REGENERATION ABILITY OF FRAGMENTS OF Ludwigia sedioides (Humb. Bonpl.) H.Hara: A POTENTIAL INVASIVE PLANT IN SRI LANKA

Ludwigia sedioides (Humb. Bonpl.) H.Hara is an ornamental aquatic plant recognized as a potential invasive in Sri Lanka. Recently concluded studies revealed that it is naturalized in the wet zone of Sri Lanka. Though this plant has not yet been recognized as an invasive plant elsewhere in the world, the current rate of spread suggests that it might become an invasive plant in the near future in Sri Lanka. Hence, present study was conducted to gain an insight into the ability of L. sedioides to regenerate via fragmentation. Shoots of six different lengths viz. 1, 2, 4, 6, 8 and 10 cm belonging to the two maturity stages (top and stem cutting) were grown in containers arranged in completely randomized design. Survival percentage and plant growth parameters were recorded in each treatment. All the fragments survived and significantly high survival percentages were recorded in all the fragments of top cuttings (70-86%) and fragments of stem cuttings greater than 6 cm. Mean length increments and root dry weights were significantly higher (P 0.05) in top cuttings. Further, mean root numbers were also significantly high in fragments of top cuttings higher than 2 cm. Hence the top cuttings performed better than stem cuttings. However, it is important to note that even a fragment of 1 cm is capable of surviving irrespective of maturity stage. Thus, it is vital to remove all the stem fragments during any attempts in mechanical control. In conclusion, as non-specialized fragments of L. sedioides can be formed throughout the year, it is suggested to exploit other control methods to prevent further spread.