Final Germination Percentage Research Articles

Germination enhancement, antioxidant enzyme activity, and metabolite changes in late Argania spinosa kernels under salinity

In arid and semi-arid environments, soil salinization has a negative impact on agricultural systems and natural vegetation. For the reforestation of low-to medium-salinity soils in Morocco, which borders one of the world's largest deserts, the argan tree (Argania spinosa (L.) Skeels) is essential. Therefore, early and late kernels were used in this study to investigate the effect of various salt levels on germination, antioxidant enzyme activities, and metabolite alterations. In terms of results, the kernels of late fruits had better germination performances under 102.6 mmol/L NaCl salinity. The final germination percentage (FGP) at the last count was at its maximum (54.4%), and the germination speed index (GSI) was significantly high, reaching 12.8 ± 0.8. Proline and sugar metabolites, as well as catalase (CAT) and peroxidase (POX) activities, have increased as salinity increased up to 102.6 mmol/L, followed by a dramatic decrease beyond 136.8 mmol/L, mainly for the early kernels. However, the late kernels have performed better in triggering adjustment pathways before entering their irreversible state. These findings represent another contribution toward comprehending the processes underlying the argan tree's resilience, which is critical to reversing desertification and soil degradation inside and potentially beyond its current biosphere.

Estimation of Genetic Parameters for Selected Quantitative Traits in Introduced African Yam Bean (Sphenosylis stenocarpa Hochst. ex. A. Rich Harms) Genotypes

A solid understanding of the genetic control of traits within breeding populations is essential for selecting superior genotypes and parent plants for African yam bean (AYB) cultivation. In this study, we explored the phenotypic breeding values and genetic parameter estimates for various traits in 10 introduced AYB varieties. These traits included seed emergence speed (SES), seedling vigor index (SVI), final germination percentage (FGP), seed yield, days to first flower bud initiation (DAYSFBI), days to first flowering (DAYSF), and days to first pod initiation (DAYSPI). We conducted the trial using a randomized complete block (RCB) design with the following varieties: TSs2, TSs60, TSs11, TSs33, TSs282, TSs450, TSs10, TSs432, TSs424, and TSs151B. Traits showing high and medium genotypic coefficient of variation (GCV) were seed yield (20.7), SVI (12.1), and seed emergence speed (10.8), respectively. Traits with high phenotypic coefficient of variation (PCV) included seed yield (36.8), SVI (22.8), and SES (37.5). The presence of variability in all studied traits was evident from both GCV and PCV values. However, PCV values were slightly higher than GCV, suggesting the influence of environmental factors on these traits. Seed yield exhibited high genetic advance (23.9) and intermediate heritability (31.5%), while SES showed low heritability (8.4%) and low genetic advance (6.5), and FGP displayed low heritability (8.3%) and low genetic advance (2.1). High heritability and genetic advance in certain traits indicate the presence of additive gene action, suggesting that these traits can be improved through direct selection. These findings suggest the presence of valuable variations that can be harnessed for AYB genetic enhancement and selection purposes. Our study results offer valuable insights for the genetic improvement, conservation, management, multi-location evaluations, short-term recommendations, and potential release of new AYB genotypes.

From seed to sprout: Unveiling the potential of non-thermal plasma for optimizing cucumber growth

Background and aimsNumerous strategies for enhancing seed germination and growth have been employed over the decades. Despite these advancements, there continues to be a demand for more effective techniques, driven by the growing global population. Recently, various forms of non-thermal atmospheric pressure plasma have garnered attention as environmentally friendly, safe, and cost-effective methods to enhance the agricultural and food sectors. This study explores the remarkable impact of non-thermal plasma (NTP) treatment on cucumber (Cucumis sativus L.) seed germination. MethodsA cost-effective, custom-designed power supply operating at line frequency was used for treating seeds, with exposure times ranging from 1 to 7 min. Various germination parameters, including water contact angle measurements, mass loss, water imbibition rate, and seedling length, were evaluated to assess the impact of plasma treatment on seed germination. ResultsCucumber seeds exposed to NTP treatment for 3 min and 5 min durations showed significant germination improvements, notably a 57.9 ± 4.25 % higher final germination percentage, 14.5 ± 3.75 % reduced mean germination time, and a remarkable 90.6 ± 4.64 % increase in germination index compared to the control. These results suggest that NTP treatment enhanced seed coat permeability, triggered essential biochemical processes, and expedited water absorption and nutrient assimilation, ultimately fostering faster and more synchronized germination. ConclusionsOur findings underscore the potential of NTP as an innovative approach to improving seed germination in agricultural practices.

Negative effects of high-temperature stress on gametophyte performance and their consequences for seed reproduction in wild plants

(1) Plant regeneration by seeds is highly sensitive to temperature stress, particularly in the gametophyte stage. However, most of the existing research has focused on one single stage of gametophyte development and/or conducted using cultivated or a very few model species. Thus, it is unclear whether the results of such studies can be applied to natural populations. (2) To fill this gap, we investigated a) the effects of chronic heat stress (CHS; 17 days) at 35/30 °C (moderate stress) and 40/35 °C (severe stress) on gametophyte performance, and b) how these effects translated into seed quantity and quality. We measured six traits related to male (anther length, pollen production and size) and female (ovary length, ovule production, and size) gametophyte performance and leaf chlorophyll fluorescence (Fv/Fm) in four wild Silene species. The ripe seeds of the treated plants were used to measure seed mass and seed production; the seed germination was characterized in terms of germination percentage, speed, and synchrony. (3) Fv/Fm decreased significantly in both heat treatments, confirming a negative effect of CHS on overall plant performance. All male gametophyte traits decreased significantly in both CHS treatments compared to the control. The length and size of the ovary were significantly smaller in the 40/35 °C treatment than in the 35/30 °C treatment and the control, while ovule production decreased significantly in both CHS treatments compared to the control. The negative effects on gametophyte performance translated into significantly fewer seeds in the 35/30 °C and 40/35 °C treatments compared to the control. CHS treatments did not affect the seed mass. The final germination percentage differed weakly significantly between the severe treatment and the control but did not show any negative impacts by heat stress, whereas seed germination was significantly faster in the treated plants, both moderate and severe. Germination synchrony was not affected by heat treatments. (4) The high sensitivity of gametophytes in vascular plants to high-temperature stress implies that climate change-associated heat waves can significantly impact seed reproduction in wild plants. The altered seed quantity could have potential consequences for the long-term survival of the wild plant populations and the performance of the granivores.

Effect of growing media on seed germination and seedling growth in Magnolia gustavii, a Critically Endangered tree species

The experiments were carried out to study the effect of growing media on seed germination and seedling growth of Magnolia gustavii King. – accredited as a Critically Endangered tree species naturally occurring in Assam, India. The trials were conducted in Complete Randomized Design (CRD) with three (03) different treatments with different combinations viz. T1 – Soil: Sand (1:1), T2 – Coarse Sand and T3 – Soil: Sand: FYM (1:1:1). The seed germination data were recorded on a daily basis and germination parameters viz.- final germination percentage (FGP), mean germination time (MGT), first day of germination (FDG), last day of germination (LDG), coefficient of velocity of germination (CVG), germination rate index (GRI), germination index (GI), time spread of germination (TSG), and peak value of mean germination (PVMG) were estimated and data were statistically analyzed. Synergistic weightage given to all the parameters led to the conclusion that Coarse Sand is the most appropriate medium with respect to seed germination and seedling vigour in M. gustavii King.

Effects of hormonal and magneto-priming on seed germination traits of sorghum (Sorghum bicolor L. Moench)

Sorghum (Sorghum bicolor L. Moench) seeds were tested to discover how different priming techniques affected their germination rates, a pot experiment was conducted by the combination procedures for seed priming with magnetic fields (magneto-priming) and hormonal priming seed with gibberellic acid (AG3) or ascorbic acid (AsA). Final germination percentage (FGB), mean germination time (MGT), germination rate index (GRI), coefficient of the velocity of germination (CVG), mean daily germination (MDG), peak value (PV), and germination value (GV) are all included as germination metrics. Among the two durations of exposure time to magneto-priming used, the significantly highest FGB, GRI, CVG, MDG, PV and GV were reported in the primed with the time duration 1 h (MP2), significantly lowest MGT for MGT in days. Whereas among the two hormonal primings used, GA3 recorded the highest increases upon the unprimed seeds for FGB, GRI, CVG, MDG, PV, and GV, in addition, significantly lowest MGT for MGT in days. However, when magnetic seed is combined shows the highest increase rates compared to the control treatment for time exposure for 1 h (MP2) with GA3 or AsA in all studied traits, in addition to the lowest rates decrease in MGT. Overall, the findings imply that seed priming by magnetic field and hormone priming via GA3 or AsA may be promising and practical priming techniques because of their favorable impacts on some physiological sorghum characteristics. Keywords: Wheat, physiological parameters, gibberellic acid, UV-C radiation, hydro-priming.

Seed Priming with Salicylic Acid Alleviates Salt Stress Toxicity in Barley by Suppressing ROS Accumulation and Improving Antioxidant Defense Systems, Compared to Halo- and Gibberellin Priming.

Plants are highly sensitive to various environmental stresses, which can hinder their growth and reduce yields. In this study, we investigated the potential of seed priming with salicylic acid (SA), gibberellic acid (GA3), and sodium chloride (NaCl) to mitigate the adverse effects of salinity stress in Hordeum vulgare at the germination and early seedling stages. Exposing H. vulgare seeds to salt stress reduced the final germination percentage and seedling shoot and root growth. Interestingly, all seed treatments significantly improved salt-induced responses, with GA3 being more effective in terms of germination performance, plant growth, and photosynthesis. SA priming exhibited promising effects on antioxidant defense mechanisms, proline, sugar, and ascorbic acid production. Notably, SA priming also suppressed reactive oxygen species accumulation and prevented lipid peroxidation. These findings highlight the ability of SA to manage crosstalk within the seed, coordinating many regulatory processes to support plant adaptation to salinity stress.

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.

Deep neural network and molecular docking supported toxicity profile of prometryn

In this study, the versatile toxicity profile of prometryn herbicide on Allium cepa was investigated. In this context, 4 different groups were formed. While the control group was treated with distilled water, Groups II, III and IV were treated with 200 mg/L, 400 mg/L and 800 mg/L prometryn, respectively. After 72 h of germination, cytogenetic, biochemical, physiological and anatomical changes were investigated. As a result increase in malondialdehyde levels, decrease in glutathione level, changes in superoxide dismutase and catalase activities in root tip cells show that prometryn causes oxidative stress. The decrease in mitotic index values and the increase in the frequency of micronucleus and chromosomal abnormalities observed after prometryn treatment indicate genotoxic effects. The genotoxic effects may be due to the induced oxidative stress as well as the promethryn-DNA interaction. Molecular docking analyses revealed that prometryn interacts with various bases in DNA. As a result of the Comet assay, exposure to prometryn was found to cause DNA fragmentation. In physiological parameters final weight, germination percentage and root length decreased by 23.8%, 59.1% and 87.3%, respectively, in the 800 mg/L prometryn applied group. Deep neural network (DNN) model was optimized to predict the effects of different doses of prometryn on 4 different endpoints: micronucleus, mitotic index, chromosomal abnormalities and DNA Damage. The predicted data was found to be very similar to the actual data. The performance of the model was evaluated using MAE, MAPE, RMSE and R2, and these metrics indicate that the model performed well. Overall, the findings of this study suggest that the DNN model developed here is a valuable tool for predicting genotoxicity biomarkers in response to the application doses of prometryn, and has the potential to contribute to the development of safer and more sustainable agricultural practices.

Impact of Hydrochloric acid on breaking seed dormancy and germination enhancement in native Alhagi graecorum Boiss ( Al-Agool ).

Despite the great importance of legumes plants, most of them have a hard and impermeable testa, which causes physical dormancy of the seeds and prevents germination even when environmental conditions are favorable. This is considered one of the major problems in successful seed germination. Alhagi graecorum plant is a wild native legume. It has a hard and impermeable testa, which causes physical dormancy of seeds, and to overcome hard coat imposed dormancy, softening the hard seed coat by soaking Hydrochloric acid ( HCl ). The present study was conducted to evaluate various duration of soaking seeds in HCL to breaking physical dormancy for A.graecorum in 10, 20, and 30 minutes. The results showed that, final germination percentage (FGP) in treated seeds significantly increased when compared with the control were 55, 62 and 68 % respectively, while in control was only 12 %. Seed germination influenced by HCL is due to its capability to break the hard seed coat that leads to water absorption and imbibition of seeds. As for the mean daily germination ( MDG ), the results revealed that, there were significance increased in seventh day of sowing in germination between the treated seeds in duration of soaking 20 and 30 min were 23 and 24 % respectively, as they were most effective in germination, while the germination in the control stopped in the fifth day of sowing at 12 %. While the mean germination time (MGT), the results indicated that the seeds soaked in acid recorded 9.66, 9.13, and 8.62 days, respectively. The minimum MGT for treated seeds was detected in 30 min., 8.62 days. The reason for the long period of the mean germination time may be due to the use of a low concentration of hydrochloric acid, so I recommend using higher concentrations of acid to obtain a lower mean germination time.

Germination Response of Different Castor Bean Genotypes to Temperature for Early and Late Sowing Adaptation in the Mediterranean Regions

Germination of castor seeds of seven dwarf hybrid genotypes, compared to a ‘Local’ genotype, selected from a Tunisian population by the University of Catania well adapted to the Mediterranean environment, were studied at six different temperatures (8, 12, 16, 25, 32, and 40 °C). The results indicate that the optimal temperature (25 °C) and near-optimal temperature (32 °C) are the best temperatures for ensuring castor germination (final germination percentage (FGP) ≥ 82.81%). Furthermore, these temperatures positively influenced the vigour index (VI) and the radicle elongation. At a temperature of 8 °C, no germination occurred, while temperatures of 12 and 40 °C negatively affected the seed germination, which, in some genotypes, was null or negligible (<21.25%). A temperature of 16 °C allowed good results to be reached for the FGP and the other considered parameters. Overall, the dwarf hybrids performed better at high temperatures than at low temperatures, thus, making them suitable for late sowings, with the exception of the genotype ‘C1020’, which resulted the best performance at 16 and 40 °C, being suitable for both early and late sowings. On the other hand, the ‘Local’ castor genotype, being the best-performing genotype at 12 and 16 °C, and the most tolerant to low temperature (base temperature (Tb) 12.1 °C), could be used in the early sowing in spring.

Relationship between different physiological processes of Tomato seedlings exposed to acid mine water Uncovered using correlation analysis

This study was conducted to assess the correlation between growth response, phytoaccumulation factor of different tissues, and elemental composition in tomato seedlings exposed to acid mine water (AMW). In pairwise correlation determinations values of plant height, stem diameter, seed germination indices (radicle length, final germination percentage (FGP), emergency rate index (ERI), vigour index (VI), germination percentage (G%) and germination rate index (GRI)) and the elemental compositions (Cd, Cr, Cu, Ni and Zn) in the different plant tissues, root (root accumulation factor = RAF), stem (stem translocation factor = STF) and leaves (leaf translocation factor = LTF) were selected for the relationship determinations. Pearson correlation coefficients were calculated and revealed the relationships between the paired parameters. The study concluded that the strongly correlated physiological parameters were jointly co-ordinated in tomato seedlings exposed to AMW.

Synthesis and surface morphology of banana biochar-based nano-fertilizer and its effect on first stages of growth parameters of cucumber, broccoli, and red okra

Smart agro-practices over the years have revolutionized the agriculture sector and promoted the concept of sustainable agriculture. One such practice is use of agro-waste biochar in agricultural, environmental, and climatic operations. The viability of using a biochar-based nanocomposite as a support fertilizer for the gradual release of nitrogen, potassium, and phosphorus in various media is examined in this study. The banana peel biochar (BPBC) and its nanocomposite (BNF) were prepared using a simple yet comprehensive chemical process. Synthesized materials were evaluated using FT-IR and SEM/EDX. Physical attributes as well as fertilizer basic characteristics were determined and prepared nanocomposite demonstrated noticeably better water absorbance ratio (68%), equilibrium water content (78.97%), and swelling ratio (3.64 g g−1) than biochar, which is advantageous for preserving soil water levels. The salt index values (0.087mmhos/cc) of the created nanocomposite performed better when compared to the conventional fertilizers due to their safer application. Long-term availability of all doped minerals to the plants, during experimental cycle, was revealed by slow-release nutrient studies in water and soil, which is ideal for promoting germination and growth. The findings of this research revealed that prepared BNF showed improved germination parameters i.e., time for 50% germination (3.4, 3.3, 4.4 days), germination index (3.1, 3.5, 2.4), final germination percentage (91.7, 100, 83.3%), mean germination time (4.0, 3.9, 4.9 days), for cucumber, broccoli and okra, respectively. In addition to that the prepared BNF facilitated enhanced shoot and root length in all the three vegetables as compared to conventional fertilizers. The dose optimization studies depicted that best results of germination as well as plant growth parameters are facilitated by BNF (37.5 kg/ha) owing to enhancement in soil quality by supplying additional organic matter in addition to provision of nutrients on slow-release.

Seed germination behavior of Teucrium santae Quézel & Simonneau: a vulnerable and endemic Lamiaceae (Northwest Algeria)

Abstract As part of the ex-situ conservation of the rare plant species Teucrium santae (Lamiaceae), which is native to Algeria flora, we conducted this study under controlled conditions to determine the optimal circumstances for the germination of its seeds in terms of light, temperature, and water stress. The seeds showed a double dormancy that could be overcome using scarification with sulfuric acid combined with soaking in Gibberellic acid at 1,500 ppm. The seed’s photosensitivity was tested afterward and found to be indifferent. The highest final germination percentage (75%) was obtained at a temperature of 20 °C. The temperature has no significant effect on the velocity coefficient, unlike the initial germination day and the mean germination time which decrease with increasing temperature. On the opposite of the velocity coefficient, water stress results in a tremendous depressive effect on the final germination percentage, initial germination time and mean germination time. The value of –1.2 MPa constitutes the water potential beyond which germination becomes impossible.

Potensi Ekstrak Daun Kelor (Moringa oleifera) sebagai Agen Priming pada Performa Perkecambahan Biji Bawang Merah

Moringa leaf extract is a biostimulant containing various phytohormones that can spur plant growth and development. This study aimed to evaluate the potential of Moringa leaf extract as a priming agent on the germination performance of shallot seeds. The experiment began with leaf extract preparation, seed priming, and germination testing. The data obtained were analyzed using ANOVA, and if there was a significant effect, further tested with the BNJ test with α = 0.05. The data were processed using RStudio software version 4.2.1. The results stated that seed priming with leaf extract concentration of 37.5% had the best effect on all germination parameters, including average germination time (2.19 days), final germination percentage (96.53%), seed germination uniformity (95.83%), germination velocity coefficient (45.85), germination rate index (50.48%/day), sprout vigor index I (790.58), sprout vigor index II (31.30), plumula length (6.53 cm), radicle length (1.66 cm), sprout fresh weight (0.32 g), and sprout dry weight (0.0233 g). It was concluded that Moringa leaf extract has the potential as a priming agent for shallot seeds.
 
 Keywords: botanical seed, moringa leaf, priming, shallot

The Effect of Zinc on Germination in Species of the Genus Echium (Family Boraginaceae)

Abstract The effect of zinc on seed germination in two species of the Echium genus (Echium russicum J.F. Gmelin and Echium vulgare L.) was investigated. Zinc was used as sulphate in three different concentrations: 100 mg∕ l; 200 mg ∕ l și 300 mg ∕ l; the treatment was applied to the seeds before germination, the exposure time being short (4 hours and 8 hours). Seed germination was monitored daily for a period of 14 days. The effect of treatment on seed germination in the test species was assessed by calculating four germination indicators: final germination percentage (FGP), germination index (GI), mean germination time (MGT) and coefficient of rate germination (CRG). The results show the following: the seeds of Echium russicum germinate faster than those of Echium vulgare; statistically insignificant changes in the indicators associated with germination, except for GI in Echium vulgare for the 8 hours exposure time; reduction of germination percentage (in both species) and increase in germination time (more evident in Echium vulgare) with increasing exposure time. The test species showed tolerance throughout the germination process to the zinc concentrations used.

Germination of alfalfa (Medicago sativa L.) seeds in Desert soil after fertilization with raw and digested animal manure

Animal manure has been approved as an appropriate soil fertilizer. However, the effect on seed germination, growth, and yield of crops still needs more evaluation across various agricultural ecosystems. A germination experiment was conducted to evaluate the performance of raw and digested sheep and poultry manure on alfalfa (Medicago sativa L.) seed germination in desert soil. Four sowing dates were evaluated in the experiment, i.e. directly, 10, 20, and 30 days after soil fertilization. The fertilizers were applied at rates corresponding to 50 and 100 kg Tot N ha-1. In addition, the response of germination to seed inoculation method was also assessed (Arabic gum as an adhesive solution and sawdust as a seed coating material). The germination was evaluated by determining seed germination time (SGT), time to reach maximum germination (TMG), germination index (GI), and final germination percentage (FGP). The results showed that sown seeds directly after fertilization with raw/digested sheep or poultry manure reduced and delayed seed germination. This was confirmed by all germination indices, long SGT, long TMG, low GI values, and a reduction in FGP. Moreover, when the seeds were sown 10 days after fertilization, all germination attributes were significantly (p<0.05) improved. Furthermore, the results revealed that the inoculation method used in the study had a positive effect on seed germination. To achieve better germination when using animal manure (raw or digested) as soil fertilizer, it is recommended to sow alfalfa seed 10 days after soil fertilization. Moreover, inoculating the seeds using Arabic gum as an adhesive solution and sawdust as a seed coating enhances germination in fertilized soil.

The Dormancy Types and Germination Characteristics of the Seeds of Berberis koreana Palibin, an Endemic Species of Korea

Berberis koreana Palibin is an endemic plant native to Korea. In this study, we aimed to study the seed germination of this species using a water imbibition experiment, gibberellic acid (GA3) treatment (0, 10, 100, or 1000 mg·L−1), cold stratification (0, 2, 4, 8, or 12 weeks at 4 °C), move-along experiment, and phenology studies. In the water imbibition experiment, the weight of the seeds increased by more than 120% in 24 h. An analysis of the internal and external morphological characteristics of the seed revealed that the embryo was already fully grown from the fruit and did not grow thereafter. The final germination percentages for the cold stratification at 0, 2, 4, 8, and 12 weeks at 4 °C were 12 ± 3.65, 32 ± 9.09, 59 ± 1.00, 59 ± 9.59, and 71 ± 1.91%, respectively. In the move-along experiment and phenology studies, a longer low-temperature treatment period resulted in a higher germination percentage. However, the GA3 treatment had little effect on the seed germination. Our results indicate that B. koreana exhibits an intermediate physiological seed dormancy.

Effect of Saline Treatment on Seed Germination of Adzuki Beans

Salinity is one of the major causes of abiotic stress for plant development and growth worldwide, and affects crop yield significantly. To analyse the level of salinity tolerance among 'Ji Hong 20' (JH20), 'Jin Xiao Dou 5' (JXD5) and 'Jin Xiao Dou 6' (JXD6) adzuki bean cultivars, nine saline levels (0.0, 32.5, 65.0, 97.5, 130.0, 162.5, 195.0, 227.5 and 260.0 mmol L-1 NaCl) were applied during seed germination. Germination potentials and final germination percentages of all cultivars were significantly reduced by NaCl with the level at which germination was affected being dependent on cultivar. The JXD5 seeds had the highest germination index and vigour index at the same NaCl concentrations, followed by the JH20 and then JXD6 seeds. The shoot and root lengths of JH20 and JXD5 were significantly shorter at NaCl concentrations > 65.0 mmol L-1, while those of JXD6 were reduced at salinity > 32.5 mmol L-1. Quadratic regression models could well predict the germination percentage of JH20, JXD5 and JXD6 seeds under saline stress.

Non-deep physiological dormancy and germination characteristics of Primula florindae (Primulaceae), a rare alpine plant in the Hengduan Mountains of southwest China.

Timing of seed germination is directly related to the survival probability of seedlings. For alpine plants, autumn-dispersal seeds should not germinate immediately because the cold temperature is not conducive to the survival of seedlings. Seed dormancy is a characteristic of the seed that prevents it from germinating after dispersal. Primula florindae is an alpine perennial forb endemic to eastern Tibet, SW China. We hypothesized that primary dormancy and environmental factors prevent seeds of P. florindae to germinate in autumn and allow them to germinate at the first opportunity in spring. We determined how GA3, light, temperature, dry after-ripening (DAR) and cold-wet stratification (CS) treatments affect seed germination by conducting a series of laboratory experiments. Firstly, the effects of gibberellic acid (GA3; 0, 20, and 200 mg L-1) on germination of freshly shed seeds at alternating temperatures (15/5 and 25/15 °C) were immediately investigated to characterize seed with a physiological dormancy component. Then, the fresh seeds treated with 0, 3, and 6 months of after-ripening (DAR) and cold-wet stratification (CS) were incubated at seven constant (1, 5, 10, 15, 20, 25, and 30 °C) and two alternating temperatures (5/1, 15/5, and 25/15 °C) at light and dark conditions. Fresh seeds were dormant, which only germinated well (>60%) at 20, 25, and 25/15 °C in light but not at ≤15 °C and to higher percentages in light than in dark. GA3 increased germination percentage of fresh seeds, and DAR or CS treatments increased final germination percentage, germination rate (speed), and widened the temperature range for germination from high to low. Moreover, CS treatments reduced the light requirement for germination. Thus, after dormancy release, seeds germinated over a wide range of constant and alternating temperatures, regardless of light conditions. Our results demonstrated that P. florindae seeds have type 2 non-deep physiological dormancy. Timing of germination should be restricted to early spring, ensuring a sufficient length of the growing season for seedling recruitment. These dormancy/germination characteristics prevent seeds from germinating in autumn when temperatures are low but allow them to germinate after snowmelt in spring.