Photophysiology of turion germination inSpirodela polyrhiza (L.)Schleiden. The cause of germination inhibition by overcrowding
1990; Institute of Experimental Botany of the Czech Academy of Sciences; Volume: 32; Issue: 6 Linguagem: Inglês
10.1007/bf02890887
ISSN1573-8264
AutoresKlaus‐J. Appenroth, W. Hertel, H. Augsten,
Tópico(s)Biocrusts and Microbial Ecology
ResumoRed-light-induced (via phytochrome) germination decreased with increasing numbers of turions per germination flask (overcrowding). Three hypotheses concerning the mechanism of this germination inhibition were tested, related to abscisic acid, ethylene, and oxygen deficiency: (i) Although abscisic acid is a powerful inhibitor of turion germination it had to be excluded as a cause, because abscisic acid was not secreted from turions into the nutrient solution, (ii) Ethylene (ethrel) strongly inhibited growth of newly formed sprouts, but germination response itself was not inhibited, (iii) Germination inhibition did not appear if short light pulses were substituted by continuous irradiation. It reappeared in the presence of the photosynthesis inhibitor 3-(3, 4-dichlorophenyl)-l, 1-dimethylurea, but it was not observed in aerated nutrient solutions, or when Petri dishes instead of Erlenmeyer flasks were used. Decreased oxygen concentrations in the nutrient solution were produced by turion respiration. Consequently, anaerobiosis within the nutrient solution caused by turion respiration was the reason for germination inhibition by overcrowding.
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