PHYTOREMEDIATION EFFICIENCY ON IMPROVING WATER ENVIRONMENT AND SHRIMP PRODUCTIVITY IN SHRIMP- RICE FARMING SYSTEM BY USING AQUATIC GRASS Scirpus littoralis AND Paspalum vaginatum

Abstract

Shrimp - rice farming systems are widely developed on seasonally saline soil in the coastal areas, U Minh Thuong region, Kien Giang province. Although it achieves high profits, this farming system still faces difficulties, with low shrimp and rice productivity, many rice fields die after a short cultivation period. The study was conducted to evaluate the improvement of water environment and shrimp productivity by using aquatic plants on saline shrimp culture system Two native aquatic grass species, Nan tuong (Scirpus littoralis) and Co nuoc man (Paspalum vaginatum) were grown in shrimp  - rice farming systems where rice crops cannot survive, farmers cultivate shrimp around the year in U Minh Thuong region. Results showed that growing aquatic grasses such as Nan tuong and Co nuoc man led to beneficial effects in improving the quality of water environment, which supported tiger shrimps to grow better. The value of pH (7.7), salinity (7.2 - 14.6‰), alkalinity (100 - 142 mg/L), dissolved oxygen (4.0 - 5.4 mg/L) and dissolved ammonium (1.33 – 1.63 mg/L) were in the optimal range for shrimp growth. These positive effect resulted in higher shrimp yield by 14 - 21% compared to the control ponds (P < 0.05). Our study can provide a basis for practical recommendation to use phytoremediation technique as Nan tuong and Co nuoc man to improve the water environment in shrimp farming that can help the shrimp-rice farming system being more effective and sustainable.