with the presence of bio-transformed organic molecules (humic substances) with high cation chelating...

Numerous studies carried out both in open field and laboratory scale have provided experimental evidence for a beneficial action of humic substances (HS) on plant growth and mineral nutrition. In fact, many products containing diverse concentrations of humic substances, mainly humic and fulvic acids, are marketed as plant growth enhancers all over...

Natural Organic Matter (NOM) and the NOM fraction present in soil solution (dissolved organic matter: DOM) are currently considered as fundamental actors in soil fertility and crop mineral nutrition. Indeed, decreases in crop yields as well as soil erosion are closely related to low values of NOM and, in fact, the use of organic amendments as both...

Background The use of reactive rock phosphate (RP) in acidic soils as a phosphate (P) source for pastures and crops presents attractive economic advantages with respect to soluble phosphate. However, some studies have demonstrated that the short-term (1-year) efficiency of RP, compared with that of water-soluble P, is relatively poor. This fact pen...

Numerous studies have shown the ability of humic substances to improve plant development. This action is normally reflected in an enhancement of crop yields and quality. However, the mechanisms responsible for this action of humic substances remain rather unknown. Our studies have shown that the shoot promoting action of sedimentary humic acids is...

Aims: The aim of this study was to evaluate the long-term effect of tillage systems on the quantity and quality of organic carbon fractions at different soil layers. Study Design: The experimental design was a split plot with three blocks. The long-term effects (25 years) of conventional- (CT) and no-tillage (NT) systems on a Tipic Argiudoll was sa...

The importance of soil humus in soil fertility has been well established many years ago. However, the knowledge about the whole mechanisms by which humic molecules in the rhizosphere improve plant growth remains partial and rather fragmentary. In this review we discuss the relationships between two main signaling pathway families that are affected...

The physiological and metabolic mechanisms behind the humic acid-mediated plant growth enhancement are highly discussed. Experiments using cucumber plants show that the shoot growth enhancement caused by a structurally well characterized humic acid with sedimentary origin is functionally associated with significant increases in ABA root concentrati...

In nature roots grow in darkness and in opposite direction from light (negative phototropism). However, most current research in root biology has been done growing the root system in the presence of light. Here, we have engineered a device, called Dark-Root (D-Root), to grow plants in vitro with the aerial part under in normal light/dark photoperio...

Previous studies have reported that a purified sedimentary humic acid (PHA) was able to increase the concentration of nitric oxide (NO), indole-acetic acid (IAA) and ethylene in cucumber roots. Here, we investigated if these effects are functionally related to the ability of PHA to improve shoot growth. The effect of specific inhibitors of NO, IAA...

The effects of the humic acid (HA) nature and the activated carbon (AC) surface chemistry on the effec-tiveness of HA removal were investigated. Brown (BHA) and gray (GHA) humic acid fractions of different structure and physicochemical properties were tested in the adsorp-tion process using mesoporous ACs. The modification of chemical structure and...

The aim of this review is to describe the main physicochemical characteristics of diverse types of humic-metal-phosphate acid complexes. The effects of these complexes on phosphorus (P) fixation in soils with different pH values and physicochemical features and on plant phosphorus uptake are also discussed. Humic-metal-phosphate complexes have appa...

The official and classical method (SOM) for the quantification of humic substances (HS) in many occidental countries is principally based on the determination of organic carbon in both the alkaline extract of the organic material or product (total organic carbon), and the extract containing the humic acids that have been obtained by precipitation a...

The aim of this study has been to investigate those structural features that are singular of a specific type of humic substances (humic and fulvic acids with diverse origins: sedimentary, lakes, composts) as well as those that may configure the humic nature in these substances. To this end several humic and fulvic acids extracted from diverse mater...

Fertilizers based on phosphate-metal-humate complexes are a new family of compounds that represents a more sustainable and bioavailable phosphorus source. The characterization of this type of complex by using solid (31) P NMR in several fertilizers, based on single superphosphate (SSP) and triple superphosphate (TSP) matrices, yielded surprising an...

Abstract Despite the rather common presence of humic acid (HA), our full knowledge of its biological effect is still lacking. In this article, we first performed a physicochemical characterization of several HAs, and next, we evaluated their ability to affect interleukin-2 secretion, antibody secretion, wound healing (an in vitro model using HaCaT...

Despite its high capacity to take up nitrate from soil, winter rapeseed (Brassica napus) is characterized by a low N recovery in seeds. Thus, to maintain yield, rapeseed requires a high fertilization rate. Increasing nutrient use efficiency in rapeseed by addition of a biostimulant could help improve its agroenvironmental balance. The effects of ma...

Supplementary Table 1 List of the differentially expressed genes in shoots and roots of rapeseed after 3 days of AZAL5 supply to the roots

Supplementary Table 2 List of the differentially expressed genes in shoots and roots of rapeseed after 30 days of AZAL5 supply to the roots

The main aim of this communication is to discuss the current knowledge about the potential direct mechanisms that are involved in the beneficial action of humic substances on plant development. To this end, we present and discuss here recent results obtained in our laboratory, along with other findings published by other authors. Finally, we propos...

Iron (Fe) chlorosis is a serious problem affecting the yield and quality of numerous crops and fruit trees cultivated in alkaline/calcareous soils. This paper describes the efficiency of a new class of natural hetero-ligand Fe(III) chelates (Fe-NHL) to provide available Fe for chlorotic lemon trees grown in alkaline/calcareous soils. These chelates...

The aims of this chapter are: (i) First, to present new experimental evidence showing the signal-role of nitrate in the correction and improvement of the deleterious effects of ammonium- and/or urea-based nutrition in different plant species, either dicotyledonous or monocotyledonous. Likewise, we discuss the different and complementary mechanisms,...

Winter rapeseed (Brassica napus) is characterized by a low N recovery in seeds and requires high rates of fertilization to maintain yield. Its nutrient use efficiency could be improved by addition of a biostimulant such as humic acids whose physiological effects have been described previously in some plant species. However, to our knowledge, no stu...

A number of studies have shown the ability of natural organic matter (NOM) in general and humic substances (HS) in particular, to affect the development of plants and microorganisms in many different natural ecosystems and agro-ecosystems. Regarding plants, these NOM and HS effects were expressed in both root growth and architecture, and shoot grow...

List of the differentially expressed genes in shoots and roots of rapeseed after 3 days of HA7 supply to the roots.

List of the differentially expressed genes in shoots and roots of rapeseed after 30 days of HA7 supply to the roots.

A new type of superphosphate (organic complexed superphosphate (CSP)) has been developed by the introduction of organic chelating agents, preferably a humic acid (HA), into the chemical reaction of single superphosphate (SSP) production. This modification yielded a product containing monocalcium phosphate complexed by the chelating organic agent th...

The increase in root growth is one of the major effects of humic substances, but the mechanisms involved in humic acid-mediated changes in root growth, morphology and architecture are poorly known. Probably, humic substances may act on plant development through an action on the hormonal balance within the plant, either directly or indirectly by aff...

This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal,...

Hydroponic plant experiments demonstrated the efficiency of a type of humic acid-based water-insoluble phosphate fertilizers, named rhizosphere controlled fertilizers (RCF), to supply available phosphorus (P) to different plant species. This effect was well correlated to the root release of specific organic acids. In this context, the aims of this...

Humic acids are compounds resulting from decomposition of organic matter. Despite their common presence, our knowledge of their biological effects is limited, and current findings are controversial. We decided to evaluate the immunological effects of two different types of humic acids, differing in source and biochemical characteristics. Using both...

Flash pyrolysis-gas chromatography/mass spectrometry(Py-GC/MS) was used to study the structural transformations of humic fractions formed as a result of composting processes of diverse organic materials (solid wastes of wineries, solid olive-mill wastes, domestic wastes, ovine manures plus straw, and mixtures of animal manures). Sodium hydroxide-ex...

A NEW CLASS OF HETERO-MOLECULAR NATURAL IRON-CHELATES AS EFFICIENT CORRECTORS OF IRON DEFICIENCY IN FRUIT TREES CULTIVATED IN ALKALINE AND CALCAREOUS SOILS

An adequate knowledge of the chemical and structural features that characterize the main fractions of humic substances in solution is of great interest to better understand a number of processes occurring in nature. Qualitative analysis of the spectra derived from diverse analytical techniques is frequently complicated, however, partially due to th...

Some studies suggest that iron (Fe) stress root responses are regulated by variations in specific plant hormones. However, this question remains unclear. A time-course experiment dealing with the relationship between the expression of the Fe-stress root responses at transcriptional (CsFRO1, CsIRT1, CsHA1, and CsHA2) and enzymatic levels [root Fe(II...

The aim of this study is to investigate the effect of a well-characterized purified humic acid (non-measurable concentrations of the main plant hormones were detected) on the transcriptional regulation of the principal molecular agents involved in iron assimilation. To this end, non-deficient cucumber plants were treated with different concentratio...

Previous studies have indicated that the main fractions of humic substances (HS), gray humic acid (GHA), brown humic acid (BHA), and fulvic acid (FA), present different molecular patterns in water solution that are probably associated with specific structural features. However, the techniques used in these previous studies did not permit clarificat...

The aim of this work is to explore the suitability of the complementary use of mass spectra and the corresponding statistical analysis (principal components-Pareto analysis (PCA) and discriminant analysis (DA)) of these spectra to differentiate diverse humic samples as a function of their structural and conformational features. To this end, the mas...

The results of this work demonstrate the properties of suspensions of humic substances (HS) used as reducing and templating agent for the formation of gold nanostructures. It is further established that a considerable degree of control over the size and shape of the nanoparticles can be achieved by selecting the appropriate humic fraction and adjus...

The aim of this work is to study the structural changes involved in humification processes. Total humic extracts (THE) obtained from five composted materials of diverse origin (solid wastes of wineries, solid mill olive wastes, domestic wastes, ovine manures plus straw, and a mixture of animal manures), and their corresponding initial raw fresh org...

The chemical and structural nature of humic substances (HS) is the object of an intense debate in the literature involving two main theoretical positions: the classical view defending the macromolecular pattern, and the new, more recent, view proposing a supramolecular pattern. In this study, we observe that both molecular patterns are present in d...

The aim of our work is firstly to investigate the presence of stable molecular aggregates in different selected humic substances (HS), and secondly, to identify the possible presence of different molecular behaviors (macromolecular and supramolecular) in these HS.Molecular aggregation was studied through the analysis of the molecular size distribut...

A supramolecular association between the sodium salt of a low molecular weight polyacrylic acid (PAA, Mw = 1200) and Fe(III) is described and characterized using ultrafiltration (UF), gel permeation chromatography (GPC), dynamic light scattering (DLS), and infrared spectrometry (FTIR). The GPC and DLS experiments indicate the presence of massive an...