Aqueous Improvement For Juvenile E.sinensis Culture By Alternanthera Philoxeroides And Bottom Aeration In Paddy Field Pond

To assay roles of aquatic plants and bottom aeration systems in paddy field ponds,water quality factors were measured during the culture season of juvenile E. sinensis.The results indicated Alternanthera philoxeroides is helpful in stabilizing aqueous watertemperature, dissolved oxygen and pH in paddy filed pond; increasing in floral proteinand starch strengthens; enhancing ATPase activity. Meanwhile, bottom aerationimproves the cultural water quality.1. Changes in water quality factor and floral nutrientsThe water temperature was less than24℃during June, then speed up to morethan27℃lasting during July and August, final slowly down to20℃from July27toOctober. The water dissolved oxygen was mainly depended on temperature and climate.Soluable protein and starch contents in July were lower than those in June. Theminimum of soluble protein was16.49mg/g on August31; and the maximum value was36.11mg/g on June27.2. The diurnal variation of aquesous factorsIn paddy field ponds, the rising temperature time was shortened while the droppingtemperature time was extended in comparision with summer and autaum. Differece inwater temperature between day and night in summer also got smaller compared to thatin autaum. Compared to the data in autumn, dissolved oxygen in summer was higher;pH range became smaller; the minimal water temperature was at5:00and the maximumwas at17:00. The trends of dissolved oxygen and water temperature were similar. Butminimal value of dissolved oxygen was at7:00. The trends of pH and temperature weresimilar. 3. The diurnal variation of floral nutrientsIn summer, the diurnal trends of chlorophyll a, chlorophyll b, and carotenoid weresimilar. The contents were minimal at5:00and maximal at9:00. Photosynthesizedproteins synthesized from19:00to1:00next day. The soluble starch content reachedmaximum at17:00, then declined the minimum that may due to respiration. In autumn,the diural trends of Chlorophyll a, b and carotenoid were simiar, and kept constantduring5:00to17:00. The content of protein decreased significantly during1:00to5:00,cycly increased to the maximum during7:00to15:00. The content of starch increasedslowly from9:00to17:00, and accumulated to the maximum at17:00, final decreasedslowly until the next5:00, which mainly due to the respiration. The contents ranges ofchlorophyll a, carotenoids, protein and starch in summer were larger than those inautumn. Chlorophyll b had a larger difference with those phtosynthesized pigmentsnoted above. Both protein and starch content in summer were higher than those inautumn. The enzyme activities of Na+/K+-ATP, Ca2+-ATP, Mg2+-ATP andCa2+/Mg2+-ATP changed significantly at21:00. The tendency of Ca2+-ATP enzymaticactivity rose from11:00to13:00, decreased from13:00to15:00. Others shared thesame trend. The activity of Na+/K+-ATPase did not change significantly at19:00and thenext19:00(without sunlight), while the other three enzymes significantly changed.4. Improvement of bottom aeration on aqeous factorsThe water temperature reached the top value at16:00; and fell to the minmal valueat6:00. In paddy filed ponds, dissolved oxygen and pH shared the same trend with andwithout bottom aeration system; ammonia nitrogen and nitrate nitrogen shared the sametrend with and without bottom aeration system. The turbidity show different trend withand without existence of bottom aeration.