Sense about Science ? equipping people to make sense of science and evidence
Plant science panel
Ash Dieback disease, GM crops, bees and pesticides, mycotoxins in food, biofuels... Plant research is central to decisions about future energy, land use wildlife, environmental protection, pest problems, nutrition and food safety. Leading research institutions and learned societies across the UK have come together to make themselves available in a public panel, where you can put down questions and opinions for response.
Please note: this panel is not for general horticultural advice.
Answers to your questions below
Species that arrive in a new region as a consequence of human action are termed non-native. Those that in some way or other threaten the environment, economy or society are termed invasive non-native species. In Britain approximately 2000 non-native species have been documented as established (that is sustaining populations) and about 10-15% of these are considered to be invasive. However, this small proportion can have devastating environmental consequences. For example some of these species are called ecosystem engineers because they have cascading effects that alter entire ecosystems. The quagga mussel is one such species. It filters its food, planktonic organisms which form the base of aquatic food chains, from the water in which it resides. Quagga mussels are such efficient filter-feeders that they alter the assemblage of planktonic species which in turn affects the rest of the food chain, consequently modifying and disrupting the function of entire freshwater habitats. Other invasive non-native species colonise protected habitats or effect species through predation and competition or by carrying diseases. So in conclusion not all non-native species threaten the environment but the invasive component do so.
"I saw an article about a slug that photosynthesises like a leaf. What is there to stop other animals from doing this? Would animals be able to use the energy they make?"
Photosynthesis converts solar energy to sugar (fuel) inefficiently. Consequently the solar-slug needs an increased surface area to get enough sunlight. It thus becomes leaf-shaped. Other animals would have to do something similar. A human needs ~100W (2.5kWh/day) of power to live. With UK sun providing ~100W/m2 and photosynthetic efficiency an optimistic 0.5%, a solar-Brit would need 14m2, the area of my bedroom. If, like our solar-slug, the solar-human supplemented photosynthesis with food, chose a sunnier spot and reduced movement, the area needed would decrease (≤ 10m2?). The thin green floppiness would mandate a “sluggy” lifestyle: floating in sunny shallow water on a low calorie diet. This could appeal to some but most animals favour compactness and mobility for catching food, avoiding becoming food and the rest. It is not a coincidence that dabbling in a bit of photosynthesis on the side has evolved in creatures not renowned for dashing about.
The occasional groves of giant sequoia (Sequoiadendron giganteum) found near coastal areas in in NW California are relict populations of those that once covered the western United States millions of years ago. Climate differences may explain their apparent decline in range, which modern day anthropogenic climate change will further accentuate. As a fire-dependent species, sequoia have been adversely affected by policies that exclude fire and thereby prevent seedling regeneration. In combination, detrimental changes for sequoia will impact on beetle and squirrel species that depend on these trees. Ultimately, however, if sequoia are eventually lost they will be replaced by another tree or shrub community with its animal species, and a new ecosystem balance found.
Experience with seed production and the need for pure seeds (approx 0.1% off types) shows that distances of 100-200m will limit cross pollination between most seed crops with small wind-dispersed pollen as well as those with insect pollinators. These are then the normal isolation distances for seed crops (eg cereals, oilseed rape, etc). However, for seed production of some specialist hybrid crops with small wind-dispersed pollen where male sterile mother plants are used (eg sugar beet), separation distances of 1-2km from other compatible flowering plants are used to produce high purity seeds. These same standards are applied for seed production of GM crops.
For crops grown for food/feed, admixtures with non-food/feed varieties are required to be kept at low levels (eg 1-2% in oilseed rape). In non-GM crops for food, a threshold limit of 0.9% GM adventitious has been set. In practice this means growing the crops at around 0.5% GM admixture to ensure that all samples are below the 0.9% threshold. For most crops this can be achieved by separating the GM and non-GM crops by between 20-50m depending on crop type, scale of production/field size, site factors such as wind, exposure, presence of pollinators, etc. These isolation distances are also appropriate for separating food and non-food crops of same species.
In organic agriculture there is a desire to have no admixture with GM crops. A zero threshold is not achievable so a compromise 0.1% threshold is agreed as this is measurable and achievable. To achieve this level, the isolation distances described for seed production (ie 100-200m for most crops, see above) are generally applicable.
Dr Wendy Harwood, John Innes Centre: "In the early days of GM technology there was a concern that modifications made using GM might have unanticipated consequences including the possible production of toxins. Despite huge amounts of research looking for such unanticipated effects, nothing has been found. Plant DNA can be disrupted in many ways other than GM, including natural mutations, and this is happening all the time. We have not seen production of toxins due to these processes so there is no reason why GM should lead to their production. GM is just a technology like many others available to us. It is what the technology is used for that is important so safety assessment should be based on the exact change made not on the technology used."
Prof Huw Jones, Rothamsted Research: "It is the explicit intention of all forms of plant breeding, GM or not, to generate changes in genomic DNA which alter biochemical pathways to improve crop performance. It is true that inserting new genes using GM technology can lead to DNA being disrupted in the same way that many other factors including natural ‘jumping genes’ (transposons) continuously disrupt non-GM plant genomes and which form one of the key drivers of natural evolution. A key difference between DNA disruptions caused by transposons or other natural mutagens and those caused by GM is that the latter are known, analysed and rigorously risk-assessed prior to commercialisation of each new GM variety to ensure that no new toxins or allergens are generated that pose a risk to human or animal health."
Prof Rob Chilcott, University of Hertfordshire: "The simple answer to this question is no: whilst it is certainly conceivable that modified genes may cause changes in cellular biochemistry, it is highly unlikely that these changes will somehow lead to the production of toxins that are harmful to humans. Indeed, GM plants are subject to specific tests to ensure they are safe. The Food Standards Agency website has further details on how GM crops are approved for consumption."
At present we apply neonicotinoids to crop plants either by seed treatment or spraying. Since the compounds are 'systemic', they move throughout the plant and end up in all tissues, including the nectar and pollen (albeit in very small amounts). Indeed this is why they are so effective.
Trying to get the plants to make the neonicotinoids themselves by GM would be a challenge! And I suspect not possible. Of course, some plants make 'nicotine' and this does give protection against pests but it is also very toxic so you wouldn't want to engineer crops to make it. Even if you could get a plant to make a neonicotinoid it would then be another challenge to prevent it being in the pollen and nectar.
Prof Jonathan Jones:
GM is a method that can be used to confer many different and useful traits. Liz Truss is right to say GM crops can reduce the environmental impact of agriculture. In the US, Bt maize and Bt cotton require less insecticide to control insect pests. Glyphosate (Roundup) is a less damaging herbicide than the herbicides it replaced. Unfortunately, like antibiotics, reliance on one compound (glyphosate) has selected herbicide-resistant weeds in the US, reducing glyphosate effectiveness for weed control. Another GM trait in maize has been used to elevate tolerance of drought stress. For the UK, blight resistant potatoes will require less fungicide applications, and there are many other potential nutritional and agronomic benefits that could be conferred using the GM method.
Prof Ottoline Leyser:
Farming practices associated with each GM crop differ, depending on the specific characteristic that has been introduced. It is therefore not meaningful to state that growing GM crops results in less water and pesticide use, because it depends entirely on which GM crop you are talking about and what the normal practices are for the equivalent non-GM variety. For example, there is very good evidence that the use of GM cotton engineered to resist insect attack has reduced the use of insecticides in cotton production compared to previous practice. However, the use of GM technology to increase vitamin A production in rice does not affect how much pesticide is used.
One type of crop where there has been a particularly vigorous debate about the environmental impacts is herbicide-tolerant crops. There is no doubt that the widespread planting of herbicide-tolerant crops has led to an increase in the use of the specific herbicides tolerated by these crop varieties. Some argue that this has reduced the use of alternative, more environmentally-damaging herbicides. Others point to the negative effects on insect biodiversity caused by the reduction in weeds associated with more effective weed management. Others still highlight the emergence of weeds resistant to herbicides. These debates are important, but they have nothing to do with GM. While many herbicide-tolerant crops have been produced using GM methods, others have been produced using conventional methods, and all the arguments are about herbicides and their use, not about GM. Just as it is inaccurate to say that GM crops reduce pesticides, it is equally inaccurate to say that they cause superweeds.
We need to be able to choose the best solutions to each challenge facing the food supply chain. In some cases this will include a particular GM crop, but in many cases it will not.
Dealing with Phytophthora ramorum-infected larch is complicated for a couple of reasons. One is that it is a quarantine pathogen, and so there are certain national and European requirements when outbreaks are confirmed and they often require destruction of affected plants. Another factor is that when larch, and specifically the foliage of larch, becomes infected, it can generate millions of spores as the needles die. These spores are dispersed aerially leading not only to the infection of more larch trees, but infection of other nearby susceptible plants and trees, although few of these are spore producers in the way that larch can be. Therefore, felling larch in the early stages of the disease (preferably before any sporulation can occur) is an effective way of preventing disease spread in the wider environment.
Not only trees with visible symptoms are removed, but also those in a buffer zone around the symptomatic trees. This is because in the early stages of infection symptoms may take a while to become apparent, but some of these asymptomatic trees go on to develop symptoms and produce spores later, hence the need to remove more than symptomatic trees to ensure that outbreaks are contained.
In the article it says that the product - 3AEY - is a 'bio-pesticide derived entirely from plants'. This alone wouldn't mean that it was not toxic to non-target organisms or safe for the environment. Many ‘natural’ plant products are extremely toxic, nicotine, solanine (from potato/tomato), oxalic acid (from rhubarb), linarmarin (from cassava), phytohaemagglutinin (from lupin) to name just a few.
However, 3AEY has obviously been tested for non-target toxicity including to honey bees and shown to be non-toxic, so this product does seem to be both effective and safe to use. The content of 3AEY is not detailed but it seems to be ‘terpene’ based and terpenes are common components of many plants, but again this does not mean all terpenes are ’safe’ they are a large and diverse class of organic compounds with very wide toxicity profiles.
The two main classes of GM crop carry either glyphosate-resistance (RoundUp Ready, or RR), or insect resistance, via expression of insecticidal Bt protein.
All farmers need to control weeds, otherwise they can lose half their yield. Before the RR trait was introduced, soybean farmers attempted to control weeds with chloramben, metribuzin, trifluralin, imazethapyr and pendimathalin. These were persistent and in dry years could affect the crop in subsequent years. In contrast, glyphosate is rapidly inactivated in soil. Use of post emergence herbicides has reduced tillage, with less ploughing required to control weeds, enabling more carbon sequestration in the soil.
Herbicides are like antibiotics. If we only use one antibiotic, we select for resistance, but we do not abandon antibiotics, but rather we use additional antibiotics. Glyphosate resistant weeds have become a problem. The solution is more science not less, and we need additional herbicide/herbicide tolerance combinations to maintain weed control.
Bt crops have reduced insecticide applications by 400,000 tons over the last 15 years. Again, deployment of Bt crops should be carefully managed to slow the evolution of Bt toxin-tolerant insect pests, but use of Bt crops is much less environmentally damaging than applying insecticides to crops.
There are no credible data, and no proposed credible mechanisms, whereby RR genes or Bt genes can be damaging to human health. Furthermore, glyphosate, which works by inhibiting an enzyme that is not present in humans or most other animals, has no mammalian toxicity. Glyphosate is preferable to the herbicides used previously (see above).
GM organisms have NOT raised more and more worrying questions about their effectiveness, their necessity, or even their safety. Activists have. But their concerns are for the most part without foundation. It is perfectly legitimate to exchange arguments about what kind of agriculture we want, but it is intellectually indefensible to make “GM yes or no” a lightning rod for concerns about globalization, monopoly power or loss of biodiversity.
GM is a method for genetic improvement of crops. There are many such methods and each of them have advantages and disadvantages. There is no evidence that any of these techniques is inherently more dangerous than any other technique. The issue is what you do with them.
One of the main applications for GM technology to date is herbicide resistance. This has caused a lot of controversy. The idea is that you make crop resistant to a herbicide, so that you can spray that herbicide on your field and it will kill all the weeds but not affect the crop. This has the huge advantage of getting rid of weeds, which reduce yield and can cause contamination problems at harvest. However, it has the disadvantage that it involves herbicide spraying and over-use of a small number of herbicides will lead to herbicide resistant weeds (co-called superweeds) and getting rid of all the weeds affects insect biodiversity. These problems are not caused by GM. They are caused by herbicide resistant crops, as an approach to weed control. There are non-GM herbicide resistant crop varieties sold by the same sorts of companies that sell the GM ones. There are also herbicides that can be used before planting, which are often more environmentally damaging than those used with GM herbicide resistant crops.
So this statement has several logical flaws. None of the problems listed is caused by GM. None of them is specific to GM. None of them will go away if GM is banned. The endless GM blame game does nothing except prevent the initiation of crucial discussions about how agriculture should be conducted in the 21st Century. For example, how should we control weeds in the optimal way to provide a safe and secure food supply, but with minimal environmental impact? This is an important question that is going unanswered because everyone seems to be pretending that getting rid of GM would solve the problem.
GM takes ages to go from lab to field. Will genome editing be any quicker?
Autism is part of a spectrum of disorders and they have been the subject of numerous reviews. One of the best is by Newschaffer et al (The epidemiology of autism spectrum disorders). This paper discusses changes in prevalence and the extent to which diagnoses of autism may be a result of factors other than a true change in prevalence, such as changes in disorder definitions over time. The authors also point out there is a strong genetic component and discuss proposed environmental factors such as MMR vaccine, metals and PCBs - none of which have been proven to cause autism. One (MMR) was the subject of proceedings at the General Medical Council, on the grounds that the paper suggesting a link with MMR was fraudulent (Editorial, Wakefield’s article linking MMR vaccine and autism was fraudulent). The correlation between use of glyphosate and autism in the article by Mercola could be made with many aspects of modern life. In fact Samsel and Seneff noted similar correlations in relation to other conditions and glyphosate.
It is important to be clear that epidemiological studies show association not causation: Sir Austen Bradford Hill suggested criteria for deciding whether an observed association indicated causation.”
The GE moths do not contain any toxic or allergenic proteins so in the unlikely event of one ending up in food it would not cause a problem. This seems to be a very safe trial that is naturally self-limiting so there would be no long-term effects.”
The trees have been extensively tested and trialled and an application to grow them commercially is currently under review by the Brazilian authorities. By ‘...would make it worse’ I assume you are referring to the clearing of natural vegetation to make way for eucalyptus plantations. Recent experience has certainly shown us that rapid expansion of non-food and high-value commodity crops, particularly in tropical regions, can have negative consequences on the environment and food security. If, as claimed, biomass productivity is increased in the GM trees, theoretically, this could reduce the need for more eucalyptus plantations.”
As well as soil particles, residual chemicals applied to the vines or soil will also then then to be carried in water runoff. The perception is that any plants in the inter-rows will compete with the vines for water and nutrients, but grapes are famously deep-rooted, so the former rationale at least may be ill-found. Even some form of dead vegetation, grown out of main season and sprayed off but left intact can be an effective erosion control measure. A strategy of deliberately compacting the soil between rows to inhibit vegetation will just exacerbate runoff by preventing infiltration.
A basic rule of thumb for soil protection is 'bare soil bad'".
Dr Greg Mitchell is a Research Biologist and Senior Lecturer at the University of California San Diego, Scripps Institution of Oceanography.
[...] I would be more comfortable if an alchemist wizard was farming than modern day scientists. There are just simple things that are not being explained without re routing it into a different question and answer."
Read Sarah's full comment on our Facebook page.
First, plants that man found here naturally had little/no quality as food, and oftentimes were poisonous. Only through years of selection have humans changed the genetics of plants to move beyond what is "natural". Everything you eat has been domesticated and genetically altered by humans, sometimes not always with great results (see Lenape Potato). Cross breeding, creation of polyploids and even mutation breeding have been accepted as safe, even though they are imprecise, resulting in unknown mixes of genetics.
Today's biotech methods allow us to move a gene or two. Moreover, we know exactly what the gene does, how it works, and what products it makes. We can follow it, test for it and monitor it.
You are far more likely to have an unintended effect from traditional breeding than you are from GM technology - far more likely. That said, both are perfectly regarded as safe. Of course, we know about plant allergens and many people do have to eat with care because of natural allergens in peanut, soy, wheat, etc.
Read a little about the GM techniques and plant domestication. I'm glad to help you with any questions, any time. Once you learn about this complex topic, it is not scary, and actually is rather amazing."
• May protect the heart and blood vessels from disease
• Supports healthy development of your baby during pregnancy and breastfeeding
• Provides other important nutrients including vitamins A and D and protein
Because of this and other health benefits it is recommended that we eat more foods containing omega 3.
Omega-3 fats come in different forms: ALA (alpha-linolenic acid) cannot be made in the body so must be eaten in our diet. It has important functions and is needed to make other omega 3 fats. ALA is found mainly in vegetable oils (rapeseed and linseed), nuts (walnuts and pistachio) and green leafy vegetables. EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) are long chain fats that can be made from ALA in our bodies. They have the most direct health benefits."
There are plenty of nonsense herbal remedies from plants that don't do anything except waste your money. However, there are many compounds that are isolated from plants that have clinically proven disease fighting properties. For example, Taxol (Paclitaxel ) is isolated from the Yew tree and is one of the standard chemotherapies used against breast cancer. Vincristine is isolated from periwinkle, and is used to treat leukaemia.
These compounds are very toxic- that’s why they kill cancer cells - and the plants have probably evolved to produce them as a defense to keep animals or insects from eating their leaves. However, a person suffering from these diseases can't simply eat the plant to treat their disease. Instead, the compound needs to be purified from the plant, and very often administered intravenously. So while plants definitely make substances that effectively treat diseases, there is a lot of purification and processing that needs to take place if the drug is to be effective.
"My response to that was that I had heard no one else saying that and that he might well have had a valid point."
Do the panel have any suggestions of how to grow a cover crop year-round in a dryland environment? What low cost methods could be applied in this environment to effectively minimise soil erosion?"
As you suggest one of the challenges of using fava beans as a source of levodopa is there is no way of measuring the dosage accurately. Individuals may under medicate and find it difficult to effectively control their Parkinson’s symptoms or over medicate and develop side effects such as uncontrolled movements (dyskinesia) which can be very distressing. Research into the use of fava beans for Parkinson’s is still fairly limited and so as yet not recommended as a treatment for those with the condition.
As I understand it, if a commercial company extracted levodopa from broad beans and intended to sell it commercially they would be heavily regulated and need to be approved by the MHRA. However this does not seem to apply to powdered broad beans."
Hannah Churchill is the Research Communications Officer at Parkinson's UK
Professor Tom Sanders is the Head of Diabetes and Nutritional Sciences Division at the School of Medicine, Kings College London.
Other candidates for the protective effects are vitamin C and potassium which are supplied mainly by fruit and vegetables. Potassium helps lower blood pressure. There has been some interest in anti-oxidants other than vitamins provided by plant foods but this has mainly focused on drinks such as tea and chocolate. There is a large group of compounds called plant phenolics that have anti-oxidant properties that are found in higher levels in organic crops than conventional crops but there is little evidence that this has any effect on health. These phenolics have potentially negative as well as positive health effect. Much of the benefit of eating your five a day is that you do eat less unhealthy food such as cakes, biscuit and confectionery."
Professor Tom Sanders is the Head of Diabetes and Nutritional Sciences Division at the School of Medicine, Kings College London.
A banana plant produces the first fruit 11 months after planting. The second and subsequent fruits are generated continuously every 3 months. The plants will continue, like normal bananas, to produce several suckers (baby plants) vegetatively. Farmers can use these to expand their gardens or share with others."
In some cases, the breeder knows the gene or has a genetic marker for a beneficial trait. By analysing the genetic fingerprint of all the many thousands of progeny plants at the seed or seedling stage, the breeder can more easily and quickly select the individuals that possess that beneficial trait.
Unlike GM, marker-assisted selection does not increase the pool of genes that a breeder can use. It simply speeds up the conventional breeding process. It uses knowledge about genes and DNA but is not, itself, a GM technique and it does not, on its own, result in a GMO. However, MAS is often used in combination with genetic modification to follow the newly-inserted gene through different generations.
There are many examples of MAS being used for developing country agriculture. For example, it has been used to select for virus resistance in breeding programmes for common beans; and to select for virus and green mite resistance in cassava both for Asian and African agriculture see more here.
There are other biopesticides, such as entomopathogenic fungi and other toxins from microorganisms, such as the Bt toxin, the latter is widely used in crops that have been ‘engineered’ to produce the toxin. Delivery by this route is clearly controversial where GM is not accepted."
After cutting the top of one tree in this way, I decided to make a lateral branch stand directly upright by caning and tying it with the hope it would form the new upright of the Christmas tree and grow on for future cuttings. I did this three years ago. However, this lateral branch still knows it is a lateral branch – it will do its damnedest to grow laterally no matter how I force it vertically. The new cells somehow know that they originated from a lateral branch, and not the central branch of the tree. Do you know how this is achieved?
We do not yet know how the set point angle is determined. Recent exciting research from the laboratory of Dr Stefan Kepinski at the University of Leeds suggests that, like the main shoot, side shoots have the same gravity response system that directs straight up growth. However, in side shoots this is off set by a system that orients growth downward. This off set system is what generates the set point angle and it is dependent on the plant hormone auxin. Hopefully over the next years we will gain some understanding of how this works, and then it will be possible to work out why in some shoots the set point angle is easy to reset, but in others not."
The biologically fixed nitrogen remains in the plant, thus would not normally be available for the next crop - unless the remnants of the crop are ploughed into the soil.
We think that if we can enable biological nitrogen fixation in non-legumes we can significantly reduce the need for nitrogen fertiliser, bringing massive savings to agriculture."
The large increases in temperatures that are expected to be caused by global warming are likely to occur on a much shorter timescale than those through which plants adapted to a particular environment. This is likely to result in changes in the distribution of plant species, with those that are adapted to the warmer conditions becoming established. In the case of crops, there is the need to breed new varieties that are adapted to the changed conditions otherwise yields will be impacted on."
The prime suspect when considering monarch decline has been deforestation in the parts of Mexico where the adults overwinter. It is very interesting to see this other factor highlighted. As so often, there is no one simple single cause in the decline of a species. The work also highlights the conflict between food production and the welfare of other species on which, through complex interactions, our own welfare ultimately depends, and it demonstrates the importance of high quality studies aimed at getting the balance right.”
That's why something that tastes wonderful to me might not be your favourite at all.
The particular flavour-molecules that a plant produces depends on interactions between genes and environment. My lab recently identified a gene in strawberries that is required for "peachy" flavours. If a strawberry doesn't have the gene, it can't make the peach notes. Environmental factors also play a role, as even if a gene is present, it may not be expressed well on a cloudy day or late in a season.
So shuffling genes by breeding to identify drought-resistant varieties could profoundly affect flavours, although it is difficult to say precisely how. Over the past 50 years fruit breeding has prioritized production traits, like yields, shippability, size, colour, etc. Flavour and aroma have been a bit down the line in terms of importance. That's why our recent varieties lack exciting flavours.
The good news is that as we further unveil the genetic basis of flavours and the genes that control them, we can now specifically breed for plant materials likely to possess improved flavours. I'm optimistic that the next generations of fruits and vegetables will be our best, and will spark renewed interest in nutritious fresh produce."
When the oilseed is crushed and the oil and seed casing are pulped, the chemicals, such as the sulphurous glucosinolates, are transferred into the oil. Sulphur-containing organic compounds will, to varying degrees, “go off”, often due to exposure to the air, producing sulphur dioxide which is notorious for its pong! However, these compounds will all be at really low levels and pose no threat to health. (In fact, sulphur dioxide is a commonly used preservative in wine making.
The resulting smell and taste will depend on many things, such as the variety of the oilseed rape, location of growth, local environment (terroir) and climate. I would encourage you to embrace the diversity!”
Organic farms often have higher soil organic matter content due to higher levels of organic matter inputs in the form of manure and compost. Organic crop rotations also include deep rooted legume and grass crops that improve the structure of soil. Many conventional crop farms operate low or zero organic matter applications into the soil and have simple crop rotations without deep rooted crops. However, some conventional livestock farms are very close to organic livestock farms in terms of crop rotations and organic matter applications."
For a look at the science of rooting and potential impacts on soil water holding capacity our plant science panelist Dr Robin Sen has written a more in depth blog.
The rapid loss of soil aeration following waterlogging drives further changes in soil properties that can trigger release of essential plant nutrients such as phosphorus and nitrogen causing a major loss of soil fertility.
Another major risk to soil life and productivity comes from the input of pollutants such as toxic heavy metals and hydrocarbons from nearby flooded urban brownfield sites and roads. Post-flooding recovery of soils is greatly dependent on a range of factors such as soil organic matter content and subsequent land management.
For more information about soil protection, consult the Soil Strategy for England report published by the Department of Environment, Food and Rural Affairs (DEFRA, 2009)."
The speed of the recession depends on the size of the river and the magnitude of the event. Where out-of-bank flow has occurred and flood plains are flooded, it may take some time for water to recede. In large lowland areas, decline of floodwater by natural outflow and drainage through the subsoil may take days or weeks, especially if groundwater levels are high."
Fazir Khan, Civil Engineer: "There is always lag period between the peak rainfall event and the peak flood event. The peak discharge experienced during a flood event occurs some time after the peak rainfall event. This time can vary depending on the size and configuration of the catchment from minutes to hours to even days for very large catchments that flow to flatter low lands.
There can also be an exacerbation of the flood event in areas where there is tidal impact in the lower reaches. A rising high tide can sometimes coincide with a rising flood to create very high flood depths for the duration of the high tide in a given area. High tides can therefore by extension, if they coincide with floods, lengthen the time it takes for surface runoff to dissipate and therefore extend the time of the flooding in an affected area.
In summary, flooding can be experienced for some time after rainfall ceases because of flat slopes in the discharge channels, constrictions in watercourses and outfall drains; backwater effect caused by high tides and other physical characteristics of the catchment in question."
Some actions to reduce flood risk may be compatible with preserving environments for wildlife. For example, washlands on flood plains may provide storage for flood waters and habitats for plants and animals. However, rarely is flood water clean, and high loads of nutrients and pollutants brought onto the land with the floodwater can cause significant damage to valuable wildlife sites.
Planting woodlands in the upper reaches of catchments can encourage rainfall to infiltrate into the soil rather than runoff over the surface (depending on the soil type and amount of rain) and managing peatlands to retain water can provide benefits to wildlife and flood risk management.”
a) Flooding may be caused by the flow in rivers exceeding the capacity of the channel (fluvial flooding). This usually occurs after long periods of heavy rain. It is what rivers naturally do, and is why rivers have flood plains. The problem arises when we want to use the flood plains for other purposes (houses, agriculture, transport routes, etc.).
b) Rain falling on the land surface at a rate greater than it can be moved away by natural or man-made drainage causes pluvial flooding. This occurs during intense rainfall and tends to be quite localised and short in duration. Urban areas are prone to pluvial flooding when the drainage systems become overwhelmed or blocked.
c) High groundwater levels after prolonged rainfall result in groundwater flooding. Groundwater emerges at the surface in depressions and hollows and basements of houses.
d) Coastal flooding occurs when waves overtop coastal defences. This usually occurs when high tide coincides with low air pressure and high winds (tidal surge).
e) Finally, flooding can occur due to breaches or failure of infrastructure (such as dam failure).”
James Dent, Independent Consultant, Hydrology & Meteorology: "There are several types of flooding.
a) Fluvial. Flooding caused by streams and rivers in response to rain and in some cases snow-melt. Can be in response to local rainfall events or, as in recent months to widespread heavy rainfall over a prolonged period. This latter type of event will cause major floods on the largest catchments, e.g. Thames, Severn.
b) Pluvial. Flooding as a direct result of heavy, localised, and usually short duration rainfall, e.g. thunderstorms. Floods of this type are most common in small, steep catchments, e.g. Pennines, Welsh Valleys, and in urbanised catchments where large extents of paving prevent infiltration.
c) Groundwater. Occurs in relation to major water-bearing strata (aquifers), such as chalk, sandstone and alluvial sands. Groundwater levels rise as a result of prolonged rainfall, especially in winter, where there are only small losses by evaporation. It is common for groundwater flooding to come after major fluvial flooding events. The delay in the response to aquifers to inflow and outflow means that groundwater flooded areas will remain for several weeks after the fluvial flood event.
d) Coastal/Estuarine. Costs and estuaries are at risk of flooding from high tides. This flood risk will be enhanced by the natural tidal cycle and incidents of high, persistent on-shore winds. Tidal surges are caused by the influence of low atmospheric pressure, i.e. the passage of depressions. Adverse combinations of high tide, wind and atmospheric pressure can cause significant events like the North Sea Floods of 1953".
Also, the pathogen [disease-causing organism] that causes blight is constantly changing, and current pathogen races can overcome resistance in the most commonly grown potato varieties in the UK. Importantly, the gene we trialled, Rpi-vnt1, confers resistance to all currently circulating UK strains (and we can never have ‘too many’ resistance genes). We are cloning additional such genes"
Read more about the research here.
Typically, soil pores contain air and water, both of which are needed for plant growth. When the pore space of soil (or rock) is completely full of water, we have ‘groundwater’. Groundwater usually exists because of some subsurface flow barrier (e.g. a layer of reduced permeability). The surface of the groundwater is often evident as a ‘water table’: If you dig a hole in the ground to reach the water table this would be the level of standing water in the hole. Water table elevation rises and falls according to groundwater recharge and discharge. Where the water table intersects the ground surface we have a ‘spring’. And with very wet conditions, groundwater discharges can take place where they may not be expected and cause surface flows – or, alternatively, groundwater can flood basements and other structures below the surface.”
Do we need more man-made rivers in low lying areas?
“Low-lying areas don’t have enough elevation difference to support soil drainage and river flows, and hence can easily become water-logged and flood. Agricultural drainage is often used to improve the ability of such soils to transmit water. Subsurface drains would normally connect to a system of open ditches and streams. These are part of the natural landscape and traditionally would become inundated during wet conditions, and act as a temporary store of water. Improved drainage removes this storage and passes the water downstream – where it may create new flooding problems. So having more man-made rivers may help a local problem, but may worsen conditions downstream.”
What do people mean when they talk about trapping flood water on higher land?
“Various agricultural practices in upland areas can help to store water in the landscape. For example, planting trees improves the ability of the soil to accept and retain water, and small reservoirs can trap water for farm use. These practices can reduce flood risk downstream. However, other practices, such as drainage, will reduce water storage and can make matters worse downstream.”
How can we get rid of water faster?
“Getting rid of water faster may often mean creating a problem for someone else downstream. The most ‘efficient’ way would be to change the natural river system into a concrete, un-vegetated channel designed to move water fast and efficiently. But this then loses the natural ecological function of the river system.”
On a positive note, British researchers have recently developed a hybrid grass which can improve the soil structure through deep rooting. This could actively reduce the run-off from upland pastures, thus mitigating the risk of flooding further downstream.”
Should farmers build more ditches and why?
Paul Temple: “It's not a case of building more ditches, but of carrying out proper maintenance on existing ones. Strategic reservoirs, to give water holding capacity, should be part of a future plan to provide irrigation.”
What will the impact of a flood be on different kinds of crops and trees? e.g Will farmers have to plant something different next year? Will prices go up? (Rebecca Gale)
Paul Temple: “Flooding basically kills roots - for annual crops, in a short time; grass can manage a little longer. If the water table rises some tree roots shallow off and the trees either die or are vulnerable to wind damage.
Wet soils lose their structure and ‘growing ability’, needing either a severe drying out or deep cultivation to put this right. Flooded soils become compacted and anaerobic with soil life (critically, worms) dying. A permanent pasture that is flooded and destroyed in this way will take several years to re-establish the same root system.
In terms of the impact on crops, Spring sowing will be delayed. Prices, however, are less likely to be directly affected - unless the crop is high value vegetables not easily replaced. A final point is that any production we lose needs replacing with imports, i.e from another country where land is not flooded. Most farms have someone with generations of experience and all of them see flooding as failure!”
The green pigment, chlorophyll, absorbs red and blue light and on to higher energies, covering the solar spectrum quite well in the UV. In fact, proteins containing chlorophyll may have existed simply as UV screens before they evolved to photosynthesise.
But the pure chlorophyll pigment is a bad idea as a sun screen. It would absorb the UV and visible light but then react with O2 (the molecule not the company) and the excited O2 would then kill your cells. This reaction has been studied as a way of killing cancer cells. In the natural environment carotene molecules prevent excited chlorophyll wreaking havoc.
So Alana’s idea of keeping chlorophyll in its native cell is a better bet as a UV screen. That said, it is quite hard to keep a plant cell alive outside a plant. Algae or photosynthetic bacteria may do better since they are used to the free-living, unicellular lifestyle but even those get contaminated with other microbes or just die.
Thus I would predict that bacterial/algal sunscreen might work for a short time in principle but would be fairly smelly, possibly slimy and certainly green: a tricky prospect for the sales department.
Selenium is not essential to plant growth but is essential to human health as it forms part of some important anti-oxidant enzymes. In some countries, including the UK, dietary intake of selenium is below recommended levels. Finland has even added supplementary selenium to cereal crop fertilisers, although other non-grain crops such as broccoli are known to be better selenium accumulators.
Selenium is thought to be taken up by plants through the same pathway as sulphate resulting in competition between the two chemicals (Ellis and Salt 2003) and so an abundance of one may inhibit uptake of the other. Flavonoids are most commonly known as plant pigments which add to the colour of fruits and petals. Selenium enrichment in tomatoes resulted in an increase in some flavonoid chemicals (Schiavon et al 2013) but a decrease in other beneficial compounds, especially containing sulphur, in broccoli (Finley et al 2005). The underlying mechanism remains unclear.
View article here
"This finding applies equally to all DNA found in our food. Our food contains large amounts of DNA and GM plants typically contain one extra gene added to at least 25,000 existing genes. The minute amounts of DNA from our food able to pass into the bloodstream do not cause us any problems. DNA from GM plants would be no different."
The article claims that:
- toxins resident within GM foods can dangerously enter (and are entering) the human organism.
- pregnant women and their fetuses had detectable levels of the toxins in their blood.
- these research findings show that GMO products contain toxins that can be absorbed by humans, and that they may cause serious side effects.
Can you comment on this article/study please, and whether it makes any sense?
see study here
See article on RNAi insecticides here
"The potential advantage of RNA gene silencing is that it is very specific and so can be used to turn off a single gene which may only occur in one organism. By targeting essential genes, it is theoretically possible to control the population of a single type of pest. However, it is difficult to get RNA into cells (where it can have an effect) because all organisms produce a form of RNAse; an enzyme which rapidly digests and neutralises the biological effects of RNA. This is one of many reasons why RNA gene silencing has yet to be established as a pesticide. The presence of RNAse in humans is also why it is highly unlikely that food containing modified RNA will cause any health effects in consumers."
"It is worth considering that we eat plant and animal RNA on a daily basis without any associated adverse effect simply because we digest RNA very effectively. Moreover, the introduction of RNA-based pesticides will be subject to national and international controls which include a requirement for companies to demonstrate the environmental and consumer safety of their products."
Link to article
So the question is: is it true that the nutritional content of food produced by modern agricultural methods has declined?
"Genetic engineering is 40 years old. It is based on the naive understanding of the genome based on the One Gene - one protein hypothesis of 70 years ago, that each gene codes for a single protein. The Human Genome project completed in 2002 showed that this hypothesis is wrong."
"The whole paradigm of the genetic engineering technology is based on a misunderstanding. Every scientist now learns that any gene can give more than one protein and that inserting a gene anywhere in a plant eventually creates rogue proteins. Some of these proteins are obviously allergenic or toxic."
This is in light of your comment in answer to another question in which Dr Gia Aradottir said '..the important outcome is what proteins the genes code for.'
See Gia's original answer in Q1 here
"It's much more difficult to answer the second part of the question - does this apply across Europe? All we can say is that many trees are affected across Europe, and the disease is now throughout most of the ash range in countries that have been affected for some years by the disease (eg Poland, Lithuania, Sweden, Norway and Denmark). So in those countries probably the majority of ash trees are affected by the disease and a high proportion, but not all, will have died as result of the disease either directly or indirectly. In the case of the latter, trees can be so weakened by the year on year effect of Chalara that they can succumb to other tree pathogens such as honey fungus (Armillaria) and these may be the final 'killing agents'."
"It's difficult to give exact figures because it would mean a huge survey effort to define the numbers of trees and then those affected/dead in all the various countries where ash is now affected by Chalara, so that's probably why there are no clear unambiguous figures for every country affected by Chalara."
"Plants are the main source of food for Man and animals. Crop plants have been slowly improved, in one sense genetically modified, by farmers and plant breeders to give the highly efficient varieties we farm today. The early methods to develop new varieties were relatively passive, making simple crosses in the field. However, over the last century, plant breeding techniques have required more human intervention to provide useful genetic variation. Methods such as wide-crossing between species that would not hybridise in the wild, artificial mutagenesis to generate random changes in genes or marker assisted selection became increasingly used. Over the last thirty years, plant breeders have learned how to move single, specific genes form one organism to another by a method called ‘recombinant DNA technology’. Crops made by this method are what we know as GMOs and fall into EU legislation for testing and labelling. Many scientists see recombinant DNA technology as one more step (albeit an important one) in the continual development of ever better and predictable plant breeding methods."
"What I can say is that the studies that have been done into gene transfer from the eaten plant material to bacteria in the gut have revealed that the risk of gene transfer is extremely small. Although, one can never exclude such possibilities in biology, it is less likely that pathogenic bacteria will acquire antibiotic resistance in this way compared to other ways. If you want to learn more, please click here. "
There are a number of scientific studies which indicate that some pesticides may have “anti-androgenic” activity: an effect which interferes with the normal response of the body to male hormones. The actual quantity of such pesticides in the food we eat is subject to very strict controls and so it is unlikely that the concentration of any one pesticide would be sufficient to cause a measureable effect. In saying that, the effects of some pesticides may be additive. That is, exposure to a number of substances (at a low dose) may result in an overall dose which may be sufficient to cause an effect. However, no studies in humans have established a link between pesticide residues and male infertility.
It is worth considering that we are exposed on a daily basis to a wide variety of chemicals present in our diet and environment which may potentially affect fertility. So, sticking to organic food would probably not make much difference to our total daily intake. It is also worth pointing out that whilst organic foods may generally contain less pesticide residues, it doesn’t necessarily eliminate exposure. The type and amounts of pesticides used on all crops are subject to strict controls which are monitored and enforced by the UK’s Food Standards Agency (FSA).
"In principle, responsible fertiliser application in optimal environmental conditions is unlikely to be detrimental; however, it is likely to affect tree volume and in doing so may affect timber quality. Whether this effect is considered detrimental or beneficial is likely to depend on how timber quality is defined."
2) Do many of the of the scientists there belong to environmental Groups/NGOs?
3) Do both the funding sources and the various affiliations of the senior staff there tend to skew the type of research that they are covering ?
~60% from BBSRC in the form of Institute Strategic Program Grants and competitive responsive mode grants
~10% from other Exchequer sources including DEFRA, DECC, DIfD, NERC
~4% Foundations such as The Lawes Agricultural Trust, Bill and Melinda Gates, Perry Foundation, Felix Cobbold etc
~12% Industrial research collaborations
~5% Levy boards and crop research agencies (HGCA, BBRO, AHDB etc)
~2% royalties, licence fees etc"
"2) Yes, but not (as far as I know) in the more extreme end of the spectrum such as GM-freeze etc. Typically, we have staff who are members of RSPB, Butterfly Conservation, Wildlife Trust, FoE, CPRE etc. However, staff are not required to divulge involvement in any NGO or political organisation."
"3) Funding from BBSRC and other research councils is for work covered in their strategic plans (e.g. http://www.bbsrc.ac.uk/nmsruntime/saveasdialog.aspx?lID=3719&sID=6953 ) and therefore the funding sources do play a role in determining which areas are studied. However, the funding bodies, including industry, have no say in how a Rothamsted scientist interprets her/his own results. The principles of academic freedom apply in Institutes just as they do in Universities."
"Like other plant cells, root cells are enclosed by a membrane, which in turn is surrounded by a cell wall. While the cell wall is permeable to water and most nutrients, specific transport proteins are required to take up nutrients, such as nitrate, phosphate or potassium, into the root cells. Water and nutrients are transported from the roots to the shoots in a system called xylem. On their way from the soil into the xylem nutrients have to cross cell membranes at least twice: (i) to get into the centre of the root which is sealed off by a hydrophobic strip that prevents transport through the cell wall; (ii) to be loaded into the xylem."
"Nanoparticles can, in theory, follow the same route, but they can also enter the roots through wounding. Whether or not they are taken up and transported to the shoots depends on e.g. their size, surface charge and also the plant species. There is concern that nanoparticles taken up by plants may be toxic to the plants themselves or accumulate in the food chain. On the other hand, it may be possible to use nanoparticles for the delivery of fertilisers, herbicides or pesticides."