| This study investigated the effect on the illumination, temperature, relative humidity inside the ridge, average wind velocity inside the ridge and DO of the surface water in paddy field , between two cultivations that were double lines width ridge（（40cm+20cm）×16cm） and conventional ridge（30cm×16cm）, and then compared their differences. The results show that there were significant differences in illumination, relative humidity inside the ridge, average wind velocity inside the ridge and DO of the surface water in paddy field between double lines width ridge and conventional ridge, and the former was effective in improving the microclimate in rice field, playing a positive role in rice growth, development, traits and disease prevention. In addition, it promoted the dissolved oxygen in surface water, avoiding the threat of crab for the lack of DO.This experiment set three treatments: A was a intensive rice-crab culture,the crabs in which was fed on high-protein（CP=30%） formula feed and living food; B was the same as A, except the crab was only fed on low-protein （CP=20%） formula feed; C was a paddy with no crab. There were three parallel groups in each treatment. A ring ditch was dug around the paddy inside, with the upper width of 60cm, lower width of 30cm and depth of 33cm.The results indicated that in earlier stage, the water environment was suitable for the crab. DO was more than 2.0mg.L-1 all day. In addition, the temperature difference between upper and lower of the ring ditches is up to 7.6℃. So, the presence of ring ditch was easy to crab for avoiding the high temperature. However, in the mid-late stage, DO in rice-crab field was significantly lower than the pappy with no crab （p<0.05）, but it would not affect the crab. Looking at the whole growth period, nitrate and phosphate of treatment A is significantly higher than C （p<0.05）. Furthermore, a notion, uninterruptible fertilization（UPF）was introduced. In rice-crab field, the existence of crab offered an uninterruptible fertilization to rice, which obviously played a positive role to rice yield increased.During the tillering, jointing, flowering and filling stages in 2009, a study had been carried out on community of algae in water environment of rice-crab culture model. This experiment set three treatments: a intensive rice-crab culture,the crabs was fed on high-protein（CP=30%） formula feed and living food; a general rice-crab culture, the crab was only fed on low-protein （CP=20%） formula feed; a paddy with no crab. There were three parallel groups in each treatment. The planktonic algae collected from the paddy field were a total of 267 species belonging to 8 phyla and 147 genera, after being identified. Phytoplankton density and biomass decreased in each treatment, while the biodiversity increased rapidly from tillering to jointing stage, and then remained stable. However, there was little significant difference among treatments （p>0.05）.During the tillering, jointing, flowering and filling stages, a study had been carried out on community of crustacea zooplankton in water environment of Rice-crab Culture model. This experiment set three treatments: a intensive rice-crab culture , the crabs was fed on high-protein（CP=30%） formula feed and living food; a general rice-crab culture, the crab was only fed on low-protein （CP=20%） formula feed; a paddy with no crab. There were three parallel groups in each treatment. After being identified, 11 species of Cladocera and4 species of Copepoda were found. From tillering to flowering stage, biological density of Cladocera changed smoothly, and the maximum appeared in the jointing stage while the minimum in the filling stage. In tillering stage, biological density of Cladocera was extremely low, only 0.6ind.L-1; and showed the highest in jointing and flowering stages, then decreased only to 3.7mg.L-1 to the filling stage. However, there was little significant difference among treatments （p>0.05）. |
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