桶柑果實發育期間碳帳及所需最少葉片數之估算

Estimation of Carbon Budget and the Minimum Leaf Number for Sustaining the Growth of Developing Tankan Fruits

調查田間桶柑植株果實生長期間獲碳量與理碳量之變化，藉以計算碳帳並求得供給果實生長所需最少葉片數，作為決定結果密度之生理基礎。結果顯示果實在採收前仍持續生長，供給果實生長之碳源90%來自果實以外，果實本身之光合作用提供10%，而果實所得到之碳量有17%用於呼吸損耗，餘83%以乾重方式累積。假設在無其它積貯器官與果實競爭碳同化物的前提下，經由葉片供給果實碳量、與葉片光合成能力，估計出供給一粒成熟時鮮重236克、乾重37克的中大型果實生長所需最少葉片數，在高峰期為39葉；若換算為鮮重200克、乾重32克的中型果實則需33葉。

The carbon supply and cost of field-grown Tankan fruits were measured through their developing period to establish carbon budget and to estimate the minimum number of leaves required for sustaining the growth of fruits. Dry material accumulated in the fruit continuously until the harvest date. On average, fruit photosynthate accounted for 10% of carbon supply for fruit growth, and other sources accounted for the remaining 90%. For the carbon cost, 83% of the total carbon was accumulated as dry material whereas the remaining 17% comprised of the respiratory carbon loss. Supposing the leaves born on current spring-flush were the only exogenous source for supplying carbon to the growing fruit and the growing fruit was the only sink for photosynthate, the minimum number of leaves required for sustaining a fruit of 236g fresh weight or 37g dry weight at maturation was 39 during maximum fruit-growth period, and it was 33 for a fruit of 200g fresh weight or 32g dry weight.