Effect of different factors on non-symbiotic seed germination, formation of protocorm-like bodies and plantlet morphology of <i style="">Cleisostoma racemiferum</i> (Lindl.) Garay

Abstract

<i style="">Cleisostoma racemiferum</i>, an epiphytic orchid of primary forest under threat in their natural habitat, was studied. Immature seeds of different developmental stages [(8-20 week after pollination (WAP)] were cultured on Knudson ‘C’, Mitra <i style="">et al</i>and MS media supplemented with sucrose (0-3%, w/v), coconut water (CW, 0-20%, v/v) and NAA (0-30 <img src='/image/spc_char/micro.gif' border=0><i style="">M</i>) + BA (0-8 <img src='/image/spc_char/micro.gif' border=0><i style="">M</i>) singly or in combination. After 7 week of culture, first sign of germination was recorded as nodular swelling of seeds. Amongst the three different basal media tested, better germination was supported by MS medium, followed by Mitra <i style="">et al</i> and Knudson ‘C’ media containing sucrose (3%) and NAA (10.0 <img src='/image/spc_char/micro.gif' border=0><i style="">M</i> ) + BA (8.0 <img src='/image/spc_char/micro.gif' border=0><i style="">M</i>). Of various developmental stages of the seed, better germination was obtained from green pods of 16 week after pollination. Younger seeds did not show any sign of germination, while mature seeds exhibited delayed and deformed germination. Though incorporation of CW in the medium did not show much influence on seed germination, but 15% (v/v) CW in the initiation medium enhanced the early differentiation of protocorm-like bodies (PLBs) into plantlets. Within 14-16 week of culture on germination medium, the PLBs started releasing the first set of leaflets. The advanced stage PLBs were converted into rooted plantlets on MS medium containing IAA (10.0 <img src='/image/spc_char/micro.gif' border=0><i style="">M</i>) + Kn (9.0 <img src='/image/spc_char/micro.gif' border=0><i style="">M</i>). Although the medium containing NAA (10.0 <img src='/image/spc_char/micro.gif' border=0><i style="">M</i>) + BA (8.0 <img src='/image/spc_char/micro.gif' border=0><i style="">M</i>) resulted in multiple shoot buds, but the leaves were thin and etiolated. Further, the medium enriched with NAA (10.0 <img src='/image/spc_char/micro.gif' border=0><i style="">M</i>) + Kn (9.0 <i style=""><img src='/image/spc_char/micro.gif' border=0>M</i>) resulted in stunted growth of plantlets, while presence of IAA (10.0 <img src='/image/spc_char/micro.gif' border=0><i style="">M</i>) + BA (8.0 <img src='/image/spc_char/micro.gif' border=0><i style="">M</i>) resulted in plantlets with poor roots.