Abstract. The aim of this study was to determine the germination characteristics of Phillyrea angustifolia L. and P. latifolia L. seeds in order to develop an optimized propagation protocol for Phillyrea species. Seeds of P. angustifolia and P. latifolia were collected from wild plants growing in Cáceres province (CW Spain) and Andalucía (S Spain), respectively. Percentage of water uptake for P. latifolia seeds was calculated. Seeds with and without endocarp were germinated at different constant and alternating temperatures. Seeds without endocarp were soaked in distilled water or gibberellic acid, and then set to germinate. Seeds with endocarp of both species were stratified at 5 ºC for 30 or 90 days and then the endocarp was completely removed from the seeds before they were sowed. Chemical scarification with sulfuric acid and mechanical scarification were tested on P. angustifolia seeds with endocarp. Phillyrea endocarp was permeable to water, since Phillyrea seeds with endocarp imbibed water, but water uptake was faster when the endocarp was removed. Moreover, the encodarp could interfere mechanically in the emergence of the radicle, since seed germination of Phillyrea species was promoted by the complete removal of the lignified endocarp surrounding each seed. Optimal germination temperature for both species was 15 ºC, and lower temperatures produced secondary dormancy. Soaking in distilled water or gibberellic acid did not significantly enhance seed germination. Cold stratification and chemical scarification treatments were detrimental for seed germination.

No abstract

No abstract

Plantago albicans L. (Plantaginaceae) is a perennial herbaceous plant widely distributed throughout the Mediterranean region. The germination requirements (under different controlled conditions of light and temperature, and after two pre-sowing treatments) and tolerance to osmotic stress (polyethylene glycol, PEG 6000) and salinity (NaCl) of P. albicans seeds were studied. Seeds were germinated under constant temperatures (5°C, 10°C, 15°C, 20°C, 25°C and 30°C) and alternating temperature regimes of 20/10°C and 25/15°C with a 16 h/8 h light/dark photoperiod. The outer layer of seeds become mucilaginous when wetted and the presence of mucilage on seeds significantly increased germination percentages at all temperatures tested. P. albicans seeds were non-dormant and temperature significantly affected germination percentages and germination rate (germination velocity expressed as mean germination time, MGT). The final germination percentages ranged from 34% to 89% for intact seeds (seeds with mucilage) and from 9% to 62% for demucilaged seeds, depending on the temperature. Temperatures of 25°C and 25/15°C gave the highest germination percentages. Light did not affect seed germination at both temperature regimes assayed (25°C and 25/15°C). Germination percentages of seeds soaked for 24 h in distilled water or in a gibberellic acid (GA3) solution were not significantly higher than that of untreated seeds. In general, both the final germination percentage and germination rate were reduced by increasing salinity and PEG concentration. Seeds germinated in up to 35% PEG and 300 mmol·L–1 NaCl. Recovery of germination for seeds when transferred to distilled water after being in PEG or salinity treatments for 15 days was quite high, suggesting that P. albicans seeds are tolerant to osmotic and salt stresses.

We studied the variability of germination, dormancy and viability loss of Hirschfeldia incana seeds in relation to seed size. Seeds were stored at 35°C under humid [75% relative humidity (RH)] or dry (33% RH) conditions. Seed germination and electrolyte leakage were evaluated periodically. Small seeds had lower longevity at humid or dry storage conditions (5 or 407 days, respectively) than large or intermediate seeds (7–9 or 536–727 days, respectively). Moreover, H. incana shows variability in seed dormancy related to seed size within a population, with small seeds having lower dormancy (13%) than intermediate (50%) or large seeds (72%). Dormancy was partially released after a short storage at 35°C and humid conditions. Under dry storage conditions, endogenous dormancy cycles were observed for over a year, and longer times of storage had a dormancy-breaking effect through dry after-ripening. Results suggest a dual strategy producing non-dormant seeds with low longevity that will germinate immediately after dispersal, and seeds with greater longevity that will delay germination. Membrane permeability increased linearly with ageing at both humid and dry storage (R2 = 0.60). Small seeds showed greater conductivity than intermediate or large seeds (0.7, 0.4 or 0.3 mS g–1 dry weight, respectively, at the 80% germination). The conductivity test could be used to evaluate the quality of H. incana seeds and would allow us to identify dormant (non-germinating) seed lots as viable. However, the influence of storage conditions and variability within a seed population on seed longevity should be taken into account when evaluating seed quality.

-The objective of this work was to evaluate the use of the conductivity test as a means of predicting seed viability in seven Passiflora species: P. alata, P. cincinnata, P. edulis f. edulis, P. edulis f. flavicarpa, P. morifolia, P. mucronata, and P. nitida. Conductivity of non-desiccated (control), desiccated, and non-desiccated cryopreserved seeds was determined and related to their germination percentage. The obtained results suggest that the electrical conductivity test has potential as a germination predictor for P. edulis f. flavicarpa seed lots, but not for the other tested species.

Plantago lanceolata is a perennial herbaceous plant widely distributed throughout the Mediterranean region. Variation in germination requirements and tolerance to osmotic stress and salinity were tested using seeds from two wild populations. Germination experiments were conducted under controlled conditions at constant (15, 20 and 25ºC) and alternating (20/10 and 25/15ºC) temperatures, and under a 16 h/8 h light/dark photoperiod. Seeds of both populations were non-dormant and incubation temperature significantly affected the final germination percentage and germination rate. Germination percentages ranged from 27 to 85% for the different temperatures and populations. Significant inter-population variation was found for the germination percentages reached at alternate temperature regimes. To determine the effect of osmotic stress and salinity, four polyethylene glycol (PEG 6000: 10, 20, 30 and 40% w/v) and four NaCl concentrations (50, 100, 200 and 300 mmol•L-1) were tested. Seed germination significantly decreased with increasing in PEG and NaCl concentration. Seed germination recovery when they were transferred to distilled water after PEG or salinity treatments was variable depending on population, suggesting that P. lanceolata seeds are moderately tolerant to osmotic and salt stresses at germination stage.

No abstract