Leaf area index and light distribution in olive tree canopies (Olea europaea L.)
By: Mouna Aïachi Mezghani, Gouta Hassouna, Laaribi Ibtissem, Foued Labidi
Key Words: Olive tree, Vase form, LAI, Photosynthetically active radiation, ratio PART/PARI.
Int. J. Agr. Agri. Res. 8(5), 60-65, May 2016.
The leaf area index (LAI) and the spatial leaf arrangements are the main factors which influenced the radiant energy distribution within the tree. The leaf area index has been shown to be an important factor of the olive productivity. Although, the photosynthetically active radiation intercepted by leaves (PAR) is the main environmental factor that determined the dry matter production, which is the main source of energy for the photosynthesis. Therefore, a commercial sensor for LAI determination (Sun scan DELTA-T Devices Ltd), was tested for olive trees, in an olive orchard located near Sousse, central Tunisia (36N, 10E). The plants were cultivated at 7m × 7m and trained on vase system. Measurements were made at two tree’s layers; on lower and upper part of the canopy and on the four cardinal directions (north, south, east and west). The results showed that the LAI was more important on the lower part of the canopy than on the upper one for all directions. LAI was also higher on South and East side of tree. The Incident Photosynthetically Active Radiation PARI, was quite constant for all directions. However, the transmitted fraction PART decreased inside the tree canopy. The lower part of the canopy was less shaded for the vase tree form. There is a significant negative relationship between LAI and ratio PART/PARI. These results will be the fundamental basis of the olive pruning basis and to establish new intensive olive orchards with fully developed canopies which intercepted the maximum solar radiation.