Photosynthetic acclimation to elevated CO2 concentration in a sweet pepper (Capsicum annuum) crop under Mediterranean greenhouse conditions: influence of the nitrogen source and salinity

Abstract

In many plant species, long-term exposure to elevated CO2 concentration results in a reduction in photosynthetic capacity, known as acclimation. This process is mainly explained by a feedback inhibition mechanism. The supply of a fraction of the nitrogen (N) in the nutrient solution as NH4+ can play an important role in the maintenance of photosynthetic activity and could mitigate the acclimation process. The aims of the present work were to study the photosynthetic response of sweet pepper (Capsicum annuum L.) to CO2 enrichment in Mediterranean greenhouse conditions, throughout the crop growth cycle and to evaluate the supply of NH4+ in the nutrient solution as a strategy to enhance the long-term response to CO2 at different levels of salinity. The experiment was conducted in two identical greenhouses: one with CO2 enrichment according to the ventilation, maintaining a high concentration when the vents were closed and a near-atmospheric level when the vents were open and one without. Sweet pepper plants were grown in both greenhouses, being irrigated with two levels of water salinity and two N sources: (i) NO3– and (ii) NO3– plus NH4+. A reduction in the response of photosynthesis to high CO2 concentration was found in the enriched plants after 135 days of CO2 supply, with respect to the reference plants. The leaf photosynthesis rate measured at high CO2 concentration showed a closer relationship with the leaf N concentration than the non-structural carbohydrate concentration. The relative yield gain of the CO2-enriched plants progressively decreased after reaching a maximum value; this was probably associated with the photosynthetic acclimation process. This decrease was delayed by the use of NH4+ in the nutrient solution at low salinity. Knowledge of the crop phase when acclimation to high CO2 concentration occurs can be the basis for deciding when to impose an early cessation of CO2 application, as a strategy to improve the economic efficiency of CO2 supply in Mediterranean conditions.

CO2 fertilization does not affect biomass production and nutritive value of a C4 tropical grass in short timeframe

“…This is enough to saturate RuBisCO and prevent any increase in CO 2 uptake with CO 2 fertilization (Von Caemmerer & Furbank, ). On the other hand, we have to consider that short‐term exposure to eCO 2 could be one of the reasons for the lack of response, although long‐term exposure to eCO 2 often results in a reduction of photosynthetic capacity due to an inhibition mechanism called photosynthetic acclimation process (Porras et al, ).…”

Fiber fractions, multielemental and isotopic composition of a tropical C4 grass grown under elevated atmospheric carbon dioxide

“…Using this strategy, C 4 species can concentrate CO 2 at the active site of the ribulose-1,5-bisphosphate carboxylase-oxygenase (RuBisCO) (Sage, 2004) and be virtually CO 2 saturated even at the current atmospheric CO 2 concentration (Tom-Dery et al, 2018). In addition, photosynthetic capacity of many plant species reduced, when they were exposed to elevated CO 2 due to an inhibition mechanism called photosynthetic acclimation, generally attributed to an alteration in the balance of the supply and sink of assimilates leading to increased nonstructural carbohydrates content in the leaves (Drake, González-Meler & Long, 1997; Porras et al, 2017). However, indirect effects of elevated CO 2 can increase leaf CO 2 assimilation rate and growth of C 4 species via increases in intracellular partial pressure, changes in fixation patterns, improvements of shoot water relations, and increases in leaf temperature (Ghannoum et al, 2000).…”

CO2 op zoek naar de grens : Literatuur- en modellenstudie

“…Het is dus van belang dat alle stappen in de keten effectief werken anders wordt de CO 2 -gradient kleiner, krijgt Rubisco een lagere affiniteit, etc. Ook groei en sinksterkte van niet-fotosynthetiserende organen, aan het eind van de keten, heeft invloed op de CO 2 -transportsnelheid Porras et al (2017). voeren een discussie of de ophoping van assimilaten door sinklimitatie een rol speelt bij minder efficiënte CO 2 -assimilatie in de loop van de teelt bij hoog-CO 2 behandelingen.…”