Abstract:
Increase in the concentration of atmospheric greenhouse gases significantly contributes to
global warming, representing a substantial challenge for crop production. The study was conducted
to determine the growth competition between rice (Oryza sativa) and barnyardgrass (Echinochloa
oryzicola) under (i) different cropping patterns and (ii) elevated air temperatures in phytotrons
under field condition, at two plant densities (4 and 16 plants per pot). Rice and barnyardgrass
were planted with varying cropping patterns (rice: barnyardgrass mixture proportions); 100:0,
75:25, 50:50, 25:75 and 0:100. Air temperatures were maintained in phytotrons as follows: Ambient–
A (Control), A +0.8 ◦C, A +1.9 ◦C and A +3.4 ◦C. Plant attributes such as plant height, number
of effective tillers, shoot dry weight and grain yield of rice were recorded in this study in the
rice/barnyardgrass mixture proportions in the order of 100:0 > 75:25 > 50:50 > 25:75. The highest
rice grain yield (37.7 g/pot) was recorded in the monoculture (100:0 rice/barnyardgrass) under
ambient temperature, whereas the lowest rice grain yield (0.3 g/pot) was recorded at the 25:75
rice/barnyardgrass mixture proportion under ambient +3.4 ◦C. The increase in temperature had a
significant impact on growth, number of tillers and shoot dry weight of both rice and barnyardgrass
plants and followed the order of ambient +3.4 ◦C > ambient +1.9 ◦C > ambient +0.8 ◦C > ambient.
However, higher temperature negatively affected the yield of rice and resulted in a substantial
decrease in the grain yield. Barnyardgrass showed the highest plant characteristics when grown
alongside rice compared to the growth in monoculture. This indicates that barnyardgrass was highly
competitive when grown under interspecific competition compared to an intraspecific competition.
In contrast, rice grew better in monoculture than in mixture with barnyardgrass
