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ABSTRACT 
Factors affecting growth and the yield of oil 
in Spanish thyme (Lippia micromera Schau.) 
Lystra-Ann U. E. Johnson 
The plants' response to levels of N (0, 20, 40 and 60kg 
N/ha) and P (10 and 20kg PCU/ha) at different spacings (50, 
100 or 150cra intra-row x 160cm inter-row), was monitored 
during the dry and wet seasons. 
The development of individual shoots was observed 
during both seasons, and distribution of oil along a single 
shoot was measured in the wet season. 
In a greenhouse experiment, the effect of varying 
levels of water stress on plant growth and oil content was 
observed. 
Finally, the development of leaves was observed over 8 
weeks. 
Application of N significantly increased fresh herbage 
yield/plant (wet season), while there was no significant 
effect in the dry season. Application of 40kg N/ha 
significantly increased herbage yield/ha in the wet season. 
Phosphate application did not affect herbage yield/plant nor 
per hectare. At 100cm intra-row spacing herbage yield/plant 
was significantly increased in both seasons. However, 
herbage yield/ha increased significantly as spacing 
decreased. Herbage yield was significantly higher in the wet 
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than in the dry season. Neither N, P nor spacing affected 
oil yield per plant, but oil yield/ha increased 
significantly with increased plant density. Oil content (% 
v/w) was lower in the wet season, while oil yield/ha was 
higher in the wet season. 
There was a decrease in fresh and dry weights with 
increased water stress, while oil yield (ml/plant) and 
content (% v/w) increased with increasing stress. 
The young shoot tips yielded the most oil, while the 
base of the shoot yielded the lowest. 
Three hair types (short, long and sessile) were 
observed. Their involvement in oil production was suggested. 
Densities of sessile and long hairs were higher on the 
abaxial leaf surface than on the adaxial surface with the 
opposite being true for short hairs.