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of alginate are strongly viscous, even at 1% solute concentration (Chap-
man and Chapman 1980). By adding calcium to an aqueous solution of
sodium alginate, the solution changes to a semi solid state by forming
the calcium salt of alginate (calcium alginate).
Generally, low viscosity alginate is used for protoplasts and somatic
embryo encapsulation (Castillo et al. 1998). Moderate and high vis-
cosity alginate is used for non-embryonic encapsulation (Gardi et al.
1999). Most of the non-embryonic studies report on using alginate con-
centrations ranging from 1% to 3%. Gardi et al. (1999) reported using
2.5% sodium alginate while Piccioni et al. (1995) reported using 2%
for encapsulating woody species. Janeiro et al. (1997) and Ballester
et al. (1997) reported using 3% for encapsulating shoot tips ofCamellia
japonicaandCamellia reticulata.
B. Orchid Synthetic Seed
Synthetic seeds of orchids are produced by encapsulation of PLBs in an
alginate matrix (Hew and Young 1997; Saiprasad and Polisetty 2003).
Orchid synthetic seeds can revolutionize the propagation and trans-
portation of orchid germplasm by providing an easy way to deliver
seeds from commercial tissue culture laboratories to orchid growers
(Singh 2006; Mohanraj et al. 2009). There are some reports on usage
of synthetic seeds in orchids such asDendrobium wardianum(Sharma
et al. 1992),DendrobiumSonia,Cattleya,Oncidium(Saiprasad and
Polisetty 2003),Coelogyne breviscapa(Mohanraj et al. 2009),Laelia
ancepsssp.dawsonii(Lee-Espinosa et al. 2009),Cymbidium devoni-
anum(Das et al. 2011),Phalaenopsis bellina(Khoddamzadeh et al.
2011),Vanilla (Divakaran et al. 2006; Sarmah et al. 2010), Vanda
coerulea(Sharma et al. 2010), andDendrobium nobile(Mohanty et al.
2013).
Sharma et al. (1992) observed high frequency of germination of PLBs
fromD. wardianumpreviously maintained in low temperature storage.
InCattleya,Dendrobium,andOncidium, encapsulation consisted of 3%
sodium alginate dissolved in MS medium without CaCl 2 .2H 2 O and sup-
plemented with NAA and BA forDendrobiumand NAA forOncidium
andCattleya(Saiprasad and Polisetty 2003). Encapsulated PLBs had
over 88% germination and all regenerated plants were transplanted into
potting mix (Saiprasad and Polisetty 2003). Shoot buds and protocorms
of severalVanillaspecies,V. andamanica,V. aphylla,V. pilifera,V. plan-
ifolia,andV. wightianawere encapsulated in % sodium alginate. They
were stored for up to 10 months at about 22◦C and showed 80% germi-
nation, but once standardized, the cultures were maintained for more