To investigate the influence of chemical and physical factors on the rate and extent of germination of Clostridium difficile spores. Germination of C. difficile spores following exposure to chemical and physical germinants was measured by loss of either heat or ethanol resistance. Sodium taurocholate and chenodeoxycholate initiated germination together with thioglycollate medium at concentrations of 0·1-100 mmol l⁻¹ and 10-100 mmol l⁻¹ respectively. Glycine (0·2% w/v) was a co-factor required for germination with sodium taurocholate. There was no significant difference in the rate of germination of C. difficile spores in aerobic and anaerobic conditions (P > 0·05) however, the initial rate of germination was significantly increased at 37°C compared to 20°C (P < 0·05). The optimum pH range for germination was 6·5-7·5, with a decreased rate and extent of germination occurring at pH 5·5 and 8·5. This study demonstrates that sodium taurocholate and chenodeoxycholate initiate germination of C. difficile spores and is concentration dependant. Temperature and pH influence the rate and extent of germination. This manuscript enhances the knowledge of the factors influencing the germination of C. difficile spores. This may be applied to the development of potential novel strategies for the prevention of C. difficile infection.

The effects of nutritional, hormonal, and physical factors on the germination and growth of isolated mature zygotic embryos of Pinus heldreichii were studied under in vitro conditions. The optimum medium for embryo germination and adequate conversion into seedlings was basal Gresshoff and Doy (1GD) medium. All tested carbohydrates at the applied concentrations stimulated embryo growth, but only 3% sucrose increased embryo germination compared to the control, while maltose had an inhibitory effect. Among the applied plant growth regulators, only gibberelic acid (GA3) had a few benefits on the development of isolated embryos into plantlets, while the others had a negative effect. Embryos cultured on an agar-solidified medium grew better and the germination percentage was higher than in a liquid medium. Light treatment did not affect embryo germination, but generally stimulated seedling growth.

A study to determine the best alternative substrate paper for testing seed viability in rolled paper method was conducted with 2 experiments. The first experiment studied the physical characteristic of six substrate papers, straw, filter, stencil, CD, HVS and Samson related to seed germination. The second experiment was conducted to identify the best alternative substrate for testing germination of different seeds. High and low viability of rice, maize, peanut, yardlong bean, chick pea and leafy vegetable seeds were tested with the substrate papers arranged in a Randomized Block Design with three replications. The first experiment showed that CD and Stencil papers had good physical characters for germination substrate. Water absorption of CD and stencil papers were 28.1g and 24.4g per medium unit, lower than Straw paper (46.51 g/medium unit) but significantly higher than the international standard of filter paper (20.7g/medium unit). In rolled paper test, no significant difference of water holding ability among the papers. Water lost during the 7 day testing were less than 2 g/medium unit for all of the papers. All of the papers including stencil and CD papers were homogenous with low coefficient of variation, less than 5%. The second experiment showed that different data of germination percentages and dry weight of normal seedlings were obtained from the diferrent subtrate papers. As compared to the common substrate straw paper, the stencil paper produced the most similar data, 100% and 91.7% similarities of germination percentage and dry weight of normal seedlings, respectively, whereas the other papers performed 37.5 - 91.6% and 29.1 - 66.7%.

A study to determine the best alternative substrate paper for testing seed viability in rolled paper method was conducted with 2 experiments. The first experiment studied the physical characteristic of six substrate papers, straw, filter, stencil, CD, HVS and Samson related to seed germination. The second experiment was conducted to identify the best alternative substrate for testing germination of different seeds. High and low viability of rice, maize, peanut, yardlong bean, chick pea and leafy vegetable seeds were tested with the substrate papers arranged in a Randomized Block Design with three replications. The first experiment showed that CD and Stencil papers had good physical characters for germination substrate. Water absorption of CD and stencil papers were 28.1g and 24.4g per medium unit, lower than Straw paper (46.51 g/medium unit) but significantly higher than the international standard of filter paper (20.7g/medium unit). In rolled paper test, no significant difference of water holding ability among the papers. Water lost during the 7 day testing were less than 2 g/medium unit for all of the papers. All of the papers including stencil and CD papers were homogenous with low coefficient of variation, less than 5%. The second experiment showed that different data of germination percentages and dry weight of normal seedlings were obtained from the diferrent subtrate papers. As compared to the common substrate straw paper, the stencil paper produced the most similar data, 100% and 91.7% similarities of germination percentage and dry weight of normal seedlings, respectively, whereas the other papers performed 37.5 - 91.6% and 29.1 - 66.7%.

Venice mallow is an emerging weed problem in many regions of the world in various crops. Studies on its hard seed coat were conducted by scanning electron, light, and fluorescence microscopy. The effects of environmental factors on germination and seedling emergence were examined in laboratory experiments. Seeds possessed physical dormancy (90%%) that required immersion for 0.5 h in concentrated sulfuric acid to break without damaging the seed. After scarification, 29%% of seeds exhibited primary embryo dormancy. Exposure of seeds to even short periods of 15 d of prechilling induced secondary dormancy (10%% germination). The surface of hard seeds had a velvety appearance from numerous papillate structures and deposits (hydrophilic material). The location of the water barrier was very superficial in the outer seed coat. Although, in hard seeds, the hilar area appeared to have vertical ruptures and the hilum fissure appeared to be open, there was no water entry. It was observed that microruptures could be the region of structural weakness of hard seeds in relation to water permeability during prolonged burial (8 mo).The highest (60%%) germination was recorded at a day/night temperature of 30/20 C with a 12-h photoperiod. No germination was measured at either 10 or 45 C constant temperature. Germination was recorded with a broad range of pH (3––11) and seeds were rather tolerant to low water potential (20%% germination at ––1.2 MPa). Seedling emergence was higher for seeds buried at 2 cm than for those placed on the surface (54 vs. 38%%, respectively). These results showed that Venice mallow is a rather unique species that possesses a complex mechanism of dormancy (physical, primary, and secondary). Information gained in this study will be used in developing management strategies for this species.Nomenclature: Venice mallow, Hibiscus trionum L. HIBTR.

<jats:p>Prostanthera eurybioides (Lamiaceae) is an endangered shrub endemic to South Australia. Fruits consist of four mericarps enclosed by a persistent calyx, with each seed characterised by the presence of what we are defining as a mericarp plug. Research focussed on understanding the role of the mericarp plug in the germination process, determining seed dormancy classification and germination cues. Treatments tested included combinations of pulse dry heat (60–120°C) for up to 60 min, continuous application of gibberellic acid (100 mg L–1), smoked water (10% (v/v)) and excision of the mericarp plug. Seed imbibition experiments dispelled the presence of physical dormancy. The mericarp plug was found to be acting as a mechanical barrier preventing germination. Pulse dry heat (80°C) significantly improved germination, as did removal of the mericarp plug. Smoked water inhibited germination. Based on germination response, seeds have been classified as having non-deep physiological dormancy, with maximum germination (86%) observed following a pulse heat treatment (80°C, 10 min) and removal of the mericarp plug. Natural mechanisms for overcoming dormancy are proposed.</jats:p> | P. J. Ainsley, M. K. Jones and T. E. Erickson

Seven important plant pathogenic fungi (Botrytis cinerea, Colletotrichum acutatum, C. fragariae, C. gloeosporioides, Fusarium oxysporum, Phomopsis obscurans, and P. viticola) valuable in screening fungicides were tested. Our procedure included washing conidia to reduce germination times, incorporating Roswell Park Memorial Institute 1640 as a medium of known composition, and using coverslips in the 24-well cell culture clusters to document the effect of fungicides on fungal morphology. The natural product-based fungicide, sampangine, a sampangine analog, 4-bromosampangine, plus seven conventional fungicides (benomyl, captan, cyprodinil, fenbuconazole, fenhexamid, iprodione, and kresoxim-methyl) were tested in vitro for their ability to inhibit germination and growth of the seven fungal species. Sampangine inhibited germination in all fungi except C. acutatum. Comparison of results of germination and morphology microbioassays with results of microtiter assays suggests that some fungicides stop fungal germination, whereas others only slow down fungal growth. We hypothesize that sampangine, except against C. acutatum, has the same physical mode of action, germination inhibition, as the conventional fungicides captan, iprodione, and kresoxim-methyl. 4-Bromosampangine caused morphological anomalies including excessive branching of germ tubes of C. fragariae and splaying and branching of germ tubes of B. cinerea.

We investigated the relationship between the fruit phenology of Prunus jamasakura and the fruit-feeding period of the Asiatic black bear (Ursus thibetanus). The purposes of this study were to determine (1) when bears feed on the fruit of P. jamasakura in relation to phenology; (2) whether ingestion damages seeds; and (3) how ingestion influences seed germination. We assessed the relationship between the phenology of fruit maturation (size, sugar concentration, color, persistence, and germination percentage) and the feeding period of bears in the field, as judged from bear shelves and claw marks. We also compared the germination percentage of seeds ingested by captive bears with that of uningested. Bears fed on the fruit from days 50 to 66 after flowering, when most of the fruits were on the tree and became large, the germination percentage of seeds increased, and the sugar concentration became high. Bears fed only on mature fruits and so obtained high-quality nutrients. Germination tests showed that ingestion of fruits by the bears caused no physical damage to the seeds. Ingested seeds did not show a significant difference in germination percentage from seeds, whose pulp was artificially removed. These results indicate that bears are potentially effective dispersers from a qualitative perspective and, to some extent, from a quantitative perspective.

A number of broomrapes (Orobanche spp.) are major threats for grain legumes in the Mediterranean area. Previous studies have shown very high levels of resistance to Orobanche crenata in Medicago truncatula with little variation among accessions hampering, therefore, its use for genetic analysis. In order to identify alternative systems for ulterior genetic and genomic analysis, we studied early stages of the interaction between M. truncatula accessions and a range of Orobanche species. We found significant differences in the induction of germination on Orobanche aegyptiaca, Orobanche foetida var. broteri, Orobanche minor, Orobanche nana and Orobanche ramosa seeds. Accessions also varied in the number of O. aegyptiaca, O. crenata, O. foetida var. broteri, O. nana and O. ramosa attachments supported. Applications of the synthetic germination stimulant GR24 increased the germination level of Orobanche cumana and O. minor. No attachments were observed for any of these species because of physical barriers typical of host resistance. On the contrary, increase of O. nana germination by GR24 led to an increase in number of attachments albeit the normal development of the nodules was stopped in a later stage. The genetic variation observed for induction of germination and subsequent attachment will be useful for isolating and characterising genes involved in early stages of Orobanche-host plant interaction and for the study of the biosynthetic pathways of production of germination stimulants.