Optimized tillage regimes in a rice-oilseed rape rotation system enhance system productivity by delaying post-flowering senescence

Abstract

Context

In the Yangtze River Basin (YRB), soil compaction and inappropriate tillage practices hinder crop yield improvement in the rice-oilseed rape rotation system. Hence, exploring suitable tillage regimes and their impacts on crop yield formation is essential for agricultural development in this region.

Objective

This study aims to investigate the effects of an optimized tillage regime on post-flowering senescence and yield formation in the rice–oilseed rape rotation system, providing a theoretical foundation for the development of high-productivity tillage management systems in the YRB region.

Methods

A five-year field experiment was conducted, employing shallow tillage (ST) and moderate deep tillage (MT, 20–25 cm tillage depth) in the oilseed rape season, followed by no-tillage (NT) in the rice season. Key parameters evaluated included soil compaction, post-flowering physiological activity in roots and photosynthetic organs, pre-flowering dry matter translocation, and crop yield.

Results

Compared with ST, MT significantly reduced soil compaction in the 15–35 cm soil layer during the oilseed rape season and in the 20–35 cm layer during the subsequent NT rice season. The reduced soil compaction under MT enhanced post-flowering root activity and root xylem sap in both crops, promoting nutrient uptake. MT increased antioxidant enzyme activity, nitrogen and total chlorophyll contents while reducing O₂^-, H₂O₂ and malondialdehyde levels in oilseed rape silique walls and rice flag leaves, indicating delayed post-flowering senescence. Pre-flowering dry matter translocation rate and its contribution to yield significantly increased under MT, resulting in oilseed rape and rice yield increases of 23.9 % and 18.3 %, respectively. Furthermore, increasing planting density from 25 × 10⁴ hills ha⁻¹ to 37.5 × 10⁴ hills ha⁻¹ resulted in a 6.2 % and 11.2 % increase in rice yield, respectively, under the ST/NT and MT/NT, indicating that the yield of NT rice can be enhanced by further improving planting density under MT in the oilseed rape season.

Conclusion

Implementing MT in the oilseed rape season, followed by NT in the rice season, enhances crop yield by delaying post-flowering senescence and promoting pre-flowering dry matter translocation to seeds. This optimized tillage regime holds great potential as a sustainable paddy-upland rotation production technology with broad application prospects in China and beyond.