桶柑果實生長期間二氧化碳交換率之研究

Estimation of CO2 Exchange Rate in Developing Tankan Fruits

本試驗以LI-6200可攜式光合作用測定系統，調查田間桶柑植株果實在不同生長階段二氧化碳交換率之日（包括晝間遮光）、夜變化，並求得與溫度之迴歸關係，藉以計算呼吸率、光合作用速率及總淨呼吸損耗率。結果顯示，在9個月生長期間，以鮮重為基礎，各項交換率均於著果最初期最高，而隨果貿發育而漸次下降，至採收前為最低。呼吸率由0.49mg/g·FW·hr降至0.02mg/g·FW·hr ;光期下淨呼吸損耗率由0.32mg/g·FW·hr降至0.004mg/g·FW·hr;光合作用速率由0.16mg/g·FW·hr降至0.02mg/g·FW·hr ;總凈呼吸損耗率由0.55mglg FW·hr降至0.02mg/g·FW·hr。若以單粒果重為基礎，則均呈增加趨勢，但波動較大。本試驗証明果實具有光合成能力，能抵消部份日間呼吸損耗，其模式可為爾後估算碳帳之生理基礎。

Diurnal CO2 exchange rate of field-grown Tankan fruits were measured through their developmental penod to estimate respiration, photosynthesis and net total respiration loss. During fruit development, the rate of respiration under dark and light, photosynthesis and net total respiration loss declined markedly during first four months, then decreased near to zero on fresh weight basis, whereas increased continuously on fruit basis. It is suggested that fruit photosynthesis and total net respiration loss might be used to establish carbon 、budgetofTankan fruits in the future.