SALINITY AND PARENT-OF-ORIGINS AFFECT LEAF NEOGENESIS OF Avicennia officinalis L. IN THE SUNDARBANS, BANGLADESH

Photosynthetic efficiency as well as growth of mangroves are closely associated with its new leaf production and leaf area. Avicennia officinalis L. is one of the exclusive and ecologically significant mangrove pioneer tree species in the Bangladesh portion of the Sundarbans. The effect of salinity and parent-of-origins on the new leaf production and leaf area of the mangrove A. officinalis in the less salinity zone (LSZ), moderate salinity zone (MSZ) and high salinity zone (HSZ) of the Sundarbans were studied under experimental conditions in a randomized block design. The results of the experiment highlighted that the number of new leaf production and leaf area of A. officinalis from the less, moderate and high salinity zones were reduced significantly (p<0.05) with the increase in salinities. Yet, new leaf numbers as well as leaf area of this species did not differ significantly (p<0.05) between and among the three salinity zones from 0 to 20 ppt salinities. However, from 25 ppt and above salinities, the new leaf numbers and leaf area of the moderate and high salinity zones were significantly higher (p<0.05) compared to less salinity zone. Hence, saline environments and parental origins affected leaf neogenesis, and thereby influence the growth of this species. Therefore, the seedlings of A. officinalis of moderate and strong salinity zones origin can sustain in the increasing saline environments, and thereby contribute to the sustainable vegetation cover of the Sundarbans. Further, A. officinalis seedlings generating from the MSZ and HSZ can be used for mangrove plantation establishment in the high salinity areas of Bangladesh.