The Green Revolution: dramatic increases in crop production, especially in developing
countries
- Norman Borlaug came up with several lodging-resistant, high-yielding semi-dwarf
grain varieties
- Semi-dwarf: more energy went into grain, instead of growth
- Turned grain importer countries into grain exporter countries
- The flip side of it:
- Intensive pesticide use
- Intensive fertilizer use
- Intensive water use
- Reduced soil fertility
- Loss of genetic diversity
Rice paddies produce a lot of methane, because of the anaerobic metabolism in the
flooded environment.
A growing population is not the only reason for increased food demand. There is also an
increased demand for meat, as a result of increased welfare in developing countries where
more people are now in a position to afford meat.
The amount of available arable land is decreasing.
- Arable: fit for cultivation
A ‘second’ green revolution that integrated sustainable intensification of agriculture, that can
generate stress-tolerant crops that do more with less.
Improving crop stress tolerance
1. Fungi on the move: a challenge to global food security and ecosystem health
Fungi and oomycetes make up a major threat to global food security.
Farming systems:
1. Intensive rain-fed crop production systems
a. Sufficient rainfall during growing season and/or deep soils to provide sufficient
water
b. High input: pesticides and fertilizer
c. Mechanised – often vast areas
d. Thought to be less sensitive to climate change, but more vulnerable to
disease
2. Intensive rice-wheat systems (Tropical Asia)
a. Cool, dry winters and warm, wet summers
b. Sufficient rainfall during growing season and / or deep soils to provide
sufficient water
c. Need access to irrigation
, d. Some use of pesticides and fertilizers, but slow down in production despite
high yielding varieties • Deteriorating soil quality
e. Adverse weather effects such as droughts & deluges, rising sea levels
3. Low input cropping / farming systems (developing countries)
a. Low input: little use of bought pesticides and fertilizers
i. Use of “on-farm” inputs – manure, cover crops and management
b. Low rainfall
c. Coarse soil and erosion-prone and of low fertility
4. Organic farming
a. One formal, certified and clearly delineated
i. Crop rotation
ii. Green manures and compost
iii. Biological control
iv. No pesticides, fertilizers or GMOs
b. One informal “agro-ecological” system
i. Less patrolled, lack of input due to poverty
CPP: Crop Pests and Pathogens
Approaches to model CPPs:
- Statistical
- Correlative, on a large scale, static and with minimal assumptions
- Mechanistic
- Process-based, on a small scale, dynamic, “forward modeling” using
extrapolation
What determines the global distribution of crop pests and pathogens?
The number of pathogens should reflect the volume and diversity of agriculture of a given
country. More pests at the equator could be due to the latitudinal gradient in spp richness as
with wild species. Fewer pests on islands could be explained by the “Island Biogeography”
theory, which suggests lower immigration rates and higher extinction rates on islands
2. Plants and abiotic stress
Most important aspects that you learned during this lecture:
It is important to make crops more stress-resistant, since the food demand will continue
increasing, just like the climate variability.
Paths to close the gap between actual yield and potential yield:
1. Use more land
2. Grow more
3. Improve stress resilience
4. Reduce fertilizer use
Yield stability: maintained production of biomass despite climate variation
Drought and heat resilience without yield loss is hard to achieve
- DRO1: deeper rooting in rice for drought tolerance
, - PUP1: low Pi soil tolerance in rice
- SUB1A: submergence tolerance (limits growth, economizing reserves)
- Ethylene triggers elongation of submerged roots
- SNORKEL1/2 and SEMIDWARF1 enhance elongation
Membrane transporters reduce cytosolic Na2+ for salt tolerance in wheat and other grasses.
MATEs: aluminum tolerance through metal activated malate transporters.
Opabactin (OP): an effective ABA mimic for crops → drought resistance
- A plant's response to ABA is stomatal closure
How could the presented knowledge be used to boost food production sustainably?
Improving stress resilience, for example through genome-editing, and reducing fertilizer use
are sustainable methods to boost food production.
Crop yield stability can be increased through:
1. Breeding assisted by phenotyping and genomics
a. Identify existing stress tolerance within a crop species
i. Obtain seed collection with genetic diversity
ii. Screen collection for yield under stress condition (phenotype)
iii. Map traits to a chromosomal region (QTL), or
iv. Map nucleotide difference and associate specific differences with trait
(GWAS)
v. Move chromosomal region into farmer-preferred cultivars by marker-
assisted breeding
vi. Confirm effectiveness of trait in farmers’ fields
vii. Validate safety and seek adoption
2. Engineering (remodeling) and other disruptive technologies
a. Transgenesis: add new genes
i. GM: biolistics or T-DNA
b. Editing: targeted modification of genes and their regulatory regions
i. CRISPR-Cas9
c. Synthetic biology: re-engineer response pathways / photosynthesis /
beneficial plant-microbe interactions
d. Innovative management: protective compounds / beneficial microbes
How could the knowledge gained be communicated to the general public?
Through incorporating knowledge applicable to people in certain regions in local education
and offering courses to anyone interested.
Could solutions for one stress be beneficial under another stress?
Solutions for one stress might be beneficial under another stress if they make use of similar
pathways and/or often occur at the same time.
Could solutions work in multiple species?
Solutions might work in multiple species if they use similar pathways with similar metabolites
and messengers.
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