The genus Cinnamomum

70 P.N. Ravindran et al.
correlation between flush colour and quality – the purple coloured plants having more
bark oil (about 29% more).
Correlation and path analysis studies conducted by Joy et al. (1998) indicated that
the economic yield characteristics (fresh leaf yield, leaf oil yield and eugenol yield)
were highly correlated among themselves, the values ranging from 0.92 to 0.99.
The component characteristics, plant height and canopy spread, were highly and
positively correlated between themselves as well as to the three economic characteristics
mentioned above. On this basis of high correlation, plant height, canopy
spread, fresh leaf yield, leaf oil yield and eugenol yield were used for working out
multiple regression and path coefficients. High coefficients of determination existed
for all equations, and values ranged from 0.72 to 0.99. However, the R 2 value for leaf
oil yield on plant height, canopy spread and fresh leaf yield did not show improvement
over the correlation between leaf oil yield and fresh leaf yield ( 0.93).
Similar was the case with the multiple regression equation of eugenol yield on plant
height and leaf oil yield ( 0.99). The above workers suggested that variability in
eugenol yield was determined more by the indirect effects rather than by the direct
effect of plant height, canopy spread or fresh leaf yield. Similarly, the variability in
leaf oil yield was determined more by the indirect effects than by the direct effect of
plant height or canopy spread. The path diagram suggested by the above workers
(Joy et al., 1998) is given below. The characteristic, that is ultimately important is
the eugenol yield. There is a unidirectional relationship among fresh leaf yield → leaf
oil yield → eugenol yield as indicated by the high path coefficients. Canopy spread
is directly linked to plant height, but is poorly associated with fresh leaf yield.
Canopy
yield
0.74
γ = 0.69 Fresh
leaf yield
Plant
height
0.14
0.93
Oil
yield
R 2 2 = 0.72 R = 0.86
0.99
Eugenol
yield
2 R = 0.99
Therefore, selection for improvement in oil or eugenol yield, which requires
cumbersome procedures, can be done indirectly using leaf yield, which in turn is
related closely to canopy spread.
Krishnamoorthy et al. (1988) observed significant variability for bark oil content in
cinnamon germplasm. Krishnamoorthy et al. (1991) also reported significant variation
in progeny performance of nine lines for plant height, number of branches per tree,
fresh and dry weight of bark and percentage recovery of bark. Krishnamoorthy et al.
(1992) also studied the variability and association studies in 71 cinnamon germplasm
accessions maintained in the germplasm conservatory of IISR, Calicut (Table 2.14).
Among the characteristics, the highest variation was for dry weight of bark followed by
fresh weight of bark, bark oleoresin and leaf oil. Moderate variability was noted for
bark oil and leaf size index. High association existed between fresh weight of bark and
leaf oil with dry weight of bark. Ponnuswamy et al. (1982) also conducted some
studies on variability among seedling progenies of cinnamon. In field plantations of