DISTRIBUTION OF ASSIMILATES FROM THE FLAG LEAF OF RICE DURING THE REPRODUCTIVE PERIOD OF DEVELOPMENT

We studied the distribution of C-14-labelled assimilates from the flag leaf of rice (Oryza sativa L.) during the reproductive period in cult ivars with different morphotypes. At the outset of the reproductive pe riod-when the sink capacity of caryopses is slight-C-14-labelled assim ilates exported from the flag are deposited in the upper two stem inte rnodes. Thereafter, up to 95% of C-14-labelled assimilates synthesized by the flag enters the panicle, up to 84% being deposited in the endo sperm. Transport of C-14-labelled assimilates from the flag into the p anicle declines at the end of the reproductive period. Entry of C-14-l abelled assimilates from the flag into the lower internodes and tiller ing zone increases. In order to raise the influx of assimilates to car yopses at the last stages of ripening, the authors consider it possibl e to influence plants during this period through growth regulators tha t increase the sink capacity of the panicle.