Seasonal courses of CO2 exchange and carbon balance in fruits of Cinnamomum camphora

Abstract

Carbon dioxide exchange in fruits of Cinnamomum camphora Sieb. was followed over a growing season from July to December 1992. Dark respiration was exponentially related to temperature, with a Q(10) value near 2. Light dependence of photosynthetic CO(2) refixation, i.e., the ratio of gross photosynthesis to dark respiration, was approximated by a hyperbolic function. Seasonal variation in maximum CO(2) refixation capacity ranged between 52 and 174%, reaching a maximum in early August. Daily photosynthetic CO(2) refixation ranged between 17 and 51% over the growth period. We evaluated seasonal variation in translocation rate to the fruit on the basis of the seasonal rates of gross photosynthesis, dark respiration and increase in fruit dry weight, and used the results to develop a simple carbon flow model of fruit development. Seasonal changes in translocation rate paralleled those in fruit growth rate, with two peaks during the periods before and after September. Seed formation took place in the period between the two peaks. The relationship between fruit growth rate and translocation rate was approximated by a linear function. The carbon flow model estimated that, over the reproductive period, the amount of assimilate translocated to each fruit was 377.2 mg dry weight, of which 58.5% was accounted for by weight growth and 41.5% was consumed by net respiration. Carbon dioxide refixation accounted for 22.9% of the carbon balance of the fruit.

Phonological characteristics of reproduction and seed formation in Durio zibethinus Murray

“…(1) can be regarded as the maximum relative growth rate (RGR). The values of 0.419 to 0.794 week -1 in the present species were higher than the maximum RGRs in other species: 0.303 week -1 in Pinus sylvestris strobili from sub arctic areas (Linder and Troeng 1981) and 0.342 week -1 in Cinnamomum camphora fruits from temperate areas (Ogawa and Takano 1997). Since there is no thermal seasonality in the humid tropics, it is thought that fruit, as well as the trees themselves, grow vigorously in tropical areas.…”

Quantitative analysis of carbon balance for reproduction in woody species

“…In the published data sets, respiration loss was seasonally determined in the dark at an air temperature equal to mean daily temperature (Bazzaz et al 1979;Ogawa and Takano 1997), or a certain air temperature, considering that Q 10 of respiration is about 2 (Linder and Troeng 1981; Koppel et al 1987;Dick et al 1990;Birkhold et al 1992). Photosynthesis was seasonally assessed at saturated light intensity (1,000 µ mol m -2 s -1 , Birkhold et al 1992), at average daily light intensity (700 µ mol m -2 s -1 , Bazzaz et al 1979), or at several light intensities (Linder and Troeng 1981; Koppel et al 1987;Dick et al 1990;Ogawa and Takano 1997).…”

“…Photosynthesis was seasonally assessed at saturated light intensity (1,000 µ mol m -2 s -1 , Birkhold et al 1992), at average daily light intensity (700 µ mol m -2 s -1 , Bazzaz et al 1979), or at several light intensities (Linder and Troeng 1981; Koppel et al 1987;Dick et al 1990;Ogawa and Takano 1997). Daily values for photosynthesis were calculated from the photosynthesis measured at a certain light intensity during daytime (Bazzaz et al 1979), or on the assumption of a 12-h photoperiod (Birkhold et al 1992).…”

“…Daily values for photosynthesis were calculated from the photosynthesis measured at a certain light intensity during daytime (Bazzaz et al 1979), or on the assumption of a 12-h photoperiod (Birkhold et al 1992). On the other hand, daily values for photosynthesis were calculated from a lightresponse curve that assumed the photon flux densities above the stand were reduced by 25% (Linder and Troeng 1981;Dick et al 1990), 20% (Koppel et al 1987), or not reduced at all (Ogawa and Takano 1997) to give a reasonable estimate of the light conditions at a level where most of the reproductive organs were found in the canopy. Because the estimation of respiration and photosynthesis is basically the same among the published data sets, there are no problems for using the published data listed in Table 1 in the present analysis.…”

“…In the present paper, the carbon balance in reproduction over the whole reproductive period was estimated on 20 woody species by applying the translocatory model (Ogawa et al 1996;Ogawa and Takano 1997) to the published data ( Table 1). The estimated carbon balances of the 20 species were used to analyze the quantitative interrelationships among dry weight growth, CO 2 exchange, and translocation in the reproductive organs.…”