Response of Soybean to Air Temperature and Carbon Dioxide Concentration

Abstract

Documented increases in global atmospheric CO2 concentration have stimulated interest in the direct effects of CO2 on plant growth and yield as well as the interactive effects of CO2 with other major climatic variables. This study was conducted to determine the effects and interactions of CO2 concentration and air temperature on the development, growth, total nonstructural carbohydrate (TNC), and final seed yield of soybean [Glycine max (L.) Merr., cv. Bragg] grown season‐long in naturally lit, controlled‐environment chambers. Day/night air temperatures of 26/19, 31/24, and 36/29 °C were maintained in CO2 treatments of 330 and 660 μmol CO2 mol−1 air. Both CO2 enrichment and increasing air temperature decreased main stem plastochron interval, while increasing air temperature increased final main stem node number. Leaf area and above‐ground biomass increased with CO2 enrichment and with temperature from 26/19 °C to 31/24 °C. The nonlinear increase with temperature in leaf area, aboveground biomass, and plastochron interval was attributed to the highest temperature treatment being near or above the optimum for soybean growth and development. Seed yield increased with CO2 enrichment due mainly to an increase in seed number rather than weight per seed. Individual seed weight decreased, while seed number increased with increasing temperature. Leaflet TNC displayed large diurnal variations, while stem TNC was relatively stable throughout the day. Stem TNC was less affected by CO2 than by temperature treatment and decreased with increasing temperature. These results indicate that the response of soybean to elevated CO2 concentration is highly temperature dependent.

Elevated Carbon Dioxide and Soil Moisture on Early Growth Response of Soybean

“…Our results on dry matter production in agreement with many previous studies on different crops showed increase in total dry matter production of soybean [38] [65]- [67], dry bean [43], peanut [68] 2 ] at later stage was attributed due to the partitioning of greater amounts of assimilated carbon towards the growing organs. Earlier studies also showed that the extra carbon fixed by the plants due to [CO 2 ] enrichment translocate to the growing axis [71].…”

“…This agrees many with the results of previous studies of [38] and [39] and contradicts the findings of [40] [29] and reported alterations both in physiology and growth and . Carbon dioxide (a) and soil moisture levels (b) on number of root nodules of soybean at 44DAP ( ** P < 0.014 and * P < 0.048 for CO 2 and soil moisture levels, respectively).…”

Response of soybean yield components and allocation of dry matter to increased temperature and CO2 concentration

“…A mean temperature range of [29][30][31] o C has been indicated as the optimum range for soybean vegetative growth (Ziska and Bunce, 1995;Setiyono et al, 2010), and the mean temperature of T2 and T3 were close to this range. Similarly, the main stem plastochron interval decreases and the final main stem node number increases in soybean with higher [CO 2 ] (660 μmolmol −1 ), accompanied by a rise in mean temperature between 22.5 and 32.5 °C (Baker et al (1989).…”

Simulation of CO2 enrichment and climate change impacts on soybean production

“…In contrast, reduced stomatal conductance and transpiration are additional reasons for the measured crop yield enhancement under water stress conditions. Because the upper optimum temperature of most soybean varieties ranges from 20 to 30°C (Baker et al, 1989), an increase in air temperature would also significantly limit production.…”