Abstract
This study investigated the influence of different light intensities on the early growth of Jatropha curcas seedlings. Forty (40) seedlings were randomly selected from the germinated seedlings in the nursery and arrayed under four different treatments (0, 20, 40 and 60% light intensity). The amount of light being received by each of the seedlings was regulated, using constructed wooden box covered with wire gauze (1 mm in size) and measured with photometer. The results on seedlings germination under different light intensity revealed that, the highest mean height (29.2±1.94 cm) was observed in seedlings covered with 60% wire gauze, while the least mean height (27.0±1.24 cm) was observed in the seedlings placed under control treatment (0% wire gauze). Also the highest mean seedlings girth (2.69 ± 0.15 mm) was observed in seedlings not restricted with light intensity (0% wire gauze), while, the least mean girth (2.27±0.08 mm) was found in seedlings restricted with 60% light intensity. The average number of leaves in the four treatments ranges between 6 and 7. The result on analysis of variance (ANOVA) conducted shows a significant effects (P<0.05) of light intensity on J. curcas seedlings girth and number of leaves, while, the seedlings height shows no significant difference (P>0.05). Conclusively, the finding has shown that, J. curcas seedlings required light for its survival, but at varying intensity, and it was noticed that the thicker the light regulator (wire gauze), the lower the amount of light being absorbed by the seedlings. Key words: Jatropha seedling, light intensity, wire gauze, influence survival.
Highlights
Seed germination and plant growth are greatly influenced by external conditions such as the intensity and duration of light and temperature
0.605 covered with 60% wire gauze; this was followed by seedlings covered with 40% wire gauze (29.1 ± 2.06 cm), while the lowest mean height (27.0 ± 1.24 cm) was observed in the seedlings without light intensity restriction (0% wire gauze)
It was noticed that the thicker the light regulator, the lower the amount of light being absorbed by the seedlings
Summary
Seed germination and plant growth are greatly influenced by external conditions such as the intensity and duration of light and temperature. Aside from its effect through photosynthesis, light influences the growth of individual organs or of the entire plant in less direct ways. The most striking effect can be seen between a plant grown in normal light and the same kind of plant grown in partial darkness or total darkness. The plant grown in the partial dark or total dark will have a tall and spindling stem. According to Dennis (2009), the leaves of plant deficient in light fails to expand in both length and width, lacking chlorophyll and are always pale yellow colour, as such a plant is said to be etiolated. Light intensity and its duration (length) may have different and characteristic effects upon plant growth and development.
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