Phosphorus supply enhances the response of legumes to elevated CO2 (FACE) in a phosphorus-deficient vertisol

Plant growth responses to elevated atmospheric CO2are increased by phosphorus sufficiency but not by arbuscular mycorrhizas

“…Edwards et al , 2005; Rogers et al , 2009), P fertilization does not always increase the eCO 2 response in grasses (Grunzweig and Körner, 2003) and this variation appears to relate to differences in root production between the two plant groups ( B. distachyon had higher root length at low P). The limited growth response to eCO 2 in the highly P-responsive M. truncatula exposed to low soil P accords with previous findings in chickpea, field pea, barrel medic, and soybean (Sa and Israel, 1998; Jin et al , 2012; Lam et al , 2012; Singh et al , 2014). In contrast, the ~50% growth response to eCO 2 over the full soil P range in B. distachyon is very much in line with a predicted 46% increase in C gain in C3 plants at the atmospheric concentrations of CO 2 expected for the middle of this century (Leakey et al , 2009).…”

“…The physiological background for the C–P trade balance as influenced by eCO 2 and low P conditions are appropriately investigated in experiments under controlled conditions to minimize possible masking of C–P trading by non-nutritional influences that are common under field conditions. Previous studies on eCO 2 ×P interactions have shown that eCO 2 can increase growth of C 3 grasses even in low-P soil (Newbery et al , 1995; Imai and Adachi, 1996; Newbery and Wolfenden, 1996; Pandey et al , 2015 a ), whereas the response in legumes (also C3) is usually limited under low-P conditions (Stocklin and Körner, 1999; Edwards et al , 2005; Jin et al , 2012; Lam et al , 2012; Singh et al , 2014). Such differences between functional plant groups are influenced by patterns of C partitioning and by efficiencies in P acquisition by their root systems (Jin et al , 2015).…”

Nitrogen inputs and losses in response to chronic CO<sub>2</sub> exposure in a subtropical oak woodland

“…Several experiments have demonstrated the importance of P availability for the responses of N 2 fixation to elevated CO 2 : the stimulation of growth and N 2 fixation by elevated CO 2 was higher with P addition for clover (Edwards et al, 2006), Azolla (Cheng et al, 2010), soybean (Lam et al, 2012), chickpea, and field pea (Jin et al, 2012). The CO 2 -stimulation of N-fixer growth and N 2 fixation in several grasslands experiments was higher with P addition compared to controls without supplemental P (Niklaus et al, 1998;Grunzweig and Korner, 2003).…”

“…(Smith, 1992). Responses of N-fixation to elevated CO 2 can be limited by availability of these nutrients (Niklaus et al, 1998;Jin et al, 2012). The response of N fixation to elevated CO 2 across multiple studies was only significant when non-N nutrients were added as fertilizer; without nutrient amendments, the effect of CO 2 on N fixation was negligible and not significant (van Groenigen et al, 2006).…”

Improving crop mineral nutrition

“…Below ground traits that influence the acquisition of mineral elements by plants include, (1) root characteristics, such as root elongation rate, lateral root production, specific root length (length/mass quotient), root length density (root length / soil volume), reduced metabolic load of roots (aerenchyma formation) and root hair length and abundance, all of which increase the volume of soil explored by the root system and the surface area for the uptake of mineral elements, (2) the proliferation of roots in discrete patches of soil containing greater concentrations of mineral elements, such as topsoil horizons rich in organic matter, (3) modification of rhizosphere pH and the exudation of low molecular weight organic solutes and/or enzymes, which influence the concentration of mineral elements in the soil solution, (4) high-capacity uptake systems for mineral nutrients, and (5) interactions with microbes either intimately, through mycorrhizal associations or nodulation by rhizobia, or loosely, through the culture of beneficial microbes or exclusion of detrimental microbes in the rhizosphere. None of these below ground traits work in isolation of one another and it is, therefore, important to consider (1) how they interact with one another , (2) how they interact with the environment (Oburger et al 2011;Jin et al 2012), and (3) how they interact with crop management practices (George et al 2011;Nazeri et al 2013).…”