CARBOHYDRATE-LEVELS AND ASSIMILATE TRANSLOCATION IN MANGOSTEEN (GARCINIA-MANGOSTANA L)

Diurnal variations in soluble sugar and starch levels in mature leaves of two-year-old mangosteen (Garcinia mangostana L.) seedlings with im mature, semi-mature, and mature terminal flushes were studied. Glucose , fructose, sucrose, and starch concentrations in leaf extracts increa sed significantly after midday, reaching a maximum at 1800 hours, rega rdless of the ontogenetic stage of the terminal flush. A time course s tudy of C-14-assimilate translocation and distribution in unbranched s eedlings with semi-mature terminal flushes showed that more than 49% o f C-14 activity was exported from the source (pulsed) leaf within 1 da y, with less than 16% remaining in the source leaf after 8 days. Immat ure flushes attracted more than 75% of C-14 within 3 days. When the sh oot system was non-flushing 53% of the total C-14 remained in the sour ce leaf after 3 days, with stems and roots exhibiting the strongest si nk activity. High translocation rates in flushing and non-flushing see dlings observed in this study suggest that assimilate production rathe r than translocation may be a major factor limiting the growth of mang osteen seedlings.