Environment-acidification-induced Changes in the Level of Endogenous Cytokinins, Gibberellins and Ethylene Production by Spruce (Picea abies (L.) Karst.) Seedlings

1991

S. 889-898

28 Lit. Ang.

Unselbständiges Werk

200062066

The effect of artificial acid rain on the time course of changes in endogenous cytokinin and gebberellin activities was investigated in short- term experiments in spruce seedlings. The seedlings grown in nutrient solution under controlled climatic conditions for one month were exposed to the effect of artificial acid rain in the form of 0.05 mol sulphuric acid at pH 1.6. The activity of endogenous cytokonins and gibberellins was analysed in epicotyls of initial seedlings (control) and after their influence by acid rain. The interval of analyses following the acid rain application was 24, 48 and 72h in the first group of seedlings. In the second group the spray was repeated after 24h and the changes in activities were analysed after 24 and 48h. In the first group the activity of endogenous cytokinins was increased by acid rain within 24 and 48h intervals and the decrease occured after 72h. In the case of repeated acid rain effect (the second group of seedlings) the decrease in cytokinin activities appeared both after 24 and 48h (Fig.1). The activity of endogenous gibberellins in the first group of seedlings decreased after 24h and incteased after 48 and 72h. Repeated spraying was responsible for increased activity of gibberellins (Fig.2). Furthermore, ethylene production by spruce seedlings was under investigation. Analogously to the previous experiments, the seedlings were precultivated in nutrient solution under controlled climatic conditions. The seedlings were exposed to increased root environment acidity at pH 3.0 (control pH 5.6). The ethylene produced by seedlings was measured after 1, 8 and 10 days. Within these days ethylene production was analysed in 1 to 7h intervals following the transfer of seedlings in air proof chambers. In all intervals under study the ethylene production was higher in seedlings influenced by increased root environment acidity (Fig.3). The ethylene production decreased in time during one day of measurement and the decrease was recorded from the 8th to 10th day, as well. Stress ethylene production is typical for numerous stimuli exerting their negative influence on plants. In this case spruce reactivity on enhanced root environment acidity was confirmed which can be used in diagnostics. The spruce seedlings precultivated in nutrient solutions for 6 months under controlled climatic conditions were exposed to chlorethylphosphonic acid (0.01 and 0.1% CEPA) sprayed on needles once a week. Simultaneously with this treatment, a half of seedlings was subjected to artificial acid rain in the form of 0.02 mol sulphuric acid at pH 2.0. The effect of CEPA was realized on the basis of consideration that CEPA intervening in ethylene production and thus in the plant defence system could modify enhaced acidity effects. After 4 months the growth parameters of seedlings were evaluated. CEPA stimulated the fresh, dry matter ....