Ecological Mechanisms of Row Spacing and Sowing Rate on Weed Suppression During the Tillering Stage of Next Generation Dryland Rice

Purpose This paper aimed to investigate the dynamic regulation of canopy light transmittance in next generation dryland rice (NGDR) during the tillering stage by row spacing and sowing rates, and further analyzing their effects on weed growth and crop yield.

Methods Using a two-factor crossover experiment, the field effects of different row spacing (10, 15, 20, 25, and 30 cm, denoted as L₁₀, L₁₅, L₂₀, L₂₅, and L₃₀, respectively) and sowing rate (1, 3, 5, 7, and 9 seeds per hill, denoted as D₁, D₃, D₅, D₇, and D₉, respectively) combinations were compared.

Results When the row spacing was 20 or 25 cm (L₂₀, L₂₅), sowing five seeds per hill (D₅) exhibited no significant difference in yield of NGDR compared with seeding seven or nine seeds per hill. Compared with the L₂₅D₅ treatment, the L₂₀D₅ treatment could form a canopy structure with an open middle layer and a closed bottom layer at the early tillering stage of the rice. This structure not only inhibited the germination and growth of bottom weeds, but also ensured the photosynthetic efficiency of NGDR functional leaves, leading to the L₂₀D₅ treatment effectively controlling the occurrence of dominant weeds (Galinsoga quadriradiata, Eleusine indica, and Ageratum conyzoides) at the middle and late tillering stages.

Conclusion The L₂₀D₅ treatment achieves the optimal balance between improving NGDR yield and controlling weeds, and can be used as the optimal choice for NGDR cultivation. The findings provide theoretical basis and technical support for high-yield and high-efficiency planting measures of NGDR.