Category: Crops

The success of humans on Mars will largely depend on the growth of plants as a food source and as such, one must determine whether this is possible given the harsh Martian environment. In this essay I will discuss the potential problems to cultivating crops on Mars as well as possible solutions.

Atmospheric conditions: hypobaria and elevated CO2

Atmospheric pressure on Mars is ~0.6 kPa, significantly less than that of Earth which is insufficient for photosynthesis and water vapour pressure subsequently putting plants under water stress (Wheeler et al., 2001). In order to get around this crop cultivation would have to occur in pressurized greenhouses (Andre & Massimino, 1992). Plants also need to be grown in an enclosed environment to prevent exposure to the harsh Martian environment (Kanervo et al., 2005). However, these greenhouses will require large amounts of bottled gas which becomes costly. By incorporating the Martian atmosphere in the greenhouses the cost will be reduced (Wheeler et al., 2001) and oxygen can be supplemented by means of cyanobacteria, such as Synechocystis which can tolerate high CO2 concentrations (Kanervo et al., 2005), or decomposition of perchlorates in Martian soil. The Martian atmosphere also contains high amounts of CO2 which may affect the functioning and morphology of plants (Wheeler et al., 2001, Schwartzkopf & Mancinelli, 2001). At 0.6 kPa and high CO2 levels germination of seedlings is suppressed but this can be mitigated by the addition of O2 (Schwartzkopf & Mancinelli, 2001).

Implications of gravity, day length, and cold temperatures

Due to Mars experiencing only one third of the gravity that Earth does plants may have adverse effects on plant growth. However, research shows that even under low gravity conditions, plants can be successfully grown provided that other requirements for growth are met (Brown et al., 1997; Croxdale et al., 1997). Where plants are particularly reliant on detecting gravity for root establishment and growth, germination or growth can occur within centrifuges to establish an artificial sense of gravity (Wheeler et al., 2001).

Day length on Mars is 24.6 hours (Wheeler et al., 2001). The natural photoperiod on Mars is thus very similar to Earth’s circadian cycle however, the amount of solar radiation reaching the Martian surface may not be sufficient for plant growth. Mars receives only 45% of the incident solar radiation that Earth receives and the amount of solar radiation reaching the Earth will also be further reduced during dust storms (Wheeler et al., 2001). This can easily be mitigated by the use of artificial light supplemented with the use of incident solar radiation when possible to reduce costs. Mars also experiences greater temperature extremes than Earth. The average temperature on Mars is 210 K which is much colder in comparison to Earth’s average temperature of 275 K. Temperatures on Mars may also exceed 273 K in some areas (Wheeler et al., 2001). Due to the cold conditions Martian greenhouses or plant growing enclosures will need to be well insulated (Wheeler et al., 2001).

Using human waste as a source of nitrogen

Plants have been successful on Earth due to the characteristics of Earth soil. Martian soil contains sufficient quantities of the essential minerals to sustain plant life with the exception of reactive nitrogen such as NO3 and NH4 (Wamelink et al., 2014). This is due to the absence of organic matter on Mars which when mineralised forms reactive nitrogen (Stevens et al., 2011). This can be solved by use of nitrogen-fixing bacteria. The fixation of nitrogen by these bacteria requires atmospheric nitrogen which may pose another problem as Mars’ atmosphere is extremely thin and contains only trace amounts of nitrogen (Wamelink et al., 2014). Nitrogen can be obtained by the use of human waste to fertilise Martian soil. Organic faecal nitrogen (in the form of NO3) can be retained in compost while pathogens are eliminated by employing thermophilic composting (Wang & Wang, 2008; Bai & Wang, 2010). Composting at a high temperature range (50°C – 65°C) has been found to result in the loss of only 0.7% of organic faecal nitrogen (Bai & Wang, 2010). Nitrogen-fixing bacteria, which can be grown on Mars (Kral et al., 2004) can be used to convert nitrogen from faecal matter and urine into forms usable by plants.

Soil toxicity

Martian soils contain heavy metals such as aluminium and chromium as well as toxic concentrations of perchlorates (ClO4) which are known to impair thyroid function in humans. Perchlorates are very persistent and may occur in ground ice as well as soils and bio-accumulate in plant tissues (Ha et al., 2011), thus contaminating potential food and water resources on Mars (Davila et al., 2013). Removal of perchlorates from Martian soils can be done while producing oxygen which can then be used in Martian greenhouses to provide an atmosphere suitable for plant respiration (Musgrave et al., 1998) or alternatively for human respiration, by using micro-organisms that reduce perchlorates under anaerobic conditions. This method will also result in minimal alteration to the soil (Davila et al., 2013) thus maintaining its quality for crop cultivation.

Aside from the lack of reactive nitrogen and presence of toxic substances, Martian soil simulant has proven to sustain plant growth better than nutrient-poor Earth soil (Foy et al., 1978). Martian soil simulant containing organic matter has a greater water carrying capacity than earth as well as a lower pH which may promote a more stable nutrient balance (Wamelink et al., 2014).

Conclusion

Due to the capabilities of technology, the adverse surface conditions on Mars can be overcome to sustain crop growth. Crop cultivation will also be possible largely due to the potential of Martian soil to enhance plant growth. With further research and crop selection, crop cultivation on Mars may be feasible to support human colonies.

Traditional breeding techniques have been used for years to alter the genomes of plants and animals. With the progress of science and technology, many achievements have been made by humans in the field of biology. Advances in genetic engineering have made it possible to precisely control the genetic changes introduced into an organism. Crops are the most frequently cited examples of genetically modified organisms (GMO). In recent years, with the rapid development of genetically modified (GM) technology and its application in crops, the safety of GM foods, especially agricultural products, has gradually become a global focus. The paper discusses the advantages, needs and safety of GM crops, as well as the development and application trends of GM crops in the future.

Introduction

Traditional breeding techniques have been used to alter the genomes of plants and animals. Crossbreeding has been around since the agrarian age. Artificial selection for certain desirable traits has produced a wide variety of organisms. The most striking example of artificial selection in plant genetics is the evolution of corn. Corn was originally a wild grass called teosinte with spikelet and very few kernels. Over hundreds of years, the ears of teosinte grew larger and with more and more kernels to form what we know as corn. Most of the foods we eat today were created through traditional breeding methods. But it usually takes a long time to change plants through traditional breeding. The long process of traditional breeding has been unable to meet the needs of population growth and social progress. And it is difficult to make concrete changes. The development of genetic engineering in recent decades have made it possible to precisely control the genetic changes introduced into an organism. Scientists were able to make changes in more concrete ways and in a shorter time frame. Faster and more accurate is genetic engineering, which allows scientists to copy genes with desirable traits from one organism and transplant them into another. More recently, methods such as genome editing have given us more targeted ways to create new crop varieties. A notable example of GMO food safety is Bt corn. To turn corn into a GM crop, scientists need to identify the genes that produce the genetic traits of interest and separate them from the other genetic material from the donor plant. The donor organisms can be a bacterium, fungus, or other plant. The donor organism for Bt corn is Bacillus thuringiensis (Bt). Bt is a soil bacterium that produces an insecticidal toxin. Bt genes are inserted into crops to make them resistant to certain pests by producing an insecticidal toxin.

Body

The study published in the prestigious science journal ‘Nature’, aims to prove that the DNA from GM crops can be transferred to humans who eat them. What they finally found contradicted their hypothesis. Plant DNA can generally be found in the human bloodstream with no prescribed harm. The study found GM crops protein in 93% of blood samples from pregnant women, 80% of umbilical cord blood, and 69% of blood samples from nonpregnant women. The toxin they used was an insecticidal protein produced by the Bt bacterium, a gene inserted into the DNA of corn to make what is known as Bt corn. Bt corn has been used in animal feed. As it is found mainly in animal feed, there is no direct evidence of how it got into women. Researchers initially thought it might be due to exposure to contaminated meat. Bt was considered as a toxin. In fact, it is a toxin to corn worms, but not necessarily to humans. There is no data showing that Bt toxin is harmful to humans. Evidence suggests that Bt is one of the few non-toxic pesticides that are regularly sprayed on organic fruits and vegetables. The study confirms the safety of GM crops.

As a result of an ever-growing global population and changes in dietary habits, the demand for food has increased the demand for high-yielding food and feed crops. It is estimated that the global population will grow to about 9.7 billion by 2050. It is extremely time-consuming to produce plants with improved quality traits such as disease resistance, extended shelf-life, and drought resistance by conventional breeding. In this case, GM crops can be seen as the most effective way to increase food and feed production efficiently by producing plants with higher yields and greater nutritional benefits in a reasonably short period of time. The most common GM traits are insect resistance and herbicide tolerance in GM crops. GM soybean, corn, rapeseed, and cotton are the most common crops in markets and life. GM crops contain transgenic traits with improved quality and can significantly speed up the developmental process. GMOs overcome the barriers to interspecies incompatibility and greatly increase the size of the available gene pool. GM crops allow breeders to introduce specific genes from a variety of sources to produce more useful and high-yielding crops. The future adaptability of GM crops within the agricultural sector has increased agricultural productivity, contributed to economic growth, and satisfied global food demand.

Conclusion and Future Prospects

The future of GM crops is very promising. It meets the future global demand for food, feed and fiber in a sustainable and responsible manner. Since the introduction of GM crops in 1996, GM crops yields have been recorded to increase by about 100 times. Many studies have confirmed that the introduction of GM crops has a positive impact on food safety and dietary quality. As the global population continues to grow, traditional breeding has been unable to meet the global food demand. GM crops can be seen as an effective means to solve the problems of hunger and malnutrition. It could become an important part of a broader food security strategy.

Bibliography

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Genetically modified foods will enhance food security. Food security is defined as ‘when all people, at all times, have physical, social and economic access to sufficient, safe and nutritious food that meets their dietary needs and food preferences for an active and healthy life’ (World Food Summit, 1996). Genetically modified foods (GM foods) are used in the agricultural industry to increase crop protection (resistance against plant viruses/diseases and tolerance towards herbicides); and additionally, are of greater nutritional benefit to the consumer of these foods (World Health Organization, 2014). Through the identification of certain characteristics of crops, scientists can transfer these desired characteristics between living organisms and produce a crop with enhanced nutrition levels or higher tolerance to herbicides (Food Standards, 2019).

Golden rice is a genetically modified crop with increased micronutrients and filled with essential minerals such as iron, zinc and vitamin-A (β-carotene) (Majumder, S. & Datta, K., 2019). It is estimated that one out of three humans suffer from micronutrient deficiencies also known as ‘hidden hunger’, and a repercussion of this ‘silent epidemic condition’ is vitamin-A deficiency (VAD) (Majumder, S. & Datta, K., 2019). For over half the world’s population, rice contributes up to 70% of daily calories – so to what extent can golden rice assist with vitamin-A deficiency? With the world’s population rapidly increasing and land suitable for agriculture is scarce, mass amounts of staple crop production are required to ensure developing countries don’t suffer from micronutrient deficiencies and vitamin-A deficiency. Genetically modified rice (golden rice) was researched and developed by professors and plant scientists, Ingo Potrykus and Peter Beyer in the 1990s (Krimsky, S., 2019). The aim was to create rice enriched with either beta-carotene or provitamin-A to save millions of children suffering from vitamin-A deficiency (VAD) (Krimsky, S., 2019). Vitamin-A has proved to contribute significantly to bone growth, immune response, vision, reproduction and epithelial cell development (Krimsky, S., 2019). Without the correct daily intake of vitamin-A, people who have insufficient access to varied dietary recourses can be diagnosed with blindness, later putting them at risk of infections, and possibly death (Majumder, S. & Datta, K., 2019). Approximately 250 million children are vulnerable to subclinical VAD and are accountable for a million fatalities annually (Biomedical Central, 2017).

Golden rice is a genetically modified, biofortified food. During seed maturation, golden rice synthesizes and accumulated β-carotene, and after harvesting, polishing and consumption, the human body efficiently converts the β-carotene into vitamin-A (Biomedical Central, 2017). Golden rice’s genetic construct was to entirely express the rice endosperm (grains) (Golden Rice Project, 2020). This genetically modified rice accumulates phytoene in the seed which is a crucial intermediate of vitamin-A (Majumder, S. & Datta, K., 2019). The orange/yellow color of the rice is due to the ‘seed-specific introduction of the carotenoid biosynthesis pathway’ and concentration of β-carotene (Majumder, S. & Datta, K., 2019). There are several rice lines with different concentrations of β-carotene to cover the estimated average requirement (EAR), which has been achieved in today’s society (Golden Rice Project, 2020). It is estimated that 3 billion people consume rice as a staple crop, and 10% of these people are affected by vitamin-A deficiency (Krimsky, S., 2019). If 40 grams of concentration level 4.0 μg/g golden rice is consumed, then children will receive 36% of their EAR. However, if 40 grams of concentration level 11.2 μg/g is consumed, children will receive 102% of their EAR, and consequently resulting in the vast majority of rice consumers consuming nutritionally enhanced staple foods. This is also demonstrated in adults; if they consume 100 grams of concentration level 11.2 μg/g, then they will receive 140% of their EAR. Consuming rice containing GR2E (or golden rice) could potentially contribute 57-99% and 89-113% of the EAR for vitamin-A for children in the Philippines and Bangladesh. The recommended daily intake (RDI) is the average daily dietary intake level to meet the nutrient requirement (between 97-98%) and is the goal for healthy individuals. In the Philippines and Bangladesh, it is inferred that school-aged children (6-14 years) would be able to reach 78% of their RDI. This is a drastic improvement, as a previous study conducted showed that women and children in Bangladesh had 93% prevalence inadequate intake of vitamin-A. At the end of the experiment, the prevalence of inadequate intake dropped from 93% to roughly 20% and 13% for children and women with the consumption of biofortified golden rice (De Moura, F., Moursi, M. & Donahue Angel, M., 2016). Through the use of the quantitative data, it is evident that golden rice is a nutritionally enriched staple crop containing high levels of provitamin-A. The information and evidence were widely sourced and sufficiently credible, which thoroughly supported both the claim and research question. However, there were limitations behind the evidence which included a narrow sample size in race. The data would be more in-depth if the sample size included people suffering from vitamin-A deficiency from other countries and other races to ensure results are representative of everyone as much as possible. A combination of race, age and gender should be used in the study to ensure this. Whilst sufficient information on the research question was obtained, there was little to no detail and data on the before and after effect of golden rice. Potential and predicted statistics on the matter was calculated, however, there lacked information on the mortality rate before and after the consumption of golden rice.

If this report were to be rewritten in the future, further research would be conducted. More time would be spent searching and gathering data about golden rice not only for vitamin-A, but also iron (more specifically iron deficiency anemia), zinc and also the cost-efficiency. Additional research would also be conducted to examine whether golden rice is used in the agricultural industry to increase the crops’ protection against plant viruses, disease, herbicides and animals/insects. Genetically modified foods will enhance food security and the consumption golden rice greatly assists with vitamin-A deficiency. The evidence provided concerning golden rice clearly shows the efficiency in aiding food security and the potential to contribute 57-99% and 89-113% of the estimated average requirement for vitamin-A for children in the Philippines and Bangladesh. With largely added benefits and few limitations including a narrow sample size in race, it is evident that in the future, golden rice could be a solution to aiding food security and hidden hunger.