Competitive interaction of rice (Oryza sativa) and Echinochloa glabrescens as a function of planting density under elevated CO2 and high temperature
1997
Alberto, A.M.P. | Ziska, L.H. | Cervancia, C.R. | Manalo, P.A. (Central Luzon State Univ., Munoz, Nueva Ecija (Philippines). Coll. of Arts and Sciences)
Potential competition between rice and Echinochloa glabrescens in terms of their vegetative and reproductive characteristics were examined at different planting densities at different CO2 levels (ambient,ambient + 200) and temperature regimes (27/21 deg C; 37/26 deg C). Increased CO2 concentration promoted greater biomass, tiller number, grain yield, panicle weight and percentage filled spikelets for rice relative to E. glabrescens. Comparison between the two species showed that the ratio of rice/E. glabrescens for total above ground biomass, leaf area, tiller number and grain yield increased with increasing CO2 concentration indicating a potential competitive advantage for rice under elevated CO2. However, if CO2 and temperature increased simultaneously the increase in rice biomass declined relative to the elevated CO2 condition alone. It was also observed that with increasing CO2 and temperature, weeds became taller than rice. Interestingly, no grain yield was produced at the higher growth temperature for rice at either CO2 concentrations. Overall, this experiment suggested that the relative effect of increasing atmospheric CO2 and high temperature on reproduction could still favor C4 over C3 with global climate change
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