In: Biology
Define, with illustrations if necessary, the following terminologies: Cyclophysis, Topophysis, and Periphysis. Explain how potential for rooting and subsequent growth habits of a cutting are influenced by these processes.
Cyclophysis In order to describe the shoot
individuality as dependent on life stage or meristematic age
in one single word SEELIGER (1924) introduced the useful
term "cyclophysis" (Kreisnatur). Hence we speak of cyclophysis in a
woody plant sh~ot refwring to properties conditioneld exclusively
by the development stage of that
sholot."
The change frmn one development stage to another is
now comrnonly called phase change. WAREING (1959) distinguishes
between two types of phase change, which he
terms 'maturatio~n' and 'ageing' respectivelly. Maturation is
the stable juvenile-to-adult plhase change and ageing other
changeis such as lsss of vigour, changes that are easily reversed.
He further says that ". . . maturation is analogous
to 'genetic' changes, whereas ageiing corresponds rather to
'plhenotypic' effects." These two types of phase change are
als10 termed 'ontolgenetical ageing' and 'physiological
ageing' by FORTANIER and JONKERS (1976), whol considelred
ontogenetical ageing to be "genetically programmed, localizeld in
the meriskerns, accellerated by improved growth
conditions and difficult to reverse."
Using WAREING'S term 'maturation' SEELINGER'S term 'cyclolphysis'
can be more explicitly defined as the changes
which take place with age in the apical meristems and
which coatrol the process of maturation, and we may
define cyclophysis as: The process of maturatian of the
apical meristem. (Or, using FORTANIER and JONKERS' terrninology,
cyclophysic is the process of ointogenetical
ageing).
Topophysis occurs when scions (young shoots and twigs), buddings, or root cuttings continue to grow in the same way after grafting as they had while growing on the ortet.
When the scion or propagule grows in the same branchlike way, it is called plagiotropicgrowth. Orthotropic growth is when the scion begins to grow in the same upward manner as the ortet. The duration of plagiotropic growth habit depends on the tree species and developmental stage (whether bud or scion) when cut, before the rametchanges to orthotropic growth and matures.This maturation is dependent on the position of the scion growth in relation to the axillary buds.The rate of maturation is decreased in lateral shoots for every order they are removed from the apical meristem and the total distance grown from the apical meristem.
Stem cutting propagation is one of the vegetative propagation techniques, which is used by nurserymen to propagate some tree species. There are difficult-to root tree species, which need the optimization of many factors that effect rooting success. In this experiment, age of the stock plants, position and length of cuttings were studied. Different age/cyclophysis groups of A. pseudoplatanus (5, 15, 20 and 30 years old stock plants), three cuttings positions/topophysis (bottom, middle and top) and two cutting lengths (long 50-120 cm and short 15-30 cm) were used. The experiment was laid in a complete random design with four replications. The result showed that cuttings from different age of stock plants and from different cutting positions differ in rooting success. Cuttings that were harvested from five years old A. pseudoplatanus were capable of giving of rooting success whereas those collected from 30 years old mother trees resulted in 1.5rooting. Cuttings from 15 and 20 years old trees gave and of rooting success, respectively. Rooting success of five years old plants was significantly higher (p=0.05) than all the others, while rooting success of 15 and 20 years old trees were not significantly different from each other. But, both of them were significantly different from those 30 years old mother trees. With respect to position of cuttings on the stock plants, about of bottom cuttings of five years old plants (A. pseudoplatanus) were capable of producing root, which is significantly different (p=0.05) from top cuttings with 45.of success. Cuttings that were derived from middle part resulted in of rooting which was not significantly different from both bottom and top cuttings. In the case of 15 years old stock plants it was observed that bottom and middle cuttings resulted in andof rooting success, respectively. Both positions were significantly different from top cuttings rooting success. Middle cuttings of 20 years old mother trees showed better rooting success than those of bottom and top cuttings. Bottom cuttings of A. campestre showed the highest result, of rooting success while those of middle and top cuttings were respectively. Long cuttings have better rooting success than short cuttings in both five and fifteen years old stock plants of A. pseudoplatanus. Well-rooted cuttings were planted in field in autumn and spring. The survival percentage and height growth that was conducted in June 2004 showed that autumn planted A. pseudoplatanus ere better in both aspects. However, none of the planted cuttings of A. campestre were survived.