Dry matter partitioning and growth dynamics of two short duration rice varieties at variable doses of nitrogen

Abstract

Nitrogen availability is a major factor influencing rice growth and developmental processes. The present research was conducted at the West Byde Research Field of the Bangladesh Rice Research Institute (BRRI), Gazipur to evaluate the effects of different nitrogen levels on growth dynamics and dry matter partitioning in short duration Boro rice varieties. The experiment was laid out in a randomized complete block design (RCBD) with two factors: six nitrogen levels N₀, N₃₀, N₆₀, N₉₀, N₁₂₀, N₁₅₀ and two short duration rice varieties, BRRI dhan81 and BRRI dhan88 comprising twelve treatment combinations. Forty days old seedlings were transplanted with the planting geometry of 20 cm × 20 cm. Nine plants were randomly sampled from each plot at 15-day intervals to record dry matter production, growth parameters and grain yield. Dry matter partitioning and different growth parameters showed insignificant interaction for variety × nitrogen levels. However, nitrogen levels significantly influenced all evaluated parameters. Higher dry matter partitioning in leaves, culms and panicles was recorded under N₁₅₀ and N₁₂₀ followed by N₆₀ and N₉₀ across all growth stages.  Growth parameters such as Leaf Area Index (LAI), Crop Growth Rate (CGR) and Net Assimilation Rate (NAR) were lowest at initial stage and reached to peak during 60-75 days after transplanting (DAT). The result indicated that nitrogen level N₁₅₀ and N₁₂₀ were most effective in enhancing growth and yield of rice followed by N₆₀ and N_90.   Therefore, optimum nitrogen management specially N₁₂₀ – N₁₅₀ produced the highest dry matter at all growth stages resulting higher grain yield followed by N₆₀ and N₉₀. Growth parameters (LAI, CGR, and NAR) were lowest at the initial stage and peaked at 60–75 DAT. Overall, optimum nitrogen levels (N₁₂₀–N₁₅₀) enhanced growth dynamics more effectively and dry matter accumulation, resulting in higher grain yield in short duration rice varieties.

Bangladesh Rice J.29(2): 25-34, 2025