Soil CO₂ concentration does not affect growth or root respiration in bean or citrus

Abstract

Contrasting effects of soil CO2 concentration on root respiration rates during short-term CO2 exposure, and on plant growth during long-term CO2 exposure, have been reported. Here we examine the effects of both short-and long-term exposure to soil CO2 on the root respiration of intact plants and on plant growth for bean (Phaseolus vulgaris L.) and citrus (Citrus volkainenana Tan. & Pasq.). For rapidly growing bean plants, the growth and maintenance components of root respiration were separated to determine whether they differ in sensitivity to soil CO2. Respiration rates of citrus roots were unaffected by the CO2 concentration used during the respiration measurements (200 and 2000 ^niol nioP'), regardless of the soil CO2 concentration dnring the previous month (600 and 20 000 pniol nioP'). Bean plants were grown with their roots exposed to either a natural CO2 diffusion gradient, or to an artificially maintained CO2 concentration of 600 or 20 000 ^/niol niol"'. These treatments had no effect on shoot and root growth. Growth respiration and maintenance respiration of bean roots were also unaffected hy CO2 pre-treatment and the CO2 concentration used dnring the respiration measurements (200-2000 //mol mol"'). We conclude that soil CO2 concentrations in the range likely to be encountered in natural soils do not affect root respiration in citrus or bean.

Effects of a Reduction in Soil Moisture from One Month beforeFlowering through Ripening on Dry Matter Production and Ecophysiological Characteristics of Wheat Plants

“…A slight decrease in the concentration of O 2 in the soil air does not inhibit root respiration (Palta and Nobel, 1989). The increase in the concentration of CO 2 in the soil air was also unremarkable, and no consistent effects of extremely high concentrations of CO 2 in soil air on the physiological activity of roots have been reported (Bouma et al, 1997;Qi et al, 1994). Thus, the earlier leaf senescence in the plants in the W pots does not seem to be caused by decline in physiological activities of roots owing to an oxygen defi cit.…”

Responses of Japanese Soybeans to Hypoxic Condition at Rhizosphere Were Different Depending upon Cultivars and Ambient Temperatures

“…Irving et al suggested that waterlogging injury was caused the 15% of increasing in carbon dioxide accompany with 20% of decreasing in oxygen, in their pot experiment using lucerne [19]. In contrast, Bouma et al showed no toxic effect of carbon dioxide to root respiration and the elongation using bean plant [16]. In the experimental equipment, actually, the pH in Hypoxia treatment was significantly decreased in compared with Cont., and this may mean that the solution in Hypoxia was acidified by increasing carbon dioxide ( Table 2).…”

“…oxygen: 0% -21%, carbon dioxide: 0.03% -21% [15]. The origin of plant watterlogging injury has been understood as their condition, "low oxygen" [16] or "high carbon dioxide" [17][18][19].…”

Reduced Lateral Root Branching Density Improves Drought Tolerance in Maize

“…Intact root respiration was measured for a short time (approximately 5 min; Fan et al, 2003;Zhu et al, 2005a). In this study, we assumed that the amount of natural soil and the respiration of microbes were the same in all cylinders (Bouma et al, 1997a(Bouma et al, , 1997b and used the intact root system plus medium respiration as a proxy for total root respiration. The intact root system respiration values were divided by the total root length obtained by WinRhizo scanning (described below) to obtain the specific root respiration per unit of root length (mmol CO 2 m 21 root length s 21 ).…”