Changes in Water Relations, Solute Leakage and Growth Characters During Seed Germination and Seedling Development in Trigonella coerulea (Fabaceae)

Akhalkatsi, Maia and Lösch, Rainer (2001) Changes in Water Relations, Solute Leakage and Growth Characters During Seed Germination and Seedling Development in Trigonella coerulea (Fabaceae). Journal of Applied Botany and Food Quality, 75 (3/4). pp. 144-151. ISSN 1613-9216

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Changes in water and osmotic potential, water content and dry mass were studied that proceed during seed imbibition, germination, and seedling development under constant environmental conditions in Trigonella coerulea. Germination percentage of seeds imbibed in mannitol solutions (0MPa to -2 MPa) declines with decreasing substrate water potential. Germination is completely suppressed at -1.0 MPa. Germination time becomes prolonged from 48 h at 0 MPa to 96 h at – 0.5 MPa. Changes in water relations, water content and dry mass of the seed and seedling tissues, quantified by pressure-volume analysis, can be paralleled with morphogenetic phases and physiological events during germination and seedling growth. The lowest osmotic potential at water saturation, -2.6±0.35 MPa, is reached when the radicle emerges, on the third day after imbibition started. After a transient increase osmotic and water potential decline again when the seedlings have attained the photoautotrophic growth, approx. one week after the imbibition commenced. Only then dry mass of the antire seedling increases whereas during radicle and hypocotyl elongation a decrease of dry weight was obvious. Leakage of phenolic substances and probably also solutes to the surrounding started about six hours after the seeds began to swell, accompanied by a transient decrease in seed water content. Otherwise, seed resp. seedling water contents increased with saturation type kinetics in two steps, the first lasting from seed imbibition until hypocotyl development, the second comprises the time period of the development of cotyledons and primary leaves. Substances released from the imbibing seeds are tannins and various flavonoids. Only seeds releasing these substances germinate successfully, from hard-seeded ones and from imbibed ones without solute exudation never a radicle emerges. Interindividual variation of the water relation parameters is considerable, but general trends of increase and decrease follow allows the same pattern. This variation may be an important selection factor under field conditions offering different chances for survival and successful establishment among a population of germinating seeds.

Item Type: Article
Subjects: Q Science > Conservation Biology
Q Science > QK Botany
Depositing User: Prof.Dr. Maia Akhalkatsi
Date Deposited: 17 Mar 2014 05:54
Last Modified: 17 Mar 2014 05:54

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