Flowering and reproductive biology of two endemic bamboo species of the Western Ghats - Dendrocalamus stocksii and Pseudoxytenanthera ritcheyi

摘要

Dendrocalamus stocksii, a common cultivated bamboo species in Konkan area was observed in flowering in Kerala during September 2003 - January 2006. Similarly, Pseudoxytenanthera ritcheyi, endemic to the Western Ghats, also flowered in 2006. The offsets of both the species collected previously and planted in Kerala Forest Research Institute campus flowered synchronously. The previous record of flowering of D. stocksii dates back to more than a hundred years, while that of P. ritcheyi was in 1987`88. Observations were recorded on flowering behaviour, reproductive biology and seed set in both the species. P. ritcheyi showed 98 per cent viability of pollen both in acetocarmine staining and in vitro germination tests. Pollen germinated within 15. to 20 min. in the medium containing sucrose, calcium nitrate and boric acid with tube length six times greater than the diameter of the pollen grain. Although pollen grains of D. stocksii showed 90 per cent viability in the acetocarmine staining method, in vivogermination was absent and in vitro germination was very poor (maximum 11%). There was no seed formation in D. stocksii and many flowered clumps reverted to vegetative phase. Profuse seed formation was observed in P. ritcheyi and flowered clumps died after seed set. Lack of in vivo pollen germination could probably explain absence of seed set in D. stocksii. Reversion to vegetative phase is a promising trait that can be used for selection of mother clumps for large-scale planting.