Protocols for Micropropagation of Woody Trees and Fruits

LIGHT-EMITTING DIODES AND IN VITRO BANANA CULTURE 531
Use the spectral energy distribution of red and blue LEDs described by Tanaka et al.
(1998). The red LED (Figure 1) has a peak emission at 660 nm with a spectral
bandwidth of 25 nm and the blue LED has a peak emission at 450 nm. The emission
spectrums of red and blue LEDs coincide with the maximum absorptions of chlorophylls
a and b.
2.5. Data Collection
The numbers of leaves, plant height, shoot fresh weight, number of roots, and root
length and root fresh weight of plantlets are recorded after 1 to 3 months of culture
depending on the plant material.
Chlorophyll measurement. Chlorophyll content in the third leaf from the top
downwards of the sampled plantlets was measured as SPAD value by a chlorophyll
meter (SPAD-502, Minolta Co., Ltd., Japan). Fresh weight of shoots (stems and
leaves) and roots of the plantlets were determined separately.
Determination of dry weight. Shoot and root are dried in an oven at 105°C for 30
min and then kept at 60°C for 48 h to constant weight.
Measurement of photosynthetic rate. the Portable Photosynthetic System (LI-COR
Inc., USA) can be used for measuring the photosynthetic rate in plantlets after 3
months of culture.
2.6. In Vitro Growth of Banana Plantlets Cultured in Various Culture Systems
on Sugar-containing and Sugar-free Media without CO2 Enrichment
Excise shoots from banana shoot masses derived from shoot-tip culture on sugarcontaining
MS agar medium containing 5 mg·l –1 6-benzylaminopurine (BA) with or
without 3 mg·l –1 sucrose.
Shoots can be cultured on different substrates, RW, Oasis (Smithers-Oasis,
USA), 8 g·l –1 agar, 8 g·l –1 Difco Bacto agar (Difco Laboratories, USA), and 2.4 g·l –1
Gellan gum (Gelrite ® , Merch & Co., Inc., USA) using 70 ml MS medium supplemented
with 0.02 mg·l –1 IBA in two different culture systems, BO (Bottle) and CP.
Grow plantlets in two culture systems under PGF for 30 days. Figures 4, 5, and 6
show in vitro growths of banana plantlets cultured in various culture systems on
sugar-containing medium without CO2 enrichment after 30 days of culture.
Using the CP system for Musa paradisica cv. ‘Nam Dinh’ (Figure 5), Nhut (2002)
demonstrated that the plant height and the number of leaves of plantlets cultured in
CP·RW, CP with Oasis (CP·Oasis) and CP with Gellan gum (CP·Gel) were greater
than plantlets cultured in CP containing Agar (CP·AG) or CP supplemented with
Difco Bacto agar (CP·D·AG) (Figure 4).