ISHS Acta Horticulturae 559: V International Symposium on Protected Cultivation in Mild Winter Climates: Current Trends for Suistainable Technologies
INFLUENCE OF SHOOT BENDING ON THE PHOTOSYNTHETIC CAPACITY OF A GREENHOUSE ROSE (ROSA HYBRIDA) CANOPY |
| Authors: | R.P. Gutiérrez Colomer, M.M. González-Real, A. Baille |
| Keywords: | Rosa hybrida cv. Dallas, photosynthetic parameters, light absorption, modelling |
| Abstract:
The effect of shoot bending on leaf photosynthetic capacity and light absorption was studied in a rose crop (Rosa hybrida cv. Dallas) growing under greenhouse conditions in Southern Spain. Maximum net assimilation (Alm) at saturating light was measured on mature leaves located at different layers along the flower stem and bent shoots. A biochemical model of leaf photosynthesis was parameterised for each layer of leaves, supplying values of the photosynthetic Rubisco capacity (Vlm) and the maximum rate of electron transport (Jm). Maximum values of Alm decreased from 16.4 μmolCO2m-2s-1 for the upper leaves of the flower stem to 10.0 μmolCO2m-2s-1 for the upper leaves of the bent shoots. Similarly, Vlm decreased from 68.4 μmolCO2m-2s-1 to 51.5 μmolCO2m-2s-1. A rather constant value of the ratio Jm/Vlm was found throughout the plant. The photosynthetic capacity of the flower stem leaves appears to acclimate to the time-averaged light profile, although the influence of internal plant control due to the presence of a main assimilate sink (flower bud) could not be excluded. The photosynthetic capacity of the bent shoots decreased dramatically (Vlm about 30 μmolCO2m-2s-1 for the lower bent shoots) as they increased in age and became more shaded. These results suggest that the bent shoots must be renewed at regular time intervals. | |
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