Effect of seed rate on yield performance of dry direct seeded winter rice

Abstract

Seedling transplanting into the puddled soil is the conventional and most popular rice establishment method in Bangladesh but water scarcity is posing a serious threat to this system of rice cultivation especially in boro season. Dry direct seeding (DDS) is an alternative rice establishment technology which have potentiality to save irrigation water significantly. Seed is sown manually on dry cultivated land at 25 cm × 15 cm spacing but continuous line sowing can be done by power tiller operated seeder. Therefore, there is a need of evaluating the yield performance of line sown dry seeded rice at various seeding rates to standardize the seeding rate for further machine sowing recommendation. Two mega rice varieties for winter (boro) season viz. BRRI dhan28 and BRRI dhan29 were cultivated at five seeding rates (30, 40, 50, 60, and 70 kg ha⁻¹) in continuous line sowing and a spaced seeding (25 cm × 15 cm) using 30 kg seed ha⁻¹ as a control treatment. The results reveals that the highest grain yield (6.73 and 7.13 t ha⁻¹ in 2009–10 and 2010–11, respectively) was obtained from the seeding rate of 50 kg ha−1 for BRRI dhan29 but this yield was significantly lower than that obtained (7.07 and 7.46 t ha⁻¹ in 2009–10 and 2010–11, respectively) in control. Although higher grain yield was obtained from the spaced seeding plots, this method is not economically viable as the machine seeding would save huge labour costs. Therefore, considering both yields and labour cost, dry direct seeding would be practiced with continuous seeding at 25 cm apart rows using 50 kg seed ha⁻¹ for both the boro rice varieties.