Phenological changes in rate of respiration and annual carbon balance in a perennial herbaceous plant, Primula sieboldii

Abstract

Primula sieboldii E. Morren is a clonal herbaceous species with a short foliar period from spring to early summer. We have studied the temperature-dependence of the rate of respiration at the whole-ramet level throughout the phenological stages of P. sieboldii to reveal its photosynthate-utilization strategy. P. sieboldii ramets were grown in a chamber enabling simulation of seasonal changes in temperature. Rates of respiration were measured at three phenological stages--the foliar period, the before-chilling defoliated (BCD) period, and the after--chilling defoliated (ACD) period. In the foliar period the rate of respiration, on a biomass basis at 20 degrees C (R (20)), of the above-ground plant parts was 2.5 times that of the below-ground parts. The R (20) of the below-ground parts in the foliar period was 6.5 times that in the BCD period and 1.6 times that in the ACD period. Estimation of the ramet carbon balance under these growth conditions showed that ramets respired 87% of total photosynthate production during the experimental period (8.5 months). Respiratory consumption in the foliar period accounted for 70% of the yearly total, whereas 24 and 6% were consumed in the BCD and ACD periods, respectively. An extremely low rate of respiration during the long defoliated period led to a positive net annual carbon balance for P. sieboldii ramets.

Characteristics of leaf photosynthesis and simulated individual carbon budget in Primula nutans under contrasting light and temperature conditions

“…CO 2 uptake was calculated from microsite light and temperature data measured at 1-min intervals from June to August and from the photosynthetic parameters obtained under different light and temperature conditions of plants growing in the field. Root respiration was estimated from the leaf dark respiration rate in this study and respiration ratio of leaf to root derived from Noda et al (2007) and the biomass ratio of leaf to root obtained by Shen et al (2006). Data of 44 days from 16 sites (five sites from hummock and 11 sites from hollow) were used for the simulation gain (Kikuzawa 1995(Kikuzawa , 2003, while A max changes often with leaf aging, in particular in leaves in the open (e.g., Mediavilla and Escurdero 2003).…”

“…(2) calculated the leaf carbon loss (R leaf ) from leaf dark respiration by assuming that daytime and nighttime respirations were the same function of temperature; (3) estimated the carbon loss due to root respiration (R root ) from the mean root dry weight and soil temperature measured in the study, by using the respiration-temperature relationship from Noda et al (2007) under the assumption that a mass-based respiration is the same in P. nutans and P. sieboldii. The daily net carbon gain was obtained by GPP -R leaf -R root .…”

“…(2) the root respiration rate under different temperature conditions, which was estimated from the ratio of leaf dark respiration to root respiration of congeneric species Primula sieboldii derived from Noda et al (2007) and from the leaf dark respiration rate obtained from our field plants;…”

“…Even for the genus Primula there are only a few reported studies dealing with photosynthesis (Whale 1983;Combe et al 1993;Noda et al 2004Noda et al , 2007. Whale (1983) reported that the maximum photosynthetic rate of three Primula species declined steadily as the growing season advanced; this suggests the importance of early spring in the carbon economy of these species.…”

“…Whale (1983) reported that the maximum photosynthetic rate of three Primula species declined steadily as the growing season advanced; this suggests the importance of early spring in the carbon economy of these species. Noda et al (2004Noda et al ( , 2007 found that photosynthetic and respiration characteristics of Primula sieboldii are highly dependant on environmental temperature.…”