Quantitative analysis of carbon balance in the reproductive organs and leaves of Cinnamomum camphora (L.) Presl

Abstract

We investigated seasonal changes in dry mass and CO(2) exchange rate in fruit and leaves of the evergreen tree Cinnamomum camphora with the aim of quantitatively determining the translocation balance between the two organs. The fruit dry mass growth peaked in both August and October: the first increase was due to fruit pulp development and the second to seed development. Fruit respiration also increased with the rapid increase in fruit dry mass. Therefore, the carbohydrates required for fruit development showed two peaks during the reproductive period. Fruit photosynthesis was relatively high in early August, when fruit potentially re-fixed 75% of respired CO(2), indicating that fruit photosynthesis contributed 15-35% of the carbon requirement for fruit respiration. Current-year leaves completed their growth in June when fruit growth began. Current-year leaves translocated carbohydrates at a rate of approximately 10-25 mg dry weight (dw) leaf(-1) day(-1) into other organs throughout the entire fruit growth period. This rate of translocation from current-year leaves was much higher than the amount of carbohydrate required for reproduction (ca. 3 mg dw fruit(-1) day(-1)). Given the carbon balance between fruit and current-year leaves, carbohydrates for reproduction were produced within the current-year fruit-bearing shoots. C. camphora would be adaptive for steadily supplying enough amount of carbohydrate to the fruits, as there was little competition for carbohydrates between the two organs. As assimilates by leaves are used for processes such as reproduction and the formation of new shoots, photosynthesis by reproductive organs is considered to be important to compensate for reproductive cost.

Possible Negative Effect of General Flowering on Tree Growth and Aboveground Biomass Increment in a Bornean Tropical Rain Forest

“…The fruits of some evergreen tree species have photosynthetic activity, although their contribution is generally low (Ogawa et al . , Imai & Ogawa ). Dipterocarp fruit wings have low photosynthetic ability (Kenzo et al .…”

Photosynthetic characteristics of leaves and fruits of Hickory (Carya cathayensis Sarg.) and Pecan (Carya illinoensis K.Koch) during fruit development stages

“…The dry mass/fresh mass ratio of fruits can be used to assess the different phases of fruit growth (Imai and Ogawa 2009). In present study, fruit development of hickory can be divided into two phases according to the fruit growth pattern.…”

“…Fruit respiration can be separated into two components: maintenance respiration, which supplies the energy necessary for maintaining a healthy existing phytomass and growth respiration, which is required for the synthesis of new phytomass (Amthor 1989(Amthor , 2000. Imai and Ogawa (2009) suggested that increased dark respiration on a fruit basis is related to the fast dry mass accumulation for the fruit and seed development. Thus, we suggest that the increase of R d on a fruit basis is due to the growth respiration by fruit and seed development.…”

“…This might be related to a higher photosynthetic capacity in pecan. Assimilates in leaves are usually used for current-year reproduction, maintenance and growth of woody parts or energy storage for reproduction and new shoot growth during the next growth season, while the photosynthesis by fruits is important to compensate for reproductive cost (Imai and Ogawa 2009). Thus, we suggest that fruit photosynthesis of hickory and pecan also play an important role in offsetting the costs of reproduction.…”

“…Photosynthesis of non-foliar green plant tissue can provide an important additional contribution to carbon requirements (Aschan and Pfanz 2003). Communicated Analysis of the time-course of photosynthetic rate in both leaves and fruits has the potential to quantitatively reveal temporal changes in carbon requirements for fruit development (Hieke et al 2002;Imai and Ogawa 2009). For example, Lychee fruit contribute about 3 % of the total carbon requirement during fruit development (Hieke et al 2002).…”