New York, Dec 25 (IANS): You might not notice it, but plants actually wage war with each other to outgrow and absorb sunlight! Their weapons? Special sensors that can detect depletion of red and blue light - wavelengths absorbed by vegetation.

If a plant is shaded by another, it becomes cut off from essential sunlight it needs to survive. To escape this deadly shade, plants have light sensors that can set off an internal alarm when threatened by the shade of other plants.

Their sensors can distinguish between an aggressive nearby plant from a passing cloud.

Scientists at the Salk Institute in the US have discovered a way by which plants assess the quality of shade to outgrow menacing neighbours -- a finding that could be used to improve the productivity of crops.

The new work shows how the depletion of blue light detected by molecular sensors in plants triggers accelerated growth to overcome a competing plant.

"With this knowledge and discoveries like it, maybe you could eventually teach a plant to ignore the fact that it's in the shade and put out a lot of biomass anyway," said study's senior author Joanne Chory.

It was known that plants respond to diminished red light by activating a growth hormone called auxin to outpace its neighbours.

However, this is the first time researchers have shown that shade avoidance can happen through an entirely different mechanism - instead of changing the levels of auxin, a cellular sensor called cryptochrome responds to diminished blue light by turning on genes that promote cell growth.

This revelation could help researchers learn how to modify plant genes to optimise growth to grow more aggressively and give a greater yield even in a crowded, shady field.

The findings appeared in the journal Cell.