Determining the Optimal Wide - Narrow Row Spacing for TBR225 Rice Variety in Vietnam

This study aimed to evaluate the effects of alternate wide-narrow row spacing on growth, development, pest and disease incidence, and yield of the TBR225 rice variety. Five planting treatments (F1-F5) were tested. Recorded parameters included plant height, accumulated dry matter, tillering ability, pest and disease occurrence, and yield components. Results showed that wider row spacing (F4-F5) significantly increased accumulated dry matter at panicle initiation and heading stages. The maximum tiller number, effective tillers, and proportion of effective tillers of TBR225 were markedly higher in F4-F5 compared with the narrower row treatments. At the same time, the incidence of major pests and diseases (blast, sheath blight, stem borer, leaf folder) was substantially reduced under wider rows, reflecting improved microclimatic conditions in the paddy field. Yield components such as panicles per m², filled grain ratio, and 1000-grain weight remained almost unchanged, whereas grains per panicle and actual yield increased significantly in F4-F5 (6.37-6.42 t ha⁻¹, 8-10% higher than F1). These results confirm that selecting appropriate row spacing is a key agronomic measure to improve growth potential, reduce pest and disease pressure, and increase rice yield. This study provides a scientific basis for recommending cultivation techniques to maximize the production potential of TBR225 rice under actual field conditions.