Cumulative Germination Percentage Research Articles

Impact of eco-physiological factors on the weed seed germination and emergence: A review on its role in weed management

Dormancy is a typical feature of many weed seed populations, which makes forecasting the time and magnitude of weed emergence difficult. The mean minimum temperatures required for undergoing germination of different weed seeds varies considerably depending on the place of their origin as well as the season on which the plants grow. For instance, the temperature requirement for the germination of summer weeds was observed to be 40% higher than for the winter weeds. Decreasing the water potential from 0 Mpa (mega pascal) to -1.0 Mpa tends to reduce the germination capacity of many weed seeds with some seeds totally failing to germinate at -1.0 Mpa (Chloris truncate, Retama raetam). The effects of planting depth on seed germination and seedling growth of Aframomum citratum on varied soil types indicated that sowing depth greatly influenced the plant's cumulative germination percentage and early growth. The seeds of Sysimbrium officinale (L.), a summer annual species, displayed greater sensitivity to nitrates and lost dormancy throughout the winter. The germination of Thlaspi arvense was also discovered to be stimulated by nitrate only in the presence of light. Tilling the surface of soil has a positive impact in the weed seed germination, however if the tillage depth increases more than 9cm, it tends to lower down the germination of several weed species. However, weed seeds of Bernard grass are among the exceptions in which they germinate better at a shallow depth (2cm). The nature and the thickness of the mulching component influence the germination of weed seeds. Thicker mulches and mulching materials like pearl millet resulted in a greater suppression of the weed seed germination due to an increased allelopathic effects.

Alleviation of Water-Deficit Stress on Seed Germination of Barley and Fenugreek in a Sandy Soil Using Superabsorbent Polymer

Water deficit is one of the major limiting factors of seed crop germination and productivity. Consequently, superabsorbent polymers (SAPs) are among several technologies that enhance water use efficiency, leading to worthy seed germination. The objective of this study was to investigate the potential effect of three rates of SAPs (0.0%, 0.5%, and 1.0% w/w) on the seedling emergence of barley and fenugreek sown in a sandy soil using three replicates in a randomized complete block design. Outdoor pot experiments were conducted in Aswan Province, Egypt. The differences in the final germination percentages (FGPs) were not significant for both seeds, while the application of SAPs enhanced the seedling germination index (GI) with significant differences for both crop seeds. The application of SAP at 0.5% gave the highest GI for barley (2.47 day−1) and fenugreek (2.66 day−1) seeds. The sigmoidal function effectively described the cumulative germination percentage rates for both seeds as a function of time under the SAP levels with R2 greater than 0.992. The maximum rates were 69.4 and 64.6 day−1 for barley and fenugreek seeds at SAP 0.5%, respectively. The corresponding rates for 0.0% SAP were 11 and 12 day−1. The water germination efficiencies (WGE) were 27.76 and 30.04 cm−1 for 0.0% and 0.5% SAP for barley, while they were 23.07 and 29.9 cm−1 for fenugreek. Accordingly, SAPs could represent a promising solution for increasing moisture conservation for seed germination in a sand soil. For strategic management, barley is recommended for growth over fenugreek in a semidried soil.

Seed Priming with Nanoparticles and 24-Epibrassinolide Improved Seed Germination and Enzymatic Performance of Zea mays L. in Salt-Stressed Soil

Saline stress is one of the most critical abiotic stress factors that can lessen crops' productivity. However, emerging nanotechnology, nano-fertilizers, and developing knowledge of phytochromes can potentially mitigate the negative effects of saline stress on seed germination. Therefore, the aim of this study was to investigate the effects of seed priming either with zinc oxide nanoparticles (ZnO-NPs; 50 and 100 mg L-1) or 24-epibrassinolide (EBL; 0.2 and 0.4 μM) and their combinations on maize (Zea mays L.) grains sown in salt-stressed soil (50 and 100 mM NaCl). Saline stress treatments significantly affected all germination traits and chemical analysis of seeds as well as α-amylase activity. Compared to un-primed seeds, seed priming with ZnO-NPs or EBL and their combinations significantly increased the cumulative germination percentage, germination energy, imbibition rate, increase in grain weight, K+ content, and α-amylase activity, and significantly reduced germination time, days to 50% emergence, Na+ uptake, and Na+/K+ ratio of maize sown in salt-stressed-soil (50 or 100 mM NaCl). The combination of 100 mg ZnO-NPs L-1 + 0.2 μM EBL resulted in the highest improvements for most of the studied traits of maize seeds sown in salt-stressed soil in comparison to all other individual and combined treatments.

Effect of salt stress and nitrogen supply on seed germination and early seedling growth of three coastal halophytes.

Due to high salinity and low nutrient concentrations, the coastal zone is considered as one of the most vulnerable of the earth’s habitats. Thus, the effect of salt and nitrogen on growth and development of coastal halophytes has been extensively investigated in recent years, but insufficient attention has been paid to the crucial stages of plant establishment, such as seed germination and seedling growth. Thus, we carried out a field experiment to evaluate the effects of salt stress (6, 10 and 20 g/kg NaCl) and nitrogen supply (0, 6 and 12 gm−2year−1) on seed germination and seedling growth of three coastal halophytes (including two dominant herb species Glehnia littoralis and Calystegia soldanella, one constructive shrub species Vitex rotundifolia) from September 2020 to June 2021. The results of our experiment showed that seeds of G. littoralis exhibited an explosive germination strategy in the early spring of 2021 with 70% of the seeds germinating. Conversely, the seeds of V. rotundifolia exhibited slow germination in the late spring of 2021 with only 60% of the seeds germinating. C. soldanella seed germination exhibited two obvious peak periods, but only 6% of the seeds germinated, which means that most seeds may be stored in the soil by stratification or died. All three halophytes showed greater sensitivity to nitrogen than salt stress during the seed germination stage. Nitrogen supply significantly delayed seed germination and reduced the cumulative germination percentage, particularly for G. littoralis. Despite the large impact of nitrogen on seed germination, nitrogen had a larger impact on seedling growth suggesting that the seedling growth stage of halophytes is more vulnerable to changes in nitrogen supply. Moreover, nitrogen supply significantly reduced the individual biomass of G. littoralis, C. soldanella and V. rotundifolia, with greater decreases seen in the dominant species than in the constructive species. Conversely, nitrogen supply increased underground biomass allocation of G. littoralis and C. soldanella, suggesting that the constructive species were less sensitive to nitrogen and exhibited a stronger anti-interference ability than the dominant species. Therefore, increasing nitrogen supply may firstly affect the seed germination and seedling growth of the dominant species, but not the constructive species.

Seed germination behaviour of Quercus leucotrichophora (Banj oak) in Western Himalaya

Quercus leucotrichophora A.Camus (Banj oak) is one of the keystone species in the mid-elevation forests across western and central Himalaya. Its regeneration in many parts is reported to be poor due to low germination and seedling emergence. Present study aims to investigate the germination behaviour of Quercus leucotrichophora. Seeds were collected from 5 different sites and sown in polybags under open, poly-house and shade-net-house conditions. Seed germination started in 20 days and was completed in 92 days. Higher seed germination was observed in poly-house conditions (76.66%-82.66%) followed by shade-net-house conditions (68.23-76.66%), while, minimum germination was observed in seeds placed under open conditions (61.66%-74.33%). Mean Germination Time was found rapid in poly-house conditions (8.4-10.13) followed by shade-net house conditions (8.79-12.71) and open conditions (20.39-24.66). Among all the sites, higher germination was recorded for the seeds collected from the mid altitude regions (1300-1400 m asl). A significant positive correlation (P<0.05) between seed size class with cumulative germination percentage was also noticed. The findings of the present study indicated that, site of seed collection can play a crucial role in seed germination. Thus, for raising quality planting material of Q. leucotrichophora, seed collection should be done from specific habitats that ultimately help in restoring the declining population.

Germinability of annual bluegrass seed during spring in the Eastern United States

AbstractSoil seedbank management via collecting clippings may be a means of combatting herbicide resistance in annual bluegrass (Poa annua L.) by minimizing recruitment from the deposition of viable seed into the soil. Our objective was to assess the germinability of annual bluegrass seed in spring to determine when collecting clippings would be most impactful. Research was conducted across 2019 and 2020 in five locations: Knoxville, TN; Starkville, MS; Griffin, GA; West Lafayette, IN; and University Park, PA. Annual bluegrass seed was harvested every 100 growing degree‐days (GDD0C; base 0 °C with accumulation beginning on 1 January each year from 400 to 1,100 GDD0C. Seeds from each harvest timing were placed on moistened blotter paper in petri dishes and randomized in a growth chamber set to a 77:68 °F and 8:16 h light–dark cycle. Germination was assessed every 3 d until 21 d of incubation. Cumulative germination percentage after 21 d of incubation increased at research locations in northern latitudes. In Tennessee, germination was greatest from 600 to 900 GDD0C. In Indiana, germination did not exceed 50% until 600 GDD0C and increased with GDD0C accumulation. Clippings should not be collected until at least 600 GDD0C in these locations. In Pennsylvania, little variation existed among GDD0C harvest times, indicating that clipping collection may be a valuable practice any time mature seedheads are present. Turfgrass managers should consider geographic location when selecting a time to implement clipping collections and will probably need to conduct multiple clipping collection events.

Evaluation of pre-germination treatments in Carapa guianensis AUBL

Understanding seed germination of native forest species of the Tropical wet forest is essential for ecosystem regeneration and conservation, which have been affected by the exploitation of wood and non-wood forest products. Carapa guianensis Aulb. (Meliaceae) has been exploited due to the high quality of its wood and seeds. Particularly, the latter is a source of a medicinal oil of high value to the pharmaceutical industry. The indiscriminate use of this species has reduced its population size; therefore, scientific knowledge of its sexual propagation in nurseries is vital. This research aimed to evaluate seed germination of C. guianensis under different pre-germination treatments and substrates at the Centro de Investigación El Mira of AGROSAVIA. Pre-germination assays were conducted in a split-plot design with a random distribution of four repetitions. The cumulative germination percentage (CGP) and mean germination time (t50) were calculated and analyzed through an ANOVA, and Tukey’s multiple comparison test using InfoStat V.2016. Significant differences for CGP among treatments (p<0.0001) and interactions (p<0.0096) were found. The highest germination percentage (61%) was achieved in S1+T4; however, the T50 did not show significant differences (p=0.24). This research demonstrates that the highest germination percentage is achieved through a scarification treatment with imbibition in sand substrate under the agroclimatic conditions of Tumaco.

English

Series of investigations have been carried out on the effect of sowing depths on seed germination and early seedlings growth of Aframomum citratum and has shown that sowing depth influences germination and early growth of most plant species. Thus, the importance of varying planting depths has received much attention from researchers for some time now. The depths studied in this research were 0, 3 and 6 cm, respectively. Using a split plot complete randomized design (CRD) in a non-mist propagator, a total of 864 seeds (432 fresh and 432 dry) of A. citratum were sown with three replicates for each soil type in prepared polyethylene bags. Germination was monitored daily for a period of six weeks while data for germination parameters was collected. Early growth parameters such as average number of leaves (NL), average leaf surface area (SA) and average height of seedlings, (SH) were measured every week for two months. Results revealed that germination started 2 months after fresh seeds were sown in all soil types. Dried seeds being treated with 50% dilution of concentrated sulphuric acid for 20 min did not germinate during the germination period that ranged from 2 to 7 months. Sowing depths significantly affected the cumulative germination percentage and early growth (p<0.05). Thus, the highest percentage of seedlings was produced at 0 cm sowing depth, followed by 3 cm sowing depth and the least was at 6 cm sowing depth. Germination of A. citratum seeds can be done based on the information given in this study. Key words: Aframomum citratum, seeds, sowing depths, germination, early growth.

Dormancy break and germination requirements in acorns of two bottomlandQuercusspecies (Sect.Lobatae) of the eastern United States with references to ecology and phylogeny

AbstractQuercusspecies are ecologically and economically important components of deciduous forests of the eastern United States. However, knowledge pertinent to a thorough understanding of acorn germination dynamics for these species is lacking. The objectives of this research were to determine dormancy break and germination requirements for acorns of two eastern United States bottomland species,Quercus nigraandQuercus phellos(SectionLobatae), and to present results within ecological and phylogenetic contexts. Three replicates of 50 acorns of each species received 0 (control), 6, 12 or 18 weeks of cold stratification, followed by incubation in alternating temperature regimes of 15/6, 20/10, 25/15 and 30/20°C. Eighteen weeks of cold stratification were not sufficient for dormancy break inQ. nigraacorns. Cumulative germination percentages at 4 weeks of incubation were ≥77%, but only in incubation temperatures of 25/15 and 30/20°C. Dormancy break inQ. phellosacorns was achieved with 18 weeks of cold stratification, and cumulative germination percentages were ≥87% at 4 weeks of incubation in all test temperature regimes. Gibberellic acid solutions were not an effective substitute for cold stratification in either species. Phylogenetically,Q. nigraandQ. phellosare closely related species and, ecologically, both grow in the same habitat. Acorns of both species possess deep physiological dormancy (PD), but dormancy break and germination requirements differ in acorns of these twoQuercusspecies.

Application and Use of Presowing Treatment Methods to Improve Germination of Vachellia karroo (Hayne) Banfi & Galasso

A germination experiment of Vachellia karroo seeds was conducted at the Botswana University of Agriculture and Natural Resources, Department of Crop and Soil Sciences laboratory, from September to October 2018. Seeds were collected along the Segoditshane River in Gaborone to investigate the effect of different pre-sowing treatment methods on their germination. The experiment was laid out in a completely randomized design (CRD) with five treatments (control, mechanical scarification, boiling water, hot water and concentrated sulphuric acid (98.8%). Boiling water (30, 60, 180 and 300 seconds) and concentrated sulphuric acid (15, 30, 45 and 60 minutes) had four levels of exposure time. The highest significant (p < 0.01) cumulative germination percentages were recorded in seeds subjected to sulphuric acid for 45 and 60 minutes, mechanical scarification (shortest germination mean time of 2.0 - 2.3) and boiling water at 30 and 60 seconds (moderate germination mean time of 5 - 5.9) whereas, the control treatment had the least cumulative germination percentage of 2%. As expected, the same trend was revealed for germination index. The seeds possess seed coat imposed dormancy, which requires sowing treatments. The best treatments for releasing dormancy in V. karroo were sulphuric acid and mechanical scarification and because of the risks associated with the use of sulphuric acid, the researchers recommend mechanical scarification as the suitable treatment method in tree nurseries. Keywords: Seed dormancy, Germination mean time, Germination index, Pre-sowing treatment, Germination percentage, Germination rate, Tree nursery.

Creeping bentgrass seed germination in growth chambers at optimal and suboptimal temperatures

AbstractTurfgrass managers attempting to establish creeping bentgrass (Agrostis stolonifera L.) from seed following winterkill episodes may benefit from cultivars that germinate and establish quickly during cold temperature periods. The purpose of this study was to identify the percentage and time until germination of different cultivars of creeping bentgrass under a suboptimal temperature regime. Twenty‐seven seed samples showing ≥90% germination under the optimal temperature regime of 77:59 °F on an 8:16‐hour light–dark cycle were selected for germination tests at the suboptimal temperature of 50 °F on an 8:16‐hour light–dark cycle. The results show differences among creeping bentgrass samples with respect to cumulative germination percentages (CGP) and days to germination when incubated at 50 °F. Seed samples of ‘Pure Select’, ‘Penn A’‐4, ‘Crystal BlueLinks’, and ‘007’ were most consistent with respect to high germination percentages and days to germination at 50 °F. However, where multiple seed samples of the same cultivar were examined, variation in CGP and days to germination were detected among samples. Cultivars with superior germination characteristics at low temperatures may improve creeping bentgrass establishment from seed following winterkill episodes. However, practitioners should be aware that germination at low temperatures may vary among seed samples or seed lots of individual cultivars because of factors associated with seed vigor, such as seed age, preharvest environmental conditions, seed storage methods, and other factors, which could result in variable rates of establishment in early spring.

Effects of soil type, period of burial and moisture levels on the germination of Oncocyclus iris seeds

Understanding germination of seeds constituting a persistent soil seed bank is important because the ability to predict longevity of a seed in soil and a particular combination of environmental conditions supporting dormancy break and germination can be critical for restoration of threatened species having poor regeneration. We studied the pattern of germination under experimentally manipulated environmental conditions in several threatened iris species of section Oncocyclus. In the first experiment, spanning 11 years, we manipulated soil type and precipitation regime, and in the second experiment, spanning 7 years, we tested an effect of cumulative amount of rainfall during a season on germination. In all studied species the germination process was intermittent, with distinct germination pulses separated by years with no or very low germination. High innate dormancy appears to be a general property of newly produced seeds of Oncocyclus irises, but there are exceptions. Although in three tested Oncocyclus species considerable (above 25%) germination fraction was observed only in the second and subsequent seasons regardless of the soil moisture experienced by a seed, in Iris atropurpurea it occurred in the first season under watering equivalent or exceeding cumulative seasonal precipitation of 100 mm. In the three other species, although high cumulative germination percentage was observed by year four under all experimental conditions a substantial fraction of seeds was still ungerminated and viable. Our results have important conservation implications. We recommend for mass seed germination creation of a soil seed bank under natural conditions with minimal modifications, monitored for more than two years. Supplementary watering (if feasible) will speed up the germination process and shading will have a similar effect but neither of these two is a requirement.

Aspects of the population biology, life history and threats to Aloe ortholopha Christian and Milne-Redh.: A serpentine endemic from the northern Great Dyke of Zimbabwe

Background: Aloe ortholopha is a rare endemic confined to serpentine soils of the Great Dyke of Zimbabwe. Its International Union for Conservation of Nature (IUCN) status is listed as Vulnerable; however, its population biology and life history are poorly documented.Objectives: The aim of this article is to provide information on the population biology and life history of A. ortholopha through assessment of its size-class distribution, population size and density, reproductive output and fitness, and threats related to fire and mining.Method: Circumference of A. ortholopha leaf rosette was used to ascertain size-class distribution. Population size and density were determined by enumerating flowering individuals. Per-capita reproductive output was determined as mean number of flowers per plant, fruit set and mean number of seeds per fruit. Fitness was determined from seed germination capacity. Impact of fire and mining were recorded photographically.Results: Determination of size-class distribution of A. ortholopha from three study sites (southern region [SR], central region [CR] and northern region [NR]) revealed a bell-shaped curve dominated by intermediate size classes. Population size (number of flowering individuals) ranged from 36 to 66 per site. This translated to a density of 4.0–7.3 flowering plants per hectare. Per-capita reproductive output, measured as mean number of flowers per plant, was significantly different in SR and CR compared to that in the NR region. Mean number of fruits per plant did not significantly differ across the three regions. Mean seed set per plant in CR and NR was significantly different to that in the SR region. Species fitness, as determined from in vitro germination assays, showed that seeds harvested from fire-damaged capsules have the lowest cumulative germination percentage. It was also observed that leaf rosettes curled up to form a ball that protects the apical centre of plants from fire damage.Conclusion: A. ortholopha occurs in small population clusters of low density. The species has a low per-capita reproductive output characterised by production of many flowers, but with very low percentage fruit and seed set. The species has low fitness as evidenced by nominal recruitment of saplings and juveniles. Conspecific mates are frequently lost owing to fire and mining activities.

English

This study aims to evaluate the effects of seed pre-treatments on the germination of Echinops giganteus. The pre-treatments used were partial manual removal of the pappus (T1), total removal of the pappus (T2), roasting for 2 min (T3), roasting for 4 min (T4), roasting for 6 min (T5), soaking in water for 6 h (T6), soaking for 12 h (T7), soaking for 24 h (T8) and the control (T0). The experiment was laid out in a completely randomized design with three replicate and 60 seeds per pre-treatment in March 2016 at IRAD Bambui. Germination was monitored daily for a period of one month and data on latent period, germination percentage and germination speed was collected. Early growth parameters such as shoot height (H), collar diameter (CD) and number of leaves (NL) were measured after every two weeks from the 11th to the 17th week while root length (RL) was measured at 17th week. Germination commenced 5 days after sowing for pre-treatments T1, T2, T6, T7 and T8, respectively while seeds from the control pre-treatment (T0), T3, T4 and T5 germinated 8 days after sowing. Germination was delayed and scanty in pre-treatments T4 and T5. Cumulative germination percentage and germination rate were highest in pre-treatment T1 followed by T2 and T6 while T4 and T5 were the least. Height and collar diameter of seedlings was highest in pre-treatments T6, T7, T2 and T1 respectively. Influence of pre-treatments on number of leaves and root length of seedling was not significant. Germination of E. giganteus seeds can be done based on the information given in this study. Key words: Echinops giganteus, seed germination, pre-treatments, early growth. &nbsp

Regulating acorn germination and seedling emergence in Quercus pagoda (Raf.) as it relates to natural and artificial regeneration

Dormancy break and germination requirements for Quercus pagoda (Raf.) acorns were determined, as well as the effects of acorn pretreatment and post-germination temperatures on epicotyl emergence, seedling development, and seedling biomass accumulation. There was an inverse linear relationship between length of cold stratification (5/1 °C for 0–12 weeks) and cumulative germination percentages in all incubation temperatures (15/6, 20/10, 25/15, 30/20 °C). Acorns required 12 weeks of cold stratification to break dormancy. Gibberellic acid substituted for cold stratification; although, it was not as effective as 12 weeks cold stratification. At 16 weeks of cold stratification, 20% of acorns had germinated, and the remaining 80% of ungerminated acorns reached ≥ 97 ± 1% cumulative germination within 4 days in all incubation temperatures. Post-germination time to epicotyl emergence and to leaf flush was a function of temperature, and time decreased with increased temperatures. With light held constant (50 μmol m−2 s−1), seedlings accumulated greater biomass in temperatures > 20/10 °C. Q. pagoda acorns possess Type 2 nondeep physiological dormancy, and this allows for artificial manipulation of timing and duration of germination. Extending cold stratification 4 weeks beyond dormancy break (i.e., 16 weeks) yields more uniform germination across a range of temperatures. Epicotyl emergence, seedling development, and biomass accumulation may be regulated by manipulating growing temperature. In this study, the most uniform seedling cohort with the greatest total biomass was produced when acorns received 16 weeks of cold stratification, followed by transfer of germinants to 30/20 °C.

Seed dormancy-breaking in a cold desert shrub in relation to sand temperature and moisture.

Seasonal periodicity of seed germination and its relationship to seasonal changes in temperature and soil moisture have been well studied in seeds of species with physiological dormancy. However, relatively little information is available on the role of these environmental factors in controlling germination of seeds with physical dormancy (PY). Our primary aim was to determine if seeds of the cold desert sand dune semi-shrub Eremosparton songoricum exhibits seasonal periodicity of seed germination and the relationship between seed dormancy break and soil temperature and moisture. In the laboratory, seeds incubated on dry, wet, wet-dry and dry-wet sand were exposed to a 1-year sequence of temperature regimes simulating those in the field. In the field, seeds were buried at different depths on a sand dune, and germination of periodically exhumed seeds was tested at five temperature regimes during a 2-year period. In the one-year sequence of simulated natural temperature regimes, breaking of PY was more effective under constantly wet than under constantly dry conditions, and germination percentage was significantly higher under dry-wet than under wet-dry conditions. Seeds buried in the field exhibited a distinct peak of germination in spring and little or no germination in other seasons. The final (two-year) monthly cumulative germination percentage differed among burial depths and temperature, and it was highest (47%) in seeds buried at 3 cm and tested at 25/10 °C. A seed cohort of E. songoricum likely exhibits a long-term annual periodicity of spring germination in the field, and dormancy break appears to be driven by low (winter) temperatures and relatively high sand moisture content. To our knowledge this is the first study to document seasonal periodicity in seed germination in a cold desert species with PY and to identify the mechanism (at the whole-seed level) of its occurrence.

Effect of growing media, sowing depth, and hot water treatment on seed germination and seedling biomass of &lt;i&gt;Acacia senegal&lt;/i&gt; (L) wild

To optimize seedling production for reforestation of degraded dryland with A. senegal seeds, a study was conducted on the effect of boiled water treatment, growing media, sowing depth on seed germination and seedling growth of A. senegal. Three different growing media (farm soil, forest soil and sand soil), boiled water seed pre-treatment for 5 and 10 minutes, untreated seeds as control and three sowing depths (2, 4 and 6 cm) were the treatments investigated. The experimental design was a nested (Split plot) design. It was observed that sowing depth significantly affected the germination percent of the seeds and seedling growth; seedling emergence time increased with sowing depth. The highest cumulative germination percentage (CGP) (100%) was obtained from untreated seeds sown in sand soil at 2 cm depth while the lowest germination percentage (8%) was obtained from seeds pre-treated for 5 min in boiled water and sown in sand soil at 6 cm depth. Untreated seeds sown at 2 cm depth in sand soil germinated completely on the seventh day after sowing while it took about 17 days in farm and forest soils but 18 days in sand soil to reach the maximum recorded CGP for the treatment. Seedling height and branch number were higher for seedlings grown on forest soil. It was concluded that among the depths considered 2 cm was the optimum sowing depth for the species in all the tested growing media. Likewise, sand soil was found to be the best growing medium for germination of untreated seeds sown at 2 cm depth. Moreover, seed pre-treatment for 5 min in boiled water could be recommended for A. senegal seeds if farm and forest soil should be used as growing media. Seedling growth was found to be the best in forest soil when seeds were sown at 2 cm depth.Keywords: A. senegal, Sowing depth, Growing media, Seed treatment, germination, Seedling growth

Germination Traits of Millettia Pinnata (L.) in Response to Salinity

Millettia pinnata is a mangrove associates and found to occur in the Sundarbans mangrove forest of Bangladesh. We have examined the effect of salinity on seed germination of this species. Seed germination experiment was conducted with different salinity levels (0 to 35 ppt) at 5 ppt interval. Throughout the experiment Cumulative Germination Percentage (CGP) varied from 73.89% to 27.78% among 0 to 10 ppt and from 17.22% to 4.44% between 15 to 20 ppt salinity. Final germination percentage (FGP) of M. pinnatta seeds varied significantly (p

Reproductive properties of Zostera marina and effects of sediment type and burial depth on seed germination and seedling establishment

The dynamics of reproductive properties of Zostera marina in the Shandong Peninsula was recorded based on field investigations. Influences of sediment type and burial depth on seed germination and seedling establishment were studied in controlled laboratory conditions. In the field, the reproductive stage occurred from late March to late August. The reproductive properties showed obvious seasonal variation and had a significant impact on the cumulative seed production. Seed release began in early June, and the cumulative seed production was 10451±371.0seedsm−2, while the maximum production in a single week was 2907±258.1seedsm−2. The seed germination experiment showed significant effects of seed burial depth as well as the interaction between sediment type and burial depth on both seed germination and seedling establishment percentages (p<0.001). Seeds on the sediment surface or buried to 1cm could maintain high germination percentages (76±11.5% and 90±1.5%, respectively) regardless of sediment type. With increasing burial depth, germination percentages decreased gradually and were lower than 40% in all sediment types. Only seeds in sand:silt mixtures 2:1 could germinate when the burial depth increased to 5cm; the earliest germination appeared in the fifth week and the cumulative germination percentage was lower than 3%. Seedling establishment showed a similar trend to seed germination; seeds buried in shallow depths showed a higher seedling establishment percentage, and the maximum value was recorded in seeds that were buried to 1cm in sand:silt mixtures 2:1 (30.67%).

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.