Majority Of Seeds Research Articles

Grain diversity of rice collection from South Sulawesi, Indonesia

Abstract South Sulawesi province is among the Indonesia rice barns, which is expected to buffer the national rice supply. Although rice stock is mainly produced from high-yielding superior varieties, local germplasm is still the main basis for variety development. Local germplasm has been adapted to various agro-ecosystems and thus has potential as a genetic source for adaptation to climate change. This study was aimed at measuring the diversity of rice germplasm from South Sulawesi based on its grain characteristics. A total of 98 rice accessions that were conserved in the agricultural genebank were examined. Grain length, shape, color, and other grain-related characters were observed following the international standard descriptors for rice. NTSYS-PC software version 2.2 was used to perform clustering analysis. Rice collections from South Sulawesi showed diversity in their grain characteristics. The majority of seeds are awnless, have medium length, medium shape, and straw-colored lemmae-palea and attributed with medium-sized and straw-colored sterile lemmae, and the dehulled grain bran is predominantly white. The rice accessions can be grouped into eight clusters at a similarity level of 52%. This diversity and similarity information is important for germplasm management and utilization. However, due to the limited number of characters used, information from this study cannot yet be used as a basis for their management. More comprehensive characterization efforts need to be conducted in order to make this study more usable, both in supporting conservation and for their utilization

Pregled proizvodnje biodizela transesterifikacijom esterifikovanog ulja Carica Papaia (CSO)

As a result of global urbanization and modernization, the use of petroleum (fossil fuel) is on the increase and there are growing concerns among stakeholders in the oil and gas industry over the depletion rate of petroleum reserves and its rising cost. The conversion of readily available sources of biomass to produce different types of biofuels to address the future energy crisis is one of the preferred attractive choices. Biodiesel is generally produced by the transesterification reaction of vegetable oils, waste vegetable oil or animal fats in the presence of a suitable catalyst. The choice of biodiesel as a preferred renewable source of energy was based on its biodegradability, non-toxic, lower emissions, sulphur free, low levels of polycyclic aromatic hydrocarbons (PAHs) and their nitrated compounds. This alternative source of energy is environmentally friendly and could be used in the existing diesel engines with little or no modifications. This will reduce the world's dependence on fossil fuels that are non-renewable with the attendant environmental benefits to mankind. However, the use of these edible vegetable oils will put pressure on the food uses of such oil which will result to fuel-food crisis in the future. This impending crisis can be readily averted by exploring non-edible crops/agricultural waste biomass that can be grown or harnessed domestically and capable of producing oils as valuable raw materials for the emerging industry. A free fatty acid (FFA) lower than 3% is necessary to carry out the base catalysed reaction to end. For biodiesel production, the higher the acid value of the oil, the lesser the conversion efficiency hence the need for esterification process. Papaya seed contains 27.3% to 28.3% protein, 28.2% to 30.7% lipids, and 19.1% to 22.6% crude fibers, it is not economically used. The majority of seeds are produced as residues and discarded as agricultural waste during fruit processing, generating environmental issues. Oil is abundant in papaya seeds (13.9% to 40.0%), which is rich in monounsaturated fatty acids and beneficial phytochemicals as tocopherol, carotene, and phenolics. This provides information on how to reduce pollution and make waste seeds lucrative. As a result, the CPSO is receiving an increasing amount of attention.

Seed germination behaviour of the narrow endemic Daphne arbuscula (Thymelaeaceae) compared to the more widespread Daphne cneorum

Diminished reproduction success in species with narrow distribution ranges might be one of the factors responsible for their limited dispersal and colonization abilities. We investigated here various aspects of the seed biology of the West Carpathian endemic Daphne arbuscula (Thymelaeaceae) and compared it with its more widespread relative D. cneorum. In both species, we investigated (i) differences in seed viability and germination ability; (ii) differences between the two observed fruit morphotype groups, and (iii) the effect of cold stratification in breaking seed dormancy and enhance germination in stored seeds. To determine seed viability, a tetrazolium test and an imbibed cut test were performed. Several seed germination tests with gibberellic acid and with a sequence of cold and warm stratification, using different temperatures and durations, were carried out. We uncovered that (i) D. arbuscula seeds show significantly lower viability than D. cneorum seeds, but this difference is due to the smaller-fruit morphotype; (ii) seed quality and viability of the big-fruit morphotype are significantly greater than the smaller-fruit morphotype in both species, although the seed viability of the latter is not null and the dormancy level seems to differ between them; (iii) a warm stratification at 15°C for 13 weeks, followed by cold stratification at either 0 or 5°C for 28 weeks, followed by 4 weeks at 15°C, break physiological dormancy and allow the majority of seeds of D. arbuscula (63%) to germinate. We recommend including both fruit morphotypes when collecting seed of Daphne for ex situ conservation and reintroduction initiatives, to maintain the original genetic diversity of the species.

Evaluation of Seed Quality Attributes of Sorghum Germplasm Accessions from Eastern, Coastal and Nyanza Regions, Kenya

Sorghum (Sorghum bicolor L.) is an important cereal crop in Kenya. Despite the crops importance, the yields attained by farmers in Eastern, Coastal and Nyanza regions of Kenya remain low. Access to good quality seeds of sorghum is one of the constraints facing the subsistence farmers. Good quality seed is important for increasing yield to attain food security. The aim of this study was to evaluate quality attributes of the seed used by farmers. A total of 108 germplasm accessions were obtained from 76 farmers. The seeds were tested for time and percentage of germination, seed vigour index, shoot and root dry weight. Data collected was subjected to analysis of variance. Means were separated using Fisher’s Least Significance Difference test at p ≤ 0.05. Seed samples of 26 accessions attained germination percentage below stipulated standards by Seeds and Plant Varieties Act CAP 326. Majority of seeds showed longer mean germination time with only nine accessions germinating in less than ten days. Seed vigour index was relatively high in most of the accessions, while biomass accumulation varied from high to very low among accessions. Though most of the seeds attained a high germination percentage, about 92% of seeds showed longer mean germination time. The environmental conditions in the fields, pre and post harvest handling practices impact on the seed quality hence the wide variability in germination percentage, germination time, seed vigour index and dry matter accumulation. Therefore the need to improve quality of seeds used by subsistence farmers by providing extension services on best pre and post harvest handling practices. Increasing production of sorghum in these regions will contribute significantly towards realizing food security. Further analysis could be carried out on genetic and sanitary quality aspects of the seeds planted by farmers in Eastern, Nyanza and Coastal regions.

Temporal patterns of seed germination in early spring-flowering temperate woodland geophytes are modified by warming

Understorey species in temperate deciduous woodlands such as wild daffodil (Narcissus pseudonarcissus) and common snowdrop (Galanthus nivalis) have complex dormancy: seeds that are shed in late spring require warm summer temperatures for embryo elongation and dormancy alleviation, but then cooler temperatures for germination in autumn. As seasons warm and tree canopies alter, how will different seasonal temperature sequences affect these complex dormancy responses? The effect of different sequences of warmer (+5 °C), current or cooler (-5 °C) seasons (summer to spring) on seed germination patterns over seven successive seasons were investigated, with all sequences combined factorially to determine the consequences of differential seasonal temperature change for the temporal pattern of germination (and so seedling recruitment). Little (<1 %, G. nivalis) or no (N. pseudonarcissus) seed germination occurred during the first summer in any treatment. Germination of N. pseudonarcissus in the first autumn was considerable and greatest at the average (15 °C) temperature, irrespective of the preceding summer temperature; germination was also substantial in winter after a warmer autumn. Germination in G. nivalis was greatest in the warmest first autumn and influenced by preceding summer temperature (average > warmer > cooler); the majority of seeds that germinated over the whole study did so during the two autumns but also in year 2's cooler summer after a warm spring. Warmer autumns and winters delay first autumn germination of N. pseudonarcissus to winter but advance it in G. nivalis; overall, warming will deplete the soil seed bank of these species, making annual seed influx increasingly important for recruitment and persistence. This study provides a comprehensive account of the effects of temperature changes in different seasons on seed germination in these early spring-flowering geophytes and consequently informs how these and other temperate woodland species with complex seed dormancy may respond to future climate change.

Desiccation Tolerance: Avoiding Cellular Damage During Drying and Rehydration.

Desiccation of plants is often lethal but is tolerated by the majority of seeds and by vegetative tissues of only a small number of land plants. Desiccation tolerance is an ancient trait, lost from vegetative tissues following the appearance of tracheids but reappearing in several lineages when selection pressures favored its evolution. Cells of all desiccation-tolerant plants and seeds must possess a core set of mechanisms to protect them from desiccation- and rehydration-induced damage. This review explores how desiccation generates cell damage and how tolerant cells assuage the complex array of mechanical, structural, metabolic, and chemical stresses and survive.Likewise, the stress of rehydration requires appropriate mitigating cellular responses. We also explore what comparative genomics, both structural and responsive, have added to our understanding of cellular protection mechanisms induced by desiccation, and how vegetative desiccation tolerance circumvents destructive, stress-induced cell senescence.

The effects of grasshopper carcasses as dockage in stored wheat

In years of high grasshopper field populations, large numbers may be collected with harvested grain and deposited into storage. Little is known about the impact of grasshopper carcasses on stored-wheat quality; therefore, this study was conducted to determine such effects. Ninety-six glass bottles (237 mL capacity) were filled with 120 g of clean No. 1 wheat conditioned to 14.5% or 15.5% moisture content. Two-striped grasshoppers, Melanoplus bivittatus were collected in the summer of 2004 near Elie, MB, Canada and euthanized. Six grams of whole grasshoppers were mixed into half the bottles of each moisture content. All bottles were sealed and 12 bottles with and without grasshoppers were incubated at 25 °C and 50% relative humidity (r.h.), 25 °C and 75% r.h. 30 °C and 50% r.h. and 30 °C and 75% r.h. for 24 wk. Four bottles with and without insects were assessed every 4 wk for fat acidity value, seed microfloral infection and germination. The experiment was repeated and data pooled for statistical analysis (ANOVA). Significant differences (P < 0.05) arose between grasshopper and control treatments. Mean fat acidity values for wheat reached 32.99 mg KOH/100 g with grasshoppers compared to 25.23 mg KOH/100 g without carcasses. Initial seed germination of 98% rapidly declined to below 20% with grasshoppers between 4 wk and 8 wk; the majority of seeds were dead in the 75% r.h. treatments by 12 wk. Mean infection by the post-harvest fungi, Aspergillus glaucus group with grasshoppers ranged from 80.5 to 92% compared to 25–79.8% in controls. Penicillium spp. infection at 25 °C and 75% r.h. was 16.8% with grasshoppers and 4.2% without. Results from this experiment clearly demonstrate that the presence of grasshopper carcasses in stored wheat has negative consequences on grain quality. The implications of our research are discussed with respect to harvest practices and climate change.

A prospective, single-arm, multicentre clinical evaluation of a new localisation technique using non-radioactive Magseeds for surgery of clinically occult breast lesions

To evaluate the safety, usefulness, and outcome of Magseed localisation for surgery of non-palpable breast lesions in a non-experimental setting. An audit was undertaken of a prospectively maintained database of patients who had undergone breast surgery under Magseed guidance in two high-volume institutions in the UK. Patients were selected for Magseed localisation depending on service convenience. Wire localisations were used in other patients in accordance with previous normal practice. One hundred and thirty-nine Magseed localisaton procedures were performed between September 2017 and March 2019. Data were collected on age, body mass index, size, bra cup size, weight of specimen, surgery, histology, re-excision rate, and time and mode of insertion of seeds. A total of 137 patients had Magseed localisation with a total of 139 seeds. Sixteen patients had a diagnostic procedure and 121 had therapeutic surgery. The distribution of procedures were similar between the two institutes (n=63 and n=74). Mean age was 60 (range 28-81) years. The majority of seeds were placed under ultrasound guidance (n=112) and 25 lesions were targeted under stereo guidance. Mean size of the lesions was 15.2 (range 1-85) mm. The mean weight of the specimen was 75.5 (range 2-1,900) g. The mean body mass index was 30.56 (range 18.1-48.3). All Magseeds and index lesions were retrieved. The re-excision rate for patients who underwent therapeutic surgery was 14.8% (n=18). The Magseed localisation technique of non-palpable breast lesions is a safe, easy procedure, and comes with the advantage of better utilisation of theatre and radiology resources. The re-excision rate in this series is lower than the national average.

African Indigenous Vegetable Seed Systems in Western Kenya

African indigenous vegetable (AIV) production systems are often constrained by the availability of high-quality seed. Concerted efforts to improve the informal seed sector could increase farmers’ access to seed, but these efforts are hampered by a lack of knowledge around the quality of farmer-produced seed and seed growers’ motivations for producing seed. This study collected seed samples and survey data from 127 farmers in western Kenya on their AIV seed production practices, uses of AIV seed, and motivations for growing seed. Germination tests showed that seed quality varied significantly between species. Seed access was still a constraint, even though the majority of seeds used by farmers are self-produced. Income from selling AIV seed differed significantly depending on gender, with men earning more than twice as much as women. This study demonstrates that the constraints farmers face in accessing high-quality AIV seed can vary significantly between species and over short distances. Female seed producers are not necessarily empowered to earn equal income as men, despite AIVs traditionally being considered a women’s crop. This study speaks to the importance of using localized information to develop programs for improving informal seed systems and continuing to employ gender-sensitive and transformative activities.

Measuring short distance dispersal of Alliaria petiolata and determining potential long distance dispersal mechanisms.

IntroductionAlliaria petiolata, an herbaceous plant, has invaded woodlands in North America. Its ecology has been thoroughly studied, but an overlooked aspect of its biology is seed dispersal distances and mechanisms. We measured seed dispersal distances in the field and tested if epizoochory is a potential mechanism for long-distance seed dispersal.MethodsDispersal distances were measured by placing seed traps in a sector design around three seed point sources, which consisted of 15 second-year plants transplanted within a 0.25 m radius circle. Traps were placed at intervals ranging from 0.25–3.25 m from the point source. Traps remained in the field until a majority of seeds were dispersed. Eight probability density functions were fitted to seed trap counts via maximum likelihood. Epizoochory was tested as a potential seed dispersal mechanism for A. petiolata through a combination of field and laboratory experiments. To test if small mammals transport A. petiolata seeds in their fur, experimental blocks were placed around dense A. petiolata patches. Each block contained a mammal inclusion treatment (MIT) and control. The MIT consisted of a wood-frame (31 × 61× 31 cm) covered in wire mesh, except for the two 31 × 31 cm ends, placed over a germination tray filled with potting soil. A pan filled with bait was placed in the center of the tray. The control frame (11 × 31 × 61 cm) was placed over a germination tray and completely covered in wire mesh to exclude animal activity. Treatments were in the field for peak seed dispersal. In March, trays were moved to a greenhouse and A. petiolata seedlings were counted and then compared between treatments. To determine if A. petiolata seeds attach to raccoon (Procyon lotor) and white-tailed deer (Odocoileus virginianus) fur, wet and dry seeds were dropped onto wet and dry fur. Furs were rotated 180 degrees and the seeds that remained attached were counted. To measure seed retention, seeds were dropped on furs and rotated as before, then the furs were agitated for one hour. The seeds retained in the fur were counted.ResultsFor the seed dispersal experiment, the 2Dt function provided the best fit and was the most biologically meaningful. It predicted that seed density rapidly declined with distance from the point source. Mean dispersal distance was 0.52 m and 95% of seeds dispersed within 1.14 m. The epizoochory field experiment showed increased mammal activity and A. petiolata seedlings in germination trays of the MIT compared to control. Laboratory studies showed 3–26% of seeds were attached and retained by raccoon and deer fur. Retention significantly increased if either seed or fur were wet (57–98%).DiscussionWithout animal seed vectors, most seeds fall within a short distance of the seed source; however, long distance dispersal may be accomplished by epizoochory. Our data are consistent with A. petiolata’s widespread distribution and development of dense clusters of the species in invaded areas.

First evidence of epizoochorous seed dispersal by golden snub-nosed monkeys (Rhinopithecus roxellana) in temperate forest

Although many primates are identified as effective endozoochorous seed dispersers in forest ecosystems, epizoochorous seed dispersal by primates has generally been overlooked. In this study, we report epizoochorous seed dispersal in a group of free-ranging golden snub-nosed monkeys (Rhinopithecus roxellana) residing in the temperate forests of central China by identifying seeds carried by 12 well-habituated individuals. The results showed a total of 1920 seeds (five families, seven genera) belonging to eight plant species attached to the monkeys’ fur; the three most abundant species were Geum aleppicum (54% of the total), Torilis japonica (17%), and Agrimonia pilosa (14%). The majority of seeds (95.3%) that attached to the monkeys’ fur had special morphologies such as hairs, hooks, or awns. We also found that the quantity of seeds attached to the fur was not significantly different by age-sex class, even though adult males have very long fur. Our study provides the first empirical evidence of epizoochorous seed dispersal by primates and suggests the role of primates in seed dispersal may be greater than previously assumed.

Cranberry SSR multiplexing panels for DNA horticultural fingerprinting and genetic studies

Cranberry (Vaccinium macrocarpon) is in need of inexpensive high-throughput DNA fingerprinting methods for genetic research and germplasm purity testing for agricultural purposes. Therefore, we designed and validated 16-multiplexing panels containing 61 evenly distributed simple sequence (SSR) markers, with non-overlapping allele ranges, throughout the 12 cranberry linkage groups. Several important cranberry cultivars and selections (n=18) and a diploid accession of V. oxycoccos were genotyped with the multiplexing panels and separated through principal component analysis (PCA) to demonstrate their effectiveness for DNA fingerprinting and genetic diversity analysis. A subset of three multiplexing panels containing 12 SSR markers was used to genotype 174 seedlings from fruits collected in a commercial cranberry bed of the cultivar Stevens, and identification of intra-cultivar heterogeneity was investigated in the bed to validate the use of the markers in such future applications. Furthermore, determining the likelihood that each seedling was self- or cross-pollinated provided the first quantitative evidence (p<0.0001) that the majority of seeds within commercial cranberry beds are self-pollinated. These multiplexing panels represent an important, applicable resource for cranberry researchers and farmers of the North American industry. These markers can be used to assess the genetic homogeneity of grower and licensed propagators’ cranberry beds, to protect the intellectual property rights of plant breeders, and to enable cranberry researchers to monitor the genetic identity of genotypes within their breeding programs and genetic studies.

Long-distance seed dispersal by straw-coloured fruit bats varies by season and landscape

On-going fragmentation of tropical forest ecosystems and associated depletion of seed dispersers threatens the long-term survival of animal-dispersed plants. These threats do not only affect biodiversity and species abundance, but ultimately ecosystem functions and services. Thus, seed dispersers such as the straw-coloured fruit bat, E. helvum, which traverse long distances across fragmented landscapes, are particularly important for maintaining genetic connectivity and colonizing new sites for plant species. Using high-resolution GPS-tracking of movements, field observations and gut retention experiments, we quantify dispersal distances for small- and large-seeded fruits foraged by E. helvum during periods of colony population low (wet season) and high (dry season) in an urban and a rural landscape in the forest zone of Ghana. Gut passage time averaged 116 min (range 4–1143 min), comparable to other fruit bats. Movements were generally longer in the urban than in the rural landscape and also longer in the dry than in the wet season. As the majority of seeds are dispersed only to feeding roosts, median dispersal distances were similar for both large (42–67 m) and small (42–65 m) seeds. However, small seeds were potentially dispersed up to 75.4 km, four times further than the previous maximum distance estimated for a similar-sized frugivore. Maximum seed dispersal distances for small seeds were almost twice as long in the rural (49.7 km) compare to the urban (31.2 km) landscape. Within the urban landscape, estimated maximum dispersal distances for small seeds were three times longer during the dry season (75.4 km) compared to the wet season (22.8 km); in contrast, distances in the rural landscape were three times longer in the wet season (67 km) compared to the dry season (24.4). Dispersal distances for large seeds during the dry season (551 m) in the rural landscape were almost twice that in the wet season (319 m). We found no influence of food phenology on dispersal distances. The maximum likelihood for seed dispersal beyond feeding roosts (mean distance from food tree 263 m) was 4.7%. Small seeds were dispersed over even longer distances, >500 and >1000 m, with a likelihood of 3.0 % and 2.3 % respectively. Our data show that E. helvum retains ingested seeds for very long periods and may traverse large distances, probably making it an important long distance seed disperser in tropical Africa. We suggest E. helvumis important for ecosystem functioning and urge its conservation.

Completing the life history of Castanopsis fargesii: changes in the seed dispersal, seedling and sapling recruitment patterns

The spatial distribution of species in forest ecosystems involves the underlying ecological processes or mechanisms of population and community structure, as well as forest dynamics. Because the relative importance of these factors can shift across life history stages, assessment of local population and community structures in the context of life history stages is essential for understanding forest dynamics. In this study, we investigated the changes in the spatial patterns of seed dispersal as well as seedling and sapling recruitment for Castanopsis fargesii, a dominant tree species in a subtropical evergreen broad-leaved forest in China. We found notably aggregated spatial patterns for C. fargesii seeds during the seed dispersal. A majority of seeds and newly germinated seedlings aggregated under adult tree canopies, suggesting a decreased efficiency in secondary dispersal for C. fargesii within this evergreen broad-leaved forest. During the later stages of life history (i.e., seedling and sapling stages), the spatial distribution of C. fargesii getting segregated. This is caused by a negative density dependence mechanism in seedling recruitment, rather than by spatial dispersion due to secondary dispersal. By incorporating the patterns and processes across the life history stages of dominant species of evergreen broad-leaved forests, we can add specific details in developing methods of stage-based in situ forest management and conservation frameworks.

CHARACTERIZATION OF SEED AND EMBRYO ABORTION DURING FRUIT DEVELOPMENT IN CITRUS CULTIVARS POLLINATED BY 'NISHIUCHI KONATSU' (CITRUS TAMURANA) AND A PRELIMINARY TRIAL OF EMBRYO RESCUE IN ABORTING EMBRYOS

‘Hyuganatsu’ (HY) is a self-incompatible citrus cultivar grown in specific prefectures in Japan. However, its bud mutation, ‘Nishiuchi Konatsu’ (NK), is self-compatible, although the majority of seeds are aborted in mature fruits. In our previous studies, we revealed that NK produces a proportion of unreduced 2n pollen grains, resulting in unusual seed development. In this study, we therefore focused on seed and embryo development after pollination of HY, NK, and ‘Hassaku’ (HS), which is compatible with both HY and NK, with NK pollen. Seeds from HY A— NK and NK A— NK fruits were significantly smaller than those from HS-pollinated fruits (i.e. HY A— HS and NK A— HS) at 10-12 weeks after pollination, suggesting that the seed abortion phenotype was expressed during this time period. Moreover, embryos that formed from NK self-pollination were shown to have aborted at 10 weeks after pollination, whereas control embryos reached the globular or heart-shaped stage. HS A— NK resulted in both normal and aborted seeds present in the fruit. Development of some embryos was found to cease at 12 weeks after pollination. At 14 weeks after pollination, normal and aborted seeds were easily distinguishable. Preliminary attempts of embryo rescue were also conducted in order to recover triploid seedlings. Aborting embryos obtained from HY A— NK and NK A— NK were placed on MT media supplemented with 500 mg/L malt extract, 50 g/L sucrose, and 5 mM GA3. As a result, several triploid plantlets were confirmed by flow cytometry after embryo recovery from both crosses, although the success rate was not high.

Detection of apple latent spherical virus in seeds and seedlings from infected apple trees by reverse transcription quantitative PCR and deep sequencing: evidence for lack of transmission of the virus to most progeny seedlings

We used reverse transcription quantitative PCR (RT-qPCR) to test for apple latent spherical virus (ALSV) in cotyledons of seeds and true leaves of seedlings from apple trees infected with ALSV to accurately determine the status of infection in seedlings from ALSV-infected trees. The amplification curves of ALSV-RNAs from cotyledons were classified into three patterns: fast (F), slow (S), and no amplification (N/A). Viral RNA was detected in high concentrations (F pattern) in cotyledons from approximately 1 % of the seeds, a proportion broadly consistent with previously reported ALSV seed transmission rates (from zero to a few percent). In the majority of seeds (94.4 %); however, minute amounts of RNA related to the virus were detected (S pattern). Minute amounts of viral-related RNA were also detected by siRNA analysis using a next-generation sequencer. After the seeds germinated, however, no viral RNA was detected in the true leaves, so we concluded that the viral RNA in the seeds lacked the capacity to replicate. No ALSV-RNA at all was detected (N/A pattern) in the remaining 4.6 % of seeds. We concluded that almost all apple seedlings from ALSV-infected trees (approx. 99 %) can be considered as virus-free. Therefore, we think that apple seedlings from the generation obtained after the use of ALSV vector technology can be exempted from restrictions on genetically modified plants after they have been confirmed to be virus-free by virus testing.

Taiwanese montaneSambucus chinensisseeds require warm stratification, contrasting with other congeneric temperate members

AbstractMany temperate plant genera, likeSambucus, have species with range disjunctions among North America, Europe and/or Asia. Cold stratification (sometimes in combination with warm stratification) is the primary mechanism to break seed dormancy in these species. For some of these genera showing Northern Hemispheric disjunctions, members also occur in subtropical or tropical regions, mostly confined to higher elevations where climate and vegetation differ from those in northern latitudes. We made two hypotheses concerning germination for the subtropical TaiwaneseSambucus chinensis: (1) seeds from populations exposed to warm temperatures would require warm stratification, and (2) seeds from populations exposed to cold temperatures need cold stratification. We investigated the germination (including embryo growth) of non-stratified seeds over a range of temperatures and tested the effects of cold stratification and of gibberellins GA3and GA4on germination. The amount and timing of germination among populations varied substantially in response to temperature treatments. Seeds from all populations of this species required warm temperatures for dormancy break and germination, regardless of environmental conditions. As such, the majority of seeds had non-deep simple morphophysiological dormancy, which, until now, has not been reported in any members ofSambucus. The seed characteristics of the subtropicalS. chinensisare different from those of temperate members of the genus in which cold stratification is the predominate treatment to overcome dormancy.

Phosphatidylglycerol biosynthesis is required for the development of embryos and normal membrane structures of chloroplasts and mitochondria in Arabidopsis

Phosphatidylglycerophosphate (PGP) synthase, encoded by PGP1 and PGP2 in Arabidopsis, catalyzes a committed step in the biosynthesis of phosphatidylglycerol (PG). In this study, we isolated a pgp1pgp2 double mutant of Arabidopsis to study the function of PG. In this mutant, embryo development was delayed and the majority of seeds did not germinate. Thylakoid membranes did not develop in plastids, mitochondrial membrane structures were abnormal in the mutant embryos, and radiolabeling of phospholipids showed that radioactivity was not significantly incorporated into PG. These results demonstrated that PG biosynthesis is essential for the development of embryos and normal membrane structures of chloroplasts and mitochondria.

The Influence of Stratification on Seedling Emergence and Growth of Narrow-Leaved Lavender and its Cultivars

The research was conducted in the years 2009-2011. The research material included narrow-leaved lavender Lavandula angustiolia and its three cultivars: ‘Hidcote Blue Strain’, ‘Hidcote Superior’ and ‘Rosea’. Five variants of seed stratification were used: 1. control (seeds which did not undergo stratification); 2. seeds stratified for 4 weeks; 3. seeds stratified for 6 weeks; 4 seeds stratified for 8 weeks; 5. seeds stratified for 10 weeks. The following measurements and observations were performed during the experiment: earliness of seedling emergence depending on the stratification time, biometric characteristics of the seedling height, number of leaves, number of stems and the average root length. Seeds of narrow-leaved lavender and its cultivars, emerge more rapidly and effectively when subjected to a stratification treatment at 4C, as compared to unstratified seeds. Regardless of the taxon, a 4-week stratification period is too short to overcome dormancy in the majority of seeds and to improve their emergence.

Post-Dispersal Seed Predation Rates in a Puerto Rican Pasture

The dispersal and survival of seeds are two of the main factors limiting forest regeneration in tropical pastures of anthropogenic origin. Here we report on the quantity, diversity, and predation rates of seeds dispersed by birds in a pasture in northern Puerto Rico. From May through August of 2009, we sampled the bird-generated seed rain under isolated trees and shrubs in the pasture using seed traps. The pasture was adjacent to a fragment of secondary forest that served as the source of seeds. The seed traps collected 3,844 seeds (including pieces) belonging to 28 plant species, with five species accounting for 78.6 percent of the sample. Predation of seeds —calculated as the ratio of seed fragments to intact seeds- was detected in eleven plant species, with some species suffering significantly higher predation rates than others. For example, seeds of Cissampelos pereira and Casearia Sylvestris experienced low predation (<0.3), while the majority of seeds from Cordia polycephala and Erythroxylon brevipes where predated (>0.6). Predation rates where in an inverse relationship with the density of seed deposition and with seed size across species. The physical evidence on the seed traps (i.e., seed coat fragments, fecal samples) points to rodents as the main agents of seed predation. We conclude that post-dispersal seed predation by rodents can serve as an important ecological filter that could shape the early community dynamics of forest recovery in abandoned Puerto Rican pastures.