Questions Flashcards
Why finger millet, and not a different opportunity crop?
In my opinion, finger millet is an opportunity crop that is just beginning to gain traction. As opposed to more commonly known opportunity crops such as sorghum, the research delineating its opportunities and challenges is far more current, and therefore has intrinsic interest.
I also personally have a great interest in Southern Asia, where finger millet is a staple food crop. I aim to do a postgraduate project at the Kerala Agricultural University.
Is finger millet a more promising opportunity crop than sorghum, for example?
I would say that the purpose of opportunity crops is not necessarily to outcompete each other. This is a very “intensified” way of thinking. Instead, we should aim to think about the different qualities that opportunity crops can provide in an integrated system.
So for example, here I have covered the advantages for finger millet in phenolic compounds for anti-diabetic aims, resilience to increased soil salinity and in its yield potential.
However, sorghum for example has advantages in a high quantity of slow release starch, resilence to heat stress and also in its use as a biofuel.
How do opportunity crops fit into a highly intensified agricultural system?
I am not saying we should do away with megacrops. I’m also not saying that we should stop investing in megacrop research.
What I am saying is that megacrops have left us in this Anthropocene, with a variety of symptoms: poor health, instability to changing conditions and yield gaps. In this way opportunity crops can provide a local solution to a global problem. They can tackle these localised health problems, changes that are arising due to climate change, and location-specific yield gaps.
How are opportunity crops superior to megacrops?
For example, maize, wheat and rice are all lower in phenolic content than finger millet.
Maize, wheat and rice are also intolerant of salinity to varying degrees, and in different ways. So for example: maize is particularly liable to have its seed germination interfered with, wheat is particularly susceptible to stunted growth and rice can have its photosynthetic capacity inhibited.
And finally, the yield gaps – so the amount of yield between requirmeents and productions that these megacrops leave are also location specific. Maize yield gap is localised to Eastern Central America, Southern Africa, Eastern Europe and Southeastern Asia. Wheat’s yiled gap is centralised in Europe and South Asia; and rice’s is also to South Asia and West Africa.
Clearly, these global problems require local solutions, and believe that opportunity crops could be part of this.
How do opportunity crops fit into land use?
And I’m not even necessarily saying that these opportunity crops have to take away from the land use that has been set aside for the megacrops. Clearly, in this Anthropocentric agricultural context we have set aside a vast amount of land, and the majority of this is allocated to megacrops: wheat, and then maize and then rice.
However, a study by Gururani in the Uttarakhand Hills of the Himalayas utilised a generations old Barahnaja intercropping system between wheat, rice and finger millet. This improved soil fertility, therefore reducing the need for inputs and decreasing this cost to both farmers and the environment.
Are there any other crucial characteristics for an opportunity crop to have?
Yes! One crucial characteristic of an opportunity crop that I unfortunately did not have time to mention is “cultural significance”. I believe cultural significance is important because, for a lot of populations, interactions with plant species is a huge factor of their culture; and crop intensification threatens this generational relationship.
One example in which I think finger millet satisfies this characteristic is in its use in making Chibwantu – a fermented probiotic drink that is traditional at several ceremonies such as weddings. The probiotic potential of these also ties into the health benefits of finger millet, as probiotics have been shown to help strengthen the immune system; as well as helping the synthesis of various nutrients such as B12.
How did the phenol analysis work?
Fractionation of polyphenols extracted by high performance liquid chromatography compared to a reference.
Ambali made and consumed. FRAP evaluates the ability of plasma antioxidants to reduce ferric ion into ferrous ion, which forms a blue colored complex when binding to 2,4,6-tripyridyl-s-triazine (or, for the sake of everyone’s time and convenience TPTZ), that you can measure using spectrophotometry; absorbance at this wavelength is an indicator of the antioxidant capacity.
Describe the FRAP in this case
In this specific case, Kumari et al took 30 μL of plasma and added to 1 mL of Fe(III)-TPTZ reagent. Antioxidants in the plasma then reduce Fe(III) to Fe(II). The reaction takes place for 4 minutes at 37°C and after 4 minutes, the reaction is considered complete, and the measurement is taken. The absorbance of the resulting colored solution is measured at 593 nm using a spectrophotometer. The greater the reduction of Fe(III) to Fe(II), the higher the antioxidant power of the plasma sample.
Standard curve
To calculate the antioxidant capacity of the plasma, a standard curve is prepared using a known concentration of a standard antioxidant solution.
To do this, they used a stock solution of FeSO4.7H2O (Iron (II) sulfate heptahydrate), which is then diluted to create a series of standards with known concentrations, ranging from 0.1 to 1 mM/L. The standard curve correlates the known concentrations of antioxidants (using FeSO4) with the absorbance readings at 593 nm. The curve allows the conversion of the plasma’s absorbance into a value for its antioxidant capacity.
Results are ultimately expressed in terms of μmol/L of antioxidant power.
How do phenolic compounds work?
Phenolic compounds are iron chelators. This means that they react with ferric iron in the labile pool using their phenolic hydroxyl groups that are attached to their aromatic rings, reducing into it into ferrous iron by forming bi- or di-dentate bonds. This means that the iron cannot participate in the Fenton reaction; production of hydroxyl reactive oxygen species via hydrogen peroxide. Essentially, they are sequestering the volatile iron.
How do you tradeoff phenols with iron?
Both are good! Return to oppocrop logic…
What is cubic spline analysis?
Restricted cubic splines can be used to assess non-linear relationships. It is natural to assume that total dietary antioxidant content might have a non-linear relationship with the odds ratio of developing type 2 diabetes mellitus, because there may be thresholds where certain extremely low antioxidant contents are not related to diabetes mellitus, because other health conditions are more prevalent first. From a statistical perspective, it is safer to assume a non-linear relationship, rather than a linear one. Restricted cubic splines are alsp constrained to avoid over-interpretation of a more rigid linear relationship.
Restricted cubic splines are also good at introducing confounding variables. For example, in this study confounding variables such as age, sex, smoking status, alcohol consumption, physical activity,BMI, hypertension and health supplement intake were controlled for in the model. I might also have controlled for socioeconomic status, for example.
What other ways could you have investigated this effect?
Piecewise model to elaborate on thresholds.
What is the significance of using an odds ratio?
Odds ratio are often used in case-control studies; individuals with the disease are compared to individuals without. Ideal for measuring risk vs odds. Since it isn’t a cohort study, you don’t have incidence of the disease; you can’t directly ascertain risk. Calculate the odds of exposure to the risk agent. Very practical in observational studies.
Are there other health conditions which also need to be tackled?
Yes! Lots. For example finger millet is famed for having high levels of calcium. Osteoporosis displays high rates in southeastern asia. 52% of women in India suffer with osteopenia, the precursor to osteoporosis.
What other symptoms of climate change could you have considered?
Drought stress, which finger millet also displays tolerance to through similar mechanisms in Nepalese landraces. These display qualities such as early maturity. For example, the Dibya Sinha variety takes just 80 days to mature (down from 180); a proxity trait for breeding drought escape. Completes life cycle before drought.
Also Striga parasitic weed tolerance is exhibited by some varieties of finger millet, which demonstrate an enhanced immune reaction to infection by the parasite (by preventing attachment, HR and cell death near haustoria).
Finally, resistance to Magnaporthe grisea is also selected for.
