References

424 V.Ninkovic,R.Glinwood,J.Pettersson
Fig.28.2. Twin-chamber cages for the exposure of barley plants to volatile chemicals from
neighbouring plants. The chambers permit only interaction via plant volatiles, while eliminating
root contact and competition for water and nutrients
and space. To prevent communication between roots, the pots are placed in
Petri dishes (Fig. 28.2), or are grown in separate plastic bags placed under
the bench (Ninkovic 2003). Air is drawn into the first chamber, where it collects
volatiles from the inducing plant, it then passes through a hole in the
wall to the second chamber containing the responding plant and is drawn
out from the top of the second cage to a fan-equipped vacuum tank before
being vented out of the room. A computer-controlled watering system
simultaneously delivers precise amounts to the plants in all the cages.
28.2
Allelobiosis in Barley
28.2.1
Barley Plant Responses to Plant Volatiles
Studies on plant–plant communication in barley have mostly focussed on
barley, Hordeum vulgare, as a responder to, rather than an emitter of,
volatile cues. For instance, the growth of barley seedlings and the respiration
rate of germinating seeds were inhibited when they were exposed to
volatiles released from leaves of A. tridentata var. vaseyana (Weaver and
Klovich 1977) and sasa, Sasa cernua (Li et al. 1992). These, and further,
negative effects on barley plants, e.g. lowered content of water and chlorophyll,
were observed in experiments with crude volatile oils and the pure
terpenes from leaves of Eucalyptus globulus and E. citriodara (Kohli and
Singh 1991).