The effects of propagation environment and foliar area on the rooting physiology of Cordia alliodora (Ruiz & Pavon) Oken cuttings
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The effects of propagation microclimate and foliar area on the rooting of Cordiaalliodora (Ruiz & Pavon) Oken cuttings were investigated using non-mist propagators with and without shade. Photosynthetic rates (P n ), stomatal conductance (g s ) and chlorophyll fluorescence ratio (Fv/Fm) of the cuttings were assessed during propagation. Pronounced differences in microclimate were recorded between treatments, with lower temperatures and vapour pressure deficit (VPD) under shade. During the first 8 days after insertion, P n varied between 2.21 and 4.96 and 0.47 – 2.54 μmol CO2 m – 2s – 1 in the shaded and unshaded propagators, respectively. In the unshaded propagator, Fv/Fm decreased to a minimum of 0.72 2 days after insertion, recovering thereafter. In two separate rooting experiments, rooting percentage was reduced by high irradiance in the 20 and 30 cm2 leaf area treatments, but not in the 10 cm2 treatment. P n decreased with an increase in leaf area in both shaded and unshaded propagators. Fv/Fm also declined with increasing leaf area in the high irradiance treatment. PAR and P n were positively correlated under shade (r2 = 0.51) but negatively correlated in the unshaded treatment (r2 = 0.49); maximum P n values were recorded at a PAR of 400 μmol m – 2 s – 1. No significant differences in g s were found between treatments, values ranging between 130 and 194 mmol H2O m – 2 s – 1. Positive correlations were found between rooting percentage and mean Fv/Fm. These results indicate that rooting of C. alliodora cuttings is related to photosynthetic activity during propagation, which is itself influenced both by propagator microclimate and cutting leaf area.
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