The Role of the Internal Structure of Fabaceae Seeds in the Processes of Dormancy and Germination

*Enoc Jara-Peña and Manuel Marín-Bravo*

#### **Abstract**

The germination processes of Fabaceae seeds are well studied based on physiological parameters. However, in many cases, especially in wild seeds, there is a predominance of dormancy processes that must be reversed to finally produce germination, generally applying scarification processes. In the anatomical studies of seeds, a certain conformation of the structure of the cover is appreciated, with a predominance of sclerenchymatic tissues and waxy covers that are the cause of the difficulty of the entry of water to produce the imbibition of the seed. Mechanical or chemical scarifications are usually recommended to produce effective scarification. The characterization of the anatomical details of the seed coat allows us to predict the appropriate scarification technique with which optimal seed germination can be obtained.

**Keywords:** anatomy, seminal seed coat, mechanical scarification, ecological restoration, Fabaceae seeds

#### **1. Introduction**

The seed is the main reproductive organ of the spermatophytes. In nature, the seed is a basic food source for many animals and can be stored alive for long periods, thus ensuring the preservation of valuable plant species and varieties [1]. The seed plays a fundamental role in the dispersal, renewal, persistence of plant populations, forest regeneration, and ecological succession. For this reason, it is considered to be one of the main resources for the agricultural and silvicultural management of plant populations, for reforestation and the conservation of plant germplasm.

Knowledge about the germination of native species is considered the initial step in ecological restoration processes [2]. This knowledge is not only related to germination requirements, but also includes storage techniques to ensure its availability in the medium and long term [3]. Although there are few studies on the propagation of native Andean species [4], the importance of the ecological requirements of seeds in relation to ecological restoration programs is currently recognized [5]. Among the physiological processes that control germination is dormancy, which allows the seeds to remain for long periods of time in the soil until the environmental conditions are favorable for the establishment of seedlings [6]. Several types of dormancy have been described, including physical dormancy, which is determined by the

characteristics of the seed (or fruit) cover and prevents the absorption of water by the embryo [7]. This type of dormancy is considered one of the most evolved in angiosperms and one of the families that presents them in a notorious way is the Fabaceae, which has the so-called hard seeds in which the characteristics of the thickening of the seed coat that prevent the adequate hydration of the embryo and therefore the triggering of the germination process; [8, 9]. The identification of the anatomical components of physical dormancy in seeds and the methods for the seed to get out of this state are key to understanding the germination and dispersal process of species that present this type of dormancy [9, 10]. This paper reports the effects of mechanical scarification in the germination of three promising Fabaceae seeds from the Peruvian Andean zone in relation to the structural anatomical characteristics of the seed coat.

### **2. Taxonomics aspects**

The Fabaceae is one of the largest and most important families of angiosperms and is considered monophyletic in both morphological and molecular analyses [11]. Geographically, the Fabaceae are trees, shrubs, and herbs distributed in the South American Neotropics. In Peru around 145 genera and 1000 species have been registered, the endemic species occupy mainly the so-called Mesoandean regions, such as the humid and dry puna and the humid montane forests, between 1100 and 4800 meters of altitude [12]. The genus with the largest number of endemic species is *Lupinus*, in contrast to the genus *Astragalus* with few endemic species. Many of the Fabaceae species are promising phytostabilizing species, and there is a priority need to carry out detailed taxonomic studies and a greater collection of specimens of these genera [12]. *Astragalus garbancillo* Cav. (**Figure 1A**, **D**), It is a species that forms dense shrubby perennial tufts that in very cold places are small-sized plants, frequently glabrous and erect or sometimes decumbent stems. The fruit is an oblong

#### **Figure 1.**

*Evaluated species and their seeds. A, D* Astragalus garbancillo*. B, E* Lupinus ballianus*. C, F* Lupinus condensiflorus*.*

*DOI: http://dx.doi.org/10.5772/intechopen.109627 The Role of the Internal Structure of Fabaceae Seeds in the Processes of Dormancy…*

legume, sometimes compressed and puberulent with 3–4 seeds [13]. *Lupinus ballianus* C.P. Sm. (**Figure 1B** and **E**), is a shrub approximately 1.50 meters tall, with branches and petioles with an attenuated pubescence [13]. *Lupinus condensiflorus* C.P.Sm. (**Figure 1C** and **F**), is a shrubby species 60 to 110 cm long, with sericeousadpressed stems and branches. Fruits are 2.9 cm x 2.9 cm x 0.8 cm broad, hairy, with 3–5 seeds, and rostrate [14].

#### **3. Methodology**

#### **3.1 Method of collecting fruits of species of** *Astragalus* **and** *Lupinus*

The fruits of the seeds of the evaluated species were collected in different localities of the Peruvian high Andean region (**Table 1**). Aspects of the reproductive phenology of the species were previously defined, through a previous visit to the natural populations of these species, taking into account that the beginning of flowering, fruiting, fruit ripening, and seed dispersal; they are different if we compare it with the fruits of non-domesticated plants [15]. The ripe fruits were manually detached from the floral clusters and then stored in Kraft paper bags. Once the collection was finished, the fruits were wrapped with a paper towel to reduce humidity [16]. The criteria established to determine the maturity of the fruits were the change in coloration and the reduction in moisture content. It was observed that in most of the fruits and seeds of the high Andean plant species, maturation ends in the month of July, while the dispersal of the seeds begins in the month of August and ends in the month of October, this physiological process coincides with the dry season that prevails in the Andean region of the country.

#### **3.2 Determination of seed moisture content**

Seed moisture was determined based on dry weight (dw) by weighing them in Petri dishes on an analytical balance. For each species, five replicates and 20 seeds per Petri dish were weighed in the case of Lupinus ballianus and L. condensiflorus and 100 seeds in the case of *Astragalus garbancillo*, because the seeds are small in the latter. For the determination of the dry weight, the seeds were dried in an oven at 105°C for 4 hours. Seed moisture content was expressed in terms of the weight of water contained in seed as a percentage of the total weight of the seed before drying, known as wet weight based on fresh weight (fw) [17, 18] and was calculated using the following equation [19]:

Moisture Content %dw fresh weight – dry weigh ( ) = ( ) ( t / dry weight ]x ) ( ) 100 (1)

#### **3.3 Seed pre-treatment by mechanical scarification**

A part of the evaluated seeds was subjected to a mechanical scarification treatment to ensure their hydration and ensure the appropriate conditions to achieve optimal germination. The outer coverings of the seeds were scraped using fine sandpaper, taking care not to deeply damage the testa. The scarified seeds were disinfected in a 30% sodium hypochlorite solution for 20 minutes, rinsed several times in distilled


#### **Table 1.**

*Places of origin, altitude and geographic coordinates (UTM) of fruits, and seeds of Andean species of* Astragalus *and* Lupinus *evaluated.*

water and then sown in Petri dishes conditioned with filter paper and sterile water, hermetically covered and incubated in a growth chamber at 21°C during the day, 15°C at night, with a photoperiod of 12 hours of light and 12 hours of darkness and with a relative humidity of 80% during the day and 90% at night. A germinated seed was considered when it presented the emergence of a radicle of at least 0.5 mm long. Finally, on the tenth day, the calculation of the accumulated percentage of germinated and non-germinated seeds was made according to the species and treatment evaluated.

#### **3.4 Experimental design and statistical treatment**

The experiment was carried out under laboratory conditions using a completely randomized experimental design. They were evaluated under two light conditions (with and without light) and with two scarification treatments (with mechanical scarification, and without scarification). For each species, four treatments were evaluated, with five repetitions for each treatment (Number of Petri dishes). For the germination test, 20 pre-treated seeds of each species were added to each Petri dish. The distribution of the experimental units (Petri dishes with seeds) within the growth chamber was carried out at random. In the statistical analysis, it was carried out according to the experimental design, and the variance analysis (ANOVA) was carried out, and the multiple comparison test of means by Tukey (α = 0.01), using the Infostat program version 2016e.

#### **3.5 Observation of the internal structure of the seed**

Representative seeds of the evaluated species were cut transversally by freehand, rinsed in 50% sodium hypochlorite, washed, stained with 1% toluidine blue, and mounted in diluted glycerine for observation at 100 and 400 magnifications in light microscopy [20]. For the observation of the seeds in scanning electron microscopy, the material was treated following the steps of fixation with Carnovsky, post fixation with 1% osmium tetroxide, dehydration with a battery of alcohols, drying of the samples at a critical point with CO2. Mounting of the samples with double-sided adhesive tape, conductive tape, and gold plating on an ion coating. [21]. Observations were made between 90 and 5000 magnifications in the INSPECT S50 Scanning Electron Microscope (FEI, Hillsboro, Oregon), from the equipment laboratory of the Faculty of Biological Sciences of the National University of San Marcos.

*DOI: http://dx.doi.org/10.5772/intechopen.109627 The Role of the Internal Structure of Fabaceae Seeds in the Processes of Dormancy…*

#### **4. Results**

#### **4.1 Moisture content of** *Astragalus* **and** *Lupinus* **seeds**

Significant statistical differences (p < 0.0093) were obtained in the moisture content of *Astragalus garbancillo* seeds compared to *Lupinus ballianus* and *L. condensiflorus* seeds. The highest moisture content in the seeds was registered in *Astragalus garbancillo*, while in the *Lupinus* species the moisture content remained at values below 10% (**Table 2**).

#### **4.2 Germination of the seeds of** *Astragalus* **and** *Lupinus* **species**

In the germination of the seeds of the species, significant statistical differences (p < 0.001) were obtained in the analysis of variance (ANOVA) between the evaluated treatments. In the mean separation analysis by Tukey's test of the number of germinated seedlings, differences were obtained, being the highest values obtained in the number of germinated seeds with the treatment with mechanical scarification in the species of *Astragalus garbancillo* and *Lupinus condensiflorus* compared with the lower value obtained by the seeds of *Lupinus ballianus*. Additionally, the seeds of *A. garbancillo* presented the least thickness in the seed coat (**Table 3**).

In the germination of the seeds of the evaluated species, statistically significant differences (p < 0.001) were obtained with the scarification and light factors according to the analysis of variance (ANOVA). The seeds with mechanical scarification of the testa and light treatment were the ones that germinated in the highest quantity (except *L. ballianus*) (**Table 4**).


#### **Table 2.**

*Moisture content of the seeds of the evaluated species.*


#### **Table 3.**

*Accumulated number of germinated seeds of the evaluated species in relation to scarification and thickness of the seed coat.*


#### **Table 4.**

*Number of germinated seeds accumulated in the species according to the scarification factor and light evaluated in laboratory conditions.*

#### **Figure 2.**

*Anatomical characteristics of the* Astragalus garbancillo *seed. A, internal view of the seed. B, sagittal section of the seed. C, detail of the seed coat. D, detail of the aleurone layer and cotyledon. Em, embryo. Hi hilum. Ln, lens. Co, cotyledon. Sc, seed coat. Cl, clear line. Pl, palisade layer. Os, osteosclereids layer. P, parenchyma. Al, aleurone layer.*

#### **4.3 Internal anatomical structure of the seed**

In the transverse plane, the internal structure of the seminal layer of the seeds of the evaluated species shows a characteristic color for the species (**Figures 1A**–**3A**). An epidermal coat composed of a compact uniseriate layer of palisade sclereids

*DOI: http://dx.doi.org/10.5772/intechopen.109627 The Role of the Internal Structure of Fabaceae Seeds in the Processes of Dormancy…*

(macrosclereid type), with non-uniformly thickened walls, about 10 microns thick, thicker in *Lupinus ballianus* and thinner in *Astragalus garbancillo* (**Figures 2B, C, 3B**, and **4B**). At the level of the hilum region, the palisade layer is thickened. On the outer wall of this palisade layer, there is a refringent linear region in the cell walls, thick in *L. ballianus*, thin in *A. garbancillo*, and intermediate in *L. condensiflorus*. **Table 3** shows the comparative results of the seminal coat thickness for the three species. The cells of the adjacent sub-epidermal layer differentiate into hourglass-shaped cells called osteosclereids (**Figures 2C, 3B**, and **4B**). The tissue underlying this layer is a type of colorless large elongated cell parenchyma with a tangentially collapsed appearance. Next, a single-stratified inner layer of quadrangular cells containing Aleurone granules. The innermost tissue, with a positive reaction to Lugol, corresponds to the cotyledon with starch-reserving parenchyma (**Figures 2D**–**4D**).

Under the scanning microscopy view, the thin cuticular surface of the testa appears finely rough and uniform in *Astragalus garbancillo* (**Figure 5A**), smooth and uniform in *Lupinus ballianus* (**Figure 6A**). and irregularly alveolate in *L. condensiflorus* (**Figure 7A**). In the region of the hilum, the funicular tissue can be seen, made up of a fine pubescence with a loose appearance, leaving in the central part the fine fissure of the hilar groove, oriented longitudinally in *Lupinus* species (**Figures 6B** and **7B**) and transversally oriented in *A. garbancillo* (**Figure 5C**). thin refringent line of this palisade layer of sclereids can be highlighted on its outer part (**Figures 5D, 6D**, and **7C**). In this hilar region, the palisade cell layer of the seed

#### **Figure 3.**

*Anatomical characteristics of the seed of* Lupinus ballianus*. A, internal view of the seed. B, detail of the seed coat. C, detail of the aleurone layer and cotyledon D, cotyledon storage parenchyma. Em, embryo. Hi hilum. Ln, lens. Co, cotyledon. Sc, seed coat. Cl, clear line. Pl, palisade layer. Os, osteosclereids layer. P, parenchyma. En, endosperm. Al, aleurone layer.*

#### **Figure 4.**

*Anatomical characteristics of the seed of* Lupinus condensiflorus*. A, internal view of the seed. B, detail of the seed coat. C, detail of the aleurone layer and cotyledon D, cotyledon storage parenchyma. Hi hilum. Ln, lens. Co, cotyledon. Sc, seed coat. Cl, clear line. Pl, palisade layer. Os, osteosclereids layer. P, parenchyma. En, endosperm. Al, aleurone layer. Pa, storage parenchyma.*

#### **Figure 5.**

*Scanning microscopy images of* Astragalus garbancillo *seeds. A. Detail of the surface of testa. B. Longitudinal section at the level of the hilum. C. Surface view of the hilar region. D. Cross section of the seed coat.*

*DOI: http://dx.doi.org/10.5772/intechopen.109627 The Role of the Internal Structure of Fabaceae Seeds in the Processes of Dormancy…*

#### **Figure 6.**

*Scanning microscopy images of* Lupinus ballianus *seeds. A. Detail of the surface of testa. B. Detailed view of the hilar region. C. Longitudinal section of the seed. D. Cross section of seed coat.*

#### **Figure 7.**

*Scanning microscopy images of* Lupinus condensiflorus *seeds. A. Detail of the surface of testa. B. Detailed view of the hilar region. C. Longitudinal section of the seed. D. Detail of the seed storage parenchyma.*

coat is particularly thickened (**Figures 5B, 6C**, and **7C**). In *L. condensiflorus*, the endosperm cells are irregularly polygonal in shape (**Figure 7D**).

#### **5. Discussion**

The seeds of *Astragalus garbancillo* had the smallest diameter of the seed coat, associated with the palisade layer of sclereids (**Figure 2C**), which would explain the greater effectiveness of mechanical scarification expressed in the greater number of germinated seeds (**Table 3**). On the contrary, the seeds of *Lupinus ballianus* presented the thickest seed coat associated with the largest diameter of the palisade layer and the lowest germination percentages, which indicates that mechanical scarification was not effective for this species. A separate case represents the seeds of *L. condensiflorus*, which presented a thick seed coat and yet had a high percentage of germination. In the seeds of this species, its seminal coat was characterized by presenting a thin refringent line (**Figure 4B**), if we compare it with the thick refringent line shown by *L. ballianus* (**Figure 3B**), hence we associate this characteristic with effective mechanical scarification and its high percentage of germination. In fact, both species, *A. garbancillo* and *L. condensiflorus*, presented high germination percentages with the light factor associated with its thin refringent line (**Table 4**). Indeed, the presence of the thickened line on the outside of the seed coat and its hydrophobic cuticular layer would be determining a certain degree of impermeability of the seed coat to water and oxygen, which can be broken with a simple mechanical scarifying action. Seed dormancy refers to the state by which viable seed does not germinate when provided with favorable conditions for germination, such as adequate moisture, an appropriate temperature regime, normal atmosphere, and, in some cases, light [22]. This form of dormancy found in the evaluated seeds would correspond to the so-called physical dormancy, where the seminal seed coats (or fruit pericarps) are impermeable to water. This type of impermeability is considered to be one of the most evolved types of dormancy [23]. In this type of dormancy, the impermeability of water in the seed is caused by the presence of palisade cells, which constitutes an impermeable layer to water, so it forms a barrier to its entry [24]. For this reason, the effectiveness of scarification is demonstrated, which is a mechanical or chemical method, by which germination is induced through breakage, abrasion, or softening of the seed coat, making it more permeable to the inhibition of humidity [1].

Dormancy is considered to have evolved as a strategy to avoid germination in conditions where seedling survival is low [15, 19]. Seed dormancy breaking also depends on a balance between growth inhibitors and growth promoters. Among the numerous plant germination inhibitors, some are located in the fruit wall or in the seed coat. The stimulating effect of the elimination of the seed coat and the covers associated with germination determines that this is considered in itself as one of the inhibitory sources of germination. In this sense, in Fabaceae seeds, it is usual to find that the quality of light does not greatly affect the germination process [25]. Germination and seedling establishment are critical stages in the biological cycle of plants [26]. Seedling emergence is the event most important phenological of a crop's establishment. It represents the moment in which a seedling becomes independent of the non-renewable seminal reserves and when photosynthetic autotrophism begins. Emergence time often determines whether a plant competes successfully with its neighbors, whether it is consumed by herbivores, infested by diseases, and whether it flowers, reproduces, and matures at the end of its growth stage [27].

#### *DOI: http://dx.doi.org/10.5772/intechopen.109627 The Role of the Internal Structure of Fabaceae Seeds in the Processes of Dormancy…*

The seed coats of some species have characteristics that help germination and seed emergence. The testa of seeds eaten by animals and by humans can resist digestive processes and allow them to pass through the intestinal tract unharmed and thus facilitate seed dispersal. However, the use of corrosive chemical agents such as sulfuric acid may not always be considered the appropriate simile of this biological process [28]. In studies carried out on the emergence of seedlings in other *Lupinus* species under greenhouse conditions, it is mechanical scarification that determines the highest percentage of seedling emergence obtained with testa scarification, presenting up to 80% efficiency compared to chemical scarification with sulfuric acid [29]. Although the International Rules for Seed Testing (ISTA) recommends using concentrated sulfuric acid, for 2 to 45 minutes depending on the species, to scarify the test, this method is mentioned to be expensive and dangerous and should be followed with caution [19]. Under natural conditions, it has also been suggested that exposure of the seeds to high temperatures will be responsible for the release of dormancy [30].

The humidity factor is one of the conditions for triggering the seed germination processes. It is considered that the thread acts as a hygroscopic valve, by forming a fissure capable of interacting with the moisture content from the outside [7]. It is known that the combination of an impermeable testa with the valvular action of the thread allows reaching a high degree of desiccation in the hard seeds of Fabaceae, thus obtaining a certain percentage of humidity that is not affected by fluctuations in the external humidity content. of the seed [31]. This moisture is kept in equilibrium with the environment outside the seed and is the most important factor in determining the rate at which seeds deteriorate. For this reason, the moisture content within the seed is also an important aspect to consider in the postharvest of the crop. The determination of the moisture content before storing the seeds makes it possible to accurately predict the storage life potential of the accessions [19]. The highest moisture content recorded for *Astragalus garbancillo* (**Table 2**) seeds indicates their greatest potential to preserve their germination power for longer periods of time in relation to the dry season in the Andean region, in fact, we associate this feature with the shorter length of the hilar fissure compared to *Lupinus* species (**Figures 5C, 6B**, and **7B**). Additionally, we know of the influence of factors such as soil depth and its composition on the germination of especially hard cover seeds, such as Fabaceae seeds, and that they can effectively plan the establishment of species in projects of ecological restoration projects [32].

#### **6. Conclusions**

It is concluded that seed dormancy of the studied Andean Fabaceae species is related to the structural characteristics of the seed coat, especially the sclereid layer. Under the evaluated conditions, *Astragalus garbancillo* seeds had the thinnest sclereid layer compared to seeds of species of the genus *Lupinus*, with a thicker seed coat. Based on the germination percentages obtained, the mechanical scarification carried out on the seeds of *A. garbancillo* was the most effective method that allows them to come out of dormancy. The seeds of this species with a thin seminal coat also had a higher moisture content, which is why they have a greater potential for conservation in function and are ideal for ecological restoration programs.

#### **Author details**

Enoc Jara-Peña1 and Manuel Marín-Bravo2 \*

1 Faculty of Biological Sciences, Applied Phytology Laboratory, National University of San Marcos, Lima, Perú

2 Faculty of Biological Sciences, Anatomy and Pharmacognosy Laboratory, National University of San Marcos, Lima, Perú

\*Address all correspondence to: mmarinb@unmsm.edu.pe

© 2023 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

*The Role of the Internal Structure of Fabaceae Seeds in the Processes of Dormancy… DOI: http://dx.doi.org/10.5772/intechopen.109627*

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#### **Chapter 3**

## The Legumes of *Neltuma spp.* (ex *Prosopis spp*.) and Their Properties for Human and Animal Food

*Marisa Jacqueline Joseau, Sandra Rodriguez Reartes and Javier Eduardo Frassoni*

#### **Abstract**

The objective of this chapter is to present the advances in the use of *Neltuma* (*ex Prosopis*) pods for human and animal consumption, taking into account their distribution in Argentina. Images of the distribution of principal species used in forest cultivation, types of pods, nutritional tables and possible uses are included. Fruit threshing machine to obtain seeds and flour from the National Germplasm Bank of *Prosopis* of the Faculty of Agricultural Sciences of the National University of Córdoba, and some regional recipes are described.

**Keywords:** Algarrobo, morphological characteristic, fruit, flour, recipes

#### **1. Introduction**

The word "*algarrobo*" refers to several species of the genus *Fabaceae*, a word deriving from the Spanish Arabic dialect ("*al jarruba*") [1] which means "the tree." This was the name given to the specimens of the species *Ceratonia siliqua* L., which were spontaneously distributed along the coasts of the Mediterranean Sea and Middle East [2]. When Spanish people arrived in America, they assigned the name "*algarrobo*" to specimens of *Neltuma* (*ex Prosopis*) and coincidentally the native communities called it "*taku*" which also means "the tree." These species coincide in being legumes with similar aspects in their shape and use, mainly food for animals and humans [3]. All of these species present pods as fruit. An example of the component of the typical pods is shown in **Figure 1**. The vulgar name for these pods is "*algarroba."*

The genus *Neltuma* (*ex Prosopis*) has a wide diffusion in various phytogeographical regions of the country, extending from Prepuna to Patagonia, mainly in the Provinces of Monte, Chaco and Espinal [4, 5]. Hughes *et al*. [6], divide the genus *Prosopis sensu* Burkart [7] into three genera: *Anonychium, Neltuma and Strombocarpa*, two of which are present in Argentina with 39 recognised taxa amongst species, varieties and subspecies (**Table 1**).

#### **Figure 1.**

*Components of a typical Neltuma pods (algarroba).*


*The Legumes of* Neltuma spp. *(ex* Prosopis spp*.) and Their Properties for Human and Animal... DOI: http://dx.doi.org/10.5772/intechopen.110436*


#### **Table 1.**

*Taxa present in Argentina of the genus* Neltuma *and* Strombocarpa *(*ex Prosopis*).*

Tree and shrub carobs are multiple-use species [8]. The aboriginal populations and the conquerors knew about these attributes [4, 9]. Species in this genus provide not only wood forest products (WFP), but also non-wood forest products (N-WFP). The tree species of this genus offer a wood that is highly appreciated for its hardness, stability and preservation. It is used in carpentry and for furniture. It is also used for poles, rods and in the manufacture of charcoal (calorific value: 4200 kcal/kg) [10].

Amongst the N-WFP of plant origin, the genus *Neltuma* (*ex Prosopis*) provides leaves, fruits and seeds that are an important source of food for animals. The fruits and their derivatives can also be used as human food. The leaves have high protein value. They contain 22% crude protein, 15% digestible protein and 55% dry matter digestibility [10].

There are numerous uses of the N-WFP of vegetable origin offered by the species of the genus *Neltuma*, amongst of them are: resin, gum, bark and fruits. For example, tannin is extracted from the bark, which is used in the tanning of leather and also in dyes [11]. The fruits, seeds, bark and flowers also have a medical use [11]. Ethyl alcohol can be obtained from the fermentation of the fruits [10, 12]. *Neltuma* species can act as biocontrol agents. Proof of this is the stem extracts of *N. chilensis* that are effective in the control of a Homoptera [13].

Other N-WFP that are obtained in *Neltuma* forests are animals and animal products, such as cattle, goats, sheep [14] from which products like meat, leather, milk, cheese and wool are obtained. The species of this genus are good producers of nectar and pollen, so beekeeping becomes important and favoured, generating other resources of animal origin, such as honey, wax, propolis and pollen [10, 15].

*Neltum*a is also important because it provides services to the forest. It acts as a protective source by providing nitrogen to the soil through the symbiotic association with fixing bacteria and also shade for cattle. Some indirect benefits are: the pasture under its canopies is of better quality, and it supplies abundant organic matter to the soil for present semi-persistent foliage, etc. [10].

In North America, soils under *Neltuma* canopy have more than 1000 kg/ha of nitrogen and more than 8000 kg/ha of carbon than soils outside tree canopies [16]. The contributions of organic matter, nitrogen and phosphorus of *N. flexuosa* forest are significant in the phytogeographical regions of Central Monte of Argentina, constituting true islands of fertility [17]. This species has not only to create edaphic heterogeneity in the region, but also contributed to create climatic heterogeneity, modifying the microclimate, water regime and light conditions under its canopy. This environmental heterogeneity allows a different spatial distribution of species and increases diversity at a regional scale [18]. In India, *Neltuma* has been used to improve high pH (10.4) soils. On the other hand, *Neltuma* species can grow in saline concentrations equal to ocean water [16].

The rural inhabitants of the southern sector of the Calchaquí Valley, province of Catamarca, recognise the use of pods of three species that they call "white," "black" and "*panta,*" identified from the morphology of its fruit and depending on its flavour. As regards the possible production, a total of 9 products obtained from the pod were mentioned (flour, coffee, fodder, liquor, "*añapa,*" "*aloja,*" "*arrope,*" "*aguardiente*" and seedlings), being used by families as a source of fodder, food, drink and medicine [19].

"*Patay*" is defined as a kind of dry bread, floury and sweet paste that is obtained by drying, grinding and sifting the fruits, compressing the flour obtained and then proceeding to cook it. It is marketed locally. The "*chuningo*" is similar to the previous one, but the ground dough is soaked and eaten without baking. The drinks are: the "*aloja,*" a native alcoholic fermented drink obtained by fermenting the pods of "*algarrobo*" which is made by grinding the fruits with water; the "*añapa,*" which is a non-fermented, sweet and refreshing drink, is prepared simply by crushing the fruits in a mortar with water. The sweet product is the "*arrope,*" which is a type of honey obtained by cooking, grinding and sifting. (4). Amongst the flours are: whole fruit flour (FF), mesocarp flour (MF), seedless fruit flour (SFF), seed flour (SF), cotyledon flour (CF) and meso- endocarp residue (R). When the flour is toasted, it can be used to prepare substitutes for chocolate and coffee [20].

#### **2. National Germplasm Bank of** *Prosopis* **of the Faculty of Agricultural Sciences of the National University of Córdoba (BNGP)**

The BNGP's main objective is the conservation and commercialization of seeds of quality and known origin. It currently has 1650 accessions in the Passive Bank corresponding to 1106 trees of 9 *Neltuma* (*ex Prosopis*) tree species from different regions of Argentina [21]. In the last 8 years, it has managed to register 24 Seed-Producing Areas (10 for *N. alba*, 5 for *N. chilensis*, 3 for *N. flexuosa*, 2 for *N. nigra*, 3 of *N. chilensis* x *N. flexuosa*, 1 of *N. alba x N.* sp.), and 2 Seed Stands (*N. alba and N. flexuosa*), from which it obtains seeds to respond to the needs of afforestation and restoration. **Figure 2** shows some of the locations of the species present in the BNGP.

*The Legumes of* Neltuma spp. *(ex* Prosopis spp*.) and Their Properties for Human and Animal... DOI: http://dx.doi.org/10.5772/intechopen.110436*

#### **Figure 2.**

*a) Phytogeographic Regions of Argentina. Distribution of the main Neltuma species in Argentina: b) N. alba, c) N. chilensis, d) N. flexuosa, e) N. nigra and f) N. caldenia.*

#### **3. Characterisation of** *Neltuma* **species**

The collected species are morphologically characterised in the laboratory. A measurement of leaf and fruit characters is carried out to confirm the taxon of belonging following the specifications proposed by Verga [22] and Joseau *et al.* [21, 23].

INASE [24] establishes marketing categories according to the degree of improvement. For a seed-producing area (APS) a morphological characterisation is necessary, whilst for a higher category (seeds from seed stands) a morphological and genetic analysis are required.

**Figure 3** presents some examples of leaves and fruits according to taxon, where the existing variability is observed.

#### **4.** *Neltuma* **("***algarrobo***") flour**

*Algarrob*o flour is a traditional food product made by the communities that inhabit the Chaco Semiarid and Monte ecoregion [25]. However, "*algarrobo"* trees are also distributed in other phytogeographic regions [4, 5].

Articles 680, 681, 681 bis, 681 tris of Chapter IX of the Argentine Food Code provide specifications for the commercialization of flour from the species of the genus *Neltuma* (*ex Prosopis*) and define "*algarrobo"* flour as "the product of the grinding of the clean, healthy and dry seeds" of *N alba* and/or *N. nigra* and/or *N. chilensis* and/ or *N. flexuosa* (Art.681) and of *N ruscifolia* (Art. 680). It also defines "*algarrobo"* "fruit flour" (complete pod with its seeds) as "the product of grinding the complete fruits" of *N. alba* and/or *N. nigra* and/or *N. chilensis* and/or *N. flexuosa* (Art. 681 tris). Likewise, the concept of "*Patay*" is incorporated in the same code as "made by kneading '*algarrobo'* flour, in any of its types: seed or fruit, with water; shaping dough into loaves before taking it to the oven to bake it" [26].

In general, the whole fruit is used to obtain flour. The types the flours obtained after drying the pods are used as substitutes for cocoa and coffee because they do not contain stimulating substances such as caffeine and theobromine. In addition, it constitutes a suitable ingredient in the preparation of sweet products such as cakes, muffins and cookies due to its high sugar content and good aroma and flavour [27]. The roasted white "*algarrobo*" seeds can also be used as a coffee substitute [15].

The fruits of the genus *Neltuma* (ex *Prosopis*) are legumes with a high content of proteins, carbohydrates, fibres and minerals. The legumes which vary in size, colour and chemical characteristics depending on the species [3]. Correa *et al*. [28] found differences between clones of *N. alba* in terms of protein and fibre content, on the one hand, and phenolic component content, on the other hand, in the SF of this species. Hence, when producing on a large scale it is necessary to know the genetic materials to be established in implanted forests.

Flour is gaining great importance in the diet for celiacs, as it is free of gliadins and gluteins. It is considered a building food as it contains protein and energy due to its sugars; in addition to providing mineral salts and vitamins [4, 29].

González-Montemayora *et al.* [20] carried out a review to incorporate legumes such as pods of some *Neltuma* species in the food industry. Some of them produce functional bread-making, protein-fortifying wheat flour with these legumes and enhancing the bioactive content of bread. These authors state that one of the main challenges of adding any legume to a bakery product is the rheological changes in the dough and the final product. Pereira de Gusmão *et al.* [30, 31], quoting González-Montemayora *et al.* [20], concluded that the use of flour from *Neltuma* fruits with a size between 500 and 100 μm is suitable for products such as bread, cakes and cookies. The rheology, tenacity and extensibility of the dough decreases as the concentration of "*algarrobo"* flour increases and the more quantity is added, the weaker the remaining dough. Escobar *et al.* [32] produce CF from *N. chilensis* added a percentage


*The Legumes of* Neltuma spp. *(ex* Prosopis spp*.) and Their Properties for Human and Animal... DOI: http://dx.doi.org/10.5772/intechopen.110436*

**Table 2.**
