Seed Dormancy Breaking Research Articles

Methods of Breaking Seed Dormancy for Four Species of Ornamental Cacti

The aim of this study was to investigate methods for breaking the seed dormancy of cacti that are cultivated in Thailand. To stimulate seed germination and decrease the production time for cacti, the research used four cacti species: Astrophytum asterias, Echinocactus grusonii, Myrtillocactus geometrizans, and Turbinicarpus alonsoi, which are extensively grown as ornamental cacti species in Thailand. The experimental design used in this study was a completely randomized design (CRD). The pot experiment consisted of 4 dormancy breaking methods and six replicates, 30 seeds per pot. For the control, seeds were sown onto planting media directly. In the experimental samples, seeds were subjected to different pre-soaking treatments: soaking for 24 h in room temperature water (28 2oC), GA3 500 ppm for 24 h, and H2SO4 (50%) for 30 min. The seed germination and plant growth data were collected after sowing cacti seeds for two months. The results showed that soaking cacti seeds in room temperature water produced the highest germination rates for A. asterias, E. grusonii, and M. geometrizans. In addition, this treatment also reduced the production time of M. geometrizans. Concurrently, A. asterias, E. grusonii, and M. geometrizans presented higher stem diameters and root lengths of the seedlings, as well as the best result on the seedling vigor of cacti. Soaking seeds with GA3 resulted in the highest germination percentage of T. alonsoi and accelerated seed germination of A. Asterias, and T. alonsoi. Moreover, this treatment led to the maximum root lengths and seedling vigor of T. alonsoi. However, soaking seeds with H2SO4 was a treatment that gave E. grusonii the maximum root length and seedling vigor.

Methodological and Physiological Study during Seed Dormancy Release of Symplocos paniculata.

Symplocos paniculata are reported to exhibit seed dormancy, which impedes its cultivation and widespread adoption. In this study, a comprehensive method was established to overcome seed dormancy by subjecting seeds to scarification in 98% H2SO4 for 10 min, followed by 1000 mg·L-1 GA3 soaking for 48 h and stratification at 4 °C for 100 days. The seed germination percentage has increased significantly, to a peak of 42.67%, though the seeds could not germinate timely by NaOH scarification. Additionally, the dynamic changes of key stored substances (proteins, soluble sugars, starches, and fats), associated enzyme activities (amylases, peroxidase, and catalase), and endogenous hormones (abscisic acid, gibberellic acid, and indole-3-acetic acid) in seeds were investigated. The results demonstrated a continuous degradation of starch and fat in S. paniculata seeds, while the levels of protein and soluble sugar exhibited fluctuations, which probably facilitated seed dormancy breaking through energy supply and transformation. The enzymatic activities underwent rapid changes, accompanied by a gradual decrease in ABA content within the seeds with increasing stratification time. Notably, GA3, GA3/ABA, and (GA3 + IAA)/ABA showed significant increases, indicating their positive regulatory roles in seed germination. This study clarified the dormancy mechanism and established an effective method for the release dormancy of S. paniculata seeds.

Transcriptome Analysis of Seed in Dormancy and Dormancy Release State of Epimedium koreanum Nakai

Epimedium koreanum is a perennial herb of the Berberidaceae family, which is a traditional tonic in Chinese medicine. Seed germination of E. koreanum is difficult. Dormancy is an intrinsic factor that affects seed germination. Elucidating the molecular mechanism of seed dormancy and the lifting process of E. koreanum is of great significance for the breeding, conservation, and utilization of E. koreanum. Previous studies have concluded that E. koreanum seed dormancy breakage requires warm-temperature stratification followed by low-temperature stratification treatments. Therefore, we performed transcriptome sequencing using freshly harvested, untreated seeds (NS), seeds that developed a cotyledonary embryo after 90 d of constant-temperature stratification at 15 °C (CS), and seeds that broke dormancy by 90 d of stratification at 15 °C and 60 d of stratification at 5 °C (ND) in order to find the responsive genes and regulatory genes that regulate dormancy. A total of 92,867 genes with differential expression were identified. GO enrichment analysis highlighted redox processes, as well as structural components of the nucleus and ribosomes. KEGG enrichment analysis revealed a significant enrichment of phytohormone signaling pathways, which play a crucial role in seed dormancy release. Additionally, protein–protein interactions (PPIs) were predicted with starch and sucrose metabolic pathways. This study introduces a novel concept for a more profound comprehension of the molecular regulatory mechanism of E. koreanum and lays a theoretical foundation for the screening of E. koreanum candidate genes.

Overcoming dormancy in Desmanthus virgatus seeds for improved viability monitoring protocols of genebank accessions

Desmanthus virgatus is a perennial forage legume used as a livestock feed source. Seeds of this species are physically dormant and thus, propagation is difficult. The dormancy also impacts the routine viability monitoring of genebank accessions. The present study investigated different methods to break dormancy in seeds collected from various locations at different times. The result showed that most pre-treatments significantly increased germination percentage. Accessions treated with concentrated sulphuric acid (25 or 30 minutes) followed by sandpaper scarification showed the highest proportion of normal seedlings (94.6 and 96%). Boiling water (2.3 or 3 minutes) was also effective in all accessions except for accession 331. However, accessions treated with hot water (3, 5 or 8 minutes) had a considerable proportion of hard seeds. The proportion of dead/abnormal seedlings was high in seeds treated with a hot wire in all accessions, ranging from 27.5 (accession 15489) to 75.5% (accession 16). The untreated seeds remained hard at the final germination count. We conclude that it is important to use concentrated sulphuric acid and mechanical scarification with sandpaper to break the dormancy for the species to enhance germination, obtain uniform field stands and make wise decisions during storage.

A pilot study on kernel germination to enhance planting materialproduction in oil palm

At present, only five oil palm seed gardens are actively involved in DXP seed production in India with cumulative capacity of 10-12 lakh germinated seeds in a year. The National Mission on Edible Oils (NMEO) – Oil Palm has targeted to increase area under oil palm to 10.0 lakh hectares by 2025-26 from the present level of 3.50 lakh hectares. For this, nearly 975 lakh oil palm seedlingsare required (Reddy, 2020). Further, conventional method of seed dormancy breaking and germination is an energy and time consuming process and produces only 40-50% quality germinated seeds. Increase in germination canfacilitate to enhance planting material production with same level of seed production. Hence, an alternate method was attempted to germinate oil palm kernel to improve germination.

Overcoming Tegumentary Numbness in Seeds of Crotalaria spectabilis and Crotalaria paulinea

Objective: To evaluate the efficiency of dormancy breaking methods in seeds of C. paulinea and C. Spectabilis. Theoretical reference: Species of crotalaria, such as C. paulinea and C. spectabilis, found in the Brazilian territory, are used as green manure in large crops and vegetable productions. However, the presence of tegumentary hardness in their seeds can result in failures in soil cover, which favor the emergence of weeds. Method/design/approach: The research was carried out at the Laboratório de Análise de Sementes of the Departamento de Agronomia, at the Universidade Federal de Viçosa, Minas Gerais. Twenty treatments were applied to the seeds to break dormancy, using mechanical scarification with 120 grit sandpaper, hot water in an oven at 90 °C for five and seven minutes, and immersion in sodium hypochlorite at four concentrations, 2%, 4%, 6% and 8%, for four times, two, four, six and eight hours. Results and conclusion: The most efficient treatments for breaking this dormancy in both species of crotalaria were scarification with sandpaper and immersion in water at 90±3 °C for seven minutes. Treatments using sodium hypochlorite were not effective in reducing the number of hard seeds. Originality/value: Feasibility of the methods applied to break dormancy in seeds of C. paulinea and C. Spectabilis, since they are used for green manure, and control of Aedes aegypti, among other purposes.

S-nitrosylation of the transcription factor MYB30 facilitates nitric oxide-promoted seed germination in Arabidopsis.

The gaseous signaling molecule nitric oxide (NO) plays an important role in breaking seed dormancy. NO induces a decrease in abscisic acid (ABA) content by transcriptionally activating its catabolic enzyme, the ABA 8'-hydroxylase CYP707A2. However, the underlying mechanism of this process remains unclear. Here, we report that the transcription factor MYB30 plays a critical role in NO-induced seed germination in Arabidopsis (Arabidopsis thaliana). MYB30 loss-of-function attenuates NO-mediated seed dormancy breaking. MYB30 triggers a NO-induced decrease in ABA content during germination by directly promoting CYP707A2 expression. NO induces S-nitrosylation at Cys-49 of MYB30 and enhances its transcriptional activity. Conversely, the ABA receptors PYRABACTIN RESISTANCE1 (PYR1)/PYR1-LIKE (PYL)/REGULATORY COMPONENTS OF ABA RECEPTORS (RCAR) interact with MYB30 and repress its transcriptional activity. ABA promotes the interaction between PYL4 and MYB30, whereas S-nitrosylation releases the PYL4-mediated inhibition of MYB30 by interfering with the PYL4-MYB30 interaction. Genetic analysis showed that MYB30 functions downstream of PYLs during seed dormancy and germination in response to NO. Furthermore, MYB30 mutation significantly represses the reduced dormancy phenotype and the enhanced CYP707A2 expression of the pyr1 pyl1 pyl2 pyl4 quadruple mutant. Our findings reveal that S-nitrosylation of MYB30 precisely regulates the balance of seed dormancy and germination, providing insights into the underlying mechanism of NO-promoted seed germination.

Variation in degree of intermediate complex morphophysiological dormancy in seeds of Bunium persicum (Apiaceae)

AbstractBunium persicum is an important medicinal plant, but the requirements for seed dormancy break and germination are not well known. Based on available information, we hypothesized that seeds have an underdeveloped embryo and physiological dormancy (PD), and hence morphophysiological dormancy (MPD), and that populations of this species may have different degrees of MPD which demand different germination requirements. In this study, we evaluated embryo growth in seeds from four B. persicum populations at different temperatures and tested germination at varying constant temperatures, with or without GA3 and cold stratification. Seeds from the four populations had a fully differentiated, small, linear but underdeveloped embryo. The initial embryo‐to‐seed length ratio was 0.14–0.17, but it increased to 0.71–0.75 before germination at 5°C. Little embryo growth occurred at 15°C and no growth occurred at 25°C. GA3 effectively increased germination percentages, replaced cold stratification, reduced the required period for cold stratification, and in combination with cold stratification increased the maximum temperature of germination. Therefore, seeds from the four populations have intermediate complex MPD. Additionally, the germination responses of seeds from the four populations to GA3, cold stratification, or both were different, suggesting variation in the degree of PD. Bunium persicum seeds developed in cool and wet conditions were more dormant than those developed under warm and dry conditions. Thus, we showed that different climates can affect the depth of PD in a species whose seeds have MPD, resulting in variation in the degree of intermediate complex MPD at the population level.

Intermediate complex morphophysiological dormancy in seeds of Aconitum barbatum (Ranunculaceae)

BackgroundSeed dormancy and germination are key components of plant regeneration strategies. Aconitum barbatum is a plant commonly found in northeast China. Although it has potential for use in gardening and landscaping, its seed dormancy and regeneration strategy, which adapt to its natural habitat, are not well understood. Our aim was to identify conditions for breaking A. barbatum seed dormancy and determine its dormancy type. Embryo growth and germination were determined by collecting seeds over time in the field. Laboratory experiments that control light, temperature, and stratification period were conducted to assess dormancy breaking and germination, and GA3 was used to identify dormancy type.ResultsSeeds of A. barbatum have undeveloped embryos with physiological dormancy at maturity in autumn. The embryo-to-seed length ratio increases from 0.33 to 0.78 before the emergence of the radical. Under natural environmental conditions, embryo development begins in early winter. Laboratory experiments have shown that long-term incubation under 4 °C (cold stratification) promotes embryo development and seed dormancy break. With an extension of cold stratification, an increase in germination percentages was observed when seeds were transferred from 4 °C to warmer temperatures. Seeds exposed to light during incubation show a higher germination percentage than those kept in the dark. Seed germination can also be enhanced by a 100 mg/L GA3 concentration.ConclusionsSeeds of A. barbatum display intermediate complex morphophysiological dormancy at maturity. In addition to the underdeveloped embryo, there are also physiological barriers that prevent the embryo from germinating. Dormancy breaking of A. barbatum seeds can be achieved by natural winter cold stratification, allowing seeds to germinate and sprout seedlings at the beginning of the following growing season. Our findings provide valuable insights into the seed dormancy and regeneration strategy of A. barbatum, which could facilitate its effective utilization in gardening and landscaping.

Effects of exogenous GA3 and warm water on dormancy breaking germination characteristics of Eucommia ulmoides

Seeds of the plant Eucommia ulmoides Oliver, have prominent dormant characteristics. In the present study, seed dormancy and germination of E. ulmoides were investigated by treating them with exogenous GA3 and different water temperatures. The results revealed that exogenous GA3 and warm water soaking treatments were beneficial to the dormancy breaking and germination of seeds. The germination rate of seeds treated with 50℃ water was 84.67%. In comparison, the seeds treated with 300 mg·L-1 GA3 had only a germination rate of 45%. This low germination rate resulted probably due to the low temperature of the GA3 solution. Another important reason is the presence of eucommia gum in the seed coat of E. ulmoides which hinders the germination process. During germination, the SOD activity in the seeds treated with GA3 (300 mg·L-1) and warm water (50 °C) increased significantly. Increased SOD activity reduced the degree of oxidative damage of the plasma membrane and resulted a continuous decrease in TBARS content. Thereby, the seeds were prompted to develop in a direction conducive to germination. In addition, GA3 (300 mg·L-1) and warm water (50℃) treatments increased the content of endogenous GA3, IAA, and ZR in the seeds, and decreased the content of endogenous ABA. This had resulted significantly higher ratios of GA3/ABA, IAA/ABA and ZR/ABA than those ratios of distilled water (room temperature) treated plants. In short, 50 °C warm water treatment has a more marked germination promoting effect on E. ulmoides seeds.

PHYSICAL AND CHEMICAL SCARIFICATION ON DORMANCY BREAKING OF ROSARY PEA SEEDS (ABRUS PRECATORIUS L.)


 
 
 
 Abstract: Seeds are part of the plant containing embryo that grows through the germination process. This process involves metabolism occurs in seeds to produce roots and shoots. However, this metabolic process is inhibited by the environment and genetics of the seeds itself. Thus, the seeds experience dormancy and fail to grow. Dormancy can be broken with help of physical and chemical scarification to accelerate seed germination. The research aim was to determine the physical and chemical scarification seed dormancy breaking in increasing the germination rosary pea seeds (Abrus precatorius L.). The research method used was experimental randomized block design using 4 treatment groups, namely cracked (F1), sanded (F2), and soaked in 50% H2SO4 solution for 15 minutes (K1) and 30 minutes (K2) and the group control with water. The viability germination, germination rate (GER), vigor index (VI), simultaneous growth (SG) normal sprouts on day 6, and growth rate (GOR) were observed for two weeks. The results obtained that immersion in H2SO4 50% solution for 30 minutes and cracking could break the dormancy of rosary pea seeds and increase germination with higher viability of germination, GER, VI, SG, and GOR than immersion in 50% H2SO4 solution for 15 minutes and sanding.
 
 
 

Multiomics strategies for decoding seed dormancy breakdown in Paris polyphylla

BackgroundThe disruption of seed dormancy is a complicated process and is controlled by various factors. Among these factors, membrane lipids and plant hormones are two of the most important ones. Paris polyphylla is an important Chinese herbaceous species, and the dormancy trait of its seed limits the cultivation of this herb.ResultsIn this study, we investigate the global metabolic and transcriptomic profiles of Paris polyphylla during seed dormancy breaking. Widely targeted metabolomics revealed that lysophospholipids (lysoPLs) increased during P. polyphylla seed dormancy breaking. The expression of phospholipase A2 (PLA2), genes correlated to the production of lysoPLs, up-regulated significantly during this process. Abscisic acid (ABA) decreased dramatically during seed dormancy breaking of P. polyphylla. Changes of different GAs varied during P. polyphylla seeds dormancy breaking, 13-OH GAs, such as GA53 were not detected, and GA3 decreased significantly, whereas 13-H GAs, such as GA15, GA24 and GA4 increased. The expression of CYP707As was not synchronous with the change of ABA content, and the expression of most UGTs, GA20ox and GA3ox up-regulated during seed dormancy breaking.ConclusionsThese results suggest that PLA2 mediated production of lysoPLs may correlate to the seed dormancy breaking of P. polyphylla. The conversion of ABA to ABA-GE catalysed by UGTs may be the main cause of ABA degradation. Through inhibition the expression of genes related to the synthesis of 13-OH GAs and up-regulation genes related to the synthesis of 13-H GAs, P. polyphylla synthesized more bioactive 13-H GA (GA4) to break its seed dormancy.

Unleashing the potential of Phlox (Phlox drummondii): Evaluating the influence of growth regulators and growing media

During the early spring in the woodlands of eastern North America, Phlox drummondii emerges as a perennial plant adorned with a profusion of blooms in shades of blue, purple, pink, or white. Its evergreen nature adds to its charm. To manage the growth of plants or specific plant parts, plant growth regulators (PGRs) are synthesized and employed, serving as valuable tools for controlling and directing the development of various plant species. A diverse range of ornamental plants, such as Phlox drummondii, have been documented to receive exogenous applications of plant growth regulators (PGRs). Among these regulators, gibberellins (GA) play a vital role by delaying senescence in flowers and promoting the breaking of dormancy in seeds, bulbs, and corms of ornamental plants. The experiment aimed to assess the performance and determine the optimal growth medium for Phlox. Five distinct growth media were employed as treatments during the study, which took place in the Horticulture Department of Gomal University. Collected data underwent analysis through ANOVA and Tuckey HSD tests. The study’s findings revealed that the highest plant height (16 cm) was observed in the control treatment with PGR 1, closely followed by PGR 2 (11.5 cm). The treatment labeled as T5, composed of a mixture of 1/3 sand, 1/3 poultry manure, and 1/3 soil, demonstrated the most favorable results across multiple parameters such as bud initiation (BI), first flower emergence (FFE), flowers per plant (FPP), branches per plant (BPP), leaves per plant (LPP), number of roots (NR), field life of flowers (FLF), and flower diameter (FD). T4, T3, T2, and T1 treatments also exhibited similar positive outcomes, aligning with the promising performance of T5.

Effects of seasonal temperature regimes on embryo growth and endogenous hormones of Taxus chinensis var. mairei seeds.

Seed dormancy is a mechanism that prevents seeds from germinating at times of the year when conditions are unfavorable, that is, when the chance of seed survival is low. Determining the seasonal dynamics of seed dormancy is important for exploring how plant regeneration is adapted to the environment. We studied the seed dormancy status of Taxus chinensis var. mairei, an endangered species in China, under simulated seasonal temperature regimes. The embryo length, embryo-to-seed (E:S) ratio, and percentage of seeds with a split seed coat increased when seeds were stratified at spring and autumn temperature regimes. The abscisic acid (ABA) content decreased during stratification at simulated seasonal temperatures, but no obvious pattern in the content of gibberellic acid (GA) and indole acetic acid (IAA) was observed. The GA-ABA and IAA-ABA ratios increased during stratification. These results suggest that T. chinensis var. mairei seeds have morphophysiological dormancy, and that the seasonal dynamics of seed dormancy break are controlled by endogenous hormones and their balances, which was confirmed by the results of a field experiment. Our study provides useful information for understanding the natural population regeneration and propagation of this threatened species.

Candidate Genes for Salt Tolerance in Forage Sorghum under Saline Conditions from Germination to Harvest Maturity.

To address the plant adaptability of sorghum (Sorghum bicolor) in salinity, the research focus should shift from only selecting tolerant varieties to understanding the precise whole-plant genetic coping mechanisms with long-term influence on various phenotypes of interest to expanding salinity, improving water use, and ensuring nutrient use efficiency. In this review, we discovered that multiple genes may play pleiotropic regulatory roles in sorghum germination, growth, and development, salt stress response, forage value, and the web of signaling networks. The conserved domain and gene family analysis reveals a remarkable functional overlap among members of the bHLH (basic helix loop helix), WRKY (WRKY DNA-binding domain), and NAC (NAM, ATAF1/2, and CUC2) superfamilies. Shoot water and carbon partitioning, for example, are dominated by genes from the aquaporins and SWEET families, respectively. The gibberellin (GA) family of genes is prevalent during pre-saline exposure seed dormancy breaking and early embryo development at post-saline exposure. To improve the precision of the conventional method of determining silage harvest maturity time, we propose three phenotypes and their underlying genetic mechanisms: (i) the precise timing of transcriptional repression of cytokinin biosynthesis (IPT) and stay green (stg1 and stg2) genes; (ii) the transcriptional upregulation of the SbY1 gene and (iii) the transcriptional upregulation of the HSP90-6 gene responsible for grain filling with nutritive biochemicals. This work presents a potential resource for sorghum salt tolerance and genetic studies for forage and breeding.

Pelleting of Physical Dormancy Small-Seeded Species in Astragalus sikokianus Nakai

Astragalus sikokianus is a rare Japanese perennial of the seashore that was reported to be extinct in the wild. The small seed size and deep dormancy of A. sikokianus make it difficult for direct seeding restoration in aspects of seed handling, transport, planting, and seedling establishment. For the large-scale economic restoration of dormant small-seeded species, seed pelleting combined with the breaking of dormancy was studied. Physiological (prechilling and plant hormones) and physical (hot water, hydrochloric acid, and sulfuric acid) seed dormancy break treatments were evaluated. The dormant broken seeds were used for pelleting. The effects of the substrate, pellet sizes, and their interactions on germination were measured. The scarification of five rubs of seeds placed between sandpapers completely broke the physical dormancy of A. sikokianus. Seed coat impermeability inhibited germination. Pelleted seeds ranging from 2.0 to 4.0 mm in diameter showed more than 90% germination on filter paper. The germination of the pelleted seeds was measured in commercial, field, and sand soil conditions. The highest germination was shown in sand (70–74% GP), regardless of the pellet size, whereas unpelleted scarified seeds germinated only 48%. These results suggest that small-seeded species with physical dormancy can be used for seed-based restoration after seed pelleting.

Regulation of dormancy break and germination of safflower seeds: the role of GA3, light and cold temperatures.

The safflower crop is considered a great alternative for crop rotation since drought tolerance and low production cost are attractive for its choice. However, safflower seeds show dormancy soon after dispersal from the mother plant, making it difficult to successfully establish plants using newly harvested seeds. The influence of temperature, gibberellin and light/dark on dormancy break of safflower seeds during storage were investigated. In a completely randomized design, freshly harvested seeds or stored for 100 and 200 days (paper bag, 20 °C/ 60% UR) were treated with GA3 (0 and 100 µM), at 4, 10 and 25 °C, in the presence and absence of light, during the germination test. Seeds were evaluated for germination percentage, germination speed and seedling survival after 21 days. The temperature of 10 °C, in combination with GA3 (0/100 µM), or light/dark, provided the highest seed germination results, for freshly-harvested seeds and stored seeds. Collectively, these observations indicate that dormancy was not affected by gibberellic acid (100 µM GA3) and the germination results at 21 days were significantly higher, in relation to the use of GA3, under light or dark. Recently harvested seeds could efficiently germinate at 10 °C in the dark, while seeds dry-stored at 20 °C had decreased germination percentages.

REVIEW ON DORMANCY, CAUSES, USES, AND MEASURES OF OVERCOMING IT

The majority of both human and animal diets are made up mostly of seed, which is also the foundation and the first input used in the transmission of genetic features in crop development. Seed dormancy, a physiological phenomenon in plants that can be brought on by internal or external stimuli, prevents seeds from sprouting even under ideal circumstances. Hard seed coats, underdeveloped embryos, primitive embryos, and inhibitory compounds can all contribute to seed dormancy. Under normal circumstances, soil melting and freezing, microbial activity, forest fires, soil activity, and animal consumption break dormancy in seeds. The most common method for releasing seeds from their dormancy is scarification, which can be carried out mechanically or chemically followed by others like scarification, light and heat treatment, dipping in hot water, etc. Leaching is another method for ending seed dormancy because it destroys the inhibitory components of the seed coat.

Breaking Seed Dormancy of Prosopis africana Seeds and its Effects on Seedlings Growth under Two Different Savanna Soils Conditions

Forest trees across the tropics can be effectively domesticated and conserved for afforestation programmes after successful overcoming by breaking the dormancy of their seed coats. The study was conducted at Forest Nursery Unit of Federal University Dutsin-Ma to assess the breaking dormancy of Prosopis africana seeds and its effects on seedlings growth under two different savanna soils conditions. A 2x5 factorial in Randomized Complete Block Design was used for this experiment in four replicates. The factors were savannah soils locations; (ZA: Zaria soil and DS: Dutsin-ma soil) and pre-sowing treatments; Seeds soaked in 60% diluted Tetraoxosulphate (VI) acid (H2SO4) (A); seeds soaked in hot water at 1000C (HW); seeds soaked in water for 24 hours (W); mechanical scarification (MS); control (C). The data were analyzed using analysis of variance at (P=.05). Zaria soil had significantly higher values (8.55cm, 12.65cm and 17.65cm, 0.15cm and 0.17cm, and 262.05, and 0.12) on seedling heights (SH) at 4-8 weeks after sowing (WAS), collar diameters (CD) at 4-6 WAS, and leaflet areas (LA) at 4 WAS respectively. Mechanically scarified seeds (MS) had consistent significantly higher values (6.54cm, 13.79cm, 19.90cm, 25.13cm and 29.15cm, 0.15cm, 0.19cm, 0.21cm, 0.25cm and 0.29cm, and 0.14, 0.16, 0.19, 0.20 and 0.23) on SH, CD, and LA at 2-10 WAS respectively. It is concluded that seeds sowed in Zaria soil performed better than Dutsin-ma soil, while, mechanical scarification was the best pre-sowing treatment for improved seedlings growth of P. africana seeds.

Emergence and initial growth of açaí palm under different light levels after seed dormancy breaking treatments

Light availability and dormancy are two factors that interfere with germination and initial plant growth. This study aimed to evaluate the influence of different pre-germination treatments on the emergence and initial growth of Euterpe oleracea Mart. seedlings subjected to different levels of luminosity. A completely randomized design was adopted in a 4 × 3 factorial scheme with four methods of overcoming dormancy (intact seed, hot water at 60 °C, soaking for 24 h in water, and mechanical scarification with sandpaper No. 100) and three levels of luminosity (25 %, 65 %, and 100 %) with 16 repetitions per treatment. The emergence percentage, speed index, and mean time were analyzed. The initial growth was evaluated using the following variables: plant height, stem diameter, shoot dry mass, root dry mass, total dry mass, leaf area, and root mass ratio. There was an interaction between light factors and dormancy breakage for plant height, stem diameter, and leaf area. The variables root dry mass, shoot dry mass, and root mass ratio showed better results with full sun. It was concluded that shade treatments provided greater initial growth for the açaí palm with intact seeds.