Ecological studies for plant characteristics of Fimbristylis miliacea under multiple resource limitations in dry-seeded upland ecosystems

Abstract

Fimbristylis miliacea is becoming a major rice weed in South and Southeast Asia. An understanding of how this weed species competes with rice and how to manage this weed under multiple resource limitations the development of cultural methods is important. Therefore, a study was conducted in greenhouse to determine the effect of varying rice seeding densities (0, 8, and 32 plants pot−1), nitrogen (N) rates (100 and 150 kg ha−1), and water regimes (aerobic and saturated) on rice and F. miliacea growth characteristics and competitiveness under multiple resource limitations under dry-seeded conditions. Both rice and weed were taller in saturated conditions than in aerobic conditions, whereas rice plants were taller than F. miliacea in both water regimes. F. miliacea grown alone had lower leaf and tiller number and less leaf, stem, shoot, root and inflorescence, biomass under saturated conditions than in aerobic conditions. However, when F. miliacea was grown with competition of rice, water regimes did not affect its growth parameters and inflorescence biomass production. N rates affected Rice growth but F. miliacea was not affected. Regardless of water regime and N rate, F. miliacea height (56 and 82%), tiller number (87 and 87%), leaf number (68 and 88%), shoot biomass (98 and 99%), inflorescence biomass (95 and 99.5%), and whole plant biomass (95 and 96%) decreased at rice densities of 160 and 640 plants m−2, compared with F. miliacea grown alone. The results suggest that growth and seed production of F. miliacea can be greatly declined by increasing rice planting density.