Yield Response of Broadcast Aus Rice to Potassium Variation in the Coastal Soil of Southwestern Bangladesh

Abstract

In the southwestern coastal region of Bangladesh, the cropping pattern is Fallow-Fallow-T. Aman, which leaves a large area of land fallow during Rabi and Kharif-1 season. However, a new cropping pattern has been emerging which incorporates broadcast (B) Aus rice before the monsoon season during early summer (Kharif-1). But the fertilizer requirement, particularly the potassium (K) rate, is still undefined. To address this issue, a field study was conducted with B. Aus rice (var. BRRI dhan48) in Pankhali, Dacope (a saline part of Agro-ecological zone, AEZ- 13), Khulna. There were 6 different levels of potassium treatment such as 0, 20, 30, 40, 50 and 60 kg ha-1. Potassium rates had statistically non-significant effects on plant height, grain yield and yield attributes (panicle length, number of grains panicle-1, effective tiller m-2 and 1000 grain weight). At harvest, numerically the highest panicle length (23.3 cm) was produced by 40, 50 and 60 kg K ha-1 respectively. The numerical highest number of grain panicle-1 (113.9) was produced by 50 kg K ha-1. The numerical highest number of effective tiller m-2 (353.3), 1000- grain weight (22.8 g) and grain yield (4.49 t ha-1) were produced by 60 kg K ha-1. Grain yield and other measured parameters were not significantly increased with the application of K. The lowest nonsignificant values of almost all parameters were recorded from no K-added treatment. As there was no statistical yield variation was found due to variations of K, it seems that cultivation of B. Aus can be possible without the application of K but long-term of this practice (applying no K) will make the soil negative K balance. Thus, a maintenance dose of K 20 to 30 kg ha-1 could be suggested for recommendation for B. Aus rice in the coastal soil of southwest Bangladesh.