Effects of elevated CO₂ and temperature on photosynthesis and Rubisco in rice and soybean

Abstract

Rice (Oryza sativa L. cv. IR-72) and soybean (Glycine max L. Merr. cv. Bragg), which have been reported to differ in acclimation to elevated CO2, were grown for a season in snnlight at ambient and twice-ambient [CO2], and under daytime temperature regimes ranging from 28 to 40 °C. The objectives of the study were to test whether CO2 enrichment could compensate for adverse effects of high growth temperatures on photosynthesis, and whether these two C3 species differed in this regard. Leaf photosynthetic assimilation rates (A) of both species, when measured at the growth [CO2], were increased by CO2 enrichment, but decreased by supraoptimal temperatures. However, CO2 enrichment more than compensated for the temperatureinduced decline in A. For soybean, this CO2 enhancement of A increased in a linear manner by 32-95% with increasing growth temperatures from 28 to 40 °C, whereas with rice the degree of enhancement was relatively constant at about 60%, from 32 to 38 °C. Both elevated CO2 and temperature exerted coarse control on the Rubisco protein content, but the two species differed in the degree of responsiveness. CO2 enrichment and high growth temperatures reduced the Rubisco content of rice by 22 and 23%, respectively, but only by 8 and 17% for soybean. The maximum degree of Rubisco down-regulation appeared to be limited, as in rice the substantial individual effects of these two variables, when combined, were less than additive. Fine control of Rubisco activation was also influenced by both elevated [CO2] and temperature. In rice, total activity and activation were reduced, but in soybean only activation was lowered. The apparent catalytic turnover rate (Xcat) of rice Rubisco was unaffected by these variables, but in soybean elevated [CO2] and temperature increased the apparent ^^at by 8 and 22%, respectively. Post-sunset declines in Rubisco activities were accelerated by elevated [CO2] in rice, but by high temperature in soybean, suggesting that [CO2] and growth temperature influenced the metabolism of 2-carboxyarabinitol-l-phosphate, and that the effects might be species-specific. The greater capacity of soybean for CO2 enhancement of A at supraoptimal tem- peratures was probably not due to changes in stomatal conductance, but may be partially attributed to less down-regulation of Rubisco by elevated [CO2] in soybean than in rice. However, unidentified species differences in the temperature optimum for photosynthesis also appeared to be important. The responses of photosynthesis and Rubisco in rice and soybean suggest that among C3 plants species-specific differences will be encountered as a result of future increases in global [CO2] and air temperatures.

Effects of elevated CO2 concentration on growth and photosynthesis of Chinese yam under different temperature regimes

“…The results of some studies have suggested that increasing [CO 2 ] will result in increased photosynthesis (Kimball et al, 2002;Vu et al, 1997;Yang et al, 2006). Several recent studies have shown that photosynthesis of C 3 plants increases by 30-50% with doubled [CO 2 ] (Ainsworth & Rogers, 2007;Baker et al, 1992).…”

Modelling soybean yield responses to seeding date under projected climate change scenarios

“…In this study region, increasing temperature in the near and distant future may not often reach the level for heat stress on photosynthesis for which the cardinal temperature is above 32 °C for soybean (Hatfield et al 2011;Vu et al 1997). Therefore the soybean response to increasing temperature will depend on current local mean temperature (Boote 2011).…”

“…Simulations by different crop models provide useful information for assessing the uncertainties in the projected crop production associated with the uncertainties in greenhouse gas emission scenarios and climate projections (Long et al 2006;Reich et al 2006;Rogers et al 1995;Twine Vu et al 1997). It is understandable that a crop model may be good in mimicking some, but not all, aspects of the cropping system.…”

Simulação do desenvolvimento da batata cultivar asterix em cinco cenários de mudanças climáticas em Santa Maria, RS

“…Plantas com metabolismo C3 são mais beneficiadas pelo aumento da concentração de CO 2 atmosférico do que plantas com metabolismo C4 (TUBIELLO et al, 2000;SIQUEIRA et al, 2001;STRECK, 2005). No entanto, se o aumento da concentração de CO 2 for acompanhado de aumento da temperatura do ar, poderá não haver aumento no crescimento e produtividade das culturas devido ao encurtamento do ciclo (WIEGAND e CUELLAR, 1981;SIONIT et al, 1987;HUNT et al, 1991;BUTTERFIELD e MORISON, 1992;SHAYKEWICH, 1995, SIQUEIRA et al, 2001) e aumento da respiração (fotorespiração e fase escura da respiração) (ROSENBERG et al, 1983;LONG, 1991;VU et al, 1997;TAIZ e ZEIGER, 2004). Portanto, em estudos de impactos das mudanças climáticas sobre os agroecossistemas, devese dar especial atenção ao efeito do aumento de temperatura (aquecimento global) no desenvolvimento vegetal e assim caracterizar mudanças no ciclo das culturas em diferentes cenários meteorológicos.…”