Objective To investigate the effects of rice-fish coculture on growth and yield of ratoon rice with different stubble heights in the double rice cropping area of South China, and provide a scientific reference for rice cultivation and stubble management of the ratoon rice-fish coculture system.

Method Using‘YeXiangYouYouSi’ as the ratoon rice variety for testing, a two-factor field experiment was conducted by setting rice cropping patterns (rice monoculture and rice-fish coculture) and stubble heights of the main season rice for ratoon rice (10 and 30 cm stubble heights), to explore the effects of rice-fish coculture on the growth characteristics and yield components of ratooning season rice with different stubble heights in the main season.

Result Under the treatment of high stubble, the rice yield of the ratooning season was significantly higher in the rice-fish coculture than that in the rice monoculture, and the rice yield was significantly affected by the interaction of the rice cropping pattern and stubble height of the main season rice. Compared with those in the rice monoculture, the effective number of spikes and seed setting rate of the ratooning season rice in the rice-fish coculture significantly increased by 18.2% and 53.2% respectively, while the number of grains per spike significantly decreased by 17.9%, which indicated that the rice-fish coculture compensated for the insufficient number of grains per spike by improving the effective number of spikes and seed setting rate of ratooning season rice population, thus enhancing the yields. In addition, stubble height significantly affected the leaf nitrogen content at the heading stage of the ratooning season rice. During the maturity stage of the main season rice, there was a significant positive correlation between the zeatin riboside content of roots and the nitrogen content of leaves, suggesting that increasing the nitrogen content of leaves at maturity might be beneficial to increase the zeatin riboside content of roots and thus indirectly promote axillary bud germination.

Conclusion Under the conditions of this experiment, the low stubble (10 cm) treatment was more appropriate for the ratoon rice monoculture system, while the high stubble (30 cm) treatment was suitable for the ratoon rice-fish coculture in the double rice cropping area of South China, which might be favorable to the subsequent growth and yield improvement of the ratooning season rice .