Day-length effects on carbon stores for respiration of perennial ryegrass
Author for correspondence:
Christoph Andreas Lehmeier
Tel: +49 8161 714136
- •The mechanism controlling the use of stored carbon in respiration is poorly understood. Here, we explore if the reliance on stores as respiratory substrate depends on day length.
- •Lolium perenne (perennial ryegrass) was grown in continuous light (275 μmol photons m−2 s−1) or in a 16 : 8 h day : night regime (425 μmol m−2 s−1 during the photoperiod), with the same daily photosynthetic photon flux density (PPFD). Plants in stands were labelled with 13CO2 : 12CO2 for various time intervals. The rates and isotopic signatures of shoot- and root-respired CO2 were measured after labelling, and water-soluble carbohydrates were determined in biomass. The tracer kinetics in respired CO2 was analysed with compartmental models to infer the sizes, half-lives and contributions of respiratory substrate pools.
- •Stores were the main source for respiration in both treatments (c. 60% of all respired carbon). But, continuous light slowed the turnover (+270%) and increased the size (+160%) of the store relative to the 16 : 8 h day : night regime. This effect corresponded with a greatly elevated fructan content. Yet, day length had no effect on sizes and half-lives of other pools serving respiration.
- •We suggest that the residence time of respiratory carbon was strongly influenced by partitioning of carbon to fructan stores.