DRY-MATTER PRODUCTION AND TRANSLOCATION O F C-13-ASSIMILATES IN TARO (COLOCASIA-ESCULENTA SCHOTT) PLANTS GROWN FROM STANDARD CORMS AND THOSE PROPAGATED BY IN-VITRO CULTURE

Taro plants grown from 1g corms propagated by in vitro culture (IF pla nts) and those grown from standard 50g corms (ST plants) were compared with respect to dry matter production, their partitioning and the tra nslocation of assimilates for 24hr after exposure to (CO2)-C-13. 1. Th e relative growth rate (RGR) of IP plants was faster than that of ST p lants. 2. IP plants exhibited a faster net assimilation rate than did ST plants except between April 4 to May 20 when the rate was equal and from Sept. 24 to Oct. 14 when IP plants had a slower NAR than did the ST plants. 3. IP plants partitioned more dry matter to corm and corme ls than was retained by the foliage during the early growth stage. In ST plants, conversely, more dry matter was retained in the foliage dur ing the first half of the growing season. 4. Although almost 70% of th e total C-13-labelled assimilates translocated to the corm and cormels in IP plants on July 14, only 35% of them did in ST plants. 5. The am ount of recoverable C-13-labelled assimilates retained by the foliage of ST plants on September 9 (44.1%) was less than that detected on Jul y 14 (58.3%); thus, a significant amount always remains unexported in the foliage. 6. The increase of cormel number in IP plants strengthens the sink demand compared with that of ST plants. It also seems that s ink strength of cormels is relatively stronger than corm in IP plants. 7. The rapid accumulation of assimilates by cormels of IP plants is a ttributed to their fast growth rate.