Prosopis as a Heat Tolerant Nitrogen Fixing Desert Food Legume: Prospects for Economic Development in Arid Lands

Prosopis describes the enormous historical importance of these trees as a human food source and reviews the contemporary food science of the fruit derived from these trees. As well, this treatise reviews the native genetic resources of this genus on 4 continents and classical genetic and horticultural techniques that could help stabilize the environment and alleviate human suffering on some of the world’s most destitute agro-ecosystems. This book is an essential read for researchers interested in forestry and plant science, environmental science, and functional foods.

The legume family (Fabaceae) contains many genera and species that through their nitrogen fixing process provide high protein food and feed for humans and animals. As evidenced by its presence in Death Valley, California, which holds the record for the highest temperatures in the world, these types of plants can thrive in extreme environments.

• Edited by the world’s leading experts on Prospis species with globally recognized contributors
• Covers the different perspectives surrounding the advantages and disadvantages of planting different Prosopis species
• Discusses the applications of Prosopis species, including how the fruits of this tree can be used as a raw food material

• Language: English
• Publisher: Academic Press
• Release date: Dec 7, 2021
• ISBN: 9780128236321

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Chapter 1: Prosopis: An empowering forest resource in the service of science for humanity

Peter Felkera,b,c; María Cecilia Puppod    a Casa de Mesquite, Salinas, CA, United States

b Altman Plants, Vista, CA, United States

c Universidad Católica de Santiago del Estero, Santiago del Estero, Argentina

d Centro de Investigación y Desarrollo en Criotecnología de Alimentos—CIDCA (UNLP-CIC-CONICET), La Plata, Argentina

Abstract

Semiarid lands occupy 25% of the earth’s surface and contain the area’s most subject to famine, extreme poverty, and political turbulence. Low soil fertility, principally nitrogen limits biomass to less than half of values predicted with water use efficiency coefficients. Annual nitrogen inputs of 50 kg provided by Prosopis could eliminate fertility limitations on water use efficiency more than doubling productivity. Deep-rooted, saline tolerant, Prosopis trees that produce copious pods for human and livestock food are adaptable to the hottest driest zones. Prosopis also produces luxury quality timber that can serve as a base for furniture industries. P. juliflora introduced into Africa has formed millions of ha of dense, thorny weedy stands that hinder grazing. In India sale of branches to biomass power plants has removed the stands and the sale of pods to produce balanced rations has eliminated seeds and increased income. Erect, thornless Prosopis with palatable pods applied in different food products have been developed and through nitrogen fixation, can sequester C, increase soil fertility, increase yields, alleviate poverty and increase political stability in the poorest areas of the planet in Africa, Asia, and Latin America.

Keywords

Archeological; Nitrogen-fixation; Soil carbon; Charcoal; Lumber; Edible pods; Nutritional compounds; Volatiles

Introduction

The world’s arid lands occupy 3400 million ha, are home to 800 million people, possess the countries with the lowest per capita income, education, health standards and have the only countries with mass starvation and animal mortality due to low rainfall (Cervigni & Morris, 2016; Ickowicz et al., 2012; Sène, 1996).

Not only is the rainfall low, but the soils are 10 times lower in soil carbon, nitrogen, and inherent fertility than temperate farmlands (Chapter 2). Unlike potassium, calcium, or phosphorus, nitrogen does not exist as a mineral in the soil but is the indispensable element for protein and the growth of living matter. In arid lands, the annual input of nitrogen (without legumes) is only 1–2 kg ha−   1 year−   1 (Aranibar, Anderson, Ringrose, & Macko, 2003; Chapman, Liebig, & Rayner, 1949) which at 1% N in plant dry matter (6.25% protein), can only support 100–200 kg of dry matter year−   1. In contrast, if 150 mm were transpired by a C4 plant (out of 500 mm precipitation), and if a C4 dryland water use efficiency of 2.96 kg dry matter per cubic meter of water (Steiner, 1986) were assumed, a dry matter production of 4440 kg ha−   1 would have resulted. At 1% N of dry matter, 44 kg of N would be required. As outlined in Chapter 2, Prosopis can fix approximately 50 kg N ha−   1 year−   1 that would allow the plant to take advantage of its high-water use efficiency. For example, in Senegal, yields of 1595 kg ha−   1 were measured for sorghum grains under the canopy of a nitrogen-fixing tree Acacia albida, but only 457 kg ha−   1outside the canopy. However, with 60 kg ha−   1 N fertilization, grain yields of 2602 kg ha−   1 were obtained under the canopy (Dancette & Poulain, 1969). As the plots not directly under the trees were only several meters from the canopy edge, some nitrogen transfer to the inter-canopy zones probably occurred to provide yields higher than 200 kg ha−   1 year−   1, possible from only 2 kg ha−   1 annual N input.

The prominence of nitrogen-fixing Acacias in Africa and Australia and Prosopis in the New World (Griffith, 1961) attests to the hypothesis nitrogen is several times more limiting to annual plant productivity than water. The problem is that the native nitrogen-fixing plants, with their 10 m deep root systems, and biochemical adaptations to low water availability and 40°C temperatures, have evolved spines to avoid predation. Historically the spine issues have been dealt with the use of heavy soil moving equipment or extensive herbicide applications to remove these N fixing plants (Chapter 4).

The importance of approximately 50 times more nitrogen than rainfall and lichens into semiarid soils by leguminous trees on soil carbon and resulting physical and chemical properties cannot be overstated (Chapter 2). Increased organic matter, decreases soil bulk density thus increasing root penetration, increases water infiltration rates, and provides increased cation exchange capacity to hold nutrients and prevent them from leaching below the root zone.

As the extensive arid lands are an enormous sink for carbon and as 12 kg of carbon needs to be taken up for every kg of the 50 kg N fixed for mature trees, arid-adapted N fixing trees could provide approximately 20% of the goal for an annual reduction in carbon (Chapter 2).

Results of technology using P. juliflora to reclaim the 6.8 million ha of sodic and saline soils in India by the Central Soil Salinity Research Institute are described in Chapter 3.

In the last 30 years evaluation of broad-based germplasm collections in replicated field trials, combined with grafting, somatic embryogenesis (Chapter 10) and hybridization techniques have identified erect, thornless, trees with abundant highly palatable pods that can provide this nitrogen-fixing service, while providing luxury quality timber that can serve as an industrial raw material and pods useful for human and livestock food (Chapter 9). The first genomic sequence from a Prosopis alba used in progeny trials (Paterson et al., manuscript in preparation https://www.ncbi.nlm.nih.gov/genome/79095) will be useful in developing molecular markers for important traits.

In spite of plantations with advanced genetic materials, significant small-scale lumber, flooring, furniture, and human food industries have developed. Wood technology studies have demonstrated that due to its reddish-brown color, above average hardness, excellent finishing properties, and perhaps the world’s most stable hardwood, Prosopis lumber belongs in the class of hardwoods suitable for the finest furniture, flooring, and architectural applications (Chapter 13). Small diameter (<   20 cm)/short length (<   45 cm) log processing technologies and high-value products for small lumber have been identified to generate high value-added products from Prosopis (Chapter 13).

Archeological and contemporary use of Prosopis

Prosopis pods were a major food resource from approximately 11,300 BP present in Argentina, P. cineraria uses were described ancient times in Ayurvedic literature by its name Sami in Sanskrit, P. farcta food remains were recognized at Levantine Natufian contexts by archeobotanical seed remains at the Syrian site of Tell about 11,500 BP (Chapter 8). In southwestern North America extensive Prosopis uses of pods (Fig. 1.1) in foods by indigenous people were related to anthropologists in the 20th century (Chapter 8). In Peru, although hunter-gather activities were well described in the mid-Holocene, the first evidence of Prosopis was from construction timbers about 5000 BP (Chapter 7). Later archeological work identified Prosopis as a staff of life for the ancient inhabitants of the coast of Peru (Chapter 7). The evolution of forestry activities in Haiti since the arrival of Europeans through current management and utilization of Prosopis for charcoal, where currently charcoal is over six times more valuable than Haiti’s total agriculture-related export market, is described in Chapter 6.

Fig. 1.1

Fig. 1.1 Prosopis pods at the home of Ruby and David Modesto of the Cahuilla Nation in southern California (thermal) growing on subterranean water in the 100 mm rainfall zone with 42°C summer temperatures.

An example of the harvest and storage of Prosopis pods that still occurs in Argentina is shown in Fig. 1.2. The rich culture, technology, use of natural epiphytic microbiota of Prosopis pods and food chemistry behind the production of Aloja, a fermented beverage typical of the region of northwestern Argentina made with whole P. alba pods detailed in Chapter 25. It is a low-grade (<   6%) alcoholic beverage that was usually drunk by the people of NOA in Argentina from times before the arrival of Spanish.

Fig. 1.2

Fig. 1.2 Overwinter storage of Prosopis flexuosa pods in Salar de Pipanaco, Provincia de Catamarca, Argentina. Photo courtesy Ricardo Miguel Zapata.

Weedy issues of P. juliflora in Africa and India

The invasive nature of the spiny P. juliflora originally from the Caribbean, and efforts to control its spread through the utilization of pods, charcoal, and biomass for energy are described in Chapters 4, 5, 11, 12, and 14 for Kenya, the Horn of Africa, Yemen, and India.

An informal introduction of P. juliflora of Caribbean origin, without a replicated comparison of indigenous varieties in a randomized trial, into tropical semiarid Africa, was made in the late 1800s and has spread throughout the semiarid zones of Sudan, Ethiopia, Somalia, and Kenya. The spread is partially due to intensive seed production and partially due to the unsustainable harvest of ecosystem N by grazing animals, resulting in low fertility soils that can be colonized by nitrogen-fixing plants. While the species is extremely well adapted to arid African ecosystems, the species is thorny, multistemmed and its pods are much less palatable to humans than other Prosopis species. This species has colonized millions of ha in the Horn of Africa, often forming spiny dense thickets that have reduced the livestock carrying capacity of grazing animals (Chapters 11 and 12). As in other forest ecosystems from pines to Giant sequoias, initial site colonization can have numerous seedlings per square meter but with natural mortality or successive thinnings, large trees on wide spacings will dominate the site that will prevent further encroachment and provide useful services (Felker, Meyer, & Gronski, 1990; Long & Smith, 1984). Numerous government programs have been enacted in Kenya, Ethiopia, Somalia, and India (Chapters 5, 11, 12, and 14) to control the spread of P. juliflora. The most successful has been in India (Chapter14) where industries have been created using the pods for balanced animal rations in compressed blocks for livestock, in the fabrication of an instant coffee/Prosopis beverage, and by the sale of 300 tons of branches per day to a biomass electrical generating facility.

Food components present in pods, mesocarp, and seeds of Prosopis species and their food technology

Abundant pods shown on a Prosopis glandulosa var. torreyana tree on the Cahuilla Nation in the California desert with 100 mm rainfall growing on groundwater were the most important food source for indigenous people in the southwestern USA as well as Argentina (Chapter 8) (Fig. 1.1). The pods were also consumed in Death Valley, California (Colville, 1892). A mature Prosopis in the dunes of Death Valley is shown in Fig. 1.3. The pods were also important for wildlife, and when included in balanced rations provide a low-cost feed source for animals in semiarid regions that produce positive weight gains and milk production (Chapter 25). The pods consist of a sucrose-rich pulp or mesocarp and a fibrous capsule (endocarp) surrounding the small hard-coated seed. The major pod components are 30%–35% sucrose which is located in the pulp, approximately 60% fiber from the flexible capsule surrounding the seed, and 10%–14% protein from the protein in the pulp portion and the hard-coated, nondigestible seed (Chapter 21, Meyer, 1984). The seeds consist of a hard seed coat, a high-protein embryo, and of a galactomannan polymer. The pods have no gluten and are appropriate for celiac diets. For challenging gluten-free applications where elasticity is important in high-rising breads, tortillas, and pasta, hydrocolloids can be helpful (Chapter 24, Padalino, Conte, & Del Nobile, 2016). When heated or baked, mixtures containing Prosopis flour, such as pancakes or breads, turn to light to brown color (Felker, Takeoka, & Dao, 2013) and the rich mixture of more than 100 volatiles (Chapter 23) produces a pleasant chocolatey, cinnamon, and coconut aroma. Due to the hand harvest from wild trees, and subsequent need for washing, drying, and several milling steps, leading to a 45% yield of flour from the pulp, the cost of the flour is significantly greater than other gluten-free products such as manioc, sorghum, rice or potato flours. Thus, in commercial applications, Prosopis flour is most appropriately used at low concentrations (10%–25%) to reduce costs, which fortuitously is also the concentration which yields optimum reception in taste panels (Meyer, 1984).

Fig. 1.3

Fig. 1.3 Prosopis in Death Valley California. Note assistant Steve Boyd at the lower right corner.

Prosopis pods can be conveniently milled into the following fractions: Fraction A a high sugar fraction (48% sugar) moderate protein (9.5%) from the pulp; Fraction B a high fiber fraction (6% sugar, 6.5% protein, 45% fiber) from the endocarp capsule which surrounds the seeds; Fraction C broken seed coats that are attached to the endosperm which is 4% protein and 82% galactomannan gum; and Fraction D the cotyledons with a tiny germ that is about 60% protein, 8% fat, and 4% fiber (Meyer, 1984). The relative proportions by weight of these fractions were: high sugar fraction 53%, high fiber fraction 22%, and seeds 12%–14% (Chapter 21).

Mesocarp flour

The mesocarp or pulp fraction which is portion commercialized by some companies as Mesquite flour contains the majority of the sugars, organic acids, and volatiles responsible for the flavor and aroma as well as proteins and polyphenolics that have nutritional value. As commercial milling processes do not provide 100% separation of the pulp from the fibrous covering surrounding the seed, consider insoluble fiber ends up in mesocarp flour which is beneficial in human diets. The sugar is principally sucrose that can be as high as 50% in this fraction (Chapter 21) and in moist, unheated flour can enzymatically be converted to glucose and fructose (Becker & Grosjean, 1980). Citric, malic shikimic, and fumaric acids occur in the mesocarp fraction with citric being by far the predominant one (Chapter 23).

The desirable aroma of Prosopis flour is due to a mixture of more than 100 pyrazines, lactones, saturated and unsaturated aldehydes and ketones, phenols, sulfur compounds, acids, and esters. An undesirable flavor/aroma from oxidation of seed oils in flour of entire ground pods results in hexanal formation. The principal favorable aroma component with a pleasant coconut and chocolaty flavor in P. alba and P. pallida, but lacking in P. velutina pods is 5,6-dihydro-6-propyl-2H-pyran-2-one (Chapter 23).

As opposed to thousands of years of domestication of P. alba/flexuosa/chilensis in Argentina (Chapters 8 and 17) and P. pallida in Peru (Chapters 7 and 16), no such domestication is known to have occurred in the Caribbean P. juliflora (Chapter 8) that has become naturalized in Africa, the middle East, and the Indian subcontinent. As such it is not surprising that when compared with the good flavor and taste of P. alba and P. pallida pods, a disagreeable flavor is noted when Haitian, African, and Indian P. juliflora pods are masticated. It now appears that high citric acid concentrations (> 2 g/100 g) for P. juliflora are correlated with an unpleasant flavor as compared to below <   0.9 g/100 g for P. alba (Chapter 23). Not only are there major differences between species, but in the species with the best tasting pods, i.e., P. alba and P. pallida, large variation in pod flavor was noted among progeny, and in this case, trees with the most flavorful profile were asexually propagated (Chapter 9).

An in-depth characterization of polyphenols in P. alba mesocarp flour found a rich diversity of free, bound, and glycosidically linked polyphenol compounds (Chapter 19) that possessed antioxidant, antiinflammatory, anticarcinogenic, and neuroprotective functions, suggesting that that P. alba mesocarp flour should be considered a functional ingredient in foods.

The protein, amino acid, sugar, lipid, and elemental composition of the entire pod pulp (pericarp) and seeds of P. alba and Prosopis nigra were characterized in Chapter 21. High levels of the amino acid lysine in the protein fraction were observed that is beneficial, since cereals are limited by this amino acid. The mineral profile indicates that these mesocarp flours are a good source of Fe and Zn. An analysis of equilibrium moisture relations in P. alba and P. nigra flours found that at lower temperatures of 10°C and 20°C P. nigra had a higher moisture content than P. alba due to the higher sugar content in P. nigra and that the water activity aw of these flours was sufficiently low <   0.7 to be considered safe from a microbial stability perspective. P. nigra mesocarp flours were found to have higher amounts of polyphenols with greater antioxidant activity than P. alba (Sciammaro et al., 2021). Though Prosopis flours have been extensively used in traditional foods since ancient years, as described in Chapter 17, they have a great potential to be explored as ingredients for the reformulation of common foods.

Seed proteins and polyphenols

Unfortunately, as Prosopis seeds comprise only 12%–14% of pod weight (Chapter 21) and contain significant quantities of seed coat and endosperm (gum), in addition to germ + cotyledons, the cotyledon plus germ is only a few percent of total pod weight, is susceptible to bruchid predation, and would be economically challenging to fractionate from the entire pods. Nevertheless, the seed germ had 65% protein with a favorable amino acid composition. P. alba and P. nigra were found to have a very rich diversity of polyphenolic glycosides with showed strong anti-oxidant activity and inhibition of proinflammatory enzymes (Chapter 18).

Flavonoid patterns of P. alba and P. nigra germs were almost identical, whereas P. ruscifolia showed minor differences, with amounts of isoschaftoside between 3.22 and 5.18 mg/g germ and enzymes (schaftoside in a range of 0.41–0.72 mg/g germ (Chapter 18). P. alba and P. nigra presented 6%–7% of very long-chain FAs (C20–C24), while lower values were detected in P. ruscifolia. In general, Prosopis spp. germ contains higher amounts of polyunsaturated FA (PUFA). P. nigra presented the highest amount β-sitosterol (a phytosterol), while P. nigra (5.68 ± 1.02) and P. ruscifolia (5.83 ± 1.00) contained higher levels of squalene (mg/kg) than P. alba (Chapter 18) The germs of these Prosopis species contained around 65% of protein. These proteins presented very high digestibility, as it was confirmed by gastro-intestinal assays in vitro. Oral gastric digestion (OG) degraded the major protein bands and released polypeptide fragments of low molecular weight. After downstream duodenal phase (OGD) digestion, faint bands were observed in the case of P. alba, while no polypeptide was detected for P. ruscifolia and P. nigra (Chapter 18).

In the specific case of P. alba seeds, not only the number of proteins of the germ was analyzed, but also their bioactive behavior after enzymatic hydrolysis (Chapter 20). Proteins, and protein hydrolysates from this germ presented antioxidant capacity and inhibitory activity of pro-inflammatory enzymes (lipoxygenase and phospholipase). Free polyphenol compounds were dominant in cotyledons being C- glycosyl flavones the main constituents. Polyphenolic compounds enriched extracts exhibited ABTS• + reducing capacity and scavenging activity of H2O2; and were also able to inhibit phospholipase, lipoxygenase, and cyclooxygenase, three proinflammatory enzymes (Chapter 20).

Seed gums

Other important compounds of Prosopis seeds are galactomannans that are found as a film surrounding the germ inside the seed (Chapter 22). Galactomannans act as fiber, as texture modifying agents, and also contribute to sensory characteristics. These molecules would constitute as an alternative to traditional hydrocolloids used in encapsulated systems, as thickening agents, as modifiers of crystallization kinetics or as biomolecule protectants. Physical properties influence functionality and define further potential uses. A multi-analytical approach, considering thermal and mechanical properties in a wide range of water contents, and spectroscopic determinations (¹H NMR, FTIR) was able to define the impact of molecular structure on supramolecular behavior. The controlled enzymatic modification of galactomannans would expand their potential use for specific purposes.

Food safety

With regard to food safety (Chapter 15), the presence of the spore-forming Bacillus cereus, which originates in the soil and is resistant to high temperatures and disinfectants is the only pathogen that has resulted in a US Food and Drug Administration (FDA) recall. However, dry heat treatment of 27 min at 110°C reduced B. cereus spores by 90%. The US FDA requires a special Bacara media to count B. cereus colonies. Aflatoxins which result from the growth of Aspergillus fungus in moist products had aflatoxin (25 ppb) a bit over the FDA limit (20 ppb) in one commercial Peruvian Prosopis flour shipment. Seed weevils known as bruchids (Algarobius prosopis) attack the seeds of Prosopis pods and also propagate spores of the Aspergillus fungus and Bacillus cereus in their intestinal tract. Bruchids can be eliminated by treating pods at temperatures higher than 55°C. Nevertheless, infected pods are discarded before milling during flour production. Seeds/endocarps that house bruchids during their life cycle are best removed in the milling process.

Food applications of Prosopis spp. flours

Becker and Grosjean (1980), Meyers (1984), and Saunders et al. (1986) of the USDA Western Regional Research Center, identified appropriate milling equipment to produce high sugar, high fiber, high protein, and gum fractions, measured protein, and amino acid composition, examined rheology of prosopis gluten and nongluten products and set the stage for the excellent work that followed. Del Valle, Marco, Becker, and Saunders (1989) examined taste panel responses to mixtures of Prosopis in various products. In Latin America, PhD theses of Cruz (1999) on Prosopis galactomannan technologies and Prokopiuk (2008) on coffee substitutes using Prosopis flour, significantly added to that knowledge base. In the last 10 years more detailed studies of protein and amino acid composition and anti-cancer/anti-inflammatory polyphenols and polyphenolic glycosides from Prosopis have appeared (Chapters 18,19, 20, 21, and 22).

Due to their sweet taste, the effect of P. alba and P. chilensis on texture, functional aspects, and shelf-life were examined in a variety of products (Chapter 24). Four products were examined with various levels of Prosopis flour, i.e., P. alba flour with wheat bread with yeast, P. alba flour with wheat and yeast for panettone-like bread, P. alba muffins with yeast but no gluten, and P. chilensis gluten-free biscuits without yeast (but NaHCO3) that were evaluated from a technological, sensorial and nutritional point of view. Two uses were examined, as a wheat flour replacement (breads and muffins) or as a sugar replacement (semisweet biscuits). Improvements in the nutritional and functional aspects of all products were obtained, by increasing the content and quality of proteins, dietary fiber, minerals, and polyphenols with antioxidant activity. The products had good acceptability by untrained evaluators, with levels of acceptance similar to that obtained for baked products without Prosopis flour. Technological quality, evaluated through specific volume, was slightly affected in wheat-based breads (lower volume) but the shelf-life, detected by the decrease in retrogradation of starch during time, was improved. This effect is attributed to changes in the protein gluten matrix exerted by the fiber and the globular proteins of Prosopis flour. Prosopis flour led to dough with low volumes after fermentation and the breads had firmer crumbs with small alveoli, although with good sensory acceptability. No changes were observed in the texture parameters of breads with Prosopis flour that were subjected to Part-Baking technology (8 weeks of frozen storage at −   18°C) in comparison with nonfrozen bread.

In the case of gluten-free muffins and biscuits, no negative technological changes were generated. All these products had very good physical and sensory characteristics. Nutritional analysis of the muffins indicated that those with a high level of Prosopis alba flour had higher amounts of proteins, minerals, dietary fiber, and compounds with antioxidant activity. Sensory and nutritional analysis showed that this flour contributed in a positive form to the muffin’s quality, being a suitable ingredient as mimetic of chocolate-based breads. The replacement of free sugar in semisweet gluten-free biscuits with 10% Prosopis chilensis flour led to products that did not develop changes in texture and color but contained high amounts of dietary fiber and compounds with antioxidant activity.

In the US interesting synergisms between the rich suite of aroma/flavor volatiles of Prosopis and chocolate have attracted the attention of culinary leaders such as Rick Bayless of the Topolobampo restaurant in Chicago as evidenced by a flourless chocolate/Prosopis cake shown in Fig. 1.4.

Fig. 1.4

Fig. 1.4 Flourless chocolate/ Prosopis cake at the Topolobampo Restaurant in Chicago developed by the team under Chef Rick Bayless.

In summary, the flour from edible pods of Prosopis spp. while little used at the industrial level constitutes a valuable alternative for the nutritional improvement of the traditional bakery products for the development of new products designed for people who require nutritionally balanced diets. The scientific studies of the uses of Prosopis spp. pods and flours show the versatility applications of this underutilized leguminous in the food industry.

Limitations to development of Prosopis species

Past limitations to the development of superior Prosopis genetic materials, lumber, and pod utilization technologies stem from an extremely poor disenfranchised shareholder base, such as Haiti, Sahelian Africa, and arid India with almost no political influence. Universities and technological centers located in uncomfortably hot, low population density arid zones, distant from major metropolitan areas and advanced universities, simply did not have the financial or human resources to understand the salient nature of the benefits of N fixing tree ecosystems as they are very different from annual cropping systems. Additionally, a quantitative analysis of the influence of nitrogen fluxes from rainfall, microbes, grazing animals, and N fixing trees on soil fertility, plant productivity, and weediness in these tree ecosystems were not in the knowledge base of scientists and funding agencies of ethnocentric cultures of North American and European universities and were not considered worthy of study or research funding.

Insertions of single genes, or multiple genes acting independently, into crop plants has been extremely beneficial for insect resistance, disease control (Que et al., 2010), and nutritional aspects such as Golden rice (Stein, Sachdev, & Qaim, 2006). Due to the extremely complex control of multiple genes in the physiology of heat tolerance, drought resistance, or nitrogen fixation under heat/drought/salinity stress, it is unlikely that insertion or deletion of genes in soybeans or cowpeas will permit them to be strong N fixers with high yielding seeds in zones with 10-m-deep water tables, and 5-month dry seasons with temperatures over 35°C. Fertile progeny with outstanding growth and form resulted from a cross between self-incompatible, diploid North American P. glandulosa and South American P. alba (US patents PP 32, 467 and PP 32, 438) species. These species are only two of the approximately 30 North and South American species in the series Chilensis of the section algarobia of the genus that may hybridize, and that stretch from the hottest location in the world Death Valley, California, through the hyper-arid coastal regions of Peru with erect, thornless, sweet podded trees to the enormous hypersaline, high pH salars (salt flats) in Argentina. This interbreeding, gene pool offers almost unlimited potential for hybridization and cloning of elite individuals. Prosopis is a precious forest resource that can be used in many diverse applications in the service of humanity.

Needs to develop Prosopis for arid lands

There is a pressing need for applied research to create technological packages for Prosopis in arid lands that among other things includes:

–Genetic improvement of thornless, erect fast-growing, insect/disease resistance and high production of palatable pods.

–Applied genetic research in asexual reproduction, molecular markers.

–Plantation establishment and management techniques for both lumber (thinning, single stem management) and pods (canopies that permit mechanized pod harvest) and intercropping/grazing.

–Optimization of nitrogen fixation for soil improvement.

–Improved packages for recuperation of saline and high pH soils.

–Hand and powered techniques for pod harvest, cleaning, pod drying to facilitate milling, compaction for storage transportation, and storage to reduce insect damage and aflatoxin development.

–Commercial-scale pod milling into high-fiber, high flavor/aroma, and seed fractions and development of food applications.

–Food technological applications of Prosopis flour.

–Incorporation of Prosopis into carbon sequestration/global climate change programs.

–Technology for short-small diameter log sawing systems and marketing development for products of this technology.

–Development of markets for ground Prosopis pods for livestock feed, wood chips from small diameter (< 10 cm) thorny trees that have become invasive, and high value-added lumber products from small-diameter short logs that are sufficiently large to have significant macro-economic impacts.

Potential for alleviation of poverty elimination and ecosystem stabilization in Sahelian Africa by Peruvian Prosopis

Sub Saharan Sahelian Africa, stretching from Senegal to Somalia, with its 5-month long dry seasons, low 250–500 mm rainfall, and high (>   40°C) temperatures contains some of the world’s poorest countries (Ickowicz et al., 2012). Due to these adverse and highly variable climatic conditions, agriculturally based economies produce low and variable revenues. Low soil fertility is often the major constraint for the production of food grains and natural vegetation that in turn constrains animal production (Van Keulen & Breman, 1990). Peruvian Prosopis pallida has been shown to fix nitrogen (Felker & Clark, 1980) and in all likelihood the soil under mature trees can accumulate 17,0000 kg ha−   1 of C and 4000 kg ha−   1 of N as does P. glandulosa (Geesing, Felker, & Bingham, 2000) and will fix approximately 50 kg as does P. alba (Chapter 2). As noted above, 50 kg ha−   1 of nitrogen has been shown to double sorghum grain yields (Dancette & Poulain,