Germination Speed Index Research Articles

Effect of Seed Priming on Germination, Seedling Emergence and Development of Spring Rice Var. Hardinath-1

Poor germination percentage and non-uniform seedling emergence and establishment are major causes of low rice yield in water-deficit arid ecosystems. A seed priming study with a low concentration of MoP, DAP, urea, vitamin C, ZnSO4, sucrose, NaCl, and hydro priming was conducted to assess the seed germination, seedling emergence, establishment, and seedling growth of the spring rice variety Hardinath-1. The experiment was conducted using a completely randomized design with three replications. Two test sets of experiments were carried out using blotting paper rolls and separate sand trays. Germination was observed at intervals of 24 hours up to 7 days, and germination and growth parameters were monitored. The results showed that germination (88.67%) and seedling emergence (88.67%) were high in vitamin C at 7 days after sowing (DAS). Germination energy (81%), germination speed (91.78%), and vigor index (91.78) were higher with seed priming of MoP. The lowest germination (56.44%) was observed with the priming of urea. At 30 DAS, the longest shoot length (19.93 cm) and longest root length (11.79 cm) were observed with the priming of ZnSO4. The highest seedling fresh weight (0.75 g) and dry weight (0.16 g), the highest number of leaves (3.57), and the longest leaf length (11.97 cm) were found with the priming of MoP, NaCl, and ZnSO4, respectively. However, the lowest seedling growth parameters were observed in the control priming. The overall results revealed that seed priming with MoP is an effective tool to enhance the germination percentage and seedling establishment of rice. SAARC J. Agric., 21(2): 81-93 (2023)

Microbiolization with Bacillus sp. in irrigated rice seed positively impacts physiological and phytosanitary quality

Seed treatment is an important practice for reducing pathogens. The microbiolization technique has been used to provide economic and environmental benefits, starting with the selection of microorganisms and the identification of their mechanisms of action. In this sense, Bacillus sp. has stood out, having the capacity to promote growth and phytopathogenic control of several important crops such as rice. This study was conducted aiming to evaluate the protective effects of inoculation with six isolates of Bacillus sp. in rice seeds. Germination, germination speed index, shoot fresh weight, root fresh weight, seeding size, indoleacetic acid production, cellulase production, and antagonist phytosanitary analysis were evaluated. Our results revealed the best efficacy of isolate 47b in the tests of rice seed germination, root fresh weight, shoot fresh weight, seedling size, indoleacetic acid, and cellulase index. The 47b isolate, as it expressed better results in the previous tests, was subjected to different pHs, with pH 4, pH 6, and pH 8 being more efficient as a control measure (in the antagonism test) against Curvularia sp. This 47b isolate also performed very efficiently against Colletotrichum sp. at the pH4 and Macrophomina sp. at the pH 6. Our findings revealed the potential of the isolate 47b as a plant protectant against relevant phytopathogens and demonstrated its potential as a plant growth promoter.

Light and Ethephon Overcoming Seed Dormancy in Friar's Crown (Melocactus zehntneri, Cactaceae), a Brazilian Cactus.

Seed germination in Melocactus and other cactus species is hampered by dormancy. However, most studies failed to achieve high seed-germination rates, suggesting a complex mechanism of dormancy in Cactaceae. Thus, the objective of this study was to evaluate whether factors such as light and phytoregulators overcome the dormancy in the seeds of the friar's crown cactus (Melocactus zehntneri). Two consecutive experimental sets were designed: one with seed germination under filter paper conditions and different wavelengths and Photosynthetically Photon Flux Densities (PPFDs); and one in vitro experiment using a culture medium to evaluate the influence of different phytoregulators, such as gibberellic acid (GA3), benzylaminopurine (BAP) and ethephon (ET), both in the germination of seeds of M. zehntneri. Seeds of M. zehntneri are positive photoblastic. Red light and gradual increases in PPFD resulted in the highest germination rates (60.8-61.7%) and germination speed index (4.4-4.5). In vitro seeding in culture media increased the germination percentage to 76% in control without phytoregulators. Ethephon showed a major effect in releasing the germination of dormant seeds of M. zehntneri, totaling 98% of seeds germinated under in vitro conditions, while GA3 and BAP showed minor or no effect on germination. The present study resulted in an efficient in vitro technique for germination and a better understanding of cacti seed dormancy.

Phytotoxic potential and chemical composition of Commelina benghalensis L. (Commelinaceae) on Lonchocarpus sericeus (Poir.) Kunth ex DC. (Fabaceae)

The objective of this work was to verify the phytotoxic action of the aqueous extract of Commelina benghalensis, on the initial development of Lonchocarpus sericeus. The parameters analyzed were germination, Germination Speed Index (GVI), average length of the stem and radicle, morphoanatomical alterations, cytotoxic activity and phytochemical characterization of the donor species. The 100 % extract was prepared by grinding 250 g of fresh leaves of the donor species in 1 L of distilled water and diluted to 25 %, 50 %, 75 % concentration (Treatments), the control group 0 %, consisted of distilled water only. The bioassays were placed in a germination chamber of the type BOD (Biochemical Oxygen Demand) climate-controlled chambers with a constant temperature of 25 °C and a 12 h photoperiod (light/dark). The extract of C. benghalensis at 75 % and 100 % concentration promoted a negative phytotoxic action on the average length of the rootlets of L. sericeus. The length of the stems showed a reduction only at the 100 % concentration. A significant increase in the genotoxic effect of the extract at 75 and 100 % concentration was observed, with the presence of chromosomal bridges, chromosomal adhesion, chromosome loss, C-metaphase and absence of membrane. The treatments caused changes in the internal morphology of the plant tissues of the radicle, such as necrosis of the epidermis and vascular system and disorganization of the cortex tissues. The allelochemicals present in the extract of C. benghalensis, such as alkaloids, anthocyanins, anthocyanidins, chalcones, aurones, flavonones, flavonols, xanthones, catechins, flavonones, were probably responsible for the negative effect found on the mitotic index and on the development and organization from the radicle tissues of L. sericeus.

Germination and seed vigor of Phaseolus vulgaris submitted to treatments whit aluminum sulfate

The varieties creole are traditionally grown plant, adapted in places where the crops are developed and present in seeds banks of many famers. Thus the objective of this study was to investigate the performance of the germination process and possible toxic effects. Were used seeds of creole cultivars of beans (Phaseolus vulgaris L.), using different concentrations of aluminum. We used a randomized completely design with four repetitions of 25 seeds and the treatments were distributed in 4 x 5 factorial scheme, consisting of four bean cultivars (Carioca, Butter, Black, Red) and five concentrations (0.0, 2.5, 5.0, 7.5, and 10.0 mg L-1) of aluminum sulfate. The characteristics analyzed were percentage of germination, percentage of abnormal seedlings, germination speed index, root length, length of the base of the seedling to the hypocotyl, hypocotyl length of seedlings to the epicotyl, root dry mass and shoot dry mass. The variables germination percentage and germination speed index were not affected by the toxic effect of aluminum. The variables percentage of abnormal seedlings, root length and shoot showed a significant reduction with the increase in aluminum sulfate concentrations, thus showing a greater correlation between them.
 Keywords: Aluminum; Fabaceae; Physiological quality; Toxicity

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.

Cassava, Mandacaru, and Glue as Adhesive Agents in the Coating of Heirloom Fava Bean Seeds

The seed coating technique, while not recent, has garnered attention due to its commercial implications. This process has grown in significance and feasibility, imparting greater added value to seeds, particularly in an increasingly competitive and regulated market environment, notably within the realm of heirloom seeds. Thus, the objective of this study was to investigate the impacts caused by the use of adhesive agents, including mandacaru extract, polyvinyl acetate-based glue, and cassava gum, in the pelleting process of heirloom fava bean seeds with rock dust. The experiment was conducted in the Phytotechnics Laboratory, situated within the Campus of Engineering and Agricultural Sciences at the Federal University of Alagoas. In the coating process, MB-4 rock powder was employed. The analyzed parameters encompassed water content, thousand seed weight, first germination count, germination percentage, germination speed index, mean germination time, germination uncertainty, primary root length/aboveground portion, and seedling dry mass. Polyvinyl acetate (PVA) glue and cassava gum proved to be the most efficient adhesive agents in the pelleting of fava bean seeds with rock powder.

Physiological quality of seeds of Mimosa bimucronata (DC) O. KTZE. subjected to different types of drying

Despite its potential, to date, work has not been carried out to identify the ideal drying conditions for Mimosa bimucronata (DC) O. Kuntze. Considering the scarcity of information on the drying process of this species, this work was with the objective of evaluating the sensitivity to desiccation by means of drying on activated silica gel (fast) and under laboratory conditions (slow). Rapid drying with silica was performed. For slow drying, the seeds were placed in plastic containers without lids, both at room temperature. Every hour, the seeds were weighed until reaching the pre-established points (30, 25, 20, 15 and 10%). The variables analyzed were: water content, first germination count, germination, germination speed index, dry mass and seedling length. The seeds of M. bimucronata (DC) show orthodox behavior, withstanding desiccation at levels below 15%. The desiccation of seeds at very low levels impairs the formation of seedlings, preventing their normal development.

Effect of different chemical priming agents on physiological and morphological characteristics of rice (Oryza sativa L.)

The research was conducted following a Completely Randomized Design (CRD) to investigate the effects of seed priming using various chemical treatments on the germination and growth parameters of two rice cultivars, BRRI Dhan-66 and IR 80991-B-330-U-1. Ten different priming agents, including H3BO3, CaCO3, CuSO4, DAP, FeCl2, MoP, PEG (5 %), PEG (10 %), Urea, and ZnSO4, were applied to treat the seeds, each treatment being replicated three times. A control group underwent hydro-priming. The seeds were soaked in the treatments for 24 h. After the priming treatments, the seeds were subjected to a redrying process at a temperature of 26 ± 2 °C until they regained their original weight before being transplanted onto blotting paper. Germination parameters such as germination percentage, germination speed, germination energy, and vigor index were recorded for seven consecutive days. Growth parameters including root length, shoot length, fresh seedling weight, and dry seedling weight were measured at 10, 20, and 30 days after sowing. The results indicate significant variations among the treatments for germination parameters (p ≤ 0.001). Similarly, significant variations were observed in growth parameters, including shoot length, fresh weight, and dry weight (p ≤ 0.001). Among the rice varieties, BRRI Dhan-66 exhibited better results for germination percentage (81.58 %), germination speed (62.78 %), germination energy (52.06 %), vigor index (1312), fresh weight (0.807g), and dry weight of seedlings (0.053g). In contrast, the FeCl2 treatment showed the best results, inducing respective increases of 25.19 %, 93.35 %, 94.95 %, and 29.07 % for germination percentage, speed, energy, and vigor index compared to the control, respectively. For growth parameters, the DAP and CuSO4 treatments demonstrated better results. Our findings highlight that improved germination of primed rice seedlings is associated with germination energy, speed, vigor index, and the fresh weight of the seedlings. Furthermore, Pearson's correlation coefficient revealed there is significant positive correlation between germination percentage, speed, energy and vigor index but the strongest correlation exists between germination speed and germination energy (R = 0.94***) followed by germination percentage and vigor index (R = 0.92***). Based on our findings, we propose that seed priming significantly enhances rice seedlings' germination and growth parameters. BRRI Dhan-66, along with seed treatment using FeCl2, can be effectively employed to achieve improved germination and growth in rice cultivation.

SALINITY TOLERANCE OF QUINOA (CHENOPODIUM QUINOA WILLD.) GENOTYPES TO ELEVATED NACL CONCENTRATIONS AT GERMINATION AND SEEDLING STAGES

Evaluating quinoa genotypes for salinity tolerance at germination and seedling stages is a prerequisite for plant breeders. Thus, the scrutiny of 19 quinoa genotypes at different salinity levels under controlled laboratory and greenhouse conditions occurred at the germination and seedling stages. This study aimed to identify the most tolerant genotypes to elevated salinity levels at germination and seedling stages and to determine the traits of a robust association with salinity tolerance using a factorial experiment based on a randomized complete block design in three replications. The four salinity solutions used were zero (control), 3000, 6000, and 9000 ppm NaCl. Increasing concentrations of NaCl caused a gradual and significant decrease for all studied traits except mean germination time, which significantly increased. At all salinity-stress levels (3000, 6000, and 9000 ppm NaCl), the studied 19 genotypes underwent classification based on their salinity tolerance index (STI) into three categories, i.e., tolerant, moderately tolerant, and sensitive. The four most salinitytolerant quinoa genotypes under all studied salinity-stress conditions were Rainbow-2, Ql3, RH, and KvlSRA2. The strongest correlations were between STI and each of seedling length, root length, seedling fresh weight, seedling vigor index I, and seedling vigor index II under 3000 ppm; germination percentage, speed germination index, seedling extent, root length, seedling fresh weight, and seedling vigor index II under 6000 ppm; and shoot length and seedling vigor index I under 9000 ppm salinity concentration level. Traits showing sturdy correlations with STI, high heritability estimates, high expected genetic advance, and wide phenotypic and genotypic variability were seedling dry weight, seedling fresh weight, seedling vigor index II, and speed germination index at all salinity stress concentrations; they are recommendable as selection criteria for salinity tolerance in quinoa at germination and seedling stages.

Morphophysiology of creol seeds in genotypes of Phaseolus vulgaris L.

Creole seeds are considered a local heritage because of their natural biological ability to adapt to different environments. Maintenance of seed vigor has been a challenge for farmers, often because of prolonged droughts and/or lack of technical assistance, making it difficult to renew seed vigor. The objective of this study was to evaluate the morphophysiological characteristics of native seeds of Phaseolus vulgaris genotypes. Seeds were provided by the custodian of the Creole community seed bank in the municipality of Piranhas, AL. The following were evaluated: weight of one thousand seeds (PMS g), water content (TA%), germination index (IG%), germination speed index (IVG), seedling length (CP cm), and seedling dry mass (MSP g). Scott Knott was used at 5% probability, and all analyses followed the Rules for Seed Analysis. For water content, the varieties ranged from 6.9% to 11.78% moisture. For PMS, the genotypes ranged from 351 to 123.5 g. In terms of germination, the bean genotypes presented 29 to 85% and one presented 100% dead seeds. The seeds were stored with the recommended water content, and the Creole genotypes showed great diversity in their sizes, a factor that impacts storage and planting planning. For varieties that presented germination values below 70%, it must be observed whether it is related to a specific factor of a crop and/or the storage conditions and time. Black presented good averages for all morphophysiological characteristics.

Physiological changes of Capsicum baccatum var. pendulum during ontogenesis and rest after harvest

The objective of this study was to evaluate the physiological quality of seeds of young finger pepper during ontogenesis and rest after harvest. The experiment was conducted in a completely randomized design with five replications. The treatments consisted of the harvest of the fruit at 30, 45, 60, 75, and 90 days after anthesis (DAA), and two rest conditions: no rest and post-harvest resting for 10 days. The seeds were evaluated for water content, dry mass of the seeds, germination, first germination count (germination energy) and germination speed index. The harvesting period and the post-harvest resting period of the fruits affect the physiological quality of the “Dedo-de-moça” pepper seeds. Seeds with maximum physiological quality (germination and strength) and dry matter are obtained with fruits harvested between 70 and 80 days after anthesis. The post-harvest resting period of fruits allows the anticipation of the harvest to 57 days after the anthesis, without compromising the physiological quality of the seeds.

Maturation indexes and physiological quality of seeds and fruits of Morinda citrifolia L.

The seeds of Morinda citrifolia L. present unevenness and delay in germination in relation to other fruit trees. Knowledge about the physiological quality of seeds is extremely relevant for the production of seedlings and propagation of the species. Thus, the objective was to study maturation indices and the physiological quality of seeds and fruits of M. citrifolia. Seeds from freshly picked fruits, fruits harvested after seven days of maturation and freshly dropped fruits were used. The extracted and processed seeds were submitted to the following pre-germination treatments: GA3, KNO3 and H2O. The following were analyzed: fruit length and diameter, seed length, width and thickness, number of seeds per fruit, average number of seeds per kg, weight of 1000 seeds, germination, germination speed index, shoot and root length, seedling dry mass and percentage of normal seedlings. The experimental design used was completely randomized, with three stages of fruit maturation and six treatments, with four replications of 25 seeds. M. citrifolia seeds do not show tegumentary dormancy. The seeds of freshly harvested fruits and fruits harvested after seven days of maturation do not need pre-germination treatments. GA3 promotes greater germination in seeds of fruits harvested from the ground. Fruits that have just fallen to the ground have a higher content of soluble solids and a higher content of acidity. The storage of fruit in a refrigerator for a week provides the maintenance of texture characteristics, such as hardness, adhesiveness, elasticity and gumminess. Fruits with greater hardness have higher physiological seed quality.

Physiological quality of ‘BRS’ passion fruit seeds grown at different altitudes and storage environments

The aim of this work was to study the physiological quality of ‘BRS’ passion fruit seeds grown at different altitudes stored in cold chamber and in natural environment for six months. Hybrid passion fruit seeds (BRS Gigante Amarelo, BRS Sol do Cerrado and BRS Rubi do Cerrado) grown at three altitudes (104; 711; 1016 meters) in the southern region of the state of Espírito Santo were used. Germination was carried out in germitest paper rolls, placed in BOD-type germination chambers at temperature of 20-30 ºC. The following parameters were analyzed: germination, germination speed index, shoot and root length and dry mass of seedlings. The experimental design used was completely randomized in a factorial scheme with split plot in time 4x(3x3) (four bimonthly analyses x three hybrids x three altitudes), with two independent storage environments and three replicates of 100 seeds. Hybrid Passiflora edulis f. flavicarpa seeds can be stored in natural environment or cold chamber. Hybrid yellow passion fruit seeds grown at altitudes of 104 and 711 meters show higher germination and vigor percentages. Hybrid ‘Gigante Amarelo’ seeds had lower averages for variables under study, regardless of altitude. Hybrid ‘Rubi do Cerrado’ seeds grown at altitude of 1016 meters and hybrid ‘Sol do Cerrado’ seeds grown at altitudes of 104 and 711 meters have higher germination and vigor percentages and can be stored for 180 days in natural environment or cold chamber without viability loss. Flavicarpa can be stored in natural environment or cold chamber. Hybrid yellow passion fruit seeds grown at altitudes of 104 and 711 meters show higher germination and vigor percentages. Hybrid ‘Gigante Amarelo’ seeds had lower averages for variables under study, regardless of altitude. Hybrid ‘Rubi do Cerrado’ seeds grown at altitude of 1016 meters and hybrid ‘Sol do Cerrado’ seeds grown at altitudes of 104 and 711 meters have higher germination and vigor percentages and can be stored for 180 days in natural environment or cold chamber without viability loss. Passiflora edulis f. flavicarpa can be stored in natural environment or cold chamber. Hybrid yellow passion fruit seeds grown at altitudes of 104 and 711 meters show higher germination and vigor percentages. Hybrid ‘Gigante Amarelo’ seeds had lower averages for variables under study, regardless of altitude. Hybrid ‘Rubi do Cerrado’ seeds grown at altitude of 1016 meters and hybrid ‘Sol do Cerrado’ seeds grown at altitudes of 104 and 711 meters have higher germination and vigor percentages and can be stored for 180 days in natural environment or cold chamber without viability loss. Hybrid ‘Gigante Amarelo’ seeds had lower averages for variables under study, regardless of altitude. Hybrid ‘Rubi do Cerrado’ seeds grown at altitude of 1016 meters and hybrid ‘Sol do Cerrado’ seeds grown at altitudes of 104 and 711 meters have higher germination and vigor percentages and can be stored for 180 days in natural environment or cold chamber without viability loss. Hybrid ‘Gigante Amarelo’ seeds had lower averages for variables under study, regardless of altitude. Hybrid ‘Rubi do Cerrado’ seeds grown at altitude of 1016 meters and hybrid ‘Sol do Cerrado’ seeds grown at altitudes of 104 and 711 meters have higher germination and vigor percentages and can be stored for 180 days in natural environment or cold chamber without viability loss.

Differences of two varieties of corn in germination and flooding

The present study sought to identify and evaluate the Germination Speed Index (GSI), the differences in growth and pigments in the hybrids Agroceres® (Hybrid AG 8780) and Pioneer® (Hybrid 30F53VYHR) submitted to stress by flooding in the vegetative stage. Two tests were carried out: in Trial I it was verified the GSI in both varieties, where it was found a higher germination tax and velocity for the variety Agroceres® (Hybrid AG8780). In Trial II, the plants originated from Trial I were imposed to stress by flooding. From 3 DAF (Days After Flooding) it was evaluated: NDVI (Normalized Difference Vegetation Index), height, diameter of stem and visual analysis and, in the end of Trial II it was evaluated the photosynthetic pigment content. In the analysis of growth and photosynthetic pigment content, it was possible to verify that the Pioneer® (Hybrid 30F53VYHR) variety presented a better performance, with less variations when compared to the plants in control treatment, being more suitable for situations of stress by flooding.

Effects of automotive diesel oil on germination of Avicennia germinans and Laguncularia racemosa mangrove propagules

ABSTRACT Mangrove ecosystems are sensitive to oil, as spills can impair developmental processes of mangrove vegetation. Since the 2010s, the Brazilian equatorial margin, more specifically the Pará-Maranhão Basin and the mouth of the Amazonas River, has been affected by oil runoff from urban activities and the increased risk from exploratory deepwater drilling for oil extraction. Dispersal of mangrove propagules occurs during the tidal cycles, when the presence of tensors in the water can affect germination. We analyzed the effects of diesel oil on the germination of propagules of the two most common mangrove species in the region, Laguncularia racemosa and Avicennia germinans, in six treatments of diesel oil in the water (0.5%, 1%, 1.5%, 2%, 3% and 4%) and a diesel-free control. The response variables were germinability (G%), mean germination time, mean germination speed and the germination speed index (GSI). G% and GSI in L. racemosa propagules differed significantly between the control and all treatments (G% and GSI < 10% in the 3% treatment). Propagules of A. germinans were more resistant, and the physiological variables did not differ significantly among treatments and control (G% > 90% in all treatments). Our results indicate that, at the germination stage, L. racemosa was more susceptible than A. germinans to contamination by automotive diesel oil.

Time of contact of phosphate fertilizer with Megathyrsus maximus (cv. Massai) seeds in relation to germination and growth

The aim of this research was to evaluate the effect of the contact time of simple superphosphate fertilizer with Massai grass (Megathyrsus maximus) seeds on the physiological quality of the seeds. The experiment was conducted with seeds of Massai grass in two conditions: laboratory and field. The experiment was carried out in Teresina, Piauí, Brazil. The experimental design was completely randomized, with three replicates for both conditions. The treatments consisted of seven contact times: 0, 3, 6, 9, 24, 48, and 72 h. Germination (GP) and emergence (EP) percentages, seedling height (SH), root length (RL), and germination speed index (GSI) were evaluated. The contact time of the fertilizer with the seeds had a significant effect on all variables, except root length and emergence at 7 d. For GP in the second data collection and GSI, there were no differences up to 3 h of contact; however, for GP in the first collection, SH and GSI at 21 d, the contact of seeds with fertilizer for 3 h already had negative effects on these variables, reducing them by 23.33%, 12.13 cm and 14.28% respectively. The longer the contact time between single superphosphate with M. maximus (cv. Massai) seeds, the lower the germination and vigor values.

Germinative performance of lettuce (Lactuca sativa L.) landrace seeds for organic production

Currently, it is observed a gap in the supply of seeds from organic farming production systems to meet the demand for seeds of vegetables. In this sense, landrace seeds may stand as an alternative to commercial seeds, reconciling organic farming practices with the genetic diversity of landrace seeds and family farming. This work aimed to evaluate the germinative performance of landrace lettuce seeds obtained directly from the farmer and produced with an organic system as an alternative seed source for use in organic farming. A batch of commercial seeds and two batches of landrace seeds from different places were evaluated. The following tests were carried out: germination, first germination count, germination speed index, accelerated aging test, resistance to stress induced by cold, and tetrazolium test. The obtained results underwent ANOVA and Tukey’s multiple range test at 5 % error probability. The results showed that both the conventional and the landrace seeds had germination percentages above 90 %. The vigor of the seeds produced with the conventional system was greater in the tetrazolium test. The three batches had a similar performance in the tests of resistance to stress induced by cold at 5 °C.

Allelopathic Effects of Caffeic Acid and Its Derivatives on Seed Germination and Growth Competitiveness of Native Plants (Lantana indica) and Invasive Plants (Solidago canadensis)

Allelopathy has garnered considerable attention, but the effects of different allelochemicals on invasive plants remain unclear. This study addressed the knowledge gap surrounding allelopathy and its impact on native and invasive plant species. We focused on the impact of caffeic acid and its derivatives on the growth and competitiveness of the native Lantana indica and the invasive plant Solidago canadensis. We selected three allelochemicals, caffeic acid, methyl caffeic acid, and ethyl caffeic acid, for evaluation at two concentrations (0.1 mM and 1.0 mM). Three planting methods were employed: (1) a single species of S. canadensis, (2) a single species of L. indica, and (3) a combination of S. canadensis and L. indica. In addition, a control group was also included. Results revealed that high concentrations (1 mM) of methyl caffeate (MC) and ethyl caffeate (EC) significantly reduced seed germination rate, seed germination index, and seed germination speed index of L. indica compared to a low concentration (0.1 mM). Plant height, stem diameter, biomass, and root length in the control group (CK) of S. canadensis were significantly higher than those in the treated groups. However, with increasing allelochemical concentration, L. indica’s relative competitiveness gradually decreased. These findings provide insights into the concentration-dependent effects of allelopathic compounds on the growth of L. indica and S. canadensis. By analyzing how these allelochemicals influence the growth and competitiveness of native and invasive plants, the study sheds light on the dynamics of allelochemical interactions between these species. This knowledge can be pivotal for understanding plant competition dynamics in ecosystems and could inform strategies to control invasive species or promote native plant growth.

Fruit and Seed Morphometry and in Vitro Germination of Hollyhock Seeds

Alcea rosea L. is an ornamental shrubs that has many possible uses, including medical purposes. This species is mainly propagated by seeds, however, there are few studies that describe their morphometric characteristics, in addition, previous reports show that they have dormancy that makes the germination difficult. Therefore, this work aimed to determine the morphological characteristics of the fruit and seeds of A. rosea and to evaluate its in vitro seeds germination under different pregerminative methods in different culture media. For the morphological description, 25 fruits or seeds were evaluated. For the in vitro germination in the MS and WPM culture media, the pregerminative treatments were: T1 - untreated seeds (control); T2 - mechanical scarification (cut in the seed coat); T3 - thermal scarification (immersion of the seeds in water at 60 ºC for 16 min). The experimental design was completely randomized, in a 3x2 factorial scheme (pregerminative treatments x culture media), with eight replications and twenty seeds per replication. A visual scale was proposed to classify the seedlings vigor. The schizocarp hollyhock fruit is flattened and its diameter is greater than its height, and each fruit contains 33 seeds, on average. The seeds have approximately 4.2 mm in length and 100 seeds weight, on average, 0.89 g. The culture medium does not influence the seeds germination and the pregerminative treatments are not necessary for the germination. However, the mechanical scarification promoted the best germination speed index and the production of more vigorous plants.