Development of Wild and Cultivated Plants under Global Warming Conditions

Global Warming Impact on Plant Development

• Global warming affects plant growth and development throughout the life cycle.
• Influences morphological adjustments (thermomorphogenesis) and photosynthesis especially during the vegetative phase.
• Affects flowering, reproductive development, and fruit development, particularly during heat waves.
• Combined with other stressors (drought, pathogens), global warming poses significant challenges to both wild and cultivated plants.

Effects on Wild Plants

• Global warming decreases the fitness of wild plant species in their natural habitats.
• Adaptation through migration (via seeds, spores, vegetative tissue) or natural selection is slow and often insufficient.
• A significant portion of global flora may face extinction.

Effects on Cultivated Plants

• Past temperature increases have already reduced global yields of staple crops (e.g., wheat, maize, rice) by ~5% per degree centigrade.
• Crops are better able to adapt quickly to climate changes through plant breeding and selection.

Plant Development Stages

Seed Development and Germination

• Seeds' ability to germinate is temperature-sensitive and influenced by the temperature experienced during development.
• In some species, temperature differences of less than 1°C determine dormancy vs. germination.
• High temperatures can inhibit germination by inducing abscisic acid production.

Vegetative Development

• Global warming extends the growing season but can decrease the duration of vegetative development.
• Temperature influences the timing and progression of development phases (e.g., leaf initiation in Arabidopsis).
• Thermomorphogenesis: morphological changes in plant structure due to temperature changes.

Photosynthesis

• Photosynthesis can occur in a wide range of temperatures but has specific optimal ranges.
• Elevated temperatures affect photosynthesis through changes in chloroplast membrane structure and enzyme activity.
• Rising temperatures can result in increased photorespiration and respiration, reducing net photosynthesis.

Transition to Flowering

• Elevated temperatures often accelerate flowering (e.g., in Arabidopsis).
• Temperature influences floral pathway integrators like FT, affecting flowering time.
• Global warming leads to earlier flowering and phenological shifts in many ecosystems.

Reproductive Growth

• Heat waves during reproductive stages can harm meiosis, fertilization, and seed development.
• Elevated temperatures can increase recombination rates, but extreme heat may disrupt gamete viability.
• Pollen development is highly sensitive to temperature, affecting fertility.

Effects on Crop Production

Germination

• For winter wheat, global warming is unlikely to affect germination much due to lower fall heat wave risk.
• For soybeans, higher temperatures allow earlier sowing and extended growing seasons, especially in temperate climates.

Vegetative Development & Photosynthesis

• Wheat: Elevated temperatures can lead to longer but narrower leaves, reducing photosynthesis and biomass.
• Soybeans: Elevated temperatures may increase biomass but not always correlate with yield increase.
• Improving photosynthetic efficiency is crucial for crop yield under global warming.

Phenological Sensitivity

• Wheat: Elevated temperatures result in earlier phenological events (e.g., green-up, anthesis).
• Soybeans: Slightly extended developmental time with elevated reproductive growth period.

Reproductive Growth

• Wheat: Heat stress affects grain set and quality, leading to yield loss.
• Soybeans: Yield affected by lower seed numbers due to reduced pod count.

Concluding Remarks

• Global warming requires systemic understanding of temperature effects on plants.
• Need for plant breeding to adapt crops to climate change, including developing temperature-resilient varieties.
• Interaction with other climate change effects (CO2 levels, water availability, pathogens) complicates the impact on plants.
• Political action and plant breeding are essential to mitigate effects on wild and cultivated plants.