Shade avoidance

Shade avoidance is a set of responses that plants display when they are subjected to the <a href="/facts/Shade_(shadow)/nuJRxKGj">shade</a> of another plant. It often includes <a href="/facts/Etiolation/DWcDMcqa">elongation</a>, altered <a href="/facts/Flowering/7gI5Kefw">flowering</a> time, increased <a href="/facts/Apical_dominance/AjkLlThH">apical dominance</a> and altered partitioning of resources. This set of responses is collectively called the shade-avoidance syndrome (SAS).
Shade responses display varying strength along a continuum. Most plants are neither extreme shade avoiders or <a href="/facts/Shade_tolerance/JKkK4J9e">tolerators</a>, but possess a combination of the two strategies; this helps adapt them to their environment. However, the ability to perceive and respond to shade plays a very important role in all plants: they are <a href="/facts/Sessility_(botany)/ySFsrG7S">sessile</a> by nature and access to <a href="/facts/Photosynthetically_active_radiation/VYtlXA7p">photosynthetically active radiation</a> is essential for plant nutrition and growth. In addition, the time at which a plant starts to flower is affected by the amount of light that is available.
Over the past few decades, major increases in grain yield have come largely through increasing planting densities. As planting densities increase so does the proportion of far red light in the canopy. Thus, it is likely that plant breeders have selected for lines with reduced SAS in their efforts to produce high yields at high density.

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Shade avoidance