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• Stress physiology of palm trees II. The effect of heavy metals and high irradiance on the photosynthesis of palm Trachycarpus fortunei

  84-88.

  A. Neményi

  J. Kissimon

  M. Droppa

  M. Baron

  G. Horváth

  Views:

  164

  A study was carried out to analyse the individual and combined effects of heavy metal toxicity and high irradiance on the photosynthetic characteristics of young, fully expanded leaves of palm seedling Trachycarpus fortunei under laboratory conditions. Heavy metals were found to inhibit both the light and dark reactions of photosynthesis and the inhibition was more affected in the light than in the dark. Single photoinhibitory conditions caused a 60 % decrease in the electron transport activity after 120 min of light exposure which was completely reversible in the dark. In contrast, the combined effect of high light and heavy metal treatment resulted in a 90 % decrease in the activity, but no reversible recovery in the dark could be detected. This indicated that the simultaneous effect of these two stress factors led to irreversible damages of the photosynthetic machinery and as a consequence caused the general destruction of the plant.

  Abbreviations and symbols: F_o: initial chlorophyll fluorescence; F_m: maximum total fluorescence; F_v: variable fluorescence; AFi: intermediate level of fluorescence induction; PSII: photosystem 2.

   

• Relationship between flowering, fruit setting and environmental factors on consecutive clusters in greenhouse tomato (Lycopersicon lycopersicum (L) Karsten)

  111-116.

  Z. Pék

  L. Helyes

  Views:

  146

  The main season of greenhouse tomato begins late winter or early spring in the northern Temperate Zone. During this period decisive environmental factors affect flowering and fruit setting.

  In the present experiments, progress and dynamics of greenhouse tomato flowering and fruit set were examined in 1999 and 2001 spring. The beginning and the end of flowering and fruit set, the number of flowers and fruits set in each cluster were recorded. Flowering and fruit set characteristics were analysed with respect to the accumulated PAR and temperature were calculated for each cluster. One flower required 31.3 mol M^-2 of accumulated PAR and 38 °C of sum temperature as an average for anthesis. One fruit required 27.9 mol m^-2 of accumulated PAR and 33.3 °C of sum temperature as an average for fruit setting.