Effect of Intercropping with Soybean on Growth and Yield of Several Promising Lines of Black Rice in Aerobic Irrigation System

Abstract

Rice is normally cultivated by the farmers under flooded conditions. This study aimed to examine the effect of additive intercropping with soybean on growth and yield of three promising lines of black rice grown on raised-beds under an aerobic irrigation system. The experiment was carried out on an irrigated rice growing area located in Dasan Tebu (-8.653912, 116.130813), West Lombok, Indonesia, from April to August 2021, which was arranged according to Split Plot design, with three blocks and two treatment factors: black-rice genotypes as the main plots (G3, G9, G4/15), and intercropping as the subplots (T0= monocrop and T1= rice-soybean-intercropping). On the intercropping beds, soybean of Dena-1 variety was relay-planted in additive series between double-rows of black-rice at two weeks after seeding of black-rice. Results indicated that intercropping with soybean increased growth and yield components of black rice with an average grain yield of 36.95 g/clump in T1 and 32.63 g/clump in T0. Grain yield was also different between genotypes with the highest grain yield of 39.32 g/clump in G4/15 line. However, the significant interaction between factors on biomass weight indicated that both G9 and G4/15 lines showed positive but G3 negative response to additive intercropping with soybean, which reasons are still unclear and need further investigation, although it seems that the G4/15 line was the most responsive to intercropping with soybean in increasing black-rice grain yield, with the highest grain yield was on G4/15 line intercropped with soybean (42.73 g/clump or 8.55 ton/ha). Keywords—Black rice, intercropping, additive series, soybean, aerobic irrigation system