¹⁴C distribution in lemon plants

Summary14 C distribution patterns were studied on small potted trees under glasshouse conditions by supplying 14 CO2 to selected source leaves for 24 hours and then preparing autoradiographs of the entire shoots. Experiments covered the period from the emergence of new growth, through flowering and fruit-set, up to the stage of fruit maturity.Newly emerged growth drew 14 C assimilates from both current photosynthesis and stored substrate. Developing leaves represented strong sinks and did not become contributing organs until fully mature. Flowers also represented uniformly strong sinks for assimilates although after fruit-set some discrimination existed between adjacent fruitlets with respect to their ability to import assimilates. The developing fruit continued to act as sinks for assimilates up to the time of harvest.14 C assimilate turnover in mature leaves following a brief exposure to 14 CO2 was sluggish, despite the presence of developing shoots in the leaf axils. The removal of 14 C photosynthate w...