A cheap nature and an unusually high, wide-range nutrient profile enables the green form good source of nutritious food for many households in Nigeria (see Tab. 1 & 3 for phytochemical composition of A. hybridus and other Amaranthus species).

The leafy vegetable taking just 4-5 weeks from sowing to harvest ensures it serves as consistent food and income source to farming/poor households.

However, with market dynamics today, population projection and economic indicators, the way ẹfọ tẹtẹ grows or how we grow it has to change. There is still a huge demand-supply gap for the vegetable in the country.

Also, population is growing exponentially where, with widening inequality gap and an absence of safety net, more than half the nation’s populace is expected to fall under extreme hunger and poverty levels in the future.

Thus, an elevated number of hungry and poor with severely battered purchasing power to take on frequently occurring food inflation would drive high demand for cheaper foods and reliance on quick-money generating livelihood -as amaranthus and its production.

Hence a new, greater dependence on the green vegetable in focus coupled with the current unsatisfied demand deficit for it would mean the crop’s one-month (and a week) maturity period will not be enough in the unfolding times.

Table 1

Fortunately, the Nigerian spinach has quite a number of qualities that can be manipulated/utilised to prepare for the impending reality:

What does this mean? What advantages do they give?

• C4 Photosynthesis:

The C4-pathway (Hatch-Slack Pathway) is a carbon fixation mechanism that enables efficient capture and use of CO2, with maximum carbon extraction, for sugar and other bio-molecules formation.

This is an upgrade by some plants to remedy reduced photosynthesis from C02 and water loss to photorespiration and transpiration respectively of a less efficient pathway, the C3 Calvin Cycle (CCC).

In the CCC, photosynthetic activity is limited with the enzyme (Rubisco) responsible for C02-fixing provided with oxygenated environment instead, where oxygen is being fixed partly alongside C02 rather than C02 solely, which reduces C02 assimilation and enables its loss to photorespiration.

6CO2 + 6H2O + sunlight energy → C6H12O6 + 6O2 (reaction of carbon dioxide, water & light yielding carbohydrate and oxygen)

The Hatch-Slack pathway, otherwise, rectifies this problem providing a high level C02 condition with carboxylation and decarboxylation reactions in the mesophyll and bundle sheath cells in this order and with a controlled-stomata opening limiting photorespiration and transpiration (see Fig. 1).

The result is a higher C02 concentration and reduced water loss which helps in faster formation of more sugar and biomolecules.

Figure 1

Diagram detailing two distinct reactions of the C4-pathway -one (at the top) for C02 assimilation and the other (below) for C02 fixation. This is that a non-rubisco enzyme (PEPC) not susceptible to oxygenation is the one at the site where C02 assimilation and photorespiration occur. Rather, the carbon-fixing rubisco susceptible to oxygenation is in the bundle sheath cell where it comes in contact only with C02 product from the mesophyll cells to form sugar. Also, a 3-carbon compound refixed into the mesophyll cell ensures for optimal carbon use and a continuous C02 generation process.

• Leaf shape, arrangement & content

Another benefit is that the leafy green Amaranthus having a wide leaf surface area, with dense chloroplast presence (containing numerous chlorophyll cells), and the leaves arranged alternately to fill void enable maximum light interception, absorption and use.

Utilising this understanding could amount to efficient energy use and its conversion to calorie and nutrient packed foods.

Aerial view of Amaranthus with leaves arranged filling spaces around the stem which reduces incidence of sunlight radiation loss to the environment.

Credit: Garden Hunt

• Temperature

Elevated temperature serves to favour rapid germination and increased photosynthesis. For instance, A. hybridus reaches peak germination between 30°C & 35°C and A. cruentus species in the same genus has an almost similar peak at 25°C to 30°C (see Fig. 2 for other species of Amaranthus).

The species A. caudatus has been found to undergo optimum photosynthesis at 40°C. A. hybridus, A. hybridus var. cruentus, A. tricolor, A. hypochondriacus & A. thunbergii, all have been understood, in a study by Modi (2007), to accumulate highest biomass at 27°C with a continued high accumulation at 33°C although not as much as at 27°C (see Fig. 3).

Also, as general for almost all plants, growth tallies temperature rises until a certain level (see Fig. 4). Therefore, since A. hybridus can tolerate temperature up to 40°C, growth would linear temperature increase until 30°C and a little bit above where temperature becomes harmful as seen in germination and biomass accumulation.

Growing A. hybridus in the best temperature conditions that favour maximum development and growth would amount to early maturity, higher yield for the crop.

Figure 2

A graphical representation of germination rate against different temperature range (25/20°C, 35/30°C & 45/40°C) for three amaranth species, Redroot Pigweed (A. retroflexus), Palmer Amaranth (A. palmeri) & Common waterhemp (A. rudis). Germination peaked for all at 35/30°C although common Waterhemp saw more germination at 25/20°C in days 4-7 but it began seeing more at former temp at 9 & 10 days.

Figure 3

Amaranthus species biomass accumulation respective to temperature -hot (33/27°C day/night), warm (27/21°C day/night) and cool (21/15°C day/night) in 20, 40 & 60 days after sowing (DAS). Accumulation peaked at warm temperature and continued at higher degrees marking but decreased marginally as photosynthesis reaches optimum to allow for more accumulation but with enzymes being stressed, and denatured at 40°C.  

Figure 4: Temperature extremes: effects on plant growth and development

How do we best make use of the positives we know about the crop; how do we simulate these conditions?

Since we know A. hybridus (inferring directly, qualities from it and from genera in the same species informing A. hydridus’ similar capabilities) is equipped for utmost light/C02 capture and use, efficient photosynthesis and to perform well at high temperature [germination (at 25-35°C), development and growth (at 30-35°C), photosynthesis and biomass accumulation (at 30-40°C)]

We can simulate these conditions -providing more C02, light at prolonged period and temperature at required range -to boost photosynthesis, biomolecules formation, maturity and get the best of A. hybridus.

Firstly, to supply required light on extended period, Nigerian spinach can be grown in a greenhouse equipped with high pressure sodium (HPS) lights where it supplements daily light losses and increases light available to the crop (and in the night) for photosynthesis.

The Nigerian A. cruentus, for instance, which usually has longer vegetative period, on being exposed to extended daylight length has been observed to flower early.

The equivalent of the HPS is the familiar bright halogen lamps. However, the HPS has demerits. It does not provide light in the precise required spectrum of the photosynthetic active radiation (PAR) wavelengths, needed for photosynthesis.

It instead provides light in the visible light spectrum (VLS) encompassing all aspects of PAR, in which some wavelengths happen to inhibit growth -for instance, yellow waveband has been known to stress plants and studies have proved plants doing healthier with its removal in the greenhouse.

Nonetheless, instead of using a glasshouse mounted with HPS allowing for VLS, a photo-selective/screen film -one that screens light rays to required wavelengths in the PAR spectrum -can be used.

Alternatively, as scientists have found red wavelength of the PAR spectrum aids vegetative growth (which A. hybridus is grown for its leaves and where this would be important) and a mixture of the latter with blue wavelength catalyses quick flower growth (one which we desire as it enables quick vegetative period and early maturity), a greenhouse equipped with blue and red-lights radiating LEDs (light emitting diodes), scheduled for different intensities and routines, can be used to supply these wave bands.

Overall, in the cause of raising light exposure to increase photosynthesis, care must be taken to not overburden the crop with light so as to prevent light toxicity and not push photoperiodic length disrupting important physiological functions and changes.

In addition, while supplying needed light spectrum, we should be cautious not to cut out other light spectrum important to plant, as violet light spectrum of the VLS, for illustration, has been discovered to increase antioxidant, organoleptic and phytochemical properties in leaves and fruits -and in this case, a covered greenhouse installed with HPS and LED can be used or a glasshouse with LED.

NB –Greenhouse is a general structure that habours light energy and simulates conducive conditions for plant growth -it could be exposed covered with glass or film to take in sunlight, or unexposed and mounted with artificial light sources -LED and/or HPS.        

Secondly, to provide a high C02 concentration condition, clean fuel can be burnt in close proximity to the greenhouse and via a pipe connector to supply constant rich C02 raising the productivity of the rubisco enzyme and biomolecules formation in the mesophyll cells.

Commonly used fuel is the organic compound propane, which burns in a reaction with oxygen to give clean by-products -C02 and water.

Increased C02 level enables plant to grow rapidly and bigger, even the leaves; however, this would depend on other photosynthesis factors as temperature, light and water being available at required level.

Ackerly et al (1992) in their study of C02 and temperature effects on leaf area productions in two annual plants species have shown that, for A. retroflexus, overall leaf area increased with elevated C02 and temperature at 28°C and still increased a bit at 38°C but not as much as at 28°C.

This corroborates previously highlighted point of Amaranthus species reaching growth, development and biomass accumulation peak at 30°C, still seeing gains after this optimum temp although declining.

The effect of other environmental conditions being important to seeing positive result of increased C02 was observed in a study on “Plants’ response to elevated C02” by Bazzaz & Carlson (1984), where A. retroflexus performed well under ambient, independent C02 and soil moisture conditions than in an increased C02 but competitive environment for photosynthesis inputs with three other plant species.          

Thirdly, considering temperature range that positively affects A. hybridus’ growth, development, photosynthesis and biomass accumulation, glasshouse can help reach the required temp level.

The glasshouse functions to absorb light of shorter wavelengths from the surroundings and re-radiate them in longer wavelengths where they become warmer and thus raise temperature in the glasshouse.

Pictorial illustration of how required high temp is created in the glasshouse. Short wavelength radiations from the sun enter the glasshouse and are absorbed by the ground, plants and every object in the glasshouse and are then re-fluoresced to long wavelengths that are warmer where most of them are trapped within the environment and warm up the glasshouse.

Moreover -even when unexposed greenhouse LED-equipped is used -C02 from the pipe connector can help bolster greenhouse temperature as reaction yielding C02 gives off heat -an exothermic reaction.

A thermostat can be installed to check and regulate temperature, as extreme temperature at/or above 40°C has been discovered to impair amaranths and -as C02 emits heat, indirectly -drive transpiration.

Although amaranth species are known to resist extreme temperature by wilting and regrowing back when temperature is right but, wilting period takes off plant’s life cycle with a resultant delay in maturity.

Also, temperature has a differing effect on amaranths’ leaf content for instance, a study by Modi (ibid) on temperature effect and age on leaf content of 5 different amaranth species shows hot temperature (33°C) reduced leaf protein content but with significantly high iron and calcium content (see Fig. 5 & Tab. 2).

This informs that there needs to be a delicate balance of temperature as temperature 21°C gave highest leaf protein content and with warm temperature at 27°C yielding moderate iron, calcium and protein contents.

Even, findings from this study helps buttress reasons for early maturing cultivar desired as the lesser the plant’s age, the higher the nutrient content level.

Nonetheless, while transpiration appears to be damaging and with amaranths having evolved feedback mechanism regulating stomata opening to reduce transpiration and, hence, photosynthesize at high temperature and transpiration, nevertheless, there seems to be a strong relationship between reduced moisture level and dry matter presence in leaves (see Tab. 3 -A. hybridus has more proximate composition with reduced moisture content, similar for other Amaranthus species too).

The positive here is that lesser volume of water could be used for production while it amounts to more dry matter in edible parts (leaf and shoot) of A. hybridus.

Figure 5

Leaf protein content of five Amaranthus species raised in different temp -hot (33/27°C day/night), warm (27/21°C day/night) and cool (21/15°C day/night) -and harvested at 20, 40, & 60 DAS, respectively.

Table 2

Calcium and iron content in leaves of five different Amaranth spp grown under hot (33/27°C day/night), warm (27/21°C day/night) and cool (21/15°C day/night) conditions and harvested at 20, 40, & 60 DAS

Table 3

In Conclusion

The expectation is to see an early maturing ẹfọ tẹtẹ in at most 3 weeks with beneficial, healthy properties when conditions as elevated C02 level, required high temperature range and exposure to required light wavebands are delivered to maximise the advantages of C4 photosynthesis pathway, high temperature tolerance and leaf composition, shape and arrangement adapted to efficient light use and conversion.

But, of course, there is a realisation that the whole procedure of reaching an early maturing and nutrient rich A. hybridus may not necessarily be easy to achieve or may not turn out as expected since ability of A. hybridus to make best use of the proposed simulated environment is not being inferred of a sole known capability of A. hybridus, but also of other species within the same genus Amaranthus.

However, there is still a high chance of the assumption coming out positive with the simulated conditions, after all amaranth species available today have similar traits, a product of undirected or intentional breeding among the species.

For example, the A. hybridus has traits of A. viridis while the latter has of A. spinosus, with an interbreeding -according to researchers -between A. viridis and A. spinosus said to have yielded A. lividus.     

Nonetheless, the success of this idea boils down to how feasible it is, how we are able to put it to practice. Also, of paramount concern is whether crop bred in the described simulated conditions will develop fully to be mature for consumption, whether -and when it involves hydroponics -it would be safe for consumption.

Lastly, growing A. hybridus (and possibly other amaranth species) in these proposed conditions will serve to conserve increasingly stressed resources -land, water -for production and with reduced incidence of pollution since the crop is grown with lesser water and is rather being optimised to give more yield and mature early under similar conditions it is being grown than putting more land under cultivation generating more greenhouse gases.

In addition, the plant using lower levels of nitrogen (as fewer nitrogen are supplied to the rubisco enzyme in the leaf cells for photosynthesis compared to C3 plants) for growth would help limit fertiliser pollution.

In early february this year, on “World’s Pulses Day”, I joined Vestance (an agribusiness intelligence firm) on an X (Twitter) space to discuss how Nigeria can extract more value from its pulses.

Prior to this event I had always wanted to inform people on how super a crop group pulses are to sustainably reaching an encompassing development –food security, revenue and wealth creation, and income equality, without compromising the environment.

Hence, when the opportunity arose, I quickly seized it and thus the rationale for this write-up.

This writing details my responses to the questions I was asked on the space. But it also entails insights I did not say in the dialogue for reason of omission or time limit or that some information was not necessary (at that time) to the asked questions, or I wasn’t asked some questions, or all these together.

Nonetheless, I have decided to add them in this piece understanding they are crucial to helping to have a broader insight on pulses benefits to the nation.

Opportunity for huge foreign earnings is one benefit pulses present. Global pulses consumption peaked in 2021 growing by 24% in the last decade. Also, worldwide cowpea production has been rising responding to growing demand where the market is projected would reach about $10 billion in 2028 from 2023 growing averagely by 5.5%.

Fortunately, Nigeria is the global leading producer of cowpea, accounting for 61% of Africa’s (the continent constitutes 80% of the world’s total production) and 58% of global production. The country has been poised to earn $700 million annually on cowpea trade.

The above is not the only benefits cowpea/pulses promise(s). There are others and would be discussed later on. This helps in grasping the economic importance of cowpea.

In tandem to the prior discussion, Nigeria other than gain rather loses $300 million in cowpea export earnings.

Therefore, it’s quite important to understand how with such potential the nation loses on cowpea earnings and many other benefits.

It’s also pertinent to know how the country can remedy these challenges and better position her in enjoying/capturing rewards pulses promote.

It would be noted that cowpea gets a feature in the preceding write up and is used interchangeably with pulse where the question what pulses mean becomes imperative.

Answering this aids appropriate classification of pulses and in properly deriving value pulses have to offer. The first question of the space addresses this.

Pulse is a general term for certain legume families, can we enlighten the audience about the various crops under Pulses. What is their importance to the food system and agriculture as a whole?

The most important differentiating criterion to know is that pulses fall under legume hence, all pulses are legume but not all legumes are pulses.

Pulses are dried edible seeds of grain legumes. The dry nature and low oil content set them apart from other categories of crops under legume.

Without these criteria other groups under legume could be termed pulse. For instance, peanut is consumed dry but has high oil content.

Legume then has 3 distinct groups under it: oilseed legumes, pulses and fresh legumes.

Soybean and peanuts are examples of oilseed legumes and fresh beans, peas and pods are fresh legumes.

Cowpea (commonly called beans) is one of the legumes that accurately belongs to pulses and is most familiar to us among the crop group in this part of the world. Thus, the reason cowpea was used interchangeably with pulse at the beginning of this writing piece.

Other examples of pulse are lentils, dry peas, chickpeas and common beans (black beans, pinto beans and kidney beans), etc.

These mentioned pulses are all edible, rich in vitamins and minerals. Lentils interestingly can be made into bean cake and puddle, pinto and black beans cooked as would cowpea, and peas and kidney beans used in salads and soups.

However, correctly classifying pulse could be quite challenging with it (cowpea for instance the pod and leaves) consumed fresh in some places.

A low-fat content and complemented by good composition of high-quality protein, carbohydrate, vitamins and antioxidants make cowpea (as other pulses) a rich and balanced food source, easily accessible and helping with food and nutrition security.

With reduced fat level, rich nutrient profile of good cholesterol, antioxidant and fibre, cowpea aids the removal of bad cholesterol and fight against obesity, diabetes, cancer and digestive problems.

Cowpea toleration of high temperature enables the legume to grow in arid areas and support lives there.

For instance, bulk of Nigeria’s cowpea supply comes from the northern states also known to be battling food insecurity and malnutrition to adverse climate.

Cowpea being able to adapt and grow in challenging environment makes the crop of great economic importance in those states.

Also, cowpea adapts to diverse climates and thus is grown across the country ensuring not only food security in the north.

Being cultivated around Nigeria and fast-growing ensures the pulse crop provides income for numerous small farmers, rural people and households dependent on cowpea farming.

Cowpea like other leguminous crops use less inputs and instead generate its own nutrients able to fix nitrogen from the air, a process which reduces farmers spending on fertiliser, improves the soil and dissuade indiscriminate fertiliser use.

This protects the environment by preventing imbalance of soil and marine ecosystems to fetiliser toxicity and eutrophication.

Cowpea also prevents climate imbalance by mitigating greenhouse gasses emission with soil cover. All these are beneficial to agriculture and farming systems.

A lesser input use by farmers not only enable resource management but also means more margins for farmers which are multiplied by every part of cowpea being valuable –dry husk used as animal feeds, the leaves and seeds serving as food for humans.

Cowpea hence is not just of great importance to farmers but to livestock and humans in general and also support the animal feed industry, livestock rearing sector and other value chains (bean cake and pudding selling, bean flour (culinary, baking and industrial applications).

Let’s start with what Nigeria is doing right with beans. How have we become the world leader in Bean production?

About 15 million hectares of cowpea is cultivated globally. Nigeria’s cultivation represents 25% of this and 35% of Africa’s total cowpea cultivation.

The nation’s cultivation grew by 165% between 1980 and 1990 and although still continued to grow but fell to 50% from 2009 to 2019.

Clearly, Nigeria constitutes the world’s leading cowpea producer chiefly by having more land under cultivation. However, this is not the sole reason for such.

The nation being endowed with climate and soil favourable for cowpea growth ensures that cowpea easily grows, develops fast, and enjoys adoption across the country.

Niger state is the largest producer of cowpea in Nigeria. Cowpea is also well grown in sates in northeast and west of Nigeria.

These states provide growth factors just in the appropriate requirement and combination for cowpea to thrive –adequate sunlight, high temperature, mild water supply and well-drained soil.

A mild water supply with drier climate preventing pests and diseases and a well-developed irrigation system in the north provide adequate water needs that enable thriving of cowpea.

The south also with a good climate of rainfall and soil and adoption of hybrid varieties (pests and diseases resistant, climate and photoperiod adapting) undertakes considerable cowpea cultivation.

Photoperiod is important to cowpea’s proper growth (as some other crops) as it signals developmental and growth phases.

A development of photoperiod insensitive varieties and varieties with different photoperiod sensitivity range has been a game changer. The IITA for instance has developed 800 improved cultivars from 17,000 unique samples.

It then means cowpea can be grown in different times of the year, places and conditions.

Soybean is becoming a hot crop for farmers, what are the challenges with the development?

It is quite important to address soybean and its status under legume. As it has been explained in the previous section, soybean falls under the legume family in a separate group, oilseed legume grains.

However, what I’ve found is that the classification of legumes under pulse can be location-dependent and on how useful they are. When of significant usefulness a legume crop is often termed pulse.

This is the case of soybean in Nigeria. Soybean as cowpea is a highly demanded legume in Nigeria.

Soybean is one of the few crops with complete essential amino acids only found in animal protein vital for optimum bodily growth and development.

For this reason and its digestibility and easy utilisation, it has been incorporated as a major feed ingredient for fish, poultry and some other monogastric animals and is increasingly a key input in food supplement for babies.

Also, soybean although not cooked directly for consumption like cowpea, can be made into steamed or baked cheese (tofu). This delicious delicacy is being used as alternative to meat as it is rich in protein.

The legume has industrial applications, in making edible vegetable oil and biofuel and is used in the manufacture of drugs and as alternative foods in managing diabetes being low in starch and high in protein.

All these competing uses, among other factors, mount pressure on soybean production and drive input price hike and unavailability making soybean growing challenging.

Hence, while Nigeria is a leading producer of soybean in Africa, the domestic production fails to meet the nation’s demand and rather a 100,000MT or more of soybean worth over $40 million is annually imported to bridge the deficit.

This soybean import thus becomes the norm and discourages domestic production. The dwindling production is compounded by insecurity, fragmented lands and changing climate which abate large scale, frequent and continuous productions.

Even, the yields per hectare for soybean in the nation are low compared to what can be owing to inadequate use of production enhancing inputs and adoption of innovative practices, often to a lack of access to and awareness of and knowledge in accurately applying these.

Thus, soybean plants are attacked and drained by parasitic weeds and pathogens and do not receive adequate phosphorus essential for root modulation and nitrogen fixation to provide required nutrition essential for proper growth.

And when farmers face these yield-impacting challenges and to flood and postharvest losses unable to access reliable market, an absence of insurance scheme and/or bailout fund worsens issue and generally discourage them from further engaging in the crop’s production.

How is it hard to start and grow beans profitably?

Beans can be grown profitably. Most times the reason it is difficult to do so is of a lack of or inadequate knowledge on its production, spoilage and wastage, and failure of producing what the market wants and of sales and marketing.

Growing beans successfully is an important step to profitable beans production. Without this you do not have beans for retail.

However, growing and offering what the market wants is crucial. The market usually wants great quality and certain varieties. There are many types of cowpea varieties out there and with different tastes.

Cowpea is besieged by many pests and diseases both on the field and in storage that reduce yield and quality of produce.

It is crucial to then ensure conditions that guarantee intactness and quality of cowpea both on the field and in store.

Some harvest early or make sure there is a ready market in place at harvest. Irrespective, marketing is important which ensures produces are sold in time and at good margins.

The problem is that only production is often considered not the business angle of it. Best to approach the venture as agribusiness not just agriculture.

If all these are ensured, then the beans production would not go to waste but first it is important to get right the growing of beans.

Growing beans is not hard. One can grow beans successfully at one’s backyard and it turns out well. It just requires knowing the growth/impacting conditions and inputs that determines beans growth.

Cowpea is a sun-loving and photoperiod sensitive crop and thus the need to grow the legume in the period of warmth although with sufficient irrigation. The legume requires a pathogen-free, well-drained and pH-balanced soil and sufficient irrigation.

At this juncture, it is important to emphasise that growing beans at one’s backyard and on a commercial scale are two different activities entirely although insights from the former could be useful and applicable for the latter.

However, they demand different commitments of time and resources, and challenges that emerge especially with pests and diseases are at distant scale with rapidly invading and irreversible yield diminishing factors, therefore it is important to be prepared and undertake the latter as a serious business.

For a while now, you hear about government interventions in crops like rice and maize, but rarely do you hear anything about beans. Do you think the Nigerian government is neglecting the crop?

If we were to go by the interventions given generally for all grains and that have benefited grain legumes as well, it could be said that the Nigerian government has not neglected beans.

However, you would only find few and not recent interventions by the Nigerian government focused on beans and pulses.

An example is a policy in the 1940s that pursued the development and marketing of oils, oilseeds and cotton and the recent National Agriculture Growth Scheme (NAGS) with an element of distributing hybrid soybean varieties.

Major interventions for and improvement of beans and pulses in Nigeria have been led and implemented by private bodies, international bodies, research institutes, and NGOs.

For instance, like we have seen for the IITA with creating new 800 cultivars, the IART developing new varieties.

Nonetheless, the government facilitated/enabled the establishment of these research institutes that sought to improve crop performance.

Even, some of the research institutes are public and are an extension of the government arm for instance the National Biotechnology Development Agency (NABDA).

The pest Maruca vitrata is one of the pests of great economic importance to beans. NABDA has pushed for the adoption of Bt cowpea a modified variety of cowpea with the bacteria Bacillus thuringiensis that has a biological effect and control action on said pest.

We lost an important export market in 2015 when the EU banned Nigerian beans due to high rate of pesticide. As a consumer of beans myself, I have personally noticed that some retailers use pesticide to preserve their beans from pests. Talk us through the danger of this not only to health but to business opportunities.  

That’s true we lost $360 million to the ban with the legume having worrisome levels of phostoxin residue, bugs and aflatoxin. This totaled $2.8 billion in 2023.

Chemicals as sniper (insecticide) are used in the preservations of not only beans but also other products –as stockfish.

We have heard of foods also being ripened with artificial ripening agents like carbide, ethylene gas, etc.

These are dangerous chemicals and their presence in food can compromise food safety and cause food poisoning, nerve disorders, cancer and various ailments.

These chemicals are lethal to the producers themselves being absorbable by the skin and inhalable but also to consumers and with broader impact across the value chain and different market levels.

Many local consumers are becoming aware of these unhealthy practices and absolutely rejecting such beans.

We have also experienced a reduced level of competitiveness of our beans in the regional and international markets, with our beans condemned for impurities.

Another impact of this is a blanket ban on all bean export from Nigeria affecting other Nigerian exporters of the actions of few violators.

There is indeed a need to raise awareness and enforce strict adherence among producers to not only desist from the use of pesticides in preserving cowpea (and other foods) but also use of safe pesticides at harvest beyond their withdrawal periods in edible fruits.

Consumer awareness and rejection of pesticide-preserved foods are crucial in containing such unhealthy food practices.

When consumers reject such foods, the producers begin to adjust and act appropriately and therefore production becomes consumer driven.

The government, regulatory and food safety bodies want to establish holistic and rigorous safety and compliance measures that ensure wholesome food across the supply and value chains and that there is adequate traceability to address issues when they emerge and/or blacklist negligent farms so domestic and foreign earnings are not disrupted.

How can Nigeria improve the yield of its bean farms? I understand we average less than 1 ton per hectare when countries like India average 5 to 6 tonnes.

There are two ways for Nigeria to improve the yield of its beans to what can be and to match high yield per hectare realised by other countries.

First, is for the nation to address issues inherent to her that constitute impediment to achieving such and, second, is to emulate what the countries with higher bean productivity are doing.

There must be committed efforts to ensuring the developed improved varieties of beans in the research units get to, are adopted and continuously used for production by the farmers.

The government wants to employ subsidised fund schemes, work with research body, extension unit and crop specialists in ensuring affordability, accessibility, adoption and appropriate application of improved varieties.

This would also help disseminate information on and in controlling common pests and diseases and adopting good agronomic and cultural practices that enable generating expected results.

The discussed practices are also what leading cowpea producers by hectare have adopted, for instance, India, the US and Brazil committed to ceaseless research and giving their farmers huge input subsidies.

As a product of research, for instance, the US has to large extent been able to tame parasitic weeds competing with their soybean, employing a combination of resistant seed varieties and potent selective herbicides.

Despite that we gave unusual high subsidy in the last few years; our subsidy to famers is one of the lowest in the world.

This cannot help to cushion our farmers against impact of unavoidable external factors and to stay committed to production.

I understand that a major reason the subsidy given did not materialise as it should is because of unintended beneficiaries.

A verified and verifiable list of farmers should then be established to ensure effective allocation and utilisation of inputs.

Lastly on this part, is the need for a revisit of our land tenure system to encourage huge and long-term land acquisition and that allow for large scale and continuous production.

To tap into a global market, you need to have high quality products. How can we safely keep pest away from this produce knowing that weevil can wreak serious damage to the produce?

This would require being thorough, proactive and enlisting integrated pest management system.

The measure has to start prior production, with ascertaining land history for pest and procuring pest-free seeds.

Many times, incidences of pest attacks are of pests already established in farm or introduced by infested seeds or inputs.

Then, comprehensive monitoring throughout production period must be adhered to prevent pest damage to pods on the field and their transport to the store.

As it has been mentioned, a mix of physical (scouting and removing), chemical (safe pesticide), biological (natural enemies or bioagents) and cultural practices are crucial to this as well.

A vast majority of pest attack and seed lost to beans happens postharvest and in storage to weevils.

The pest management system must be an unbroken chain, where efforts during production are complemented with ensuring a pest-free storage and an unfavourable conditions for pest to thrive in the store employing different techniques.

A method is bagging in airtight container and with safe desiccants promoting the removal of oxygen needed for pest respiration and instead mounting of CO2 presence depleting oxygen, raising temperature and suffocating the pests.

Another is making used of refrigeration technique to lower temperature to a level unbearable and not survival by pests but in which the crops preserved are not denatured and still are intact.

However, this method can be energy consuming and cost incurring and may not be ideal considering poor/epileptic power supplies in this part of the world and could be quite challenging for storing commercial quantity of beans.

One other method, ingenious, often adopted is using chili –as whole or in powder form –to ward off pests by mixing with beans in sealed bags.

Whichever of these methods, the government would need to come with simple and easily adoptable preservation and storage techniques for the small-scale farmers who constitute majority of the farmers, who are often resource constrained.

The leafy green Amaranthushybridus (known as ẹfọtẹtẹ, Nigerian spinach) is one vegetable I really think the potential needs to be improved; and I strongly believe this can be done, with the plant’s special attributes.

A cheap nature and an unusually high, wide-range nutrient profile enables the green form good source of nutritious food for many households in Nigeria (see Tab. 1 & 3 for phytochemical composition of A. hybridus and other Amaranthus species). The leafy vegetable taking just 4-5 weeks from sowing to harvest ensures it serves as consistent food and income source to farming/poor households.

However, with market dynamics today, population projection and economic indicators, the way ẹfọtẹtẹ grows or how we grow it has to change. There is still a huge demand-supply gap for the vegetable in the country. Also, population is growing exponentially where, with widening inequality gap and an absence of safety net, more than half the nation’s populace is expected to fall under extreme hunger and poverty levels in the future.

Thus, an elevated number of hungry and poor with severely battered purchasing power to take on frequently occurring food inflation would drive high demand for cheaper foods and reliance on quick-money generating livelihood -as amaranthus and its production.

Hence a new, greater dependence on the green vegetable in focus coupled with the current unsatisfied demand deficit for it would mean the crop’s one-month (and a week) maturity period will not be enough in the unfolding times.

Table 1

Nutrients and nutritional composition of Amaranthus species found in Nigeria.

Source: Ogwu, M.C. 2020. Value of Amaranthus [L.] Species in Nigeria.

Fortunately, the Nigerian spinach has quite a number of qualities that can be manipulated/utilised to prepare for the impending reality:

The crop belongs to a rare group of plant species with C4-photosynthesis pathway. It can bear temperature threshold beyond its normal range, up to 40°C. Having broad, ovate leaves arranged alternately at intervals on the stem and being drought-tolerant are some of the good features.

What does this mean? What advantages doesthis give?

• C4 Photosynthesis:

The C4-pathway (Hatch-Slack Pathway) is a carbon fixation mechanism that enables efficient capture and use of CO2, with maximum carbon extraction, for sugar and other bio-molecules formation.

This is an upgrade by some plants to remedy reduced photosynthesis from C02 and water loss to photorespiration and transpiration respectively of a less efficient pathway, the C3 Calvin Cycle (CCC).

In the CCC, photosynthetic activity is limited with the enzyme (Rubisco) responsible for C02-fixing provided with oxygenated environment instead, where oxygen is being fixed partly alongside C02 rather than C02 solely, which reduces C02 assimilation and enables its loss to photorespiration.

6CO2 + 6H2O + sunlight energy → C6H12O6 + 6O2 (reaction of carbon dioxide, water & light yielding carbohydrate and oxygen)

The Hatch-Slack pathway, otherwise, rectifies this problem providing a high level C02 condition with carboxylation and decarboxylation reactions in the mesophyll and bundle sheath cells and with a controlled-stomata opening, limiting photorespiration and transpiration (see Fig. 1). The result is a higher C02 concentration and reduced water loss which helps in faster formation of more sugar and biomolecules.

Figure 1

Diagram detailing two distinct reactions of the c4-pathway -one (at the top) for C02 assimilation and the other (below) for C02 fixation. This is that a non-rubisco enzyme (PEPC) not susceptible to oxygenation is the one at the site where C02 assimilation and photorespiration occur. Rather, the carbon-fixing rubisco susceptible to oxygenation is in the bundle sheath cell where it comes in contact only with C02 product from the mesophyll cells to form sugar. Also, a 3-carbon compound re-fixed into the mesophyll cell ensures for optimal carbon use and a continuous C02 generation process.

Source: Lara MV &Adreo CS (2011) C4 plants adaptation to high levels of CO2 and to drought environments

• Leaf shape, arrangement & content

Another benefit is that the leafy green Amaranthus having a wide leaf surface area, with dense chloroplast presence (containing numerous chlorophyll cells), and the leaves arranged alternately to fill void enable maximum light interception, absorption and use. Utilising this understanding could amount to efficient energy use and its conversion to calorie and nutrient packed foods.

• Temperature

Elevated temperature serves to favour rapid germination and increased photosynthesis. For instance, A. hybridus reaches peak germination between 30°C & 35°C and A. cruentus species in the same genus has an almost similar peak at 25°C to 30°C (see Fig. 2 for other species of amaranthus).

The species A. caudatus has been found to undergo optimum photosynthesis at 400 C. A. hybridus, A. hybridus var. cruentus, A. tricolor, A. hypochondriacus& A. thunbergii, all have been understood, in a study by Modi (2007), to accumulate highest biomass at 27°C with a continued high accumulation at 33°C although not as much as at 27°C (see Fig. 3).

Also, as general for almost all plants, growth tallies temperature rises until a certain level (see Fig. 4). Therefore, since A. hybridus can tolerate temperature up to 40°C, growth would linear temperature increase until 30°C and a little bit above where temperature becomes harmful as seen in germination and biomass accumulation.

Growing A. hybridus in the best temperature conditions that favour maximum development and growth would amount to early maturity, higher yield for the crop.   

Figure 2

A graphical representation of germination rate against different temperature range (25/20°C, 35/30°C & 45/40°C) for three amaranth species, Redroot Pigweed (A. retroflexus), Palmer Amaranth (A. palmeri) & Common waterhemp (A. rudis). Germination peaked for all at 35/30C although common Waterhemp saw more germination at 25/20°C in days 4-7 but it began seeing more at former temp at 9 & 10 days

Source: Guo, P. & Al-Khatib, K. 2003. Temperature effects on germination and growth of redroot pigweed (Amaranthusretroflexus), Palmer amaranth (A. palmeri), and common waterhemp (A. rudis).

Figure 3

  Source: Modi (2007) Growth temperature and plant age influence on nutritional quality of Amaranthus leaves and seed germination capacity

Figure 4

Source: Hartfield JL, Prueger JH (2015) Temperature extremes: effects on plant growth and development

How do we best make use of the positives we know about the crop; how do we simulate these conditions?

Since we know A. hybridus ((inferring directly, qualities from it and from genera in the same species informing A. hydridus’ similar capabilities) is equipped for utmost light/C02 capture and use, efficient photosynthesis and to perform well at high temperature [germination (at 25-35°C), development and growth (at 30-35°C), photosynthesis and biomass accumulation (at 30-40°C)], we can simulate these conditions -providing more C02, light at prolonged period and temperature at required range -to boost photosynthesis, biomolecules formation, maturity and get the best of A. hybridus. 

Firstly, to supply required light on extended period, Nigerian spinach can be grown in a greenhouse equipped with high pressure sodium (HPS) lights where it supplements daily light losses and increases light available to the crop (and in the night) for photosynthesis. The Nigerian A. cruentus, for instance, which usually has longer vegetative period, on being exposed to extended daylight length flowered early.  

The equivalent of the HPS is the familiar bright halogen lamps. However, the HPS has demerits. It does not provide light in the precise required spectrum of the photosynthetic active radiation (PAR) wavelengths, needed for photosynthesis. It instead provides light in the visible light spectrum (VLS) encompassing all aspects of PAR, in which some wavelengths happen to inhibit growth -for instance, yellow waveband has been known to stress plants and studies have proved plants doing healthier with its removal in the greenhouse.

Source: http://albopepper.com/PAR-light-spectral-quality-in-horticulture.php

Nonetheless, instead of using a glasshouse mounted with HPS allowing for VLS, a photo-selective/screen film -one that screens light rays to required wavelengths in the PAR spectrum -can be used. Alternatively, as scientists have found red wavelength of the PAR spectrum aids vegetative growth (which A. hybridus is grown for its leaves and where this would be important) and a mixture of the later with blue wavelength catalyses quick flower growth (one which we desire as it enables quick vegetative period and early maturity), a greenhouse equipped with blue and red-lights radiating LEDs (light emitting diodes), scheduled for different intensities and routines, can be used to supply these wave bands.

Source: https://www.pthorticulture.com/en/training-center/basics-of-photosynthesis/

Overall, in the cause of raising light exposure to increase photosynthesis, care must be taken to not overburden the crop with light so as to prevent light toxicity and not push photoperiodic length disrupting important physiological functions and changes. In addition, while supplying needed light spectrum, we should be cautious not to cut out other light spectrum important to plant, as violet light spectrum of the VLS, for illustration, have been discovered to increase antioxidant, organoleptic and phytochemical properties in leaves and fruits -and in this case, a covered greenhouse installed with HPS and LED can be used or a glasshouse with LED.

NB –Greenhouse is a general structure that habours light energy and simulates conducive conditions for plant growth -it could be exposed covered with glass or film to take in sunlight, or unexposed and mounted with artificial light sources -LED and/or HPS.        

Secondly, to provide a high C02 concentration condition, clean fuel can be burnt in close proximity to the greenhouse and via a pipe connector to supply constant, rich C02 raising the productivity of the rubisco enzyme and biomolecules formation in the mesophyll cells. Commonly used fuel is the organic compound propane, which burns in a reaction with oxygen to give clean by products – C02 and water.

Source: https://www.alibaba.com/product-detail/Agricultural-Greenhouse-4-Burners-Carbon-Dioxide_62072452872.html

Increased C02 level enables plant to grow rapidly and bigger, even the leaves; however, this would depend on other photosynthesis factors as temperature, light and water being available at required level. Ackerly et al (1992) in their study of C02 and temperature effects on leaf area productions in two annual plants species have shown that, for A. retroflexus, overall leaf area increased with elevated C02 and temperature at 28°C and still increased a bit at 38°C but not as much as at 28°C.

This corroborates previously highlighted point of Amaranthus species reaching growth, development and biomass accumulation peak at 30°C, still seeing gains after this optimum temp although declining.

The effect of other environmental conditions being important to seeing positive result of increased C02 was observed in a study on “Plants’ response to elevated C02” by Bazzaz& Carlson (1984), where A. retroflexus performed well under ambient, independent C02 and soil moisture conditions than in an increased C02 but competitive environment for photosynthesis inputs with three other plant species.          

Thirdly, considering temperature range that positively affects A. hybridus’ growth, development, photosynthesis and biomass accumulation, glasshouse can help reach the required temp level. The glasshouse functions to absorb light of shorter wavelengths from the surroundings and re-radiate them in longer wavelengths where they become warmer and warm the glasshouse environment.

Pictorial illustration of how required high temp is created in the glasshouse. Short wavelengths radiation from the sun enter the glasshouse and are absorbed by the ground, plants and every object in the glasshouse and are fluoresced to long wavelengths that are warmer where most of them are trapped within the environment and warm up the glasshouse.

Source: https://www.hydroponics-simplified.com/how-does-a-greenhouse-work.html

Moreover -even when unexposed greenhouse LED-equipped is used -C02 from the pipe connector can help bolster greenhouse temperature as reaction yielding C02 gives off heat -an exothermic reaction. A thermostat can be installed to check and regulate temperature, as extreme temperature at/or above 40°C has been discovered to impair amaranths and -as C02 emits heat, indirectly -drive transpiration. Although amaranth species have been discovered to resist extreme temperature by wilting and regrowing back when temperature is right but, wilting period takes off plant’s life cycle with a resultant delay of maturity.

Also, temperature has a differing effect on amaranths’ leaf content for instance, a study by Modi (ibid) on temperature effect and age on leaf content of 5 different amaranth species shows hot temperature (33°C) reduced leaf protein content but with significantly high iron and calcium content (see Fig. 5 & Tab. 2). This informs that there needs to be a delicate balance of temperature as temperature 21/15°C (day/night) gave highest leaf protein content and with warm temperature at 27°C yielding moderate iron, calcium and protein contents. Even, findings from this study helps corroborate reason for early maturing cultivar desired as the lesser the plant’s age, the higher the nutrient content level.

Nonetheless while transpiration appears to be damaging and with amaranths having evolved feedback mechanism regulating stomata opening to reduce transpiration and, hence, photosynthesize at high temperature and transpiration, nevertheless, there appears to be a strong relationship between reduced moisture level and dry matter presence in leaves (see Tab. 3 -A. hybridus has more proximate composition with reduced moisture content, similar for other Amaranthus species too). The positive here is that, lesser volume of water could be used for production while it amounts to more dry matter in edible parts (leaf and shoot) of A. hybridus. 

Figure 5

Leaf protein content of five Amaranthus species raised in different temp hot (33/27°C day/night), warm (27/21°C day/night) and cool (21/15°C day/night) and harvested at 20, 40, & 60 DAS, respectively.

Source: Modi

Table 2

Calcium and iron content in leaves of five different Amaranth spp grown under hot (33/27°C day/night), warm (27/21°C day/night) and cool (21/15°C day/night) conditions and harvested at 20, 40, & 60 DAS

Source: Adapted from Modi (ibid)

Table 3

Comparative Proximate Chemical Composition of common Amaranthus species found in Nigeria

Source: Ogwu, M.C. (ibid)

In Conclusion

The expectation is to see an early maturing ẹfọtẹtẹ in at most 3 weeks with beneficial, healthy properties when conditions as elevated C02 level, required high temperature range and exposure to required light wavebands are delivered to maximise the advantages of C4 photosynthesis pathway, high temperature tolerance and leaf composition, shape and arrangement adapted to efficient light use and conversion.

But, of course, there is a realisation that the whole procedure of reaching an early maturing and nutrient rich A. hybridus may not necessarily be easy to achieve or may not turn out as expected since ability of A. hybridus to make best use of the proposed simulated environment is not being inferred of a sole known capability of A. hybridus, but also of other species within the same genus Amaranthus.

However, there is still a high chance of the assumption coming out positive with the simulated conditions, after all amaranth species available today have similar traits, a product of undirected or intentional breeding among the species. For example, the A. hybridus has traits of A. viridis while the latter has of A. spinosus, with an interbreeding -according to researchers -between A. viridis and A. spinosus said to have yielded A. lividus.       

Nonetheless, the success of this idea boils down to how feasible it is, how we are able to put it to practice. Also of paramount concern is whether crop bred in the described simulated conditions will develop fully to be mature for consumption, whether -and when it involves hydroponics -it would be safe for consumption.

Lastly, growing A. hybridus (and possibly other amaranth species) in these proposed conditions will serve to conserve increasingly stressed resources -land, water -for production and with reduced incidence of pollution since the crop is grown with lesser water and is rather being optimised to give more yield and mature early under similar conditions than putting more land under cultivation generating more greenhouse gases. In addition, the plant using lower levels of nitrogen (as fewer nitrogen are supplied to the rubisco enzyme in the leaf cells for photosynthesis compared to C3 plants) for growth would help limit fertiliser pollution.      

Author:ToheebAzeez

About the Author: ToheebAzeez hones a master’s degree in Communication for Development from the University of Reading and a first degree on Agricultural Extension from the University of Ibadan. He is passionate about sharing insightful information on the agriculture sector that inform people on happenings, rapid dynamics and opportunities in the sector which help them make good decisions and take beneficial actions. He currently innovatively farms where he gains inspiration to write creatively.

ToheebAzeez can be reached at tohzeez@gmail.com

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