Impairment of C4 photosynthesis by drought is exacerbated by limiting nitrogen and ameliorated by elevated [CO2] in maize

Abstract

Predictions of future ecosystem function and food supply from staple C(4) crops, such as maize, depend on elucidation of the mechanisms by which environmental change and growing conditions interact to determine future plant performance. To test the interactive effects of elevated [CO(2)], drought, and nitrogen (N) supply on net photosynthetic CO(2) uptake (A) in the world's most important C(4) crop, maize (Zea mays) was grown at ambient [CO(2)] (∼385 ppm) and elevated [CO(2)] (550 ppm) with either high N supply (168 kg N ha(-1) fertilizer) or limiting N (no fertilizer) at a site in the US Corn Belt. A mid-season drought was not sufficiently severe to reduce yields, but caused significant physiological stress, with reductions in stomatal conductance (up to 57%), A (up to 44%), and the in vivo capacity of phosphoenolpyruvate carboxylase (up to 58%). There was no stimulation of A by elevated [CO(2)] when water availability was high, irrespective of N availability. Elevated [CO(2)] delayed and relieved both stomatal and non-stomatal limitations to A during the drought. Limiting N supply exacerbated stomatal and non-stomatal limitation to A during drought. However, the effects of limiting N and elevated [CO(2)] were additive, so amelioration of stress by elevated [CO(2)] did not differ in magnitude between high N and limiting N supply. These findings provide new understanding of the limitations to C(4) photosynthesis that will occur under future field conditions of the primary region of maize production in the world.

Baixa temperatura noturna e deficiência hídrica na fotossíntese de cana‑de‑açúcar

“…No entanto, houve aclimatação das plantas no início do período de recuperação, ou seja, os valores de V pmáx se igualaram aos verificados em TN20 (Figura 3 C). Alguns estudos também mostraram a redução na atividade da PEPcase com a diminuição do conteúdo de água no solo (Du et al, 1996;Markelz et al, 2011) e com a baixa temperatura noturna (Kakani et al, 2008;Soares-Cordeiro et al, 2010).…”

The Influence of Climate Change on Global Crop Productivity

“…For example, heat-induced shortening of the grain-filling stage could limit the benefits from higher CO 2 ; conversely, improved water-use efficiency from higher CO 2 may help to reduce negative impacts of VPD increases or rainfall declines. Decades of plotlevel (Kim et al, 2007;Shimono et al, 2007;Markelz et al, 2011) and open-air field Wall et al, 2006;Zhu et al, 2011) experiments as well as simulation modeling exercises (Long, 1991;Brown and Rosenberg, 1997;Grant et al, 2004) have been dedicated toward understanding the net impact of interactions between competing global change mechanisms at small scales. However, the results have not always been conclusive, especially at regional scales relevant for projecting the future response of overall crop production to changing environmental conditions.…”

Adapting maize production to climate change in sub-Saharan Africa

“…However, elevated CO 2 concentration will decrease evapotranspiration (and increase water use efficiency) through the partial closure of stomata (Žalud and Dubrovsky 2002). While this may increase soil water availability and delay the onset of drought, partial stomatal closure will also decrease transpirational cooling and is likely to result in an increase in canopy temperature (Markelz, et al 2011). It is highly likely that the combination of drought and heat stress will increase in many areas of SSA.…”