Effect of Planting Dates, Potassium Fertilizer Resources and Varieties on Growth, Yield and Proline of Rice Plants Under Rainfed Lowlands

Background and Objective: Drought stress under rainfed lowlands had an inhibition the rice growth and yield. This study aimed to determine the effect of planting dates, fertilization, varieties and their interactions on the growth, yield and proline content of rice under rainfed lowlands. Materials and Methods: This study was conducted in the Deli Serdang District, North Sumatra, Indonesia from January to April, 2016. A split-split plot design was selected in this study with three replications. Main plot was planting dates (P1 = 10th, P2 = 20th and P3 = 30th January), sub-plot was potassium fertilizer resources (F0 = control, F1 = 50 kg ha–1 KCl, F2 = 5 ton ha–1 rice straw compost/RSC, F3 = 2.5 ton ha–1 RSC+2.5 ton ha–1 cattle manure/CM, F4 = 50 kg ha–1 KCl+5 ton ha–1 RSC, F5 = 50 kg ha–1 KCl+2.5 ton ha–1 and RSC+2.5 ton ha–1 CM) and sub-sub plot was rice varieties (V1 = Situ Bagendit, V2 = Towuti, V3 = Batutegi, V4 = Inpago-8, V5 = Inpago-9, V6 = Inpago-10, V7 = Ciherang and V8 = Inpari-10). The F and Duncan’s tests were selected for data analysis. Results: The P1, F3-F5, Inpago-9 variety and their interactions (P1F4, P1F5, P1V2, P1V3, P1V5, P1V8, F5V5 and F5V1) significantly increased highest of rice growth and yield under rainfed lowlands. The P1F4V2, P1F4V3, P1F4V4 and P1F5V5 interactions could increase the number of filled grains of rice under rainfed lowlands. The proline content was negatively correlated to the grain yield of all varieties due to the three interactions. Conclusion: The early planting with a combination of KCl+RSC+CM on the Towuti, Batutegi, Inpago-8 and Inpago-9 varieties can be implemented as an alternative in rainfed lowlands.