Abstract:
Replicate propagules (n=20) of three mangrove species were planted in
black and transparent polythene bags filled with lagoon soil and were
placed in open nursery beds supplying lagoon water once a day. The size of
the bags, source and the volume of the soil in the bags, the source and the
volume of water given for each bag were same for all the replicates while
for each species, same sized propagules were selected. After 8 weeks, the
stem weight, the stem height, the total height, the root weight, the total
leaves weight, the total weight, the total root count, and the total root length
were not significantly different between black and transparent polythene
bags for Ceriops tagal and Rhizophora apiculata (n=20 p>0.05: Two
sample t-test). However, Rhizophora. mucronata grown in transparent bags
showed significantly lower values (n=20, p<0.05: Two sample t-test) for
stem weight and stem height, (7.69±1.10g, 15.57±2.97cm, respectively)
than those in the black bags (8.50±1.24g, 17.75±3.45cm, respectively).
However, for the same species, significantly higher (n=20, p<0.05: Two
sample t-test) root weight, (2.23±0.69g) was recorded in transparent bags
than in black bags (1.82±0.39g). Among the used 3 species R. mucronata
had the highest root biomass. Since the temperature in bag could affect the
root growth of some species, the reduced root production of R. mucronata
in black bags could be due to the negative effects of solar heat aggregated in
the black bags. Thus, commercially available transparent bags seem more
appropriate for the root growth of R. mucronata.
