Effects of puffed straw returning on nutrient accumulation， transport， distribution and yield of rice in cold region

【Objective】To analyze effects of puffed straw returning on nutrient accumulation， transport， distribution and yield of rice in cold region， and to screen the appropriate returning amount of puffed straw，so as to provide theoretical and technical support for exploring efficient utilization of rice straw resources.【Method】 A pot experiment was conducted， in which rice variety Kenjing 8 was taken as the experimental material. Taking no straw returning（0 straw dosage）as control （CK），four treatments of puffed straw returning amount（25%， 50%， 75% and 100%）were set（local conventional straw returning amount was 7500 kg/ha）to analyze difference in nitrogen（N），phosphorus（P）and potassium（K）uptake， transport and distribution of rice plants and rice yield among various treatments.【Result】 In puffed straw returning treatments，the higher or the highest N，P and K accumulation amount in above-ground parts were all found in the treatment of 25%，and in 2020 and 2021，N accumulation amount in above-ground parts at maturity stage increased by 1.10% and 10.53% compared with that of CK respectively. In 2021，P and K accumulation amount increased by 1.30% and 3.04% compared with that of CK. The treatment of 25% could facilitate N and K transport from stem and leaf to grain，thereby lifting N and K transport amount，transport rate and contribution rate，which was beneficial to N and K accumulations in leaf，stem sheath and panicle at maturity stage. In terms of yieldand its components，puffed straw returning increased grains per panicle，seed setting rate of rice，thus boosting rice yield. Rice yield in the treatment of 25% was significantly higher than those in CK and other straw returning treatments in 2020 and 2021，rice yield in the treatment of 25% were 5.54% and 8.93% higher than that in CK，respectively.【Conclusion】 The treatment of 25% puffed straw returning amount facilitates N，P and K accumulation of rice in cold region，N and P transport from vegetative organs of the plant to grains， and the rice yield in the treatment is high. Therefore， it could be probably applied in rice production in cold region.