The effects of physical seed coat scarification and soaking in hydrogen peroxide (H2O2) were studied to determine presowing treatments that would improve germination in seed of Vangueria infausta. The study involved two experiments, the first conducted in the laboratory, and the second in the nursery. The scarification treatments were: unscarified control; partial removal of the seed coat at the radical end; and total removal of the seed coat. The other treatments involved soaking the seeds in 5 concentrations of H2O2, i.e., 0, 2, 4, 6 and 8%, for 12 h.Generally, less than 70% of the seeds germinated. The best germination results, (71% in the laboratory and 63% in the nursery) were obtained in seeds with partial removal of the seed coat when soaked in 6% H2O2 for 12 h. Germination in other treatments involving partial removal of the seed coat was higher than that of unscarified seed in the nursery, although laboratory values were nearly the same. Seeds whose seed coat was completely removed germinated poorly (5–16%), as a result of rapid water uptake which caused damage to internal seed structures.Hydrogen peroxide application at concentrations of 2–6% positively improved germination, while 8% H2O2 seemed to have a depressive effect. The impact of scarification and H2O2 on other germination parameters is discussed.
Tag: seed germination
Effect of physical scarification and Gibberellic acid treatments in germination Trichilia emetica seed
Seeds of Trichilia emetica were subjected to 3 types of physical seed coat scarification, i.e. unscarified, partial removal of seed coat at radicle end, and complete removal of seed coat. These treatments were combined in a factorial arrangement with gibberellic acid at 5 concentrations: 0, 250, 500, 750 and 1,000 ppm, and replicated 4 times. Unscarified seeds without and with gibberellic acid attained cumulative germination of up to 40%. Partial and complete removal of seed coat resulted in over 90% germination. Application of gibberellic acid to both unscarified and scarified seeds produced marginal but significant effects on cumulative germination, germination value and germination energy. Application of gibberellic acid to seeds whose seed coat had been completely removed resulted in complete emergence of all seeds sown. Observations indicate that the poor germination associated with T. emetica seeds is due mainly to the impermeability of the seed coat and aril to fluids (water and gases). It is recommended that the seed coat of T. emetica seeds be partly or completely removed before sowing.
Fruit- and seed-germination characteristics of Strychnos cocculoides an indigenous fruit tree from natural populations in Zambia
Domestication and improvement of traditionally used wild indigenous fruit trees hold great promise in agroforestry development. Strychnos cocculoides is a wild indigenous fruit tree that was ranked third by farmers and is one of the priority species chosen for domestication in southern Africa. This study was conducted with the objective of determining the variability in fruit, seed and germination characteristics of four populations of Strychnos cocculoides collected from Zambia. Results showed significant differences (P 0.05) in the number of seeds per fruit within and between the provenances. In contrast, the seed weight was significantly different (P < 0.05) within and between provenances. The heaviest seeds were found in the heaviest fruits — Kalulushi while the lightest were found in Serenje provenance. Fruit weight was positively correlated with pulp weight (P < 0.001, r = 0.70), pericarp weight (P < 0.001, r = 0.54) and seed weight (P < 0.001, r = 0.76). The provenances differed significantly (P < 0.05) in cumulative germination percentage, ranging from 56 (Kalulushi) to 83 (Kasama).
Provenance and pretreatment effect on seed germination of six provenances of Faidherbia albida (Delile) A. Chev
A nursery experiment was conducted to determine the effects of seed pretreatment methods on the germination of Faidherbia albida at ICRAF, Nairobi from six provenances consisting of Awassa, Taveta, Lake Koka, Maseno, Chinzombo and Wagingombe. Seeds were subjected to five pretreatment methods namely nicking, soaking in acid, hot water, cold water and control. Germination percentages (GP), mean germination time (MGT) and germination index (GI) were calculated and the data was subjected to ANOVA. The study revealed significant (p 0.05) differences in seed treatments among provenances in all studied parameters. Highest germination among pretreatments in Awassa (99 %) and Wagingombe (80 %) was observed in nicked seeds, Chinzombo (81 %) in nicked and acid treated seeds, Lake Koka (90 %) in acid treated seeds and Taveta (28 %) and Maseno (64 %) in cold water treated seeds. Nicking gave the highest cumulative GP (69.67) while lowest GP was observed in hot water treated seeds (23.17). Acid treatment exhibited lowest MGT (8.85 days) and highest GI (2.29) while highest MGT (24.35 days) and lowest GI (0.31) were observed in control and hot water treatment respectively. Although acid treatment gave a high GP and lowest MGT and GI, nicking and soaking in cold water for 24 h is being recommended as cheaper and less hazardous pretreatment methods to improve germination in F. albida since sulphuric acid is expensive and requires proper handling techniques. Significant correlation between geo-climatic data and germination parameters of seeds subjected to different pretreatments indicates that provenances are as important as pretreatments in germination of the species. © 2016 Springer Science+Business Media Dordrecht
Improving seed germination of Sudanian savanna-woodland species: effects of fire-related cues (heat and smoke) and sulphuric acid
A study was carried out to investigate the effects of ire related cues (heat and smoke) and sulphuric acid treatments on the germination of four woody savanna species, namely, Terminalia avicennioides, Piliostigma thonningii, Piliostigma reticulatum and Prosopis africana. The heat treatment consisted of putting seeds in a preheated oven at 100, 150 and 200 °C for 2.5 min. Seeds were then soaked in four concentrations of smoke solution (0 (tap water), 25, 50 and 100% smoke solutions). Parallel to smoke and heat treatment, seeds of the four species were each soaked in concentrated sulphuric acid for 2 hours and also according to the conventional soaking time of each species. Under experimental conditions, heat and smoke did not stimulate seed germination. For P. thonningii and P. africana, soaking seeds for 2 hours in sulphuric acid signiicantly increased germination capacity compared with conventional soaking time of 5 min. Longer soaking time reduced mean germination time. Results of this study will be useful in the establishment of these species
Direct seeding of six agroforestry tree species indigenous to the Sahel: the effect of fungicide and planting-hole depth on seed germination and seedling emergence capacity
Tree planting success has been a major challenge in the Sahel region. As a low-cost, efficient option, farmer-managed natural regeneration entails some constraints, most notably a lack of species diversity. To find alternative techniques, four experiments were carried out to determine seed germination and seedling emergence capacity, evaluate the success of direct seeding for orthodox (Adansonia digitata, Faidherbia albida, Ziziphus mauritiana) and recalcitrant species (Cordyla pinnata, Saba senegalensis, Vitellaria paradoxa), and examine the effects of fungicide treatments. A fifth experiment studied the influence of planting-hole depth on F. Albida seedling emergence capacity. The results did not reveal any significant differences based on fungicide doses. For germination test, V. paradoxa had the longest mean germination time among recalcitrant species. For both orthodox and recalcitrant species, significant differences were observed in seedling emergence parameters, survival and growth. Eighteen months after sowing, orthodox species A. digitata and Z. mauritiana showed the highest survival rates at 99 ± 1% and 95 ± 2%, respectively, while among recalcitrant species, V. paradoxa had the highest survival rate (80 ± 5%), 17 months after sowing. Analyses of the probability of ending up with a maximum of 10% empty spots demonstrated a need to sow at least 4, 5, 10 and 8 seeds for A. digitata, F. albida, Z. mauritiana, and V. paradoxa, respectively. The deepest hole, measuring 100 cm in the F. albida experiment, significantly outperformed the other holes of lower depth, displaying the highest mean emergence rate and the greatest relative growth rate. These results support the hypothesis that direct seeding in 60 cm-deep holes can be successful for A. digitata, F. albida, Z. mauritiana, and V. paradoxa.
Smoke Induced Seed Germination in Maize in Response to Self and Other Plants Biomass-derived Smoke
Fire ecology plays an important roles in germination and establishment of many plant taxa. Smoke inducedgermination and seedling vigor are well documented in many wild, crop, and weedy species. Karrikins(KAR) substances in smoke are reported to be responsible for these effects. However, only a few experimentshave been conducted on different plant-derived smoke effects on particular plant speciesâ seeds. This studywas conducted to investigate effects of self-derived and other plants biomass-derived smoke on germinationand post-germination processes in maize and its wild relative teosinte. Smoke derived from maize and alegume (Vigna unguiculata ssp. sesquipedalis) foliage burning was exposed to maize variety Guidan 162and teosinte (Zeamexicana (Schrad.) Kuntze). Germination percentage in both maize and teosinte exposedto maize smoke was found to be significantly higher than unexposed and legume smoke exposure, howevergermination in legume smoke exposure was found to slightly higher than control but not significantly so.Shoot length in maize seeds exposed to maize smoke was highest and differed significantly compared tocontrol and legume smoke exposure, while control and legume smoke exposure showed approximatelythe same shoot lengths. Coleoptile and primary root lengths showed nosignificant variation among alltreatments. Similarly, seminal root length didnâ t show much variation but legume smoke exposure seedsfound to have the lowest seminal root length. Hence direct exposure to smoke without rinsing in watermay not positively affect the shoot and root length in maize. Further studies should address morphologicaltraits, transcriptome expression, and enzyme activity to clarify effects of self-derived and other plant-derived smoke on different plant species.
Seedling emergence and environmental filters determine Ficus recruitment in a subtropical landscape
Early regeneration, involving the transition from a seed into a successfully recruited seedling, is a complex process characterized by high mortality rates and the strong association with environmental filters. However, we have limited understanding of the factors and transitional regeneration stages that lead to these broad mortality events, even in species that are key for ecosystem function and comprise the bulk of species in diversity assessments, such as Ficus species. Using eight, 1-ha long term monitoring plots, established along an elevation gradient in tropical to subtropical forests in southern China, and partitioning the early plant regeneration process into four stages (seed germination, seedling emergence, establishment and recruitment), we conducted a seed addition experiment to assess the factors driving the early regeneration process. We used four hemi-epiphytic and four non-hemiepiphytic Ficus species, specifically asking whether elevation, microsite conditions and growth form affect the success of regeneration outcomes. We observed that Ficus early regeneration was highly limited throughout the subtropical landscape with similar seed germination probabilities along all elevations, but greater seedling emergence at higher elevations. Growth form and elevation interacted significantly during seed germination and seedling emergence stages. The strongest filtering effect was observed during seedling emergence, with greater canopy openness facilitating, but drier and cooler soils being less conducive to seedling emergence, especially for hemiepiphytic species. Once emerged, Ficus seedlings were released from the environmental filters assessed here, yet, continued to face successively greater mortality during establishment and recruitment. Greater seed germination and seedling emergence on the ground observed in hemiepiphytes indicate that they may benefit from evolutionary traits associated with canopy regeneration under water and temperature stress, but only at the early regeneration stages, as seedling establishment and recruitment were similar in both groups. In general, our results demonstrate that even when seeds are available, successful recruitment is strongly limited by microsite conditions and growth form, through filtering mechanisms associated with the transition from seedling emergence to seedling establishment. The identification of environmental filters that operate during the complex and vulnerable early regeneration stages provides a baseline to develop management strategies for ex situ conservation, as well as in situ population reestablishment for restoration. © 2021 Elsevier B.V.