Allelopathic Effects of Pistia stratiotes (Araceae) and Lyngbya wollei Farlow ex Gomont (Oscillariaceae) on Seed Germination and Root Growth

Pistia stratiotes and Lyngbya wollei are the two most common aquatic weeds that flourish in farm canals within the Everglades Agricultural Area of Florida. Identifying a useful application of these weeds would not only address important environmental concerns, but would also be an incentive for farmers to harvest it. The objective of this study was to determine use of P. stratiotes and L. wollei as soil amendments for stimulation of seed germination and root growth in different plant species. The effects of different rates of dried and grounded P. stratiotes and L. wollei on germination and root length of snap bean, corn, sorghum, common lambsquarters, and rice were evaluated using a controlled petri-dish incubation bioassay study. Overall, both amendments had a negative allelopathic effect on germination of all species. The highest reduction in germination of 80 and 43% by P. stratiotes and L. wollei respectively was observed on corn. Rice was the most tolerant to allelopathic effects that emanated from both amendments. There was a significant positive increase in rice root length in response to P. stratiotes rate over the two-week period. This study shows that P. stratiotes can be used as a potential bio-fertilizer to stimulate early growth of rice.