(CO2)-C-14 FIXATION AND ALLOCATION OF C-14 INTO MAJOR BIOCHEMICAL FRACTIONS IN DIFFERENT PARTS OF INDIAN MUSTARD (BRASSICA-JUNCEA)

(CO2)-C-14 fixation and transport of C-14-photosynthates amongst diffe rent parts of Indian mustard [Brassica juncea (L.) Coss.] and the inco rporation of C-14 into major chemical fractions in different plant par ts was studied at ripening stage. Leaves, stem and pod were equally im portant as sources of carbon for developing seeds. Stem and pod togeth er contributed 70 % of the total C-14 fixed by the plant. In all plant parts neutral saccharide fraction contained maximum radioactivity imm ediately after exposing plants to (CO2)-C-14. After 24 h, the radioact ivity in this fraction declined considerably due to translocation or c onversion into other fractions. Concomitantly radioactivity in lipids and pigments, residue and starch fractions increased after 24 h. The C -14 allocation patterns in stem and leaves were similar. However, in p ods very high radioactivity was recovered from amino and organic acid fractions indicating the presence of active phosphoenolpyruvate carbox ylase in pod walls.