Early Sprouting and First Stages of Growth of Rice Seeds Exposed to a Magnetic Field

The effects of a stationary magnetic field on the germination of rice seeds (Oryza sativa, L.) and on the initial stages of growth of rice plants have been evaluated. In both tests, the seeds were exposed to one of two magnetic field strengths (125 or 250 mT) for different times (1 min, 10 min, 20 min, 1 h, 24 h, or chronic exposure) as 12 separate treatments (doses D1–D6 for 125 mT and doses D7–D12 for 250 mT). Nonexposed seeds were used as controls (C). The mean germination time (MGT) was significantly reduced compared to control when seeds were exposed to magnetic field (54.00 h for D5 and D11, and 58.56 h for control). The parameters T₁ and T₁₀, times required to obtain 1 and 10% of germinated seeds, were also reduced. The T₁₀ of control seeds was 44.40 h, while treatments D5, D6, D11, and D12 gave rise to values of 36.00, 36.96, 32.64, and 39.36 h, respectively. The higher germination rate of treated seeds obtained in the germination test is in agreement with the higher lengths and weights of rice plants exposed to a magnetic field recorded on the growth tests. All the parameters measured were over the control ones, although the highest lengths and weights of rice plants were obtained for chronic exposure to magnetic field (doses D6 and D12). Stem length of control plants (45.36 mm) measured at the tenth day was significantly lower than that obtained for doses D6 (58.58 mm) and D12 (80.63 mm); the same behavior was observed on total length, stem weight, and total weight. Our finding indicates that this type of magnetic treatment clearly affects germination and the first stages of growth of rice plants.     

Ecophysiological requirements on seed germination of a Mediterranean perennial grass (Stipa tenacissima L.) under controlled temperatures and water stress

Stipa tenacissima L. (alpha grass) steppes are one of the most representative ecosystems in arid Mediterranean ecosystems. On the one hand these steppes, which are perpetually exposed to climate and strong anthropogenic pressure, have undergone severe degradation. On the other hand, the ability of S. tenacissima to regenerate naturally is significantly reduced. In this study the germination response and seedling emergence of S. tenacissima are examined in relation to the main environmental factors (water stress and temperature) under laboratory-controlled conditions. The main aim of this paper was to investigate the influence of temperature over a temperature range (10 °C–30 °C) and water stress induced by the solutions of polyethylene glycol (PEG)-6000 (0 to − 1.6 MPa) for a period of 30 days, on the germination behavior of S. tenacissima seeds. The results showed that temperatures between 10° and 20 °C seem to be favorable for the germination of this species, with optimum temperatures among accessions found in 20 °C. When seeds were water-stressed, germination severely decreased at − 0.8 MPa, indicating that the accession resistance limits to the water stress, and was completely inhibited at − 1.6 MPa. Consequently, the final germination percentage (FGP) decreased and the mean time germination (MTG) increased. Based on the empirical data of the germination rate, we estimated that the parameters of the thermal time and hydrotime models showed different values in all accessions which proves the difference between accession adaptive capacities.     

Rapid adaptation of seed germination requirements of the threatened Mediterranean species Malcolmia littorea (Brassicaceae) and implications for its reintroduction

Malcolmia littorea (Brassicaceae) is a threatened species growing in the coastal sandy dunes of the west-Mediterranean basin. In this study, the seed germination and seedling emergence requirements of this species were investigated in the only remaining native population in Italy. The highest germination percentage was achieved in darkness with scoring under safe green light at 5–10 °C. Seedling emergence was highest when seeds were buried between 1 and 10 mm in depth. The results suggest that germination and seedling emergence are adapted to Mediterranean coastal habitats by employing a common mechanism of light-inhibited germination and by germinating at cooler temperatures before the onset of the summer drought. Seeds were also collected from plants cultivated at a botanical garden and from plants reintroduced by sowing or by transplanting. For those populations, germination was maximal between 10–25 °C, suggesting that the thermal germination behaviour may be affected by the maternal environment of seed production within one generation. It is suggested to use seeds produced in the same environment to which they will be used for the reintroduction of this species.     

Germination response and viability of an endangered tropical conifer Widdringtonia whytei seeds to temperature and light

The tropical conifer Widdringtonia whytei Rendle is an endangered species endemic to Mulanje Mountain in Malawi. A study was conducted for the first time under controlled conditions in order to assess the effects of temperature and light on germination and viability of W. whytei seeds. Seeds incubated at a constant temperature of 20 °C attained the highest cumulative germination percentage (100%) followed by 87% germination under fluctuating temperatures of 15 °C night/25 °C day. No seed germination occurred at temperatures below 15 °C. Seeds that failed to germinate at temperatures below 15 °C showed the highest (> 90%) viability compared to the seeds incubated at 25 °C (60%). Across temperature regimes, germination was significantly higher under light (44.7%) than dark (35.6%) conditions. It is concluded that temperature is one of the critical factors for germination of W. whytei seed. The ability of W. whytei seeds to germinate both in light and darkness implies that the species would unlikely form a persistent soil seed bank, an attribute which is common in species that survive in habitats frequently disturbed by fires.     

Effect of yak rumen content treatments on seed germination of 11 alpine meadow species on the Qinghai-Tibetan Plateau

The Qinghai-Tibetan Plateau is located in the ‘Third Pole’ of the world, characterized by a harsh environment. Despite this, the alpine meadow ecosystem have developed over a wide area but serious grassland degradation is threatening the ecological environment on the Plateau. Recruitment of new plants to the population, via germination and establishment, is vital to plant community survival. Previous work on the seeds in this area has mainly focused on community-wide germination strategies, seed germination characteristics and their correlations with seed size and seed mass. However, there have been no studies on the effects of soaking in rumen contents on the plant seed germination characteristics of alpine meadow species. The present study had two main objectives: (i) to determine the effect of fresh rumen content from yaks on seed germination characteristics and seedling growth of species common to the eastern Tibetan Plateau alpine meadow, and (ii) to develop an effective method to enhance seed germination. Seeds of 11 common species were collected together with fresh rumen content from three yaks that grazed there. Seed germination tests were conducted after they had been soaked in rumen content for one of six soaking periods (12, 24, 36, 48, 60 or 72 h). The seeds were incubated under natural light conditions of 8 h light at 25 °C and 16 h darkness at 15 °C, for the germination period of 34 days. The results showed that seed germination and seedling growth were affected by soaking time, seed coat completeness and seed type. After soaking in rumen content, the germination percentages of scarified (peeled or with the seed coat cut through) seeds of some species (true seeds Oxytropis ochrocephala and Medicago ruthenia var inschanica, nutlet Carex enervis, achenes Anemone rivularis and Polygonum sibiricum) and complete seeds of C. enervis, and A. rivularis were improved but the duration of soaking was also important. Seed germination of caryopsis Achnatherum inebrians (a toxic grass) was significantly inhibited by any exposure to rumen fluids. Scarified seeds generally had higher germination percentages than complete ones after treatment, but with the increase in soaking time, germination percentages declined and scarified seeds were more sensitive to the treatment than the complete seeds. After soaking in yak rumen content, the germination indices of scarified M. ruthenia at 12 h treatment, O. ochrocephala and achene Rumex acetosa at 12–24 h treatment, nutlet Kobresia humilis at 24 h treatment, P. sibiricum at 24–48 h treatment, C. enervis at 12–48 h treatment and A. rivularis at 12–60 h treatment were significantly higher than the control (P < 0.05), while the germination indices of complete C. enervis seeds at 12 h and 36 h treatment, and A. rivularis at 12–60 h treatment were significantly higher compared with the control. The germination indices of other species gradually decreased with the increase in soaking time. We concluded that yak rumen digestion could enhance, inhibit or not affect seed germination and seedling growth of the alpine meadow species, which might influence seedling recruitment, interspecific competition, and the plant community structure of the eastern Tibetan Plateau alpine meadow. Overall, yak digestion has a positive effect on alpine meadow seed germination and seed dispersal.     

Role of calcium in alleviating effect of salinity on germination of Phragmites karka seeds

Phragmites karka (Retz.) Trin, ex. steud, a perennial reed with creeping rhizome from the family Poaceae, is distributed as pure population in brackish water swamps. Populations primarily propagate using ramets but also produce numerous seeds which form part of the seed bank after dispersal and are exposed to extremes of temperature, drought, and salinity stress. Seeds were germinated under a range of salinity (0, 100, 200, 300, 400, 500 mM NaCl) and temperature (10/20 °C, 15/25 °C, 20/30 °C, 25/35 °C, night/day) regimes in 12 h light:12 h dark photoperiod or in complete darkness with 0, 5, 10, 25 mM CaCl₂. Salinity, absence of light and high temperature (25/35 °C) reduced germination while calcium generally reversed this effect, more so at cooler temperature regimes. Calcareous soil around Karachi would help alleviate the salinity effect on the germination of P. karka and facilitate its survival.     

Effects of salt,alkali and salt–alkali mixed stresses on seed germination of the halophyte Salsola ferganica (Chenopodiaceae)

Salsola ferganica L. (Chenopodianceae) is an annual halophytic species. Experiments were carried out in laboratory to determine the effects of temperature, perianths and various types of salinity on seed germination and germination recovery. Seeds were germinated at 6 levels of temperature with perianths, plus perianths and removed perianths in complete darkness for 9 days. The germination responses of the seeds without perianths at 25 °C were determined over a wide range of NaCl, NaHCO₃ or NaCl–NaHCO₃ mixed stress for 13 days. Perianths seriously affected germination as a barrier for seed germination and the optimal temperature was at 25 °C. Highest germination percentage was obtained under control and seed germination was progressively inhibited with the increase of salinity concentration. The negative effect of NaHCO₃ at the same concentration on germination was stronger than that of NaCl and NaCl–NaHCO₃ mixed. When substrate salinity was removed, seeds exposed to a high NaCl concentration (400–800 mM), NaHCO₃ (50–200 mM) and NaCl–NaHCO₃ mixed (100–400 mM) germinated well. Final germination of Salsola ferganica seeds was significantly affected by types of salt at the low salinity (?200 mM) and with increased salinity it was influenced mainly by salinity concentration for various proportion of salt–alkali mixed stress.     

Seed storage and germination in Kumara plicatilis,a tree aloe endemic to mountain fynbos in the Boland,south-western Cape,South Africa

Seed storage under appropriate conditions is a relatively inexpensive means of safeguarding plant genetic material for ex situ conservation. Post-storage germination trials are used to determine the viability of stored seeds, and hence the efficacy of the particular storage treatment. Kumara plicatilis (= Aloe plicatilis) is a tree aloe endemic to mountain fynbos in the Boland, south-western Cape. The viability and germination behaviour of K. plicatilis seeds were assessed for seeds stored for four and nine months at − 80 °C, 4 °C, 25 °C and under ambient conditions in a laboratory. Seeds were germinated under controlled conditions and germination rates and percentages determined. Ungerminated seeds were tested for viability using tetrazolium salt. Seed viability was not significantly reduced during storage. Seeds stored at − 80 °C for four and nine months exhibited the fastest germination rate overall (both 5.9 ± 0.3 weeks, mean ± S.E.), and slowest was for seeds stored under ambient conditions for four and nine months (both 7.8 ± 0.4 weeks). All seed lots showed similar percentage germination after four months of storage (78.0–90.4%). The highest percentage germination overall was for seeds stored at − 80 °C for four months (90.4%) and the lowest was for seeds kept at 4 °C and − 80 °C for nine months (39.2 and 39.6%, respectively). Respective percentage viability for ungerminated seeds in these two treatments was 82% and 87%, respectively, indicating the induction of secondary dormancy. Induced dormancy triggered by protracted cold temperatures may be an adaptation that enables seeds to survive prolonged extreme conditions that are unfavourable for germination. Further research on the long-term storage of aloe seeds would be beneficial for developing long-term seed storage and germination testing protocols for ex situ conservation.     

Effect of 28-homobrassinolide on the performance of sensitive and resistant varieties of Vigna radiata

A study was undertaken to examine the morpho-physiological alterations under different concentrations of 28-homobrassinolide (HBL) in two contrasting varieties of Vigna radiata. Sterilized seeds of V. radiata (T-44 and PDM-139) were inoculated with specific Rhizobium and allowed to grow and then 14 day old seedlings were exposed to different concentrations (0, 10⁻¹⁰, 10⁻⁸, or 10⁻⁶ M) of HBL and allowed to grow under natural environmental conditions. At the 15 and 21 day stage, plants were harvested to evaluate various parameters. Results clearly indicated that growth bio-markers, accumulation of proline and activities of various antioxidant enzymes increased significantly in T-44 at a later stage of growth in the presence of HBL whereas, 10⁻⁸ M showed the most promising response. It is concluded that HBL modifies the physiological functions and biochemical metabolism of V. radiata by increasing photosynthetic efficiency at an early stage of growth and antioxidant system in T-44 at a later stage of plant growth that are manifested in growth at later stages. It is believed that increased accumulation of proline and enhanced antioxidant system provide strength to the plants to withstand environmental cues.     

Smoke-water effect on the germination of Amazonian tree species

Smoke stimulates seed germination of a range of species from ecosystems that may or may not be fire prone. We evaluated the effects of smoke-water on germination of ten tree species of economic value in the Amazon region. Two materials were burnt to produce smoke-water: germination paper and the wood of Cecropia palmata Willd. Seven dilutions of the solutions were tested. Seeds of nine forest trees were germinated under controlled laboratory conditions (25 °C ± 2 °C) in the laboratory. Bertholletia excelsa Humb. & Bonpl., was tested in the nursery (approximately 25–36 °C) because of its large seeds. Irrespective of the material burned, smoke-water significantly increased seed germination of three species: Cordia goeldiana Hub., Ochroma pyramidale (Cav. ex Lam.) Urb. and Jacaranda copaia (Aubl.) D. Don. and there was a significant inhibitory effect on Swietenia macrophylla King. Germination was accelerated by smoke in J. copaia, B. excelsa and Bellucia grossularioides (L.) Triana. The most pronounced effect was observed in B. excelsa, as the mean germination time of 108 d (control) was reduced to 76 d with smoke-water made from germination paper (dilution of 1:25) and to 61 d with the one from Cecropia wood (dilution of 1:250). For five of the ten species studied, smoke-water either increased or accelerated seed germination, irrespective of the materials used for its production. Seeds with low vigour and prolonged germination time seemed to be more receptive to smoke.     

Effects of seed storage on germination of two succulent desert halophytes with little dormancy and transient seed bank

Seeds of both Salsola imbricata and Haloxylon salicornicum have high germination level and germination speed, and form a transient seed bank in nature. The impacts of storage period and condition on germination level and speed were assessed in the two species. Storage for three months significantly increased both germination level and speed of seeds stored under the different conditions, compared to that of fresh seeds. In both species, nine months storage did not affect germination percentage in cold storage seeds, but completely inhibited it in field seeds. Storage for longer time in room and warm temperatures resulted in significant reduction or complete inhibition in the germination of the two species, so this was more pronounced in H. salicornicum. Storage significantly increased germinate rate index of seeds stored in all conditions till 17 months in S. imbricata and till 12 months in H. salicornicum. In both species, fridge storage had little effects on final germination and germination speed of seeds incubated at the different temperatures, compared to fresh seeds. However, room temperature and warm storages significantly reduced final germination and germination speed at the different temperatures, so the reduction was more pronounced at 35 °C, especially in H. salicornicum.     

Effect of seed pretreatment by magnetic field on the sensitivity of cucumber (Cucumis sativus) seedlings to ultraviolet-B radiation

The effects of seed pretreatment by magnetic field (MF) on the impacts of ultraviolet-B (UV-B) radiation were tested using cucumber (Cucumis sativus) seedlings in phytotron. Soaked cucumber seeds were placed in MF of various strengths (0, 0.2 and 0.45 T). After germination the seeds were sowed in homogeneous garden soil and grown, then cucumber seedlings were exposed to 0 (as control) and 3.5 kJ m⁻² UV-B irradiation, respectively. Some effects of UV-B radiation and MF-pretreatment as well as their combination were investigated. MF-pretreatment increased seed germination rate, seedling growth and development, although also increased lipid oxidation and ascorbic acid contents. On the other hand, our results provided evidence that seed MF-pretreatment increased the sensitivity of cucumber seedlings to UV-B radiation. The seedling growth and development were significantly decreased by the combination of UV-B irradiation and MF-pretreatment. This combination also increased oxidative pressure and decreased actual quantum yield of PS II. Leaf UV-B absorbing compound was increased by MF-pretreatment or UV-B irradiation, whereas their combination significantly decreased it. These results suggested that the harmful effects of combination were partially due to the inhibition of secondary metabolism.     

Germination responses of Croton macrostachyus (Euphorbiaceae) to various physico-chemical pretreatment conditions

Croton macrostachyus Hochst. ex Del. (Euphorbiaceae) is a multipurpose, deciduous, and medium sized tree of pantropic occurrence. Because the species has numerous useful qualities (e.g., establishment and growth in disturbed sites, drought tolerance, fast growth rate, copious litter/necromass production, suitability for agroforestry, and ability to attract avian frugivores), its speedy restoration has become increasingly critical. Germination studies were therefore conducted on seeds pooled from five widely located provenances with a view to supporting efforts geared toward the speedy propagation and restoration of this valuable tree species. Seed pretreatments were achieved using various dilution levels of plant-derived smoke–water (1:1, 1:10, 1:100 and 1:1000), as well as gibberellic acid (GA₃) or potassium nitrate (KNO₃) ranging in concentration from 0.1 to 100 μmol. The control was to use distilled water for seed pretreatment. Seeds were germinated under either illuminated (ca 60 μmol m^− 2 s^− 1; cool-white fluorescent lamp) or non-illuminated conditions. Experiments on the impact of seed storage durations, as well as storage temperatures were also conducted. The study found that germination percentage (GP: ca 90%), and mean germination time (MGT: 14 days) were significantly (P < 0.001) better when seeds were pretreated with smoke–water and germinated under non-illuminated conditions, than when these were pretreated with various concentrations of GA₃ or KNO₃ (GP and MGT of ca 65% and 20 days, respectively). Germination percentage (GP) and germination vigor (GV) declined with increasing storage-time for all storage temperatures, but GV's decline was faster for seeds stored at 22 °C than for those stored at 5 and 15 °C. On the other hand, mean germination time (MGT) increased significantly (P < 0.01) with seed storage-time of up to 8 months at 5, 15, and 22 °C, but the increase was more marked for seeds stored at 22 °C than for those stored at 5 and 15 °C. From these investigations, it is concluded that germination of C. macrostachyus seeds through use of smoke–water is faster, cheaper, and technically less demanding, compared to that of either GA₃ or KNO₃. The study also concludes that C. macrostachyus is intermediate between orthodox and recalcitrant seeds, and that it is non-photoblastic.     

Effects of salinity levels and seed mass on germination in Australian species of Frankenia L. (Frankeniaceae)

Halophyte species demonstrate differing levels of salt tolerance. Understanding interspecific variation to salinity levels is of value from both the scientific perspective, which includes the identification of traits associated with salinity tolerance, as well as from an applied perspective, which includes identifying plant species for specific salinity restoration and remediation projects. This paper investigates the effects of salinity on germination of 12 Australian species of the plant genus Frankenia L. (Frankeniaceae). We use saline solutions that corresponded to the average soil–water salinity concentrations in the arid zones of inland Australia. These solutions consisted of 10 mM calcium chloride, 30 mM magnesium sulphate, and 450 mM sodium chloride. The aims of our study were: (1) to investigate the germination (germination rates, germination success) of Frankenia seeds to four salinity levels (0%, 10%, 20%, 30%), (2) to test for possible interaction effects between seed mass, germination, and salinity, and (3) to examine the effect of salinity levels on the inhibition of germination and/or seed damage. Species varied in their salt tolerance for germination rates and success. Species with larger seeds had higher germination rates and germination success for high salinity levels. Several species did not germinate well at any salinity level. Finally, no seeds were adversely affected by exposure to high salinity levels pre-germination. There is potential for including some Frankenia species in remediation and revegetation projects in areas affected by salinity, and also as garden plants in saline regions.     

Analysis of the germination rate,mitotic index and karyotype of Chromolaena barranquillensis (Hieron.) R.M. King & H. Rob.—Asteraceae

Chromolaena barranquillensis (Asteraceae) is an endemic plant of northern Colombia that has garnered economic and medicinal interest, because species from the genus Chromolaena have shown diverse biological activities. This study describes, for the first time, the karyotype, germination and mitotic indices of C. barranquillensis (Hieron.) R.M. King & H. Rob. The germination index was between 34% and 56% with an average germination rate of 1.2 ± 0.4 seeds/day. The mitotic index analysis allowed to determine the cell cycle time (4 h, 10 min) and the mitotic hours (3:00–8:00 h and 17:00 h). The mitosis time was 49 min, equivalent to ~ 20% of the cell cycle. Karyotype analysis showed that C. barranquillensis is a hexaploid species with a chromosomal formula 2n = 6x = 60 = 48 m + 12 sm, and the average chromosomal lengths were 1.7 ± 0.1 μm to 0.9 ± 0.3 μm. The Stebbins asymmetry index was 2B, and the total form percentage was ~ 41%. These results uncover differences between C. barranquillensis and Chromolaena odorata, one of the most abundant species found in the world and the most closely related species to C. barranquillensis.     

Effects of seed maturation time and dry storage on light and temperature requirements during germination in invasive Prosopis juliflora

The effects of time of seed maturation and dry seed storage and of light and temperature requirements during seed incubation on final germination percentage and germination rate were assessed for the invasive shrub Prosopis juliflora (Sw.) D.C., grown under desert environmental conditions of the United Arab Emirates (UAE). Seeds were collected from Fujira on the northern coast of the UAE at different times during the growing seasons (autumn, winter and spring) and were germinated immediately and after 8 months of dry storage under room temperature (20±3 °C). Seeds were germinated at three temperatures (15, 25 and 40 °C) in both continuous light and darkness. The results showed significant effects for time of seed collection, seed storage, light and temperature of seed incubation and many of their interactions on both germination percentage and rate. Fresh seeds matured during autumn and winter germinated significantly greater at 40 °C and in light than at lower temperatures and in dark. Storage significantly increased germination percentage and rate; the increase was greater for seeds matured during winter than for seeds matured during spring. This indicates that dormancy breakage was greater in seeds of winter than seeds of spring. The need for high temperature to achieve greater germination was significantly reduced after seed storage, especially for seeds matured in autumn and winter.     

Interactive effects of salinity and water depth on the growth of Melaleuca ericifolia Sm. (Swamp paperbark) seedlings

Melaleuca ericifolia Sm. (Swamp paperbark) is a common tree species in freshwater and brackish wetlands in southern and eastern Australia. The survival of this species in many wetlands is now threatened by increased salinity and inappropriate water regimes. We examined the response of 5-month-old M. ericifolia seedlings to three water depths (exposed, waterlogged and submerged) at three salinities (2, 49 and 60 dS m⁻¹). Increasing water depth at the lowest salinity did not affect survival, but strongly inhibited seedling growth. Total biomass, leaf area and maximum root length were highest in exposed plants, intermediate in waterlogged plants and lowest in submerged plants. Although completely submerged plants survived for 10 weeks at the lowest salinity, they demonstrated negative growth rates and were unable to extend their shoots above the water surface. At the higher salinities, M. ericifolia seedlings were intolerant of waterlogging and submergence: all plants died after 9 weeks at 60 dS m⁻¹. Soil salinities increased over time, and by Week 10, exceeded external water column salinities in both the exposed and waterlogged treatments. In exposed sediment, ∼90% of plants survived for 10 weeks at 60 dS m⁻¹ even though soil salinities reached ∼76 dS m⁻¹. No mortality occurred in the exposed plants at 49 dS m⁻¹, and small but positive relative growth rates were recorded at Week 10. We conclude that at low salinities M. ericifolia seedlings are highly tolerant of sediment waterlogging, but are unlikely to tolerate prolonged submergence. However, at the higher salinities, M. ericifolia seedlings are intolerant of waterlogging and submergence and died rapidly after 5 weeks exposure to this combination of environmental stressors. This research demonstrates that salinity may restrict the range of water regimes tolerated by aquatic plants.     

Effects of rabbit gut passage on seed retrieval and germination of three shrub species

It has been known for a few decades that European rabbits consume seeds and fleshy fruits of native woody plants, but relevant factors in the endozoochory processes such as seed predation (chewing and digestion), sexual differentiation, or the temporal pattern of seed recovery have been little evaluated until now. In this study, we examined seed dispersal of three Mediterranean shrub species by wild rabbits through monitoring of seed retrieval and germination after gut passage. Twelve adult wild rabbits (Oryctolagus cuniculus; six males and six females) of similar size and age were fed seeds of three shrub species with fleshy fruits (Crataegus monogyna, Myrtus communis and Pistacia lentiscus). After ingestion of fruits, seeds were retrieved from dung every 12 h for a day and a half. The viability and germination of retrieved seeds were tested along with that of uneaten seeds. Between 5% and 76% of ingested seeds were retrieved from dung, with significant differences between species and sex. Most M. communis seeds were retrieved with 12–24 h after ingestion; almost all C. monogyna seeds were recovered with 0–12 h after ingestion; no seeds of P. lentiscus were recovered. Only in the case of M. communis seed was the recovery rate greater in female than in male. Passage through the rabbit gut significantly increased seed germination in M. communis, and decreased it in C. monogyna. In conclusion, wild rabbits acted in this study as predators of C. monogyna and P. lentiscus seeds and potential dispersers of M. communis seeds.     

Enhancing seedling growth of Jatropha curcas—A potential oil seed crop for biodiesel

The effects of aerosol smoke (AS), smoke-water (SW), potassium nitrate (KNO₃), naphthalene acetic acid (NAA) and indole-3-butyric acid (IBA) on germination and seedling growth of Jatropha curcas were investigated. Seed coat removal accelerated water imbibition and germination occurred within 48 h. Seeds subjected to AS failed to germinate over a 90 day period. There were no significant differences in germination percentage between the treatments and untreated control (intact- and shelled-seed). However, shelled-seeds had the shortest mean germination time (MGT). Seedlings developed from treated seeds were planted in trays under shade house conditions and growth traits measured after 3 months. Soaking intact-seeds in SW, KNO₃ and NAA (24 h) produced significantly heavier and longer seedlings, which resulted in higher vigour indices (VI) compared to the control treatments. These results provide empirical evidence of the stimulatory effect of SW, KNO₃ and NAA on J. curcas seedling growth and vigour and the continuation of the effect over time. The approach of treating intact-seeds of J. curcas with plant growth substances prior to planting will help in producing healthy seedlings and possibly improve crop productivity.