Effects of Straw Utilization Methods on Dry Matter Production and Yield of Japonica Rice in Northern China

To study the effects of straw utilization methods on dry matter production and yield of japonica rice in northern China, taking the super japonica rice Shennong 265 as the test material, using the planting method of seedling transplanting, setting four treatments, namely, the conventional production, directly returning straws to field (6 t/ha), returning straws to field at low amount of biochar (2 t/ha) and returning straws to field at high amount of biochar (40 t/ha), this paper analyzed the changes in production and yield of super japonica rice Shennong 265. According to the experimental results, compared with the conventional production, after the straws were directly returned to the field, the dry matter accumulation of japonica rice was insufficient, and the leaf output rate and contribution rate were significantly reduced by 41.19% and 34.69%, respectively; the number of filled grains per panicle, 1000-grain weight, and panicles per plant showed negative effect, leading to a decline in the yield; under the condition of returning straws to field at high amount of biochar, the dry matter accumulation showed a decline trend, both the leaf and stem sheath significantly reduced by 21.41% and 17.43%, and the number of filled grains per panicle also declined; under the condition of returning straws to field at low amount of biochar, the dry matter accumulation increased, and the leaf contribution rate increased by 11.68%, the number of filled grains per panicle, 1 000-grain weight, and panicles per plant showed positive effect, showing the potential of yield increase. In conclusion, returning suitable straw biochar to field (2 t/ha) is favorable for promoting the japonica rice production in northern China.