Viable Seedlings Research Articles

Grab to fill the gap: key factors influencing Reynoutria japonica germination and seedling establishment in the secondary distribution range

Reynoutria japonica (Japanese knotweed) is a highly invasive female plant that primarily reproduces through vegetative regeneration during secondary distribution. Despite producing a substantial number of viable hybrid seeds, the occurrence of seedlings and young plants in the wild remains rare; the reasons for this rarity are unclear. Environmental intolerance and chromosomal anomalies during hybridisation can impede seedling development. This study evaluates the combined impact of these factors by examining substrate, temperature, and light effects on germination, as well as assessing seedling genome sizes and viability. Seeds were cultivated in both natural and controlled environments to manage external influences. Flow cytometry was employed to evaluate chromosomal arrangements. The final germination was notably high at 99%, and 68% of seedlings thrived under controlled conditions, emphasising hybrid seedling viability regardless of highly polyploid levels ranging from pentaploid to aneuploid (2C DNA genome size from 5.17 to 11.95 pg). Thus, it is evident that seeds can germinate and produce vital seedlings despite various chromosomal sets. Even fluctuating temperatures and type of substrate do not limit seed germination. However, these results were obtained under laboratory conditions, with seeds and seedlings receiving regular irrigation. A significant seedling mortality rate (99%) was observed in the field experiment, and the final germination was also low there (15%). Observations suggest that water stress might be the cause of this mortality. Further research on water stress is necessary because it could be the primary factor limiting the successful generative spread of the knotweeds.

Seed invigoration to improve viability, seed vigour and growth of porang seedlings

Abstract The porang planting area is increasingly expanding. Providing seeds from seeds is considered better, but has problems with the dormancy period so efforts need to be sought to overcome them. This research aims to determine the increase in viability and vigor of porang seeds soaked in a functional microbial solution and to obtain the best growing medium for the growth and yield of porang plants. The research was carried out in Pontianak City from April to November 2021. This research consisted of two experiments. The first experiment used a non-factorial completely randomized design (immersion in functional microbial solution) with nine treatments. The variables observed included: vigor index, growth simultaneity, germination capacity, growth speed, plumule and radicle length. The second experiment used a split plot randomized block design, where the main plot was soil type and the subplot was soaking in a functional microbial solution (same as the first experiment). The variables observed included: plant height and tuber weight. The research results showed that SE21 isolate was the best in increasing seed viability and vigor. All functional microbes were equally good at producing plant height in the two growing media. Alluvial soil growing media: cow manure: roasted husks enriched with WH31C isolate produces the heaviest weight of porang tubers.

Effects of position of seed perforation by cowpea weevils, Callosobruchus maculatus (F.), on viability and vigour of cowpea (Vigna unguiculata L. Walp) seed

Cowpea, Vigna unguiculata, is a high-protein legume crop that is often susceptible to pest damage. The cowpea weevil, Callosobruchus maculatus, predates on cowpea seeds in storage which renders grain unsuitable for human consumption. In the larval stage, cowpea weevils consume food reserves from the seed endosperm and may deter seed germination. The problem is more pervasive among resource-poor farmers in Sub-Saharan Africa, who grow cowpea for subsistence and keep the surplus grain for sale and use it as seed in the subsequent growing seasons. Unsuitable storage structures and ineffective methods of weevil control may increase weevil infestation of cowpea seeds in storage which constrains the production of cowpeas. The aim of the study was to determine if the position of seed perforation by cowpea weevils affects seed viability and growth of cowpea seedlings. Undamaged cowpea seeds ‘black-eyed peas’ were infested with cowpea weevils and stored for three months to allow for infestation. Thereafter, seeds with a single perforation or hole were selected from the infested seed lot and sorted into groups of damage according to the position of the hole on the seed. Five categories of potential damage were identified namely seeds with holes on the top, bottom, side, back or hilum area of the seed as presented schematically in the paper. The positions of holes on seeds served as treatments for the study and undamaged seed served as control. Data on germination and seedling height were collected and analysed statistically. Results reveal that the positions of damage on seed affects seed germination and seedling height. Seed germination on day two was significantly poorer for seeds damaged at the top, relative to both undamaged seeds and the alternative sites of damage. The results of top damaged seed being inferior than other treatments, remained consistent for germination on day seven and for seedling height at two weeks after the first emergence. Small holder farmers should therefore refrain from planting top damaged cowpea seed.

Verified hypotheses on the "nurse" and "burial" effects on introduced Quercus rubra regeneration in a mesic Scots pine forest.

A previous study on the encroachment of North American northern red oak Quercus rubra L. into the mesic Scots pine forest (in central Poland) revealed high abundances of seedlings and saplings under shrubs, with lower abundances in open areas or clumps of bilberry Vaccinium myrtillus L. It was unclear whether the regeneration success of Q. rubra is enhanced by the presence of shrubs due to their "nurse effect", and how burying acorns of different sizes in soil or moss affects the survival of oak seeds and seedlings (a "burial effect"). Results of a previous observational study were verified in an experimental study: a pool of 900 large-, medium-, and small-sized acorns was sown under moss cover in open areas and within bilberry clumps and in soil under shrubs in 2018 and monitored for 3 years in natural conditions. The majority of sown acorns were lost, mainly due to acorn pilferage, lack of germination and the death of sprouting acorns. However, acorn and seedling survival depended significantly on acorn size and differed among the microsites studied. Viable seedlings were twice as likely to develop from large- and medium-sized as from small-sized acorns, and they grew mainly from acorns sown under moss cover, confirming a positive "burial effect." Seedling survival was three times higher in bilberry and open areas, than under shrubs; however, seedlings "nursed" by shrubs were less threatened by large ungulates. Only a small part of the pool of sown acorns contributes to the reproductive success of Q. rubra in the mesic Scots pine forest. Microsites characteristic to this type of forest are suitable for northern red oak regeneration; however, bilberry favors acorn survival and germination and early seedling growth, moss cover favors acorn survival and germination, while shrubs protect surviving seedlings from herbivory.

NaCl Kaynaklı Tuz Stresinin Lotus corniculatus L. cv. 'Leo'nun Çimlenmesi ve İlk Fide Büyümesi Üzerindeki Etkisi

Lotus corniculatus L. is one of the agronomically and economically important perennial legume forage species with moderately salt-tolerant. It is well known that even the cultivars of the same species in plants have different responses in salinity. However, studies on the salt response of L. corniculatus and its cultivars, which are more advantageous than other forage crops such as white clover (Trifolium repens) and alfalfa (Medicago sativa L.), in the use of marginal agricultural lands affected by abiotic stress factors such as salinity, are limited. Under salt stress, the most crucial phases of the plant life cycle that are directly related to the survival of the plant are seed germination, growth, and vigour. Therefore, this study was carried out to determine the germination and growth responses of L. corniculatus cultivar 'Leo', which is known to have higher tannin content than other cultivars, under NaCl-derived salt stress in vitro. For this purpose, L. corniculatus seeds were cultured in MS (Murashige and Skoog/Gamborg) medium containing 0, 40, and 80 mM NaCl for 14 days. Seed germination percentage, mean germination time, germination rate index, shoot-root length, root to shoot length ratio, shoot-root fresh dry weight, shoot-root dry matter, the ratio of root to shoot dry matter, shoot-root water content and seedling vigour index parameters were measured. According to the results of the research, the germination percentage did not change in the applied NaCl treatments, but the germination rate decreased. However, shoot length decreased and root length increased. Although there was no statistically significant change in shoot and root fresh-dry weight, both decreased in 80 mM NaCl treatment. The shoot and root dry matter increased and the water content decreased. Also, the seedling viability index decreased. In 40 mM NaCl treatment, on the other hand, there was an increase in shoot fresh-dry weight, dry matter ratio and seedling viability index with the positive effect of low dose. Within the scope of this study, comprehensive information was presented for L. corniculatus (cultivar 'Leo'), an important forage plant, in terms of germination and seedling growth under salt stress.

<i>In vitro</i> culture of cashew (<i>Anacardium occidentale</i> L.): influence of disinfection, antioxidants and carbon source on germination and growth

This study aimed to determine the impact of disinfection protocol, antioxidants, and carbon sources on the germination and growth of cashew plants grown in vitro. Two disinfection techniques, single and double disinfection, were used on cashew seeds. The seeds were then grown on a medium supplemented with antioxidants and carbon source at different concentrations. The results showed that double disinfection resulted in the lowest contamination rates of 5.29% and 9% for calcium hypochlorite and sodium hypochlorite, respectively. Germination rates, mean germination times, and viable seedling rates were not affected by the disinfection technique nor type of disinfectant used. However, plants from seeds that underwent double disinfection had the highest growth rates. The presence of antioxidants and the interaction between antioxidants and their concentrations did not have a significant influence on germination rates, normal seedling rates, or mean germination time. On the other hand, these parameters were affected by the carbon source used. Overall, this study provides valuable insights into the factors that affect cashew seed germination and growth in.

QTL Regions and Candidate Genes Associated with Selected Morphological Traits of Winter Triticale (× Triticosecale) Seedlings

The development and viability of seedlings are crucial in overwintering cereals, as it can affect not only an adult plant physiological condition, but also the size and quality of future grain. Recent studies on the genetic control of morphological and yield-related traits have been focused on adult plants of wheat, barley, maize, and rice. However, there is insufficient research describing the genetic control of cereals in the seedling stage. To fill that gap, the winter triticale ‘Hewo’ × ‘Magnat’-doubled haploid lines population was used to locate quantitative trait loci associated with selected traits measured at the seedling stage: the width and length of the first and second leaves, the leaf blade and leaf sheath lengths as well as the length-to-width ratio. Based on the genetic map for ‘Hewo’ × ‘Magnat’ DH population, main four loci, statistically significant (P < 0.05) and strongly associated with the second leaf length and width as well as their ratio were identified. Those regions were located on rye chromosomes 4R, 5R, and 6R with LOD value up to 20.35. In addition, candidate genes in localized regions were identified. The work also demonstrated correlations between the morphology of the second leaf, especially its length-to-width ratio, and the encoded proteins. As described in this paper, results are, to our knowledge, a first attempt to determine the genetic control of triticale seedlings and can provide a new insight on this field and become a reference for developing novel triticale varieties in breeding programmes.

Germination responses with different treatments, seed vigour and seedling growth of Pterolobium stellatum (Forssk.) provenances stored from 19 to 30 years

Knowledge of the genetic variability of different species for conservation purposes and quality seedling production after longer storage time is important. The aim of the research paper was to examine the effect of longer seed storage periods (19–30 year) on seed viability, seed vigour and initial growth of seedlings from five provenances of Pterolobium stellatum (Forssk). Seeds collected from Dabena, Gambo, Agaro, Bishofitu, and Merti localities and stored for 19, 19, 21, 25, and 30 years, respectively used for the study. Different seed dormancy-breaking treatments such as; soaking in cold water for 48 h (CW-48); soaking in hot water for 10 min (HW-10); 20 min (HW-20) and mechanical scarification; i.e., nicking (NK) used for the germination of the seeds. A randomized complete block design was used for the experiment and the study undertaken in a greenhouse. For each treatment, four replications and for each replication, 50 seeds were used. One-way analysis of variance was used for germination index, early seedling growth and seed vigour index data. The results showed that for all the provenance seeds stored for different periods, NK treatment resulted relatively in a higher mean germination percentage and germination indices as compared to the other pre-treatments. The seed vigour index result showed significant differences among the different provenances (P < 0.001). Similarly, there were significant differences among the early growth of seedlings germinated from different provenance seeds (P < 0.001). The seeds collected from Merti provenance and stored for 30 years and Dabena provenance, stored for 19 years, have relatively resulted in higher mean germination index, seed vigour and seedling growth relative to the other studied provenance seeds. We observed that provenance had a more significant influence on germination, seed vigour and seedling growth than the seed storage period for the P. stellatum. Finally it is recommended that despite there is inter population variation, the seeds of P. stellatum can be stored for a longer time and application of nicking as a dormancy breaking treatment could enhance seed germination of the species.

Overcoming seed dormancy of Taxus baccata L. by embryo rescue leads to germination and seedling growth

Hairy roots generated by Rhizobium rhizogenes-mediated transformation of yew (Taxus spp.) is a promising approach to enhance production of Taxol® (paclitaxel), which is one of the most effective anticancer drugs. As a prerequisite, it is pivotal to successfully produce Taxus seedlings for transformation. However, the deep dormancy of Taxus seeds leads to extreme difficulties in seed germination. Therefore, embryo rescue has been used to break the dormancy of Taxus baccata seeds, thereby producing seedlings for transformation. In the current study, a successful strategy of embryo rescue was to sterilize the surface of T. baccata seeds collected from the field at two different maturity stages (low and high). The strategy resulted in 100% germination rate, but it was worth noting that not all germinated embryos grew into fully developed plants. As a result, the present experiment introduced an innovative indicator—fully developed seedling index—to describe the growth of seedlings developed by germinated embryos. Collectively, the data revealed that 21 ± 4% of the seedlings eventually grew into fully developed plants. Regarding the development of the seedlings, the fully developed seedling index increased initially along with seedling growth, reaching a peak after 2 weeks. Subsequently, the fully developed seedling index from low maturity seeds and high maturity seeds began to decrease until it stabilized after 4 weeks and 7 weeks, respectively. Consequently, the new findings proved helpful to select T. baccata seeds with appropriate maturity, hence developing a reliable technique to produce viable seedlings for a transformation pipeline.

Metabolomics targets tissue-specific responses in alleviating the negative effects of salinity in tef (Eragrostis tef) during germination

Main conclusionSalinity induced metabolite responses resulted in differential accumulation of flavonoids and antioxidant metabolites in shoots and roots suggesting improved antioxidant capacity in providing salt-adaptive phenotype of tef seedling.Tef [(Eragrostis tef) (Zucc.) Trotter] is an important ‘cash crop’ of Ethiopia grown mainly for human food, and development of elite tef cultivars with better performance is vital to Ethiopian farmers and breeders. Soil salinity is one of the key constraints that affects tef yield in the Ethiopian lowlands and Rift valley where cultivation of tef is limited. Being a minor crop, the responses of tef towards salinity is unknown. Salinity involves physiological and metabolite reprogramming that can have major impact on germination and seedling establishment. Here we evaluate the in vitro effect of NaCl on tef germination and associate this with metabolomic approaches to suggest salt tolerance mechanisms. In this study, 19 tef varieties were screened for NaCl tolerance and were investigated using untargeted metabolomics. Screened tef varieties showed differential germination rates with NaCl treatment varying from < 20 to 100%. Viable seedlings exposed to NaCl exhibited purple-red pigment accumulation in the roots except for Beten and Tullu nasy varieties. Metabolite comparisons between shoots and roots showed significant differences and, in particular, roots of salt tolerant tef varieties accumulated flavonoid derivatives as well as sugars and cell wall associated metabolites. These metabolic changes were correlated with patterns of antioxidant capacities and total flavonoid content in shoots and roots and suggested a mitigating response by tef to salinity. Our study highlights the role of flavonoid accumulation following salt stress on tef seedlings and further these findings could be used as targets for selective tef breeding.

Inducing The Viability of Deteriorated Jatropha Seeds Through Matriconditioning Technology and Pseudomonas Fluorescens as Biological Agent

Jatropha curcas is a prospective vegetable oil or biodiesel and various derivative products as well as phytoremediation (plants cleaning the environment) and phytomining (plants that mine metals such as gold, nickel etc.). However, the commodity often experiences problems in the supply of seeds. The seed used usually has decreased their viability after going through a certain storage period. Therefore, matriconditioning technology and the application of the biological agent Pseudomonas fluorescens were used to increase the viability and vigor of these seeds. The aim of the study was to determine the interaction between the duration of the matrioditioning treatment and the application of Pseudomonas fluorescens to increase the viability and vigor of Jatropha seeds and to determine the optimal duration of the matrioditioning treatment and the dosage of Pseudomonas fluorescens in increasing the viability and growth performance of sprouts and seedlings. Field experiments would be carried out in the greenhouse of the Faculty of Agriculture, Universitas Jember. This experiment was arranged using a factorial design (two factors) with a randomized block design (RBD) repeated 3 times. The result showed that the interaction effect of matriconditioning time and dose of Pseudomonas fluorescens was significantly different on the observed variables of growth speed, vigor index and T50. Combination of 24 hours matriconditioning treatment and dose of Pseudomonas fluorescens 100 ml l-1 produced the best treatment on variables representing seed vigor (growth rate and vigor index).

Physiological responses induced by phospholipase C isoform 5 upon heat stress in Arabidopsis thaliana.

Plant's perception of heat stress involves several pathways and signaling molecules, such as phosphoinositide, which is derived from structural membrane lipids phosphatidylinositol. Phospholipase C (PLC) is a well-known signaling enzyme containing many isoforms in different organisms. In the present study, Phospholipase C Isoform 5 (PLC5) was investigated for its role in thermotolerance in Arabidopsis thaliana. Two over-expressing lines and one knock-down mutant of PLC5 were first treated at a moderate temperature (37 °C) and left for recovery. Then again exposed to a high temperature (45 °C) to check the seedling viability and chlorophyll contents. Root behavior and changes in 32Pi labeled phospholipids were investigated after their exposure to high temperatures. Over-expression of PLC5 (PLC5 OE) exhibited quick and better phenotypic recovery with bigger and greener leaves followed by chlorophyll contents as compared to wild-type (Col-0) and PLC5 knock-down mutant in which seedling recovery was compromised. PLC5 knock-down mutant illustrated well-developed root architecture under controlled conditions but stunted secondary roots under heat stress as compared to over-expressing PLC5 lines. Around 2.3-fold increase in phosphatidylinositol 4,5-bisphosphate level was observed in PLC5 OE lines upon heat stress compared to wild-type and PLC5 knock-down mutant lines. A significant increase in phosphatidylglycerol was also observed in PLC5 OE lines as compared to Col-0 and PLC5 knock-down mutant lines. The results of the present study demonstrated that PLC5 over-expression contributes to heat stress tolerance while maintaining its photosynthetic activity and is also observed to be associated with primary and secondary root growth in Arabidopsis thaliana.

PINUS SYLVESTRIS L. БІРЖЫЛДЫҚ СЕППЕ КӨШЕТТЕРІНЕ AGRO-MIX, AGRARKA ЖӘНЕ ЭПИН БИОПРЕПАРАТТАРЫН ҚОЛДАНУ

This article presents studies of the effect of biological products "Agro-MIKS", "Agrarka" and "Epin" on the growth of annual seedlings of Scots pine (Pinus sylvestris L.) in 2022 with the financial support of KATU named after. S. Seifullin of young scientists about research work carried out within the framework of internal grant funding No. 2VGF/21. The research work was carried out in a forest nursery located in the city of Schuchinsk, Burabay district, Akmola region. In the forest nursery, a total area of 0,4 ha was surveyed, of which 0.2 ha was pre-treated and sown with seeds of Pinus sylvestris L. Some details of this research work were published in other publications, but in this paper only one object of study, seedlings of Pinus sylvestris, was fully analyzed. L. The composition of chlorophyll was studied to assess seasonal growth and physiological development, as well as the biochemical activity of seedlings. The biological products used in the experimental samples were compared with each other and with control options. The biomass, growth and viability of seedlings were analyzed. Soil cultivation, sowing and care were carried out according to generally accepted methods of experimental work. The samples were built according to the linear-diagonal method, and the data were collected throughout the season. Statistical data were processed using the SPSS, STATISTICA 13, and SNEDECOR programs.

Phytocenotic and Biotopic Parameters Affect the Condition of European Spruce Cultures during the Establishment Stage in the South-East of the Leningrad Region

In the Boksitogorskiy district of the Leningrad oblast, the study was conducted regarding the influence of phytocenotic parameters (crowns density, height, herbage density, moss cover) and biotopic parameters (illumination, acidity, moisture and soil richness) on the morphometric parameters and vitality of European spruce (Picea abies (L.) H. Karst.) BRT (bare root trees) and RBT (root-balled trees) seedlings during the establishment phase under contrasting growing conditions: under the sparse aspen canopy left in clearings and in open spaces, outside the influence of tree crowns. The positive effect of undercanopy cultivation on the safety and viability of seedlings of both types has been statistically proven; with RBT seedlings having the best indicators of vitality and growth along the main axis. However, the herbaceous layer’s height and density under these conditions adversely affected the branching of seedlings. Unlike the undercanopy conditions, when growing in the open, the condition of seedlings was more susceptible to the influence of abiotic factors. Under these conditions, a close positive correlation was found between the viability of seedlings with BRT and the main soil parameters (humidity, acidity, and nitrogen supply). Due to the better illumination on plots without canopies, seedlings with BRT had consistently high growth rates along the main axis. Under these conditions, the grass cover at the stage of spruce establishment was found to have a protective effect, maintaining a more optimal moisture regime and shading the seedlings. The practicality of using the RBT cultures in open spaces was still substantiated, since they were less susceptible to the negative influence of factors.

Proportions of sewage sludge in the production and quality of Malpighia emarginata DC. seedlings.

Sewage sludge (SS) has nutritional contents and has been implemented in the cultivation of seedlings. This study aimed to evaluate the quality of Malpighia emarginata DC. seedlings produced in different substrates with SS. Treatments were implemented with the addition of SS, and after 180 days seedling the characteristics were measured: aerial part and root system length, stem base diameter, number of leaves, fresh and dry mass of aerial part and root, and total biomass. The Dickson Quality Index (DQI) was calculated and the macro and micronutrient content of the aerial part and root. The accumulation of macronutrients in the root system followed the order of N>K>P>Ca>Mg>S, and aerial part of N>Ca>K>P>Mg>S, in the two vegetative structures N and S were in lower concentration. For micronutrients, the accumulation in the root system occurred with Fe>Zn>Mn>Cu>B, and aerial part with Fe>Mn>Zn>B>Cu. It was noted that in the two vegetative structures the Fe content was more concentrated. The use of SS in the substrate formulation proved effective in obtaining viable seedlings for field planting, being recommended the treatment with 60% SS + 40% organic compost.

Vegetation Structure and Regeneration status of Rhododendron arboreum sp. in the forests of Western Himalayas: Study of Van-Panchayat and Reserve forests in Chamoli District of Uttarakhand, India

One of the known indicators of forest health is regeneration of trees, their diversity and the age class structure. Forests which are subjected to unsustainable harvest of its products are in particular vulnerable and stressed. The present study was conducted to study the vegetation structure and regeneration status of Rhododendron arboreum in the van-panchayat and reserve forests of Uttarakhand, Western Himalaya. R.arboreum (Family Ericaceae) is an important keystone species in the region, and any significant change in the species composition due to anthropogenic pressures may also impact the forest community structure. Regeneration status of this species in the study area was enumerated with relative density of seedlings, saplings and mature tree individuals. Regeneration with viable seedling population indicates good forest health and is also a critical part of forest management. Vegetation analysis revealed a total of 13 tree species belonging to 10 families in the forest sites of the study area. Species density (ind/ha) varied from 469-525 (trees), from 322-385 (saplings), and from 435-464 (seedlings) in the van-panchayat forests and 525-572 (trees), 325-350 for (saplings) and 108-275 for seedlings in the reserve forests. Species diversity (H’) value in the van-panchayat forests ranged from 2.04-2.16 (trees), 1.52-1.86 (saplings), 1.32-1.54 (seedling) and from 2.36-2.45 (trees), 2.04-2.18 (saplings), 1.22-1.34 (seedling) in the reserve forest sites.The tree species richness and density in the reserve forests were found to be marginally higher than the van panchayat forests due to low anthropogenic pressure and limitations on the community’s extraction of forest-resources. However, fewer number of individuals of seedlings and saplings indicate less regeneration capacity of Rhododendron sp. in the reserve forest sites, which might be due to reduced seed germination of canopy species or maturation of the forests.

The challenges of growing orchids from seeds for conservation: An assessment of asymbiotic techniques.

Lewis Knudson first successfully germinated orchid seeds asymbiotically on artificial medium in 1922. While many orchid species have since been grown asymbiotically, the tremendous variation in how species respond to artificial medium and growth conditions ex situ has also become apparent in the past century. In this study, we reviewed published journal articles on asymbiotic orchid seed germination to provide a summary of techniques used and to evaluate if these differ between terrestrial and epiphytic species, to identify areas where additional research is needed, and to evaluate whether asymbiotic germination could be used more often in ex situ conservation. We found articles reporting successful asymbiotic germination of 270 species and 20 cultivars across Orchidaceae. Researchers often used different techniques with epiphytic versus terrestrial species, but species‐specific responses to growth media and conditions were common, indicating that individualized protocols will be necessary for most species. The widespread success in generating seedlings on artificial media suggests that asymbiotic techniques should be another tool for the conservation of rare orchid species. Further advances are needed in understanding how to introduce mycorrhizae to axenically grown orchids and to maximize the viability of seedlings reintroduced into natural habitats to fully utilize these methods for conservation.

Dormancy breaking treatments in Northern Wild Rice (Zizania palustris L.) seed suggest a physiological source of Dormancy

Dormancy is a limiting factor for breeding in northern wild rice (NWR; Zizania palustris L). This study developed a dormancy curve and tested a combination of scarification and hormone treatments, across three timepoints, for their ability to break dormancy in NWR and produce viable seedlings and plants. A dormancy curve was established across 9 months post-harvest, which showed maximum germination (95%) by 17 weeks post-harvest and high germination (≥ 81%) through the rest of the testing period. Subsequently, dormancy breaking treatments were tested at 1 week post-harvest; only a few seeds germinated (≤ 15%) across all treatment combinations. However, sulfuric acid increased germination shortly after harvest (5.8%), compared to water (0.5%) and NaClO (0%) but resulted in stunted seedlings, all but one of which died shortly thereafter. At 7 weeks, sulfuric acid treated seeds did not result in significantly higher germination than water and maximum germination was still below 15%. By 11 weeks post-harvest, the water treatments had the highest germination and resulted in the most viable plants, indicating that dormancy had begun to break naturally and exceeded the effect of the other scarification treatments. Hormonal treatments had no significant effect on germination or seed viability and no strong conclusions could be drawn about their effect on seedling or plant health. Due to the inability of early germinated seed to consistently produce viable plants and the increase in germination following sufficient cold storage, it is likely that NWR seed has intermediate or deep physiological dormancy.

Secondary Seed Ingestion in Snakes: Germination Frequency and Rate, Seedling Viability, and Implications for Dispersal in Nature

The importance of vertebrate animals as seed dispersers (zoochory) has received increasing attention from researchers over the past 20 years, yet one category in particular, diploendozoochory, remains understudied. As the term implies, this is a two-phase seed dispersal system whereby a secondary seed predator (carnivorous vertebrate) consumes a primary seed predator or granivore (rodent and bird) with undamaged seeds in their digestive tract (mouth, cheek pouch, crop, stomach, or other organ), which are subsequently eliminated with feces. Surprisingly, although snakes are among the most abundant predators of granivorous vertebrates, they are the least studied group insofar as our knowledge of seed rescue and secondary dispersal in a diploendozoochorous system. Here, using live snake subjects of the Sonoran Desert (one viperid and two colubrid species) and seeds of the Foothill Palo Verde (Parkinsonia microphylla), a dominant tree of the same region, we experimentally tested germination frequency and rate, and seedling viability. Specifically, to mimic rodents with seed-laden cheek pouches, we tested whether wild-collected P. microphylla seeds placed in the abdomen of thawed laboratory mice and ingested by the snakes would retain their germination viability. Second, we examined whether seeds exposed to gut transit germinated at a greater frequency and rate than the controls. While we found strong statistical support for our first hypothesis, both aspects of the second one were not significant. Accordingly, we provide an explanation for these results based on specific life-history traits (dormant and non-dormant seeds) of P. microphylla. Our study provides support for the role of snakes as important agents of seed rescue and dispersal in nature, their potential as ecosystem engineers, and crucial evidence for the investment of field-based studies on diploendozoochorous systems in deserts and other ecosystems.

Viability and performance of wheat seedlings after artificial seed aging

Abstract: Seed deterioration is a continuous irreversible process that affects cell structures and molecules and compromises the physiological quality of seeds. This study aimed to assess the effect of artificial wheat seed deterioration on germination and seedling performance. The TBIO Toruk wheat cultivar was used, with seeds submitted to different artificial aging times (2, 3, 4, 5, 6 and 7 days). The original and aged seed lots were submitted to laboratory germination and seedling performance tests (seedling length, seedling dry weight and endosperm dry weight). Alpha-amylase activity, electrical conductivity and the oxidative stress marker malondialdehyde were quantified. The exudate resulting from the electrical conductivity test was separated to quantify total soluble sugars, soluble proteins and phosphorus. The deterioration process increased lipid peroxidation and decreased initial alpha-amylase activity. During germination, the most deteriorated lots exhibited greater solute loss and lower alpha-amylase synthesis capacity. The lots with the greatest deterioration showed reduced viability and produced worse-performing seedlings.