Future Use Prospects of Legumes through Improvement and the Challenges Faced

Abstract

Legumes are important crops, being one of the most protein containing species of grain plants from their seeds which are used as food among other uses of the crop such as Nitrogen fixation (in most), which helps maintain soil nutrition at bay. The uses extend to key ingredients in livestock feeds manufacture even for marine life diets. Their roots go deep into the soil to find water and in the process hold soil particles together aiding in soil erosion control. However, low performance and production levels have been recorded over the years with Africa, for example, contributing only 10% of the entire world legume production per year. This is attributed to little breeding programs being conducted on the legume plants among less improvements aiding in the plants’ performance and production for sustainability. This book chapter therefore seeks to outline in depth some of the future prospects of legume plants species in relation to improvements that should be done on the crop such as breeding programs to sustain diverse functions, among which, increasing food security. The improvements not only aim at helping humanity, but rather the environment in general including marine life.

1. Introduction

The leguminous family of plants is the largest pods-producing flowering plants family with over 18,000 different species classified into 650 generic classes [1], under the 1/1/12th of all known flowering plants on the planet earth. Not all legumes fix atmospheric nitrogen. Among the Leguminosae subfamily, the Fabaceae species are recognized as those with the primary agricultural role in the group. Herbaceous and woody legume plant types from the Fabaceae species have been used for pastures, animal feeds, erosion control, agro-forestry purposes and as sources of green manure traditionally. Above the uses, they also yield important industrial substances such as tannin, resin for making gums and glues, synthetic dyes, perfumes, insecticides and bio-fuels. Some of these leguminous family valuable food crops include, peas, common beans, peanuts and soybean, which produce high protein grains for human consumption, making an important constituent in their diet. Of all the plants that man used as food, only the grasses are more stable as compared to the legumes [2]. Despite considerable resources being directed towards the development of grasses such as rice, maize and wheat, only peanuts and soybeans within the leguminous family have been thoroughly given priority on the same. The world’s increasing population needs adequate food to feed its citizens so as to prevent common malnutrition problems, which is prospected to be greatly contributed by dietary legumes in order to achieve food security in our nations.

Through improvements that aim in increasing the performance and yields of legumes, these plants are super contributors to the economy to ensure food security among nations in the word. Breeding programs such as gene mapping to identify and isolate traits aid in the selection and isolation of genes of interest from plants which are improved and modified then used in legumes to boost the performance [3]. Other technologies include breeding to suit performance roles such as adaptability to environments, for example deep roots in search for water. Legume produces can be improved for uses in the food industry for humanity, in feed industries such as in ruminants dies replacements and in industries and in the pharmaceutical industries in the manufacture of drugs.

Besides the improvements, there are many breeding technologies which are aimed at improving performance and yield currently. An example is the breeding for lodging resistance which reduces yield losses especially during heavy rainfall seasons by avoiding plant bends which promote rotting once the pods come into contact with moisture. Breeding is also done to increase the general yields of the plant by increasing the number of produces per plant in many agricultural crops. Breeding is done to reduce grain shattering in legumes especially during harvesting stage. This is by preventing the chances of the pods to open which leads to losses through spillage [4, 5]. All these are some of the many examples which are believed to form the basis for this chapter. This is because in order for improvements to occur, much grains must be produced, and of high quality as the grains are the requirements in implementation of most of the improvement prospects.

As agronomists, scientists and researchers, our main perspective is to think of legumes in the primary role of aiding in nitrogen fixation to otherwise deficient soils. Despite, other scientists outside the “agriculture” field view the crop for diverse benefits and uses, such as use as a vital source of food and forage, use in rotation with other crops to improve yields and also as a forest commodity essential for providing firewood traditionally or shelter. However, some scientists from the medical field now view the crops as a source of pharmaceutical ingredient in the manufacture of major drugs for hospital use in a range of maladies. This role should not be under looked when we display that legumes have been a major component of traditional medicine among communities for centuries. Despite the purpose you intend to grow the crop for, its symbiotic role, that is, the association between the nitrogen fixing bacteria in the root nodules (rhizobia) and the plants, play a significant role in agriculture production sector by reducing ca. 100 million metric tons of atmospheric nitrogen into ammonia [6], thus saving the world about US$30 billion on Nitrogen fertilizer every year. Following photosynthesis process in plants, we might consider viewing Biological Nitrogen Fixation (BNF) by legumes as the next most important essential natural occurring biological process in plants. There is still a challenge on the realization of this process as many developing and developed countries all over the world have not fully embraced Biological Nitrogen Fixation but instead rely upon nitrogen fertilizer to drive agricultural productivity. This lack of adoption of the process is majorly attributed to many factors ranging from little knowledge and expertise in both the manufacture of inoculants and in the growing of inoculated legumes with rhizobia. Some governments in many countries across the world with advanced economies also are viewed to participate in this by providing subsidies which mitigate against the use of Biological Nitrogen Fixation (BNF). Unfortunately, with the fossil fuel prices hiking, small economies will most likely be faced with either food shortages, high food costs or inflated fertilizer nitrogen prizes. Many developing countries such as those in South Eastern parts of Asian continent rely upon buying of urea (a nitrogenous fertilizer) for rice production [7]. This is a problem that needs to be addressed as soon as possible due to the current forecast that food production will have to double by the next 10 years so as to feed and sustain the expanding population. This can only be avoided with employment of Biological Nitrogen Fixation (BNF) inputs.

Apart from direct benefits of artificial nitrogen fixation from legumes, they also provide additional importance in aiding in weeds, pests and pathogens control, improving soil fertility when the plants die and form organic manure and ensuring stability from rotation in different and diverse cropping systems with different species of crops. Taking a look at a country like the United States of America (USA) alone for example, alfalfa, Medicage sativa, is currently estimated to be the third most valuable crop worth up to $7 billion annually [8]. However, intense pressure from biological, environmental, human health as well as economic sectors dictate that the legumes suite and their use in the modern civilization to be dynamic rather than fixed. This chapter outlines how legumes can be developed, more so rhizobia, for future diverse uses not only in agriculture but outside fields as well.

2. Legumes future breeding improvement prospects

2.1 Legumes use in pharmaceutical industry to solve health problems

The strong consumer-driven trend for natural products in the world has pushed for shift to natural active ingredients in medicines manufacture. Of the active ingredients prescribed in pharmaceuticals, 25% are flowering plants-derived, expected to increase to about 30% in the next 10 years to come. On this, of the antineoplastic drugs that are prescribed in the Western countries and in Japan, 54% are natural occurring products or their analogs [9]. Many consumers in the world aim at natural drugs, believing that they are safer that synthetics. This has also pushed many, more so in African countries, to go the herbal medicine direction rather than buying drugs from chemists and pharmacies. The current global market for natural pharmaceutical products is estimated at US$30 billion growing at an increasing rate of 6% per annum [10]. Herbs (which also includes many legumes), possessing anti-cancer or penile potency properties are the main focus of smuggling into the European, Japan and the USA markets. Advances in analytical chemical techniques in plants, such as High-Performance Liquid Chromatography (HPLC), Mass Spectroscopy (MS) and Nuclear Magnetic Resonance (NMR) have allowed the rapid identification of proteins in plant cells that are responsible for increasing the legumes value, particularly in regards to the pharmaceutical industry. References proposed that legume plants species combine essential genomic materials with biochemistry thus forming a compound which is of acute relevance to human health.

Non-traditional benefits of legumes in human diets have been emphasized also in the recent years commonly. These benefits include, alfalfa sprouts and soybeans use as a source of phytoestrogens which aims at reducing menopause symptoms majorly in women and also aiding in maintaining bones health. In the Chinese medicine for example, one of the old-dating known useful plants is the licorice, (Glycyrrhiza glabra, a popular legume herb known for its anti-ulcer and anti-inflammatory properties. Legumes also contain useful chemical compounds in their protein-DNA that are essential for their ant-diabetic, anti-allergenic as well as anti-inflammatory properties [11]. Plant Genetic Resource Conservation unit (PGRC) within the United States Department of Agriculture (USAID) is currently conserving 17 different legumes species containing essential phytochemical properties with positive human health impact. Some of these plant legume species include the butterfly pea, Clitoria ternatea l., known for its anti-fungal properties, hyacinth bean, Lablab purpureus., known for its anti-hypertensive properties and kudzu, Pueraria montana var. Lobata willd, known to containing isoflavone daidzein properties essential as an anti-inflammatory, anti-microbial and cancer preventive treatments. The five pyran isoflavones isolated from a Fabaceae family species rootstock, Eriosema kraussianum, contains 75% properties of Viagra which increases blood flow in rats’ penile tissue as the active ingredient. Trigonella foenum-graecum l. plant popularly known in the Indian medicine for increasing lactation in women [12], also contains numerous chemical properties of interest in the modern pharmaceutical sector, for example, diosgenin and coumarin.

Legumes also contain phytoestrogens with great biological activities currently being applied to humans for menopause and osteoporosis treatments. These phytoestrogens are plant-derives chemicals, so named due to their possession of both estrogenic and anti-estrogenic traits, although much less effective than the genetically human produced estrogens. Isoflavonoids are one major phytoestrogen class that includes genistein, daidzein and equol compounds. They are also among the most extensively classes of phytoestrogens to be researched. Isoflavonoids are the most particular prevalent classes in the Fabaceae sub-family of leguminous plants the most studied being the ones from soybeans and red clover, Trifolium pratense l., species. The isoflavonoids extracted from red clover and soybeans are now being used as alternative compounds in the Hormonal Replacement Therapies (HRT) for the treatment of the menopause-related disorders [13].

Soybeans are the main dietary source of food of the two isoflavonoids, genistein and daidzein, in humans, present in their glycoside forms. A huge consumption of foods containing high soy-based products may result in high plasms levels, high urine and prostate phytoestrogen fluid concentrates. Epidemiological studies on the other hand suggests that women in Asian countries with a high phytoestrogens dietary intakes have a decreased breast cancer risk rates and also a lower menopause-incidence symptoms. As well, the study still suggests that men consuming high-soy product traditional foods have a lower prostate cancer incidences especially Asian men as compared to European and American men. Although these claims may not provide sufficient evidence and still awaits further study, numerous in vitro studies support a role of genistein in inhibition of the growth of a number of cancers [14].

Laboratories in vitro studies have produces alcohol extracts from a wide range of legume leaves and stem tissues that aid in in inhibiting the growth of MCF7 breast and LNCaP prostate cancer cells [15]. Soybean isoflavonoids is also suspected to have a role in the maintaining of healthy brain tissues and also in the treatment of age-associated cognitive declines such as Alzheimer’s disease, loss of memory episodes, and improving the general cognitive functions in the brain.

Many of these mentioned secondary plant compounds are mostly found in small quantities and tend to be synthesized in specialized cells in the plants or at specific growth stages. This makes their identification, extraction, separation and purification processes more challenging. Nevertheless, equipment has been invented and now currently available, which are aided to speed up the extraction of the useful legume compounds for use in human medicine improvements in the pharmaceutical industry.

2.2 Legumes use in food industry

Due to most of the underutilized legume plants’ high nutritional properties, some essential proteins can be extracted from the plants and used in the food industries in the manufacture of various products. For example, edible products such as cooking oil can be extracted from soybean and the African yam bean. This is due to their high lipid contents [4]. These lipids used in the manufacture of the cooking oils is obtained from the seed grains, which are processed to produce the final product “oil”.

Underutilized legumes can also be processed into flour. This will not only extend the shelf life, but also diversify food by increasing the options for the legume produce use. The process is done after the grains have recorded a reduced moisture content of 4% or less [5]. After that, the grains are taken to the grinding machine after which processed into flour. This flour can now be stored for up to six months depending on the storage conditions. On another option, the flour can be used in preparation of foods such as the famous “ugali” in many African countries. The flour can also be used in a combination with other grain flours such as maize flour, millet flour and sorghum flour in making of porridge which is a good example of breakfast foods for use with either bread or other breakfast food choices.

The processed flour can be used in the baking industries [16]. Here, the flour is processed into legume breads. Some of these breads can be made from undermined legume crops such as soybean. This will very much aid in diversifying food uses too not only consuming the grains directly for lunch dishes, but through processing, legume-bread can also be made which is a good breakfast choice and even for export to other countries.

2.3 Legumes use for ruminants benefits

When it comes to the emergence of herbicides resistance in weed control, development and implementation of chemical control method for gastrointestinal parasites in grazing animals is an equilibrium between seeking of efficiency and avoiding the resistance development. Nematodes in sheep such as Osterstagia circumcincta, Haemonchus contortus and Trichostrongylus spp. are a major cause of livestock mortalities and reduced production, and further widespread resistance to anti-helminthics treatment effective control. However, there is sufficient evidence that plant natural occurring tannins in majority of forage legumes can reduce worm infestation issues in grazing animals, hence reducing the requirement for deworming. This in turn provides a new weapon in the management of anti-helminthic parasites resistance. The potential anti-helminthic tannin or CTs containing properties are described as proanthrocyanidins, phenolic compounds present in varying concentrates in wide range of leguminous forage plants. CTs form an important part of the plants defense against bacterial and insect predation and also against invasion into grazing vegetation for herbivores. The CTs may also have a positive impact on ruminant nutrition by increasing the efficiency of utilization of proteins. Through the reversible of binding to plant proteins, CTs are postulated to interfere with the protease activities produced by the rumen micro-organisms thus reducing the protein degradation process in the rumen and in return allowing a larger portion of protein to reach the ileum [17]. However, despite the discussed benefits of leguminous CT plants in increasing the wool growth more so in sheep, milk production in mostly dairy livestock, increasing reproductive rates and aiding in bloat control, high tannin concentrations can also reduce the voluntary feed intake rates in ruminants resulting to reduced animal performance. All these effects of CTs towards ruminants vary evidently according to the nature, concentration and the structure of different compounds and potential anti-helminthic properties.

Positive benefits of various leguminous CT forage plants in reducing worm infestation challenges in sheep have been identified in numerous studies. For example, in feed experiment trials, significant reduction in worm infestation levels have occurred in sheep grazing in tannin containing forage plants such as sulla, Hedysarum coronarium, lotus, Lotus pedunculatus, birdsfoot, trefoil, L. corniculatus and chicory, Cichorium intybus. pen studies conducted with tannin extracts also indicate that there is a large decrease in sheep-worm egg count and also a lowered worm infestation rate. In goats, pen studies as well also indicate a decreased Haemonchus contortus and their significant anti-parasitic effects with Sericia lespedeza forages in all pens in the trials. in a general view, the worms egg counts are lowered within a week post the introduction to CT-containing pasture legumes or rotations [18], with much decreases in total worm numbers up to 30–35% in relation to introduction to non-CT legume groups.

2.4 Legumes use in aquaculture and marine feeds

Aquiculture sector over the years has expanded very quickly that it currently provides over 30% of the world`s global fishery products to industrial ones. Although marine-based ingredients such as fishmeal and fish oil are manufactured in industries and remain many people’s preferrable protein and oil sources from aquaculture products, it is projected that by the next 10 years or so, 50% of the world’s fish catch will most likely be directed towards legume feeds [19]. The current and modern intensive aquaculture practices is therefore viewed as a net fish user rather than producer which is very much undesirable and should not be the trend. Almost much of the soybean meal extracts have already been approved and verified for use as alternative protein and energy source by the aquaculture industry sector. On top of that, sweet lupin, L. angustifolius, and other legume grain extracts are currently underway in evaluation appearing to be current substitutes of fish manufactured feed products. Can other legumes specifically those that can be produced intensively satisfy the increasing protein and energy demand in the aquaculture industry at large?

Fish do not require carbohydrates in their diets and their presence in grain legumes can reduce fishmeal digestibility produced from the grain legumes and cause huge decrease in protein retention in fish yet they require S-rich amino acid proteins and fatty acid or lipid oils in their diets. Even though these compounds are provided by legumes in different ratios, anti-nutritional factors similar to the ones previously discussed for humans and other monogastric animals also affect fish [20]. Most notably are the saponins, protein inhibitors, oligosaccharides and high cellular or fiber content. All these and other potential tainting molecules, for example, coumarins cannot be assumed in the formulation of fish diets, however, extracting them from legume grains requires expensive procedures or an extensive breeding program approaches to achieve.

One of the important roles of fish in human health is related to the long chain omega-3 to omega-6 oil ratios with more than 18-carbon atoms on a straight chain in marine products. Two issues of importance arise from here in relation to oil from legume plants. First, legumes produce predominantly C18 oils rather than C20 and C22 oils from fish proven to have beneficial importance to human health. Fish from fresh waters can synthesize C22 fats from C18 precursors as compared to marine fish, mainly cold-water ones, which are much less able to do so. Secondly, the omega-3-omega-6 ratio considerably between leguminous plants and fishmeal, with a much difference of up to more than 100 folds [21]. For more improved human health, a high omega-3-omega-6 ratio is essential, and if lower oil levels are ultimately reflected in fatty acid content of aquaculture end products, the legume-fed fish value in human diets needs to be supplemented.

Nevertheless, dietary substitution of fishmeal in aquaculture fish feed diets containing high protein grains is attractive, particularly those containing omega-3 and omega-6 oil fats rates.

2.5 Perennial legume improvement for increase water access from deeper roots

Another prospect for the future use of legumes is in the provision of a hydrological stable to low input agriculture ecosystems which are pocket friendly. When left undisturbed, grass fields and ecosystem ranges often contain different several annual and perennial plants species mix including herbs, shrubs, trees, grass and also legume family species as well. This unique mix of natural biological plants in the temperate climates contributes to the hydrological stability in the ground and underground water systems of the most part of the world’s land mass, with the species with deeper rooting systems translocating water from deeper depths during the drier periods of summer and autumns. In South Australia for example, the natural perennial mixes of shrubs, trees, annual grasses and herbs was violently disturbed and destroyed with the people’s ruthless clearing of 25 million hectares for agriculture in the nineteenth and twentieth centuries. In return, larger areas in the region have since been seriously affected by a combination of high salinity levels and waterlogging as a result of the rising water tables due to decrease in water utilization as a result of deforestation and vegetation clearing practices. Currently, in South Australia where the example was picked, the total affected unit land area is estimated to exceed 5 million hectares [22]. On this, the largest scale land use is observed to be under pasture for livestock use which is then the greatest potential for the disaster cause. Farming systems therefore, not only in Southern Australia but all the regions faced with the same challenge across the globe needs to be resolved by employing redesigning strategies in the current Century so as to restore the water use pattern of native flora with the main aim being the discovery of plants and improvements for both economical and hydrological benefits, including legumes.

Perennial legumes are speculated to play a significant role in the redesignation agriculture. Many studies estimate M. sativa to being adopted to 96% of most soil types in the entire world even where the soils are fertile or alkaline making the suitable for adaptability. Much of the perennial legume species that are found in the rangelands of the Mediterranean basin surroundings can be elevated to welcome M. sativa in the setting more so where improvements are required. This will not only help in water utilization but the diverse benefits which come with legumes as well as discussed previously. However, when it comes to the acidic and more coarse-textured soils, which represents approximately 30% of most agricultural lands in many regions, a different suite of perennial legumes and rhizobia to those exploited in agriculture will need to be developed as a result of breeding programs for adaptability and suitability [23]. This is because none of the current commercial legume species all over the world is adapted to the combination of edaphic aridity stresses, infertility nor acidity stresses in any region. By the development and improvement breeding programs as well, this will provide a major opportunity for the development of legumes by many upcoming scientists and breeders in the near future to serve for purposes.

3. Challenges faced in breeding improvement prospects for legumes

3.1 Health concerns

On the breeding of new legumes with high nutritional quality for monogastric or human consumption, many anti-nutritional and health factors have to be considered, more so ethical issues and points of concerns from the wild legume types and varieties. These concerns include non-protein amino acids, alkaloids, glycosides, tannins, saponins and protease inhibitors from wild legumes, which require further testing as they are ethically not yet viewed as safe healthwise. Even though some societies have found a way to deal with these anti-nutritional factors through processing techniques such as high heat boiling for long duration, soaking, leaching, fermentation and dehulling, this is often not a common practice in today’s large economies in both developing and developed worlds. Even though some of the anti-nutritional properties are driven by single genes, it will not be an easy task to isolate and combine all the necessary genes required for the domestication traits among species into a single new superior species that will in return displace the contemporary grain legumes suite in farming systems and markets across the world. The most recent example of the domestication was seen in L. angustifolius in the 1970s, following its adoption on acid sandy infertile soils in Western Australia [24]. This advancement in the crop was faced with several highlighted difficulties into the legume market by the novel legumes due to the health concern suspicion among the people thus making its utilization difficult. Despite L. angustifolius acquiring an important ground from its rotation with many cereal crops on more than 750,000 hectares of land annually, the price paid by its seeds constrained include;

1. Breeding acceptance for its quality traits in the legume industry for human consumption,

2. Placing of legumes into farming systems which is a difficult idea especially for forages in the warmer climates,

3. Selection of legumes and rhizobia well suited and adapted to both harsh soils and severe climates, adoption and

4. Discovery and acquisition of germplasms across the continent [25].

Lupin is considered primarily as an animal feed in many marketplaces whereas traditional other common grain legumes are cultivated for human consumption and fetch higher market prices, for example Cicer, Vicia and Lens legumes. However, despite this negative faced by the crops, lupins remain popular across many farming systems due to their ability to fix over 100 units of nitrogen per hectare, while still providing many additional rotational benefits associated with legumes in coexistence with other crop species in the field [26].

3.2 Social and technical adoption challenges

There exists other many social and technical barriers to the legume adoption as well in the current world. For example, farming systems are distorted by high price subsidization more often, ignoring the direct and associated benefits of legumes-cultivation especially in the rural regions. Also, much direct financial support to farmers is needed to ensure arable lands remain occupied and busy but eliminating the incentive to develop efficient farming systems which are based upon Biologically-fixed nitrogen. The recognition of the environmental pollution in manufacturing and utilization of nitrogen fertilizers should be considered as it slowly increases embracing of Biological Nitrogen Fixation (BNF) in many regions across the world. In other circumstances as a result, investment in legumes is not much often realized for long recurrent growing seasons and thus, the legumes growing of the crop that generates higher quicker instant cash flow is significantly instead lost. When it comes to communally owned lands, it often even makes it more difficult to manage the long-term practice of improved forages to incur return benefits to the investor as well which may bring disputes in the future resulting to implementation challenges [27].

3.3 Growth environment challenges

Complex hurdles are also encountered in legume adoption. These include the unfavorable soil types or climates that affect the components of legumes symbiosis benefits with other crops mainly on rotation and the presence of competition from rhizobia that compromises the process of nitrogen fixation, although yet ineffective. Legumes are also more difficult to grow many times than many cereals in an agronomic perspective. The other consideration is the introduction of the legumes to new environments which requires thorough selection of appropriate rhizobia-containing inoculants followed by their industrial manufacture which is a difficult process. Also, expertise required in the process to nature high-quality inoculant in manufacturing industries should be well trained in handling process and should not be underestimated [28].

Some of the factors limiting legume exploitation remains to be acknowledged from the key role of woody and herbaceous annual and perennial legumes in communal rangelands the drier and forest regions across the world. Where vegetation has not been disturbed or cleared for human benefits, majority of legumes and rhizobia are found in situ in these precious non-arable grounds. These repositories are now currently recognized for their extremely high conservation values particularly in ex situ germplasm centers which are becoming expensive to retain [29]. It is from there in situ natural repositories where many plant legumes and their root nodule bacteria (rhizobia) with unique prospect future roles in the field of agriculture, horticulture products and pharmaceutical medicine will be drawn.

3.4 Difficulties in understanding and studying of the CT plants

Despite this, the role of CT legume forage plants as an alternative to chemical anti-helminthic drugs is far from clear due to the results and conclusions from various research studies which vary greatly. This is for example in a study where little or no effect was noted in grazing experiments with neither sulla nor L. pedunculatus, where also variations in the effect on different worm-species were also observed. Several authors have reported reduction in Teladorsagia circumcincta infestation burdens but not on Trichostrongylus spp, where effects were found on the intestines but not in the abomasum [30]. It is therefore not clear whether these disparities vary in CTs concentrations or the presence of different CT compounds in the feed diets.

3.5 Uncertainties

There are uncertainties regarding the CTs mode of action on worm population in the ruminants’ stomachs. This is particularly driven in a case where there is unclarity whether the effects are due to direct anti-helminthic actions of CTs on various nematode stages in their life cycles to be specific. The effects of high protein diet intakes on the immunological competence of livestock have been well-established, although it does not necessarily explain all the anti-parasitic effects observed in pasture-grazing sheep which are high in meat protein as a result. Direct effects of worms have been also numerously reported in in-vitro studies, including worm-eggs inhibition and hatching and larvae migration of H. contortus, T. circumcincta and Tr. colubriformis with sulla extracts and its similar effects, birdsfoot trefoil, lotus, sainfoin, Onobrychus viciifolia and Dorycnium spp. on Tr. colubriformis on sheep and nematodes of deer. Similarly, there was decreased larval development in faecal droppings from sheep that were fed on chicory, Dorycnium spp. and L. pedunculatus. However, the significance of these study effects for the ideal natural situations is unclear as in vitro egg-hatching results have not been in accordance with the results from field experimental trials [31].

Therefore, further studies, both in vitro and in the fields, need to be conducted to indicate whether CT legumes containing forages will likely be a reliable effective addition to the non-chemical worm control strategies in livestock. The studies should as well report the CT concentration levels and proportions of the different worm species involved, as well as noting any production effects in relation to the animal in question. These mechanisms as well require much elucidation to explain any form of variable results that might be obtained in the proposed grazing trials. The identification of specific compounds linked with dose-administered dependent inhibitory effects against nematode developmental stages will aid in provision of an objective basis for the laboratory assay results in relation to those occurring in the field trials [32].

3.6 Cost

Authors of experimental sites have also reported that CT-containing legume forages are relatively more difficult and expensive to develop, establish and maintain than the traditional pastures [33]. Unless new legumes’ economic importance is clear, both in terms of anti-helminthic effects and pasture-management cost and the sociological effects are considered, their general adoption may be compromised.

3.7 Lack of knowledge and familiarity of many legumes

Before we embark on a mass legume breeding program specifically for fish feeds, we should ask ourselves whether any natural occurring plant legume seeds contains the essential nutritional range considerations essential for aquaculture feeds. On research conducted by Assefam (2021), among the legume species adapted to different alkaline soils, Trigonella balansa was found to contain a relatively high significant omega-3 and omega-6 fats levels but a lower omega-3-omega-6 ratio that T. glanduriferum. A future broader legume family search may very clearly outline other agronomically adapted plant legume species nutritionally-richer for aquaculture diets. Also, little is known regarding the essential reproductive, agronomic, rhizo-biological and physiological perennial legume forage trends in relation to other species such as M. sativa, T. repens, T. pratense and Lotus corniculatus which are much used commercially in many parts of the world [34]. This lack of knowledge is a serious constraint and challenge to the developing of other perennial legumes for future agricultural purposes.

4. Conclusion

Despite legumes widespread diverse benefits, most have neither been observed for their potential contribution to the primary production systems nor indeed their biologically active grain produce constituents. This book chapter has attempted to bring out some of the future use prospects to which legumes may be improved or manufactured for and the pathway to achieving these advancements. The genetic biodiversity of legume crops is currently constantly under much threat through the loss of natural habitats by humans for various benefits such as livestock rearing as discussed, overgrazing challenges or even illegal trading of medicinal plants across the globe. Of the 6000 known species of legumes, many are considered to be at a higher risk rate of extinction in the coming years. Currently, 10 Trifolium species native to the United States of America (USA) have been red flagged to be at a higher threat risk and their 16-world known common taxonomic classes are said to be endangered and vulnerable [35]. Medicinal plants for many centuries have also been used by farmers and pastoralists as a primary source of prevention and in the control of various diseases affecting livestock. With the rapid fading of ethnic traditional customs and cultures, some of the legume plants used in the making of organized traditional medicine will also, with no doubt, fade away too. It should become like a normal cultural practice now than ever more before that we should explore and try to put measures to preserve and conserve these plant species before they fade away and get lost from science completely. Just as most of the research in the field of Agriculture, and agronomy to be specific, on legumes is focused on yield increase in food and fiber crops, equally more emphasis should be put on research to identify the legume plants with potential to supplying of essential products in the pharmaceutical and nutrition industries in the current modern evolving society. This book chapter as well has put much attempt on the way forward prospections and anticipation on some of the roles that might be applicable and useful to the legume plants and their rhizomes. To quote, “We need to nodulate prokaryote plants”. Researches focused on continued exploitation of the enormous natural genetic variations available in both legume forage plants and their constituent micro-symbionts will contribute greatly in the application of Biological Nitrogen Fixation (BNF), which is unarguably one of the key essential biological processes on the entire planet.

This chapter closes by concluding with a very important quote for Agriculturalists in whatever diverse fields, in general, and the entire people on planet earth always to remember to save essential plants with positive benefits to the ecosystem including man, therefore, “Save Plants that Save Lives”.

Thanks

I would like to send my sincere gratitude and thanks to Blanka Gugic, who has been the personal Author Service Manager, IntechOpen, in the pioneering of the writing of this chapter by extending the offer to contribute a chapter to this book entitled, “Production and Utilization of Legumes - Progress and Prospects”, for all the support, encouragement and the advice as well as communication progress she has been offering all along. I am really glad and honored for her and much importantly I could not have done it without her, and thus, it would be a huge misfortune failing to honor her.

Thank you once again Blanka Gugic.