LEAF GAS-EXCHANGE OF MANGO (MANGIFERA-INDICA L) CUTTINGS DURING ADVENTITIOUS ROOT-FORMATION

Two mango rootstock clones with different rooting ability of their lea fy cuttings were compared. Adventitious rooting was better in 'Terpent ine' than in '13-1'. Net CO2 assimilation rates (NAR) and transpiratio n rates (E) were measured when the cuttings were still attached to the mother plant and after excision during root formation under intermitt ent mist. Under natural light conditions in the mist bed (photon flux density (PFD) = 100 - 200 mumol m-2 s-1) NAR and E of both 'Terpentine ' and '13-1' cuttings dropped after excision from the stockplant. Call us formation and subsequent rooting was accompanied by enhanced CO2-up take by the leaves. This was not observed for cuttings that failed to root. Differences in photosynthetic activity of rooted and unrooted cu ttings were more pronounced for '13-1' as compared to 'Terpentine'. Ho wever, when a saturating light intensity (PFD = 1600 mumol m-2 s-1) wa s applied during the measurement the rise of NAR at the time of root e mergence was much higher for 'Terpentine' cuttings than for '13-1'.