Mat Type Seedlings Properties Analysis of High Yielding Aman Rice Varieties for Mechanical Transplanting

It is important to analyze and optimize mat-type seedling properties of high-yielding Aman rice varieties for efficient mechanical transplanting, addressing productivity and labor challenges. A study is conducted at the Farm Machinery and Postharvest Technology Division, Bangladesh Rice Research Institute (BRRI), Gazipur, during the 2022 irrigated dry season Aman. The research aims to evaluate the mechanical and agronomical properties, along with seedling characteristics, of mat-type seedlings under different seed rates for three rice varieties: BRRI dhan71, BRRI dhan75, and BRRI dhan87. A 4-row rice transplanter (model DP 480) is used, and experiments follow a completely randomized design (CRD) with two factors: rice variety and seed rate (130–160 g/tray). Results show significant variations in seedling height, thickness, and density across varieties and seed rates. BRRI dhan75 exhibits the highest seedling height (up to 17.06 cm), while BRRI dhan71 shows the greatest thickness. Seedling density increases linearly with seed rate, reaching its highest with 60-day-old seedlings. Seedling strength is influenced by variety and location, with BRRI dhan75 demonstrating the strongest seedlings, especially in Rajshahi. For optimal seedling quality and transplanting efficiency, the following adjustments are recommended: 160 g of seeds per tray for BRRI dhan75, 150 g for BRRI dhan71, and 140 g for BRRI dhan87, with transplanter settings between 4 and 7. These adjustments ensure proper seedling height, strength, and planting efficiency, minimizing gaps and promoting effective transplanting.