KARTHIKEYAN, A.V.P.* AND K.V. KRISHNAMURTHY. Department of Plant Science, Bharathidasan University, Tiruchirappalli 620 024, TamilNadu, India. - Leader branch angles, tension wood differentiation and crown geometry in Eucalyptus tereticornis.
Tension wood, one of the two types of reaction woods, is commonly
differentiated on the upper side of leaning main stem regions and
laterally disposed branches of dicotyledonous trees. It is considered
by many to be the response to gravitational stress. There are also
reports of its involvement in the efforts of the plant to correct the
leaning portions of the main trunk. The present study is aimed at
finding out whether the differentiation of reaction wood is related to
the maintenance of the branch angle irrespective of the age and
increased mass of the leader branches in Eucalyptus
tereticornis. This species shows an almost constant branch angle
in the range of 50 degree to 60 degree in all its leader branches,
irrespective of their age. The quantum of differentiation of reaction
wood as well as the linear dimensions of its constituent gelatinous
fibre were estimated in different regions of all lateral branches from
base to tip. The results are discussed in order to highlight the role
of reaction wood in maintaining the canopy geometry of this taxon.
Key words: branch angle, crown geometry, Eucalyptus tereticornis, gelatinous fiber, tension wood