Two groups of researchers confirmed that plant siblings grown close to each other in the soil tend not to compete with each other compared to when they are grown with non-siblings. The phenomenon was observed first by Susan Dudley of McMaster University in Hamilton, Canada in 2007 and was confirmed recently by Harsh Bais of the University of Delaware. "Plants have no visible sensory markers, and they can't run away from where they are planted," Bais says. "It then becomes a search for more complex patterns of recognition."
Using wild populations of Arabidopsis thaliana, Bais, together with student Meredith Bierdrzycki, confirmed that the length of the longest lateral root and of hypocotyls of siblings planted close to each other are shallower, indicating non-competition. But, when they are grown with non-siblings, they rapidly grow more roots to take up water and mineral nutrients in the soil, and compete with each other. In addition, leaves of these plant siblings often will touch and intertwine compared to strangers that grow rigidly upright and avoid touching.
When added with sodium orthovanadate, a root secretion inhibitor to the set-up, stranger recognition is abolished. Identification and control of the root recognition signal will find application in field and landscape crops.
See the news at http://www.udel.edu/udaily/2010/oct/plantsiblings101409.html . The full article will be available at: http://www.landesbioscience.com/journals/cib/article/10118/