Acid Scarification Research Articles

Pre-sowing treatments for a better germination of Myrianthus holstii seeds

ABSTRACT The cultivation of the indigenous fruit and food security tree, Myrianthus holstii, is seriously constrained by its seed dormancy, change in land use and overexploitation, decreasing its wild population and limiting its on-farm planting in Rwanda. Therefore, we determined the effects of different pre-sowing treatments on the germination and seedling growth of M. holstii to promote its domestication in Rwanda, using mechanical nicking of seeds, boiling seeds in water for 5 min and sulphuric acid (98%) scarification for 15 and 30 min. The shortest acid-scarification produced the highest germination (93%) within 6 weeks after sowing and seedlings with longer heights and more leaves within 3 months, comparable to mechanical nicking, indicating that the two techniques are effective in improving the germination and seedling growth of M. holstii. However, mechanical scarification was recommended to small-scale farmers, since it is eco-friendly, economical and user-friendly to contribute to M. holstii domestication in Rwanda.

Influence of seed pre-treatment and storage on germination and physiological characteristics of seeds of common mullein (Verbascum thapsus L.)

We report the seed germination and associated metabolic responses of differentially stored seeds of Verbascum thapsus L. (Scrophulariaceae), an economically and medicinally important herb from the cold desert region of Lahaul (Himachal Pradesh, India) in trans Himalaya, to certain physico-chemical and GA₃ treatments. The freshly harvested seeds of V. thapsus exhibited high (96 %) viability but low germination (55 %). During the storage of seeds under ambient conditions, viability did not change until 1-year but declined progressively thereafter showing a 33 % decline in 4-year stored seeds. The seed germination was promoted to varying extents by acid scarification (AS), SNP (sodium nitroprusside), SHC (sodium hypochlorite) and GA₃ pre-treatments. Storage-dependent changes in seed germination performance and responsiveness to different effectors were evident. Germination performance improved significantly due to 1-year storage followed by a sharp decline subsequently. The responsiveness of seeds to various treatments tended to be higher in seeds stored for ≥2 years. The changes in germination were paralleled by those in α-amylase activity in seeds. Lipid peroxidation generally increased during storage that was paralleled by a gradual decline in superoxide dismutase (SOD) activity and phenolic contents. Catalase (CAT) activity increased transiently in 1-year stored seeds and declined thereafter. Data are expected to have implications for multiplication and cultivation of V. thapsus.

Studies in the seed ecology and seedling Phenology of Andrographis paniculata (Brum. f.) Wall. ex Ness in West Bengal, India

Andrographis paniculata (Brum. f.) Wall. ex Nees is an important medicinal plant of tropical Asia and has been used widely for a long time for different clinical ailments. Despite profuse flowering and a high percentage of fruit set,the number of seedlings in the natural population is the bare minimum. Knowledge regarding the seed ecology and seedling phenology of A. paniculata, is needed to formulate conservation strategies for the species. Therefore, a detailed study on seed ecology and seedling phenology has been conducted. During seed ecological studies,seed production, seed-set percentage, seed-ovule ratio, mechanism of seed dispersal, seed structure along with germination status, viability, dormancy and its breaking, and percentage of moisture content loss have been studied. Seeds exhibit some kind of dormancy [germination percentage (GP) = 28.51 ± 0.98, mean germination time (MGT) = 33.07± 0.89 days, and germination index (GI) = 0.73 ± 0.08] which can be effectively overcome through acid scarification using H2SO4 and hot water treatment. The species shows epigealphanerocotylar germination. The hypocotyls exhibit rapid growth, and cotyledons emerged at 7.52±0.27 TARA (Time After Radicle Appearance in days). Seedling is characterised by a thickened, hairy hypocotyl, a distinct collet, a pair of paracotyledons, and three pairs of eophylls in opposite decussate phyllotaxy. The studies on seed ecology and seedling phenology play a significant role in understanding how the shortening of the inception period enhances the germination status, and distinct seedling morphology provides the opportunity to formulate conservation strategies in their wild habitat.

Morfološke osobine plodova i sjemena i trajanje učinka skarifikacije sjemena sumpornom kiselinom na neke vrste iz roda Crataegus Tourn. ex L.

Hawthorn species (Crataegus Tourn. ex L.) are widely known for their medical, ecological, and economic benefits. The main issue of this study was to define the morphological characteristics of fruits and seeds as well as the impact of sulfuric acid (96% concentration) scarification with different time duration on seeds of three different hawthorn species (C. crus-galli, C. monogyna, C. laevigata). Statically significant differences were reported for all measured fruit and seed morphological traits. Highest fruit weight, length and width was recorded for C. crus-galli, while lowest for C. monogyna. Different sulfuric acid (96% concentration) scarification treatments were used for C. cruss-galli (150 and 210 min), C. laevigata, and C. cruss-galli (45, 75 and 105 min) seeds. Only significant differences were found in contrast to the control. Thickness of the tiniest part of the seed coat was significantly reduced in C. crus-gallic and C. laevigata scarified seeds in contrast to control. Thickness of the thickest part of the seed coat was significantly reduced only in C. crus-galli seeds scarified for 210 min in contrast to control. Therefore, optimal duration of scarification treatment for C. crus-galli seeds should be 210 min. The results obtained in this study will contribute to a better knowledge of morphometric characteristics and the pre-sowing treatment of seeds of some Crataegus species which can be utilized in nursery production.

Variations in Seed Dormancy Occurrence and Their Classifications in Thirteen Actinidia Species

As differences in seed dormancy between Actinidia species have not been reported previously, in this study we characterized the variation in the dormancy of seeds in 13 kiwifruit species that originated from different regions of China and Taiwan, and for which mature plants are now growing in New Zealand orchards. Dormancy-breaking treatments, including cold-moist stratification, seed coat scarification and soaking in water and gibberellic acid (GA3), were tested for their efficacy in alleviating dormancy and improving final germination and germination rates. In addition, we assessed seed viability using RNA integrity analysis to distinguish dead seeds from dormant seeds. This study identified that dormancy type in Actinidia seeds is species-specific and can be morphological, morphophysiological or a combination of physiological and physical, and that seed RNA integrity is a useful metric to incorporate into seed dormancy studies. Our results also suggest that species originating from colder climates that experience large differences between winter minimum and summer maximum temperatures exhibit physiological dormancy and require cold-moist stratification, contrasting with species originating in milder climates. Interestingly, although not all seeds from all the species were dormant, the proportion of dormant seeds in each species did not correlate to the climatic data of the region from which they originated. These findings provide new insights into mechanisms of seed dormancy in kiwifruit.

Seed Dormancy Dynamics and Germination Characteristics of Malva parviflora L.

Little mallow (Malva parviflora L.) is a notorious weed that causes substantial yield losses in winter crops. For effective weed management and seed testing, a deeper understanding of seed dormancy, germination behavior, and dormancy-breaking methods is necessary. Experiments were conducted to determine the effect of seed treatments, i.e., mechanical scarification, acid scarification, hot water treatment, and different germinating temperatures, i.e., 15 °C, 20 °C, or alternating 15–20 °C (16/8 h), on the seed dormancy in M.parviflora. A large proportion of M. parviflora seeds were physically dormant, with just 10.90% germination. Seed treatments had a significant influence on seed germination, seedling dry weight, vigor index, and water absorption (p ≤ 0.01). Among the various treatments, mechanical scarification enhanced germination by 32%, the vigor index by 487% and water uptake by 34%, and decreased percent hard seeds by 34%. Among the various germination temperatures, alternating 15–20 °C temperatures (16/8 h) gave the most significant result for germination and the lowest percent hard seeds. The findings of this study will serve as a valuable reference for seed testing and the development of suitable weed control strategies for M. parviflora.

Overcoming seed coat–imposed dormancy in wild species ofCajanusandRhynchosia

AbstractOccurrence of physical dormancy or hard seed coat prevents proper utilization and conservation of wild species ofCajanusandRhynchosia, which offers a source of many useful traits. Hence, an attempt has been made to understand the variability in hardseededness and the pretreatments (hot air treatment for 3, 5, 7, and 14 days; hot air treatment for 30 and 60 min; sulfuric acid scarification for 2 and 5 min; partial incision on seed coat) to overcome it in 44 accessions of 10 wild pigeon pea species. The level of hardseededness varied from 36% to 100% with an average of 76.5%. Likewise, time to 1% germination or time taken to initiate germination (T1), time to 50% germination (T50), and mean germination time (MGT) varied between 16.18–249.9 h, 94.7–607.7 h, and 37.5–153.2 h, respectively. Overall, all the treatments reduced hardseededness and improved germination over the control, with partial incision on seed coat being the best treatment for all the species recording 70%–98% germination, except forRhynchosia aurea(30%) andCajanus cajanifolius(59%). The hot water treatment for 30 and 60 min was the best treatment forC. cajanifoliusrecording germination of 66%–70% as compared to 11% in control. The sulfuric acid scarification for 2 min was the best pretreatment for overcoming dormancy and improving germination inRhynchosia bracteata,Rhynchosia rothii, andRhynchosia rufescens. The result indicated a significant inter‐ and intraspecific variation in the effectiveness of pretreatments in overcoming physical dormancy, suggesting that the optimum pretreatment for overcoming hardseededness should be standardized for each accession. Also, the dormancy‐breaking pretreatments not only reduced hardseededness and improved final germination percent but it also reduced time for T1, T50, and MGT, suggesting that use of such pretreatments before sowing could result into higher, uniform, and rapid germination.

Optimization of treatments for the germination and establishment of botanical yam (Dioscorea rotundata) seeds

Botanical yam (Dioscorea rotundata) seeds are currently used by yam breeders to generate and conserve new varieties of yam instead of seed yams (vegetative propagule). Yam seed treatment through scarification is one of the most effective methods of improving seed germination and seedling establishment. This study was carried out under greenhouse condition to determine the best seed treatment for the germination and establishment of botanical yam seeds. The set up involved a soil mixed with carbonized rice husk using five different seed treatments; dry heating (DHS) at 60 0C, mechanical scarification + gibberellic acid (MSS + GA), mechanical scarification (MSS), acid scarification with sulphuric acid (ASS) and soaking in hot water at 80 0C (SOS). The findings showed that the treatment, MSS + GA and MSS only, had significant (P<0.05) positive effect on the seed emergence and seedling establishment compared to the untreated control (COS) and other treatments. ASS caused seed damage resulting to no emergence. The findings showed that carbonized grain waste (rice husk) enhanced soil fertility and seed treatment (MSS + GA) was the best to improve yam seed germination and seedling establishment. These treatments can be efficiently applied to reduce the long gestation periods and increase yield in yam breeding programmes.

Effect of Sulfuric Acid Scarification followed by Organic Mulching for Papaya Seedling Growth and Development, in Pot Culture

A major obstacle to the development of papaya seeds is the aril, or sarcotesta, which is present in papaya and results in low and sluggish germination. Hence sulfuric acid was applied in order to evaluate its scarifying effect and materials like rice bran, wood chips and saw dust were used as organic mulching material for further facilitating the process of seed germination. The experiment was consisted of seven treatments and each treatment had 3 replications. The treatments were T1 (sulphuric acid scarification for 1 min + Saw dust mulching), T2 (sulphuric acid scarification for 1 min + Wood chips), T3 (sulphuric acid scarification for 1 min + Rice bran mulching), T4 (sulphuric acid scarification for 30 sec + Saw dust), T5 (sulphuric acid scarification for 30 sec + Wood chips), T6 (scarification for 30 sec + Rice bran) and T7 control (water). Experiment was carried on completely randomized design. Total leaf count and their length, number of rootlets, plant height, length of roots, germination percentage and chlorophyll content were the parameters which were observed in periodic intervals of seedling growth. From the entire experiment it can be stated that, acid scarification and use of organic mulches proved good for the papaya seedling development. However, amongst the various treatments, sulphuric acid scarification for one minute with use of wood chips as an organic mulch material was best, documenting proper results for the different attributes.

Seed Pre-Treatment and Early Growth Performance of Piliostigma thonningii (Schum.) Milne-Redhead under Nitrogen Amendment in Old Oyo National Park, Nigeria

Survival of wildlife in protected areas is dependent on innate attributes and response of vegetation to climate change. Piliostigma thonningii holds promise for wildlife conservation in Old Oyo National Park, but its population is threatened by physical dormancy. There is dearth of information on long-term benefits of its seed pretreatment and early growth response to nitrogen fertilizer. This study assessed effects of acid scarification on germination and early growth of P. thonningii under different nitrogen application rates. Seeds harvested from three purposively selected seasonal wetlands in Old Oyo National Park (OONP) were treated with 1N H2SO4 at durations ranging from 0 – 120 minutes in three replicates. Germinated seeds were enumerated over a 14-day period. Top soils from the wetlands were randomly sampled using soil auger in three replicates for physical and chemical analyses, and for early growth study with Urea fertilizer at rates 0, 50 and 100 kg/ha in experimental pots in completely randomized design. Growth and dry matter were assessed using ANOVA at P.05. Germination commenced in control treatments at 14 days after plating (DAP) and was low (13.3%). Germination progressively increased in acid treatment. At 5 DAP for soaking for 30 minutes gave 46.67%; while it was 96.67% at 40 minutes at 14 DAP. Higher soaking times gave 100% germination by 14 DAP, but with low growth vigor. The response of P. thonningii to Urea application was significantly higher in number of leaves at 12 weeks than in other rates. Other growth parameters are not significantly different at all rates. The biomass yield of P. thonningii was 1.98 g ±0.21and 2.6 g ±0.36 root and shoot dry weights at 6 weeks after sowing (WAS); and 7.3 g ±0.04 root and 6.4 g ±0.95 shoot dry weights at 12 WAS. Piliostigma thonningii can restore and improve wildlife abundance to mitigate climate change effects in the Park.

Acid scarification as a potent treatment for an in vitro germination of mature endozoochorous Vanilla planifolia seeds

BackgroundVanilla planifolia is the most widely cultivated species of vanilla with high economic importance. However, seed germination under artificial conditions is difficult and yields low germination percentages. The seeds are adapted to endozoochorous dispersal, and we therefore tried to simulate the conditions in the digestive tract by acid scarification of seeds.ResultsImmature seeds lacking dormancy, used as a control, showed the highest germination percentage. Among the treatments tested for mature seeds, the hydrochloric acid treatments were significantly the best in breaking dormancy and inducing germination, irrespective of the acid concentration and the presence of pepsin. Conventional treatment with a hypochlorite solution induced much lower germination percentage. Sulphuric acid at concentration 50% was too strong and caused damage to the seeds. Important factor is also high cultivation temperature 30 °C as there was nearly no germination at 25 °C.ConclusionsOur protocol significantly improves the efficiency of generative propagation of vanilla and allows for significantly higher germination percentages than previously described. The strongly positive effect of hydrochloric acid may be related to the adaptation of seeds to endozoochorous dispersal.

Standardization of an In Vitro Seed Germination Protocol Compared to Acid Scarification and Cold Stratification Methods for Different Raspberry Genotypes

In raspberry (Rubus idaeus L.) breeding programs, seed double dormancy causes delayed and low germination rates. In this study, an in vitro germination protocol was developed to increase raspberry seed germination rate and decrease germination time. This protocol was optimized on the cultivars “Polka” and “Tulamagic”, specifically, their open-pollinated seeds, by applying two different cutting types (transverse, or longitudinal), followed by two different treatments (direct in vitro culture at 24 °C, or 2 weeks at 4 °C followed by in vitro culture at 24 °C). The best results for both cultivars were obtained when seeds were cut transversally and directly cultured in vitro at 24 °C (germination rate 73–78%, starting germination time 4 days after treatment). The optimized in vitro protocol was applied to 14 different combination crosses, observing a germination frequency around 87%, and speed in line with “Polka” and “Tulamagic”. These results were compared to those from the 14 cross combinations having undergone acid scarification (95% H2SO4 for 30 min) and cold stratification (3 months), which, in comparison, only yielded a 25% average germination rate. The optimized in vitro protocol favors high germination efficiency for all raspberry genotypes tested, and presents advantages for the standardization of germination time and reduction in the parental genotypes’ impact on germination rate.

IEffect of Scarification and Stratification treatments on Germination and Seedling Vigour of Teak (Tectona grandis Linn.f) Drupes

The effect of scarification and stratification treatments on germination and seedling vigour of fresh teak drupes was investigated. The drupes were subjected to the following scarification and stratification treatments viz., control, acid scarification (500 mL/kg of drupe) for 5, 10, 15, 20, 25, 30, 40, 50 and 60 min. Cold stratification for 30, 40 and 50 days at 5o C. Warm stratification for 30, 40 and 50 days at 40o C. The treated and control drupes were sown in sand filled earthen pots and placed in direct sunlight for assessing the germination. The experiment was conducted in a Completely Randomized Block Design with ten replications. Germination percentage, number of seedlings/100 drupes, time taken for initial emergence, root length, shoot length, dry matter production and vigour index were recorded 28 days after sowing. Acid scarification for 40 minutes, cold stratification at 50°C for 40 days, and warm stratification at 40°C for 40 days resulted in 23.7, 29.8, and 22.7 percent germination, respectively. From this study it could be concluded that warm stratification of fresh teak drupes at 40 0C for 40 days gave maximum germination (29.8 per cent) and seedling vigour (468).

Effect of Scarification and Stratification treatments on Germination and Seedling Vigour of Teak (Tectona grandis Linn.f) Drupes

The effect of scarification and stratification treatments on germination and seedling vigour of fresh teak drupes was investigated. The drupes were subjected to the following scarification and stratification treatments viz., control, acid scarification (500 mL/kg of drupe) for 5, 10, 15, 20, 25, 30, 40, 50 and 60 min. Cold stratification for 30, 40 and 50 days at 5o C. Warm stratification for 30, 40 and 50 days at 40o C. The treated and control drupes were sown in sand filled earthen pots and placed in direct sunlight for assessing the germination. The experiment was conducted in a Completely Randomized Block Design with ten replications. Germination percentage, number of seedlings/100 drupes, time taken for initial emergence, root length, shoot length, dry matter production and vigour index were recorded 28 days after sowing. Acid scarification for 40 minutes, cold stratification at 50°C for 40 days, and warm stratification at 40°C for 40 days resulted in 23.7, 29.8, and 22.7 percent germination, respectively. From this study it could be concluded that warm stratification of fresh teak drupes at 40 0C for 40 days gave maximum germination (29.8 per cent) and seedling vigour (468).

Commercial Seaweed Liquid Extract as Strawberry Biostimulants and Bioethanol Production.

Seaweeds are increasingly intriguing as a sustainable source of bioactive compounds. They have applications in agriculture, fuels, feed, and food products. To become a cost-competitive product with zero waste, a biorefinery approach is applied, where several products are valorized at the same time. True-Algae-Max (TAM®) has been investigated for its ability to improve the yield and nutritional facts of a strawberry plant. Three concentrations of TAM (0, 50, and 100%) were examined by foliar spray in 2017 with 50% NPK chemical fertilizer. Results indicated that growth, yield, chlorophyll, and potassium content were significantly improved by TAM treatments. TAM50 % resulted in maximum root length, leaf area, plant fresh weight, fruit weight, and yield with an increase ranging from 10 to 110% compared to control. Compared to the NPK control, strawberries grown with TAM50% improved total soluble solids (TSS) from 7.58 to 10.12% and anthocyanin from 23.08 to 29.42 mg CGE 100 g-1. Noteworthily, this reduced total sugar, and total phenolics were boosted by TAM applications, while non-reducing sugar was reduced compared to control. On the other hand, whole seaweed biomass and TAM residuals were used for bioethanol production by acid scarification. The maximum bioethanol yield was observed in residual biomass (0.34 g g-1 dw), while the whole seaweed biomass showed only 0.20 g g-1 dw. These results proved the biorefinery concept of using seaweed extract as a biostimulator and bioethanol production.

Scarification in Acetic Acid, Hot Water, and Cold Sand Stratification to Improve Carob (Ceratonia Siliqua L.) Seed Germination

This study was carried out to determine the effects of acetic acid, hot water, and cold sand stratification scarification at different periods on seed germination of carob (Ceratonia siliqua L.) in Salah Alden province. The seeds were collected from Kirkuk province area on September 2016. Carob seeds stratified and not stratified treated by soaking in glacial acetic acid for 20, 40, 60, and 120 min. at lab temperature (25oC). Hot water (100oC) also used for soaking the seeds for 20, 40, 60, and 120 min. Experimental design of Randomized Complete Block Design (RCBD) with 3 replicates, and 10 seeds per each treatment per each replicate were used and the results were compared to non-treated seeds. After soaking the seeds in acetic acid and hot water, they washed thoroughly and sowed in black polyethylene grow bags. The soil used was loamy with added organic matter. After 7 months, data recorded on the germination percent and growth features including plant height, leaf area, total chlorophyll, root length, fresh and dry weight of vegetative parts, nitrogen, phosphorous, and potassium percentages in the plant. The results showed that the treatment with hot water for 60 minutes achieved the highest percent of germination (96.67%), highest leaf area 12.86 cm2, highest root dry weight (0.14 gm.), and nitrogen percent of 5.52%. The treatment for 40 minutes with hot water gave the highest fresh weight of vegetative parts was 18.6 gm. and root fresh weight (7.05 gm.). The treatment with hot water for 120 minutes achieved the highest percent of phosphorous and potassium (0.49% and 2.07% respectively).
 

Improvement of In Vitro Seed Germination and Micropropagation of Amomum tsao-ko (Zingiberaceae Lindl.)

Black cardamom (Amomum tsao-ko Crevost & Lemarié) is a spice plant of great commercial value in Vietnam, but with limited propagation ability. Its seeds are characterized by a thick and hard seed coat, a small endosperm, and a small embryo, which are the causes of the physical dormancy of the seeds and low germination. Attempts in this study to improve the germination rate and achieve uniform germination included mechanical scarification, immersion in hot or cold water, acid scarification, and the application of plant growth regulators. Although immersion of seeds in cold water and application of plant growth regulators (PGRs) (gibberellic acid (GA3) and 1-naphtaleneacetic acid (NAA)) showed positive effects on seed germination and subsequent seedling growth, mechanical scarification provided the highest germination rate of black cardamom seeds (68.0%) and significantly shortened germination time (53.7 days) compared to control (16.0% and 74.7 days). On the other hand, an efficient micropropagation protocol has been established using shoot tip explants derived from in-vitro-grown seedlings. Murashige and Skoog (MS) medium supplemented with 4.0 mg/L 6-benzylaminopurine (BAP) + 0.5 mg/L NAA proved to be most suitable for rapid multiplication and rooting, providing a mean of 5.4 shoots per explant, 6.8 cm shoot length, and 16.2 roots per explant after 7 weeks of culture. Well-rooted black cardamom plantlets have been successfully adapted to ex vitro conditions. “Fasco” bio-soil was more suitable for acclimatization, with a 48.9% survival rate, 23.3 cm plant length, and 5.7 leaves per plant after 3 months of planting. Improved germination and multiplication protocols can be used to improve propagation performances and to develop elite of black cardamom planting material.

Seed Propagation Methods for Ratibida columnifera (Nutt.) Wooton & Standl.

Variation in floral characteristics and growth habits within the native range of the North American wildflower Ratibida columnifera (Nutt.) Wooton & Standl. suggests potential for breeding and selection efforts to develop improved cultivars for commercial and residential landscapes. Experiments in seed propagation were performed to enable perpetuation of unique germplasms. Overnight hydration, storage condition variations, stratification and scarification, and seed maturation effects were assessed to determine impacts on viability and percent germination. Overnight hydration had no impact on percent germination. Germplasm had a significant effect on germination for all remaining experiments. Seed maintained viability at the same rate through 18 months, when slight reductions were noted. Cold storage at 3 °C had no effect on viability or percent germination of dry seed compared with storage at 23 °C. All three germplasms exhibited increased percent germination with some stratification period, and declined significantly in percent germination with all acid scarification treatments. Experiments indicated that most germplasms benefit from between 30 to 60 days of cold, moist stratification. There was a significant interaction effect among germplasms, location on the inflorescences, and maturity stages for R. columnifera. Data suggest that seed should be harvested as close as possible to when natural dispersal would occur for optimum germination. The degree of improvement in viability and percent germination associated with harvesting at various developmental stages, seed pretreatments, and storage conditions suggests that to achieve germination success, pretreatments should be used for propagation of seed from mature inflorescences and that variation can be expected within different genotypes of this species.

Effects of various pre-sowing treatments on invitro seed germination of Ceratoniasiliqua L.

The organic dormancy of Ceratonia seeds is associated with their water resistance, which means that Carob suffers from difficulty in natural regeneration. Before planting Carob seeds must be treated in order to disturb mechanical dormancy. The main reasons for the decline in genus Ceratonia L. are anthropogenic impact on natural ecosystems, as well as the uses of Ceratonia for many goals. This problem is aggravated by the fact that seedlings of Ceratonia in nature are very rare because of organic dormancy, and the distribution of carob occurs mainly with the help of seeds. The aim of this work was to study the methods of pre-sowing treatment of dormant Carob seeds. This study was conducted on a wild Carob genotype grown in Syria. Four different pre-sowing treatments were the following: soaking in boiling distilled water (70 С) for 10 min; soaking in boiling distilled water (70 С) for 10 min + soaking in distilled water for 24 h; acid scarification with sulphuric acid (H2SO4); acid scarification with sulphuric acid (H2SO4) + soaking in distilled water for 24 h. We applied and examined for their effectiveness stimulation of Carob seed germination. The results showed that seeds treated with sulphuric acid (H2SO4) and then soaked in distilled water for 24 h was the most effective method increasing the germination percentage by 98 % compared to untreated seeds 5 %.

Method to overcome dormancy in seeds from unconventional food plant: Phytolacca americana (Phytolaccaceae)

Plant species Phytolacca americana (Phytolaccaceae) can be classified as UFP (Unconventional Food Plant); it is used for food and/or medicinal purposes due to its analgesic, anti-inflammatory, anti-rheumatic and anti-arthritic properties; moreover, it is suitable to treat different skin diseases. However, its seeds present integumentary dormancy caused by uneven germination. The aim of the present study is to assess the effect of chemical scarification in sulfuric acid on dormancy overcome in Phytolacca americana (Phytolaccaceae) seeds. Seeds were immersed in 4 ml sulfuric acid, which was concentrated through different immersion times (2, 5, 8, 11 and 15 min), and compared to the control treatment (without sulfuric acid). The study followed a completely randomized design with six treatments and four repetitions, with 50 seeds per treatment. The following parameters were assessed: days to start germination (DSG), germination (G), germination speed index (GSI), abnormal plantlets (AP), dead seeds (DS), hard seeds (HS) and total dry mass (TDM). Data were subjected to Shapiro-Wilk test for variance normality. The analysis of variance and regression were carried out in RStudio software, version 4.1.0. Means recorded for treatments were compared through Tukey test (p ≤ 0.05). The treatment based on immersion in sulfuric acid for 2 min was the most efficient in overcoming dormancy in this species, since it led to the best results for germination variables and total biomass accumulation in plantlets.