Folia Horticulturae

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Determination of the degree of using potential efficiency of the photosynthetic process in tomato production

Jerzy Mydlarz*, Włodzimierz Starzecki*, Andrzej Libik**

**Institute of Plant Physiology
**Polish Academy of Sciences
**Sławkowska 17, 31-016 Kraków, Poland
**Department of Vegetable Crops
**Faculty of Horticulture, Agricultural University
**29 Listopada 54, 31-425 Kraków, Poland

The actual photosynthetic activity was assessed three times during the vegetation period of plants of the tomato cultivar Sidonia grown in the greenhouse. The conditions of irradiation of a particular leaf, its position on the plant, and its spacial orientation were taken into account. The potential intensity of photosynthesis was determined by exposing the leaf to direct solar radiation, which secured the saturation of photosynthesis with radial energy.

Apart from the degree of shading, the main factors deciding the actual photosynthetic level in production are: the inactivation of the photosynthetic apparatus, increasing with the age of the leaf, and the decreasing potential efficiency of the photosynthetic process of young leaves, successively set on constantly ageing plants. The actual photosynthetic intensity of shaded leaves in a stand reaches 50-70% of its potential efficiency. The improvement of irradiation conditions by defoliation may result in a fuller use of the potential efficiency of the photosynthetic apparatus.

Mydlarz J., Starzecki W., Libik A., 1993. Determination of the degree of using potential efficiency of the photosynthesis process in tomato production. Folia Horticulturae V/1: 109-118.