Liquid Culture Systems for in vitro Plant Propagation

330 F. Afreen et al.
under photoautotrophic treatment could be that at the later stages, embryos
are capable of photosynthesizing more than those at the early stages. These
results confirm the above findings and are in agreement with our previous
observation where the cotyledonary and converted embryos showed stomatal
development and scavenging of CO2.
5. Optimization of the photoautotrophic production of
cotyledonary stage coffee somatic embryos
5.1 Supporting medium and environmental conditions
For optimizing the photoautotrophic culture of cotyledonary stage
somatic embryos, three different types of supporting media were
investigated: a) agar (8 g l -1 ) b) vermiculite and c) Florialite (a mixture of
vermiculite and cellulose fibre; as described by Afreen et al. (2000). Results
revealed that the use of Florialite and/or vermiculite can improve root and
shoot growth during the development of plantlet from cotyledonary stage
coffee somatic embryos under photoautotrophic conditions.
For optimization of the environmental condition the following treatments
were investigated (Afreen et al., 2002a):
a) PPF was 50 µmol m -2 s -1 and ambient CO2 concentration was 400 µmol mol -1
b) PPF was 100 µmol m -2 s -1 and CO2 concentration was 400 µmol mol -1
c) PPF was 150 µmol m -2 s -1 and CO2 concentration was 400 µmol mol -1
d) PPF was 50 µmol m -2 s -1 and CO2 concentration was 1100 µmol mol -1
e) PPF was 100 µmol m -2 s -1 and CO2 concentration was 1100 µmol mol -1
f) PPF was 150 µmol m -2 s -1 and CO2 concentration was 1100 µmol mol -1 .
The results suggested that to develop plantlets from the cotyledonary stage
somatic embryos under photoautotrophic conditions, high PPF (100-150
µmol m -2 s -1 ) and increased CO2 concentration (1100 µmol mol -1 ) were
necessary (Afreen et al., 2002a).
5.2 Different growing systems
As noted above, in the multi-stage somatic embryogenesis of coffee, the
cotyledonary stage is the earliest stage embryo, capable of
photosynthesizing. However, the extent of heterotrophy, photomixotrophy or
photoautotrophy is dependent not only on photosynthetic ability but also on
medium composition, volume of culture vessels, their cross-sectional areas,