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The impact of change on plant adaptation: Stability of agricultural yield
The impact of change on plant adaptation: Stability of agricultural yield
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Environmental factor
scale
plant adaptation
vegetation level
morphology
physiology
biochemical
molecular
include scale of each (plant/ community/ regional/ global)
consequences and therefore outcomes for stability of agricultural yield
stakeholders impacted by/ interested in/ accountable for the outcome
or in terms of management/ solutions/ information sources
including who, what, when, where, why
and communications mechanisms/ methods
knowledge gap
future work/research could be...
Elevated CO2
scale: whole world
plant adaptation
vegetation level: increased biomass, higher grain yield in soybeans (Adeyemi et al. 2017)
morphology: greater leaf area, root cortical cells replaced with arenchyma
physiology
biochemical: increased nutrient demand
molecular
higher spore count and root colonization of AMF in soybeans at elevated CO2 (Adeyemi et al. 2017)
In FACE (free-air CO2 enrichment) experiments, C3 performed 3 times better than C4 plants in terms of carbon accumulation/ transpiration. Low N and drought treatment stunted plant growth for both C3 and C4 [LINK TO NUTRIENTS BRANCH]
include scale of each (plant/ community/ regional/ global)
consequences and therefore outcomes for stability of agricultural yield
AMF inoculated soybean variety ‘TGx1740-2F’ is most preferable in CO2 enriched environment, while variety ‘TGx1448-2E’ had the most stable grain yield in all growth environments. (Adeyemi et al. 2017)
crop yield may need to be managed with genetic engineerin (but funding and public support is limited)
collaboration between scientists (agronomy, climatology, biology) could provide solutions tailored to the food demand and production potential in certain agricultural areas across the world
They could communicate their findings with farmers to help maintain/ increase yield and profits - would need people to visit farming communities to make understanding and implementation easy and appealing to farmers
all levels of the government should support this because it would be beneficial for food security, economic security, and prevent food riots
Implications for nutrient cycles
• Carbon - more CO2, RUBISCO can increase, fix more, more sugars, plant growth is accelerated, plants need to compensate for this with N and P from the soil, so we will have to add more fertiliser to prevent stunted plants
• Nitrogen - lower microbe activity to provide N when under heat stress, decreased fixation rate while plants need more N in future, plants will be shorter and N cycle will slow
Phosphorus - longer replenishment process because of leaching,
knowledge gap: how will plant-fungi symbiosis change in response to this
future work/research could be...
Adeyemi N, Sakariyawo O, Muftau A (2017) Yield and Yield Attributes Responses of Soybean (Glycine max L. Merrill) to Elevated CO2 and Arbuscular Mycorrhizal Fungi Inoculation in the Humid Transitory Rainforest. Notulae Scientia Biologicae 9, 233-241. doi: 10.15835/nsb9210002
Salinity
can be caused by agriculture - rising groundwater table due to landclearing, conversion of woody perennials to annuals and/or irrigation adds more salt than rain can flush out (e.g. Murray Darling Basin)
risk of salinisation in coastal agricultural areas due to rising sea levels
plant impacts
Osmotic stress - can't get enough water
Build of sodium in tissues - Ratio of potassium to sodium really influences uptake of potassium and ability to deal with sodium in tissues [LINK TO NUTRIENTS]
limited vegetation growth, more so as salinity rises
reduced productivity
salinity dictates mangrove distribution - we may lose farming land as sea level rises and encourages mangroves to spread further into salt marshes
need further research into the predicted sea level rise, predicted change in mangrove distribution, and potential impact on current agriculture locations
plant adaptation
e.g. mangroves - genetic traits for salt tolerance
exclude salt at root surface, or take up some to balance osmotic potential
limit photosynthesis > limit water loss (only having stomata on the underside of the leaf)/ uptake (smaller overall size of tree) > water cannot get in or out unless it travels through cell wall, this controls ion uptake (Casparian strip)
salt glands to excrete salt
maintain water flow against huge osmotic pressure
roots that forage for water sources > access tidal water as well as ground water > Split root experiment shows that mangroves preferentially take up freshwater when it's available
can we incorporate these genetic traits into crop cultivars
Water availability
more intense and frequent drought expected in arid locations
changes in precipitation patterns - wetter tropics, drier arid areas
plant adaptations
vegetation level: trees migrating
morphology: smaller leaves and flowers to preserve water consumption
phenology: earlier flowering season, e.g. Study of 90 orchid taxas in Hungary sees flowering 3 to 7 days earlier in response to environment.
succulents store water in flesh
CAM photosynthesis prevents stomatal water loss
Brittle bush sheds all leaves in drought, dormancy means low energy use
Fringed water lily - waxy cuticle prevents water from blocking sunlight/ stomata
reduce investment into seed growth
evolve photosynthesis pathway from C3 to C4 = less water molecules lost per CO2 fixed e.g. Flaveria genus has more C4 species in warmer equatorial areas yet more C3 species toward cooler polar regions
Sorghum study: differences in root angle influence water uptake - narrow angle increases yield - related gene identified
reproduction vectors are impacted by the changes in flower size
The longer lifespan (due to earlier flowering season) may mean that plant experiences more diversity in its lifetime and will adapt to these - or maybe it will be to shocked by the changes and die? hence there's uncertainty about agricultural yield stability, and responses should be studies in crop taxa
aridity may be counteracted by reforestation - forests hold water in the ground, recharge atmospheric moisture via evapotranspiration, low P zone can draw rainfall to the forest from elsewhere, seen as cloud cover in forest satellite imagery
genetically modify rice photosynthesis to C4 pathway so that yield can be maintained as conditions get drier and population rise increases food demand - better water use efficiency increases grain yield in C4 plants
need more knowledge on:
different types of drought: Meteorological/ Hydrological/ Agricultural
drought onsite time and location
duration, severity & intensity of drought
variability in plant response between biomes
to model likelihood, severity, consequences and produce tailored management solutions
rain shadow areas may be more fertile - but having agriculture here rather than forest may negatively effect rain cycle
maximize wheat yield by determining optimal genotype and sowing date to cope with drier and warmer conditoins
plant response
increased stress > death
e.g. fossil evidence of major extinction events during hot, dry periods (Permian and Triassic periods)
increased carb use wealens plant> stomata close > less water > weaker plant defence > insect/ pathogen invasion e.g. bark beetle population booms in dry periods
drought amplifies climate-driven vegetation mortality
knowledge gap: there are insect species that take advantage of drought, can plant species that do so too? can beneficial adaptations be incorporated into agriculture systems
Reduced nutrient availability
reserves are getting depleted?
access to fertilizer will be reduced in developing countries first and then developed countries? B/c finances and exploitation
#
Biogeochemical flows (N and P cycles) are one of the 9 life support systems in the Planetary Boundaries concept. We have crossed the 'safe operating space' threshold and brought about irreversible damage. This is largely related two fertiliser use which is current twice as high as the level in the 'safe zone'
Fire
burns influence grass quality for pastures, impacting amount of cows that can be supported and therefore beef yield
(will I imply that agricultural yield include animals as well as plants?)
will the more frequent fires associated with climate change impact agricultural yield? or should i just focus on fire as a landscape change/ disturbance in itself
Invasive species spreading
urbanisation - reducing the land available for plants - have plants adapted to be more productive in less land?
Increasing temperature and heat waves
e.g. in Sorghum growing areas heat stress events nearly doubled, days of heat stress increasing from 1 to ~4 days
plants are less resistant to drought when under heat stress
#
shift diet to sorghum instead of wheat
optimized growth maximizes seed/ grain yield in Sorghum, but seed/grain yield is reduced at the cost of optimum growth at elevated temps in wheat
plant adaptations
e.g. Sorghum (optimum 30 degrees, high 38 degrees)
accerated phenology: less days to flower and maturity
reduced plant height
decline in seeds : sharp in sensitive lines, moderate in tolerant lines > impacts grain yield
sorghum reproductive phase most sensitive to high temps
mitigate seed loss by avoiding sowing in October
late sowing can mean there's less heat stress during flowering
but farmers [STAKEHOLDERS] may want to plant other crops, or concerned about increased disease risk during cooler conditions
individual plant adaptation may be more significant than community adaptation
individuals are more sensitive and adapt faster than communities
compare this to the rapid climate change seen today, old communities are likely to disappear while the individuals that adapt will establish new communities
what is the relevance of this to an agricultural context