Crop ecosystem responses and weed population under elevated temperature regimes

Abstract

The negative effects of weed infestation in paddy fields and increasing temperature are considered as the main factors of reducing rice grain yield. This study conducted to reveal the competitive interaction between rice (upland rice Dongjin 1) and weeds with different densities at ambient and 0.8℃, 1.9℃, and 3.4℃ above ambient temperature in special phytotrons at Chungnam National University, Daejeon, Korea. The competition between rice and weeds was created in the following three treatments: 1. Natural occurrence of weeds is naturally grown from the soil seed bank, 2. Standard density, the following weeds were grown in the plots: EO (Echinochl oaoryzicola) 1g, Mv (Monochoria vaginalis) 1 g, Lp (Ludwigia prostrata) 1 g, Ek (Eleocharis kuroguwai) 15 tuber, Sp (Scirpus planiculmis) 15 tuber, SS (Sagittaria sagittifolia) 15 tuber, Lpr (Lindernia procumbens) naturally occurred, Rp (Rotala pusilla) naturally occurred. 3. High density, the following weeds were grown in the plots: EO=2 g, Mv=2 g, Lp=2 g, Ek=30, Sp=30, SS=30, Lpr naturally occurred, Rp naturally occurred. Results presented that rice growth parameters such as height, the number of tillers, and shoot dry weight were increased with the increase of ambient temperature. However, rice yield negatively correlated with the increase of temperature, especially, caused enhancing the panicle senescence at the pollination period and shortening the grain filling period. The lowest rice yield was observed in high weed density treatment followed by standard weed density of weed treatment compared to natural weed occurrence treatment. From the perspective of rice: weed competitions, generally weeds exhibited more competitive ability than rice in this interspecific competition.