Limits to adaptive plasticity: temperature and photoperiod influence shade-avoidance responses

Area of Science:

• Plant biology
• Ecology
• Physiology

Background:

• The ratio of red to far-red light (R:FR) signals plant proximity and influences stem elongation.
• Increased stem elongation enhances light capture and fitness in crowded environments.
• Environmental factors can modulate plant responses to R:FR signals.

Purpose of the Study:

• To investigate how temperature, photoperiod, and maternal environment affect stem-elongation responses to R:FR.
• To determine if population origin influences these responses.
• To assess the variability of R:FR responsiveness in Abutilon theophrasti.

Main Methods:

• Factorial common-garden experiments were conducted using four populations of Abutilon theophrasti.
• Experiments manipulated temperature, photoperiod, and R:FR ratios.
• Maternal effects were evaluated by comparing seedling growth from greenhouse- and field-derived seeds.

Main Results:

• Maternal environment did not significantly alter seedling elongation.
• Higher temperatures doubled average elongation and increased R:FR responsiveness.
• Significant interactions showed population-specific responses to R:FR varied with temperature and photoperiod.

Conclusions:

• Stem elongation responses to R:FR are more variable than previously understood.
• Environmental conditions like temperature and photoperiod critically influence R:FR responsiveness.
• Competitive interactions in natural settings are likely contingent on ambient temperature, photoperiod, and population genetics.