Growth dynamics and genotypic variation in tropical, field‐grown paddy rice (Oryza sativa L.) in response to increasing carbon dioxide and temperature

Abstract

While previous studies have examined the growth and yield response of rice to continued increases in CO2 concentration and potential increases in air temperature, little work has focused on the long‐term response of tropical paddy rice (i.e. the bulk of world rice production) in situ, or genotypic differences among cultivars in response to increasing CO2 and/or temperature. At the International Rice Research Institute, rice (cv IR72) was grown from germination until maturity for 4 field seasons, the 1994 and 1995 wet and the 1995 and 1996 dry seasons at three different CO2 concentrations (ambient, ambient + 200 and ambient + 300 μL L–1 CO2) and two air temperatures (ambient and ambient + 4 °C) using open‐top field chambers placed within a paddy site. Overall, enhanced levels of CO2 alone resulted in significant increases in total biomass at maturity and increased seed yield with the relative degree of enhancement consistent over growing seasons across both temperatures. Enhanced levels of temperature alone resulted in decreases or no change in total biomass and decreased seed yield at maturity across both CO2 levels. In general, simultaneous increases in air temperature as well as CO2 concentration offset the stimulation of biomass and grain yield compared to the effect of CO2 concentration alone. For either the 1995 wet and 1996 dry seasons, additional cultivars (N‐22, NPT1 and NPT2) were grown in conjunction with IR72 at the same CO2 and temperature treatments. Among the cultivars tested, N‐22 showed the greatest relative response of both yield and biomass to increasing CO2, while NPT2 showed no response and IR72 was intermediate. For all cultivars, however, the combination of increasing CO2 concentration and air temperature resulted in reduced grain yield and declining harvest index compared to increased CO2 alone. Data from these experiments indicate that (a) rice growth and yield can respond positively under tropical paddy conditions to elevated CO2, but that simultaneous exposure to elevated temperature may negate the CO2 response to grain yield; and, (b) sufficient intraspecific variation exists among cultivars for future selection of rice cultivars which may, potentially, convert greater amounts of CO2 into harvestable yield.

Phenotypic plasticity conditions the response of soybean seed yield to elevated atmospheric CO2 concentration

“…Kimball et al, 2002), since [CO 2 ] is a growth-limiting resource for C 3 plants. There is a large genotypic variation in the yield response to eCO 2 , both among cultivars and between species, with responses ranging from -15% to +20% per 100 mmol mol -1 CO 2 increase from the current level for rice (Ziska et al, 1996;Moya et al, 1998;Baker, 2004;Shimono et al, 2009;Hasegawa et al, 2013), -6% to +35% for wheat (Manderscheid and Weigel, 1997;Ziska et al, 2004;Ziska, 2008;Tausz-Posch et al, 2015), -5% to +55% for soybean (Ziska and Bunce, 2000;Ziska et al, 2001;Bishop et al, 2015;Bunce, 2015), and -6% to +21% for field bean (Phaseolus vulgaris; Bunce, 2008). These large differences in eCO 2 responsiveness within crop species suggest that active selection and breeding for genotypes that respond strongly to gradual but steadily increasing [CO 2 ] may ensure sustained productivity and improve food security in a future eCO 2 world (Ainsworth et al, 2008;Ziska et al, 2012;Tausz et al, 2013).…”

Food security and climate change: on the potential to adapt global crop production by active selection to rising atmospheric carbon dioxide

“…Additional studies have confirmed that there is significant intraspecific variation in the yield response to elevated CO 2 among cowpea (Vigna unguiculata, L., Walp.) [7], common bean (Phaseolus vulgaris L.) [8], rice (Oryza sativa L.) [9,10], wheat (Triticum aestivum L.) [11] and soybean (Glycine max L. Merr.)…”

Up-regulation of sucrose-P synthase in rice under elevated carbon dioxide and temperature conditions

“…) show little or no photosynthetic response to elevated CO 2 , because they are CO 2 saturated and not competitively inhibited by O 2 . The increase in CO 2 is expected to cause global warming by absorbing the long wave heat radiation from the earth surface and altering the precipitation (Moya et al 1998) -i.e. climatic effect.…”