Evaluation of fish farming in paddy field and its effect on rice varieties.

In order to obtain a suitable rice cultivar in Rice-Fish farming system, six local and improved rice varieties in two fields conditions (with and without fish) were studied in three locations (Astaneh, Fouman and Rasht) during the growing season of 2007-2008 in a split plot experiment based on Randomized Complete Block Design with three replications. The size of each plot was 20 m. in the transplanting time, some small fishes (about 30-70 gr) were released in the pool. The kinds of fishes were Grass fish (Amour), Common fish (Kapour) and Silver fish (Phytophak and Big head). After 25-30 days, some temporary borderplots made in surrounding of fields and increased the level of the water, because of all fishes could be easily going to inside the fields. The traits such as grain yield (t/ha), plant height (cm), tiller number, filled grains, length of panicle, unfilled grains and 1000 grain weight (g) were evaluated in this study. Simple analysis of variance clearly showed significant differences among varieties for all traits. Combined analysis revealed significant difference for grain yield, plant height, tiller number, filled grains number, length of panicle, unfilled grains number and 1000 grain weight among the six genotypes studied. Highly significant were observed location×genotype and location×field interactions for all characters. Among all rice varieties, three cultivars such Dorfak, Hybrid rice (Bahar1) and Khazar had high grain yield with 7285, 6498 and 5859 kg/ha respectively. Echinochloa crus galli population (the most important weed in rice cultivation) was very high in rice field condition (without fish) and its density was 120 gr/m while, that was 15 gr/m in rice-fish farming. To sustain a loss of strip stem borer was very less in rice-fish farming, particular for three rice cultivars including Khazar, Dorfak and Hybrid respectively. In additional these three rice varieties had high tillers in this condition. Finally it is recommended that each rice farmer can be used this technology for increasing yield and reducing cost of weeding and pesticide in this farm.