Folia Horticulturae

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Carbon dioxide exchange in tomato cluster peduncles and fruits

Marian Czarnowski, Włodzimierz Starzecki

Institute of Plant Physiology
Polish Academy of Sciences
Sławkowska 17, 31-016 Kraków, Poland

The rate of carbon dioxide exchange in tomato cluster peduncles and fruits was determined at various development stages depending on irradiation intensity and CO2 concentration. At light saturation, the photosynthetic rate in young cluster peduncles reached 5 mg CO2 h-1 g-1 dry weight but only 3.5 mg CO2 h-1 g-1 in older ones. The dark respiration rate was very high (-2.8 mg CO2 h-1 g-1 dry weight) in young fruits, but fall about 50% after 2 hrs in the dark. Net photosynthesis in green tomato fruits, irrespective of their size, occurred below the gas exchange compensation point (-0.2 mg CO2 h-1 g-1 dry weight). However, the gross photosynthetic rate per fruit surface area was 15 to 30% of the photosynthetic rate in tomato leaves. It was show that photosynthesis in tomato fruits did not counterbalance their endogenic dissimilation processes, no photosynthetic CO2 assimilation being observed even under optimum conditions (i.e. by increased CO2 concentration and high irradiation intensity).

Czarnowski M., Starzecki W., 1990. Carbon dioxide exchange in tomato cluster peduncles and fruits. Folia Horticulturae II/1: 29-39.