While understanding that seed germination is crucial for ecological restoration activities, the seed traits of desert perennials are understudied. We experimentally determined germination traits of 43 species from 14 families from Hummock grasslands in the Great Sandy Desert, Australia. We defined morphological and physiological seed traits of framework species required for restoration and investigated the effects of fire and temperature on seed germination. We classified dormancy and explored the effect of Karrikinolide, a fire cue derived from smoke, on germination. Seeds of 38 (88%) out of 43 species were dormant: 13 (30%) with physical and 25 (58%) with physiological dormancy. Karrikinolide promoted seed germination of 9 (21%) species across all life-forms except trees, and widened the range of germination temperatures and increased germination rate of one species. Although high germination percentages were obtained over a wide temperature range, germination rate was affected by temperature. Non-dormant seeds and seeds pre-treated to overcome physical dormancy germinated quickly, with times to 50% germination of 1–5 days. Dormancy class differed between life-forms and families. Fast germination of non-dormant seeds is a trait that allows seeds to germinate during short periods of moisture availability. An absence of under-developed embryos is consistent with the global trends for hot deserts. A response to Karrikinolide shows that seed germination is related to a fire cue. These results will inform land managers of effective seed pre-treatments prior to seed broadcasting for restoration, and information on seed germination temperatures and rates will improve the understanding of when and where seeds could germinate in restored sites.

The seed germination ecology of Calycanthus floridus (Eastern Sweetshrub) has not been formally investigated. The purposes of this study were to determine the type of seed dormancy found in the species, the most effective method of breaking this dormancy, and the environmental conditions producing maximum germination. We employed a variety of standard treatments to determine the specific type(s) of dormancy present, as well as treatments to determine effective dormancy-breaking mechanisms. We determined that seeds possessed physical dormancy (PY) imposed by a water-impermeable seed coat. Mechanical scarification was the most effective method of breaking PY; submersion in acid was also moderately effective. Seed germination following scarification can occur over a wide range of temperatures. There is no light requirement for seed germination. This study represents the first case of physical dormancy reported for the genus and only the second for the family.

Background Ormosia macrocalyx is a tropical forest tree classified as endangered. Its seeds experience problems of dispersion and apparent physical dormancy due to their hard seed coating. Hypotheses 1) The stages of dehiscence of the fruits of Ormosia macrocalyx influence the germinative behavior of its seeds. 2) Pregerminative treatments will improve the germination process of the seeds stored under refrigeration. Study species Ormosia macrocalyx Ducker. Study site and period Villahermosa, Tabasco, Mexico from October 2012 to October 2014. Methods Two completely randomized experiments were conducted in order to analyze the germination process by 1) evaluating germination in seeds from fruit at three stages of dehiscence (closed, semi-open, and open fruit) and 2) applying four treatments, including three pregerminative treatments (water soaking for 24 h, mechanical scarification and scarification+1 % gibberellic acid) plus an untreated control, to seeds stored under refrigeration for 17 months. Results Differences were found in germination rate (GR), corrected germination rate (CGR) and time to attain 50 % germination (T50) among treatments in the first experiment, with the seeds from open fruits presenting the lowest response (3.31 % day-1 for GR and CGR, and 15.8 days for T50), although all treatments showed similar times for the initiation of germination (GI) and final germination percentage (GP). In the second experiment, the effect of scarification was greater than both the control and soaking treatments. Scarification treatment values were 68.0 % (GP), 12.0 days (GI), 4.53 % day-1 (GR), 6.65 (CGR) and 14.5 days (T50). Addition of gibberellic acid did not produce any further advantage over scarification alone. Conclusions Seeds from open fruits have lower germination rates, although the final GP is not affected. Stored seeds present physical dormancy but lose viability with storage and, when collected after remaining attached to the tree for undefined periods, scarification can greatly improve their germination rate.

The morphoanatomy and germination of dormant seeds of Peltophorum dubium (Spreng.) Taub. and Mimosa bimucronata (DC) O. Kuntze, Atlantic forest Fabaceae species, were examined. Temperature treatments for breaking physical dormancy were applied, and the effects of three forest environment on seed germination were examined. The location of water inlet was carried out soaking in water nondormant seeds with parts of the integument waterproofed with glue. Scanning electron microscopy and optical microscopy were employed to observe the morphoanatomy of seed coat’s surface. Wet shocks of 40 and 50 °C were effective in breaking the physical dormancy of seeds. Higher temperatures in forest clearing had greater effect on germination and emergence of seedlings. Both species presented external and internal seed morphology similar to that of most Fabaceae species. In P. dubium seeds, the water inlet appears to occur not only by the lens, but also by the micropyle and hilum. In M. bimucronata, the sites of water intake were the micropyle and lens.

The physical quality and physiological performance of seeds may be influenced by numerous factors, including the moisture content at harvest and drying temperature. This study aimed at evaluating the physical quality and physiological performance of black bean seeds (BRS Campeiro cultivar), depending on the moisture content at harvest and drying air temperature. The experiment was conducted under a completely randomized design, in a 3 x 5 (moisture content at harvest x drying air temperature) factorial arrangement, with four replications. The samples were collected when the seeds reached the moisture contents of 35.2 %, 25.2 % and 16.6 %. After harvesting, the seeds were subjected to drying at temperatures of 30 ºC, 35 ºC, 40 ºC, 45 ºC and 50 ºC. The physical quality of the seeds was evaluated by determining the 1,000-seed weight and hectoliter weight. The physiological performance was evaluated by the germination speed index, germination first count, accelerated aging, dry matter, seedling shoot and root length and electrical conductivity. The increase in the drying temperature, regardless of the moisture content at harvest, reduces the physical quality and physiological performance of the seeds. When subjected to drying temperatures lower than 40 ºC, the seeds obtained from the earliest harvests show a better physical quality and physiological performance.

The chemical interaction between plants, which is referred to as allelopathy, may result in the inhibition of plant growth and development. The objective of this research was to determine the allelopathic impact of sugarcane (Saccharum officinarum) var. ‘HoCP 96-540’ field residue and sugarcane bagasse extracts on the germination of three vegetable crops. Tomato (Solanum lycopersicum L.), Chinese kale (Brassica oleracea L. var. alboglabra Bailey), and cucumber (Cucumis sativus L.) seeds were treated with 4 extract concentrations (0, 16.7, 33.3, and 66.7 g/L) from either sugarcane field residue or sugarcane bagasse extracts. Germination of the tomato, Chinese kale, and cucumber seeds decreased as concentration of sugarcane field residue extracts increased. At the highest residue concentration (66.7 g/L), germination decreased by 44%, 82%, and 88% for tomato, Chinese kale, and cucumber, respectively. These results would indicate that sugarcane field residue would not be a suitable natural mulch or soil amendment for local vegetable production, especially where the vegetables were direct-seeded. If evaluated correctly, the sugarcane field residue may be an effective natural mulch for perennial ornamental plants in landscape applications, serving as a physical and chemical barrier to germinating and emerging weed species. Sugarcane bagasse extracts did not inhibit Chinese kale and cucumber germination, and only inhibited tomato germination by 13% at the greatest concentration (66.7 g/L) in 1 experiment. As the first documented bioassay implicating bagasse as allelopathic active, further research should investigate the subject using higher concentrations, and additional sugarcane and tomato varieties. Except for the one instance with tomato germination, it appears that sugarcane bagasse has potential as a natural mulch for vegetable production, although the mulch would only be a physical barrier to weed establishment and not a allelopathic chemical barrier. Future research should determine the allelopathic active compounds in sugarcane field residue and if the concentration of allelopathic chemicals vary by sugarcane variety.

Cyclopia is a genus of leguminous shrubs endemic to the fynbos biome of South Africa. Cyclopia spp. are used to make honeybush tea for which a high market demand has led to the overharvesting of Cyclopia species in the wild. Consequently, it has become important to study the cultivation requirements of honeybush in order to support farmers with the cultivation of this crop. Honeybush seeds are known to have either physical or combinational dormancy upon maturity, depending on the species. The plants also produce colour-dimorphic (green and brown), mature seeds in the same pod. A study of honeybush (Cyclopia maculata, Cyclopia genistoides and Cyclopia subternata) seed anatomy was carried out using light and dissection microscopy. It is hypothesized that seed physical dormancy is attributable to a relatively thick (3.5μm) cuticular layer of the integument, a layer of macrosclereid cells, and the presence of a hygroscopically activated hilar valve. There is an absence of other structural openings by which moisture may enter the seed. No consistent structural differences were found amongst the three species or their colour-dimorphic seed. Seeds of the same three honeybush species were divided by colour and their germination response to selected variables (scarification, stratification, seed age and germination temperature) was evaluated. Three dormancy-breaking treatments (wet heat, dry heat and microwave energy) were identified as potential alternatives to conventional sulphuric acid scarification. Highest germination percentage of scarified seed for the three species tested was obtained after 3weeks of cold stratification at 2°C and incubated at 15°C. Brown C. subternata seeds stored for three years gave a significantly higher germination percentage than seed stored for one year only. In non-treated seed, brown seeds had a higher germination percentage than green seeds. In treated seed (i.e. scarified and/or stratified), green seeds had a better germination percentage than brown seeds.