Infestation Of Seeds Research Articles

Genome-Wide Association Studies on Resistance to Pea Weevil: Identification of Novel Sources of Resistance and Associated Markers.

Little resistance to the pea weevil insect pest (Bruchus pisorum) is available in pea (Pisum sativum) cultivars, highlighting the need to search for sources of resistance in Pisum germplasm and to decipher the genetic basis of resistance. To address this need, we screened the response to pea weevil in a Pisum germplasm collection (324 accession, previously genotyped) under field conditions over four environments. Significant variation for weevil seed infestation (SI) was identified, with resistance being frequent in P. fulvum, followed by P. sativum ssp. elatius, P. abyssinicum, and P. sativum ssp. humile. SI tended to be higher in accessions with lighter seed color. SI was also affected by environmental factors, being favored by high humidity during flowering and hampered by warm winter temperatures and high evapotranspiration during and after flowering. Merging the phenotypic and genotypic data allowed genome-wide association studies (GWAS) yielding 73 markers significantly associated with SI. Through the GWAS models, 23 candidate genes were found associated with weevil resistance, highlighting the interest of five genes located on chromosome 6. These included gene 127136761 encoding squalene epoxidase; gene 127091639 encoding a transcription factor MYB SRM1; gene 127097033 encoding a 60S ribosomal protein L14; gene 127092211, encoding a BolA-like family protein, which, interestingly, was located within QTL BpLD.I, earlier described as conferring resistance to weevil in pea; and gene 127096593 encoding a methyltransferase. These associated genes offer valuable potential for developing pea varieties resistant to Bruchus spp. and efficient utilization of genomic resources through marker-assisted selection (MAS).

Распространенность грибной инфекции на семенах озимой пшеницы в условиях Среднего Поволжья

Abstract. The aim of this work is to investigate the composition of pathogenic mycoflora associated with the seeds of winter soft wheat in the Samara region under laboratory conditions. Research methodology and methods. The seeds of 10 varieties and lines of winter soft wheat of competitive variety trials, grown in the central soil and climatic zone of Samara Region, were examined in the Laboratory of Innovative Technologies in Breeding, Seed Breeding and Seed Science and Laboratory of Breeding and Seed Production of Winter Wheat, Volga Branch of Samara Research Center of RAS. Infestation of seeds by pathogenic fungi was determined by roll method using the method according to GOST 12044-93 and subsequent microscopy. Results. Correct diagnosis and knowledge of the causes of the disease, peculiarities of pathogen development are the basis for successful protective and preventive measures. As a result of the study we conducted in 2019–2020 revealed a high degree of infection of seeds with fungi on a natural infectious background. Dominant on the seeds, studied samples are fungi: Alternaria sp. (with a frequency of occurrence from 0.5 to 35.0% and relative prevalence from 0.7 % to 56.5 %, Fusarium sp. (with a frequency of occurrence from 2 to 45.5 %, and relative prevalence from 4.1 % to 67.4 % respectively) and the group of fungi causing seed mold (Cladosporium sp., Mucor sp., Penicillium sp. etc.). Differences in the amount of precipitation and relative humidity may be a probable reason for differences in the frequency of a particular fungus and species detected on seeds of winter soft wheat in different years. Scientific novelty. The phytopathological estimation of seeds as applied to the conditions of Samara region has been carried out and pathogenic complex of fungi associated with the seeds of winter wheat has been established.

Effect of temperature and humidity on the composition of wheat phytopathogens during grain storage

High humidity, low temperature and pathogens can significantly reduce the quality of cereal crop seeds during storage. The effect of temperature and humidity on the infestation of wheat seeds by phytopathogens during storage was studied. A decrease in infestation of seed material with all types of fungi in a warm warehouse at 14% humidity was found. When humidity increased to 20%, there was an increase in total infestation. The dependence of seedling infestation on seed storage conditions is shown. Warm storage mode of seed storage at normal humidity (14%) revealed the highest index of disease development – 2.9 times higher compared to cold storage mode, but with similar humidity. Similar data were obtained when determining the prevalence of root rot. The highest incidence of the disease was noted in plants sown with seeds stored at 20% humidity in a warm warehouse, which is 1.5 times higher compared to the seeds sown at standard humidity (14%). When seeds were stored cold, the prevalence of root rot at high humidity (20%) was 63% – 7% higher than at standard humidity (14%). At higher humidity (20%) in both warm and cold storage, the prevalence of root rot is higher than at standard humidity. It was noted that under warm seed storage conditions at 20% moisture content, organotropic specialization is characterized by allocation of pathogens in all plant organs.

Reproductive biology of two threatened and highly traded medicinal plants, Salacia gambleana and Salacia oblonga, from the Western Ghats of India

Salacia is a genus of flowering plants in the family Celastraceae, consisting of woody climbers distributed in tropical America, Africa, and Asia. In India it is represented by 21 species, of which 15 occur in peninsular India. Most species of the genus have been used in traditional medicine, mainly the Ayurvedic system. Apart from overexploitation for medicinal purposes, the low fruit set and infestation of seeds have affected natural regeneration, and led to the rarity of Salacia species in their natural habitats. The reproductive biology of Salacia oblonga and S. gambleana was studied for the first time to understand the reproductive constraints of these threatened and medicinally important species. The flowering phenology, pollen viability, germination, stigma receptivity, and insect-pest interaction were analyzed. The obligatory entomophily coupled with insufficient pollinators and seed pest infestation were found to be the main reproductive constraints responsible for the low fruit set and poor natural regeneration of these species.

Silver Nanoparticles (AgNPs) in Urea Solution in Laboratory Tests and Field Experiments with Crops and Vegetables.

Nanotechnology and nanomaterials, including silver nanoparticles (AgNPs), are increasingly important in modern science, economics, and agriculture. Their biological activity involves influencing plant health, physiological processes, growth, and yields, although they can also be toxic in the environment. A new fertiliser was made based on a urea solution with a relatively low content of AgNPs obtained by the reduction of silver nitrate V. Laboratory tests were used to assess the effect of a fertiliser solution containing 10 ppm AgNPs on the germination of agricultural plant seeds (barley, peas, oilseed rape) and vegetables (radish, cucumber, lettuce) and its foliar application on chlorophyll content, stomatal conductance, and seedling biomass. Field experiments were conducted to assess the effect that a foliar application of 15 ppm AgNPs in working liquid had on physiological plant parameters and yields of rape and cucumber. The AgNPs in the tested fertiliser reduced infestation of the germinating seeds by pathogens and positively affected the physiological processes, productivity, and yields of plants. Plant response depended on plant species and habitat conditions. Reduced pathogen infestation of seeds, higher germination energy, increased chlorophyll content and stomatal conductance, and higher seedling masses all occurred under the influence of AgNPs, mainly in oilseed rape and cucumber, and especially under thermal stress. The beneficial effect of AgNPs on the yield of these plants occurred in years of unfavourable weather conditions. The positive agricultural test results, especially under stress conditions, indicate that fertiliser produced with AgNPs as an ingredient may reduce the use of pesticides and highly concentrated mineral fertilisers. Such a fertiliser is fully in line with the idea of sustainable agriculture. However, research on the effects that AgNPs and fertiliser have on the environment and humans should continue.

Direct Aulacaspis yasumatsui Infestation of Pre-Harvest Cycas Seeds Reduces Germination and Performance of Seedlings

The invasion of numerous countries by the armored scale Aulacaspis yasumatsui Takagi has caused widespread mortality of host Cycas species. Few studies have looked at reproductive biology responses of host plants to the herbivore. This study was conducted to determine the influence of direct Cycas seed integument infestation of A. yasumatsui on germination and seedling performance. An observational study in a Tinian ex situ Cycas micronesica K.D. Hill garden revealed that germination percentage was reduced two-thirds by heavy pre-harvest integument infestation, and more than half of the seedlings from infested seeds died in the nursery. Multi-year mortality of plants was six times greater for plants from habitats with infested seeds than for plants from minimally infested habitats. Stem height of nine-year-old plants from habitats with infested seeds was 64% of that of plants from habitats with un-infested seeds. A controlled study in a Philippine ex situ C. micronesica and Cycas edentata de Laub. garden corroborated these findings. Germination of infested seeds was about 30% of that for un-infested seeds. Seedling mortality in the nursery following experimental infestation of seed integuments with A. yasumatsui during seed maturation was about 50%, but was minimal for seedlings from un-infested seeds. These results indicate that limitations in regeneration and recruitment of host Cycas plants following A. yasumatsui herbivory may be partly due to the influence of direct seed infestations. Conservationists may use this new knowledge to improve in situ seed selection criteria and use prophylactic treatments to ensure lack of integument infestations for ex situ gardens.

Insect pest susceptibility of grains and seeds recently introduced to the Italian market: An experimental evaluation

To assess the susceptibility of pseudocereals (amaranth and quinoa), minor cereals (teff and millet), and oilseeds (chia and hemp), now commercially available on the European market, to attacks by polyphagous and cosmopolitan insect pests, laboratory tests were set up. Tests involving controlled infestation of seeds, using laboratory-bred insects (Tenebrio molitor, Tribolium confusum, Oryzaephilus surinamensis, Cryptolestes pusillus and Plodia interpunctella), were carried out in a climatic chamber at 23 ± 2 °C and 65 ± 5% R.H.. Development time, the number of adults and the weight of these adults were evaluated. The results show that each considered foodstuff has a different susceptibility to infestation and differences both in the number of adults emerged and in their weight compared to control. Millet was the only product that allowed larval development up to the adult stage for all the species examined. No species developed on amaranth. T. confusum and O. surinamensis reached the adult stage on the greatest number of products, 5 and 4 respectively; C. pusillus and T. molitor completed their life cycles on only two commodities: millet and teff, while P. interpunctella only on millet and hemp seeds. Considering the impact of the different pests on the studied grains, T. confusum was the only species able to develop on all the grains, but the number of emerged adults was lower than on the standard diet. These results show that, even if these commodities are new in the European market, they are susceptible to the infestation of common stored product pests that could led to a removal from the market of a contaminated stock, so a continuous monitoring is needed.

Assessing Megastigmus specularis (Hymenoptera: Megastigmidae) infestations in a Fraser fir (Abies fraseri (Pursh) Poir.) clonal seed orchard of the southern Appalachians

ABSTRACT The Christmas tree industry is mainly supplied with seeds from natural stands and genetically improved germplasm from clonal seed orchards (CSOs). Chalcid wasps (Megastigmus spp.) have a negative effect on the value of seedlots by reducing the quantity of viable seeds and represent a risk for national and international seed trade. Seed radiographies, field observations and seed-dissections from 25 Fraser fir (Abies fraseri (Pursh) Poir.) clones were used to determine chalcid infestation in a CSO of the southern Appalachians. We provided direct evidence that Mesopolobus cf. pinus is an ectoparasitoid of M. specularis, proposed a model that linked different aspects of the biology of these species and discussed host–insect phenological relationships. Infestation of seeds in some clones across surveys, suggested a potential genetic component to chalcid wasp's prevalence. Cold and dark rearing regimens were used to identify changes in adult insect emergence after variation of overwinter conditions. Both the frequency and the time of emerging M. specularis adults from seeds were affected by the duration of the treatments but not statistical differences were found for Mesopolobus cf. pinus. We present evidence for the efficiency of a gravity-seed cleaning method eliminating upwards of 95% of chalcid-infested seeds.

Mycobiota of asparagus vigna seeds (Vigna unguiculata (L.) Walp.) on the south of Western Siberia

Composition of seed mycobiota of 87 accessions of asparagus vigna (Vigna unguiculata (L.) Walp.) from the N. I. Vavilov All-Russian Institute of Plant Genetic Resources (VIR) and the Bioresource Scientific Collection of the Central Siberian Botanical Garden (CSBG SB RAS) UNU No.USU 440534 have been investigated on 2018-2019. Seeds of accessions were grown on the south of Western Siberia (54 ° N lat. 83 ° E) in the unheated plastic film greenhouse and examined for fungal microbiota in the Central Siberian Botanical Garden and Novosibirsk State Agrarian University (Novosibirsk). The seed infestation of micromycetes was determined according to GOST 12044-93 (similar to common beans) using the methods of mycological analysis and the Petri dish moist chambers, also on Chapek and KDA media. The following pathogens were assigned to the permanent inhabitants of mycocenosis of asparagus vigna seeds: Fusarium spp., Mucor mucedo, Penicillium spp., Rhizopus spp., Aspergillus niger, to the occasional – Alternaria spp. Botritis sinerea and Sclerotinia sclerotiorum occur moderately and intermittently in the samples of vigna seeds.The highest frequency of occurrence and infestation of asparagus vigna seeds were found for Aspergillus niger (min-max: 30-100% and 0-100%, respectively), the minimum for Alternaria spp. (0-10%).

Management Control Points Related to the Lag Phase of Fungal Growth in a Stored Rapeseed Ecosystem

AbstractThe quality of rapeseed oil largely depends on the quality of postharvest preservation of raw seeds. Fungal infestation at early stages of the storage of rapeseeds is a major cause of their spoilage. The knowledge of relations between the storage conditions, fungal contamination, and technological quality of rapeseeds is essential to specify key control points that can be used to improve postharvest management systems and maintain rapeseed quality. The aim of this study was to define decisive control points on the basis of the kinetics of early mold growth in ecosystems of rapeseeds in a hazardous initial microbiological state, stored under various water activity and temperature conditions (a w =0.78–0.96 and t =12–30 °C). A correlation between the acid value (AV), germination, and fungal infestation of seeds was found in ecosystems with significant mold activity. The analysis of the mold growth kinetics with regard to AV, seed germination, and visible mold time showed that the detection of early (invisible) fungal growth could be a good basis for determining the time during which rapeseeds should be protected from deterioration. The research results showed how to use the length of the lag phase to identify decisive control points, which are necessary to improve the existing control systems of rapeseed preservation and storage.

Infection Courts in Watermelon Plants Leading to Seed Infestation by Fusarium oxysporum f. sp. niveum.

Fusarium wilt incited by Fusarium oxysporum f. sp. niveum is a seed-transmitted disease that causes significant yield loss in watermelon production. The pathogen may infect watermelon seeds latently, which can be an important inoculum source and contribute to severe disease outbreak. However, information regarding infection courts of F. oxysporum f. sp. niveum leading to infestation of watermelon seeds is limited. To determine how seeds in watermelon fruit can be infested by F. oxysporum f. sp. niveum during the watermelon growing season, greenhouse and field experiments were conducted in 2014 and 2015 where watermelon flowers and immature fruit were inoculated with F. oxysporum f. sp. niveum. Seeds were extracted from mature watermelon fruit, and infestation of watermelon seeds was determined by isolation of F. oxysporum f. sp. niveum and further confirmed by real-time polymerase chain reaction (PCR) analysis. Inoculation of the pericarp of immature fruit resulted in 17.8 to 54.4% of infested seeds under field conditions and 0.6 to 12.8% of infested seeds under greenhouse conditions when seeds were not surface disinfested prior to isolation. Seed infestation was also detected in 0 to 4.5% of the seeds when seeds were surface disinfested prior to isolation. Inoculation of pistil resulted in 0 to 7.2% and 0 to 18.3% of infested seeds under greenhouse and field conditions when seeds were surface disinfested or not disinfested before isolation, respectively. Inoculation of peduncle resulted in 0.6 to 6.1% and 0 to 10.0% of infested seeds in the greenhouse and field experiments when seeds were surface disinfested or not disinfested before isolation, respectively. Seed infestation was also detected in all the experiments using real-time PCR assay when pericarp or pistil was inoculated, and in three of four experiments when peduncle was inoculated, regardless of whether seeds were surface disinfested or not disinfested. Pericarp and peduncle of immature watermelon fruit and pistil of watermelon flowers could be potential infection courts for F. oxysporum f. sp. niveum leading to infestation of seeds in asymptomatic watermelon fruit.

Влияние предпосевной обработки семян КВЧ на пораженность растений болезнями и урожайность озимой пшеницы

Under the sharp increase of energy costs, man-made pollution of agro-ecosystems we need find environmentally safe and cost-effective material and energy resources. As an alternative, new nanotechnology SHF (superhigh frequency) and EHF (extremely-hifh frequencies) of preplant seed treatment are introduced, as an alternative to chemical methods. Among the promising agricultural practices, that have a stimulating effect on plant growth and development, should include the use of electric and magnetic fields, which are used as for pre-sowing preparation of seeds and during the growing season by increasing the resistance of plants to stress factors and an increase in the utilization rate of nutrient substances from soil. The research has shown, that under the influence of the electromagnetic field there is a mobilization of power and release of the energy reserves of an organism, the physiological and biochemical processes in the early stages of seeds germination are activated, there is an increase of intro-changably processes and a steady increase of germinative energy, capacity, initial growth froce, spring and summer survival rate, which favorably affect the entire subsequent period of plant development. The aim of our research is the introduction of short-wave technology in agriculture in wheat cultivation. The results of our studies showed, that in the Kama region of the Republic of Tatarstan the presowing seed treatment with “EHF - 15 meters + Vialt - 2 kilogram per ton + Tsirkon10 millilitre per ton”, reduced the infestation of seeds compared with seed treatment option without Bipolaris sorokiniana 11.9 times, Fusarium spp. 12.8 times, Alternaria spp. - 7.5 times and the musty seeds in 5.2 times. In this option, we noted the minimal plant damage by phytopathogens, compared to the control one, the spread of root rots in the phase of wax ripeness decreased to 13%, leafy mycoses - to 9%. The use of electromagnetic influence (EHF) for 15 minutes + protectant + growth stimulator increases the winter wheat productivity to 0.46 and 0.48 tons per hectare. Application of calculated doses of NPK of 4.0 tons per hectare increases crop yield to 1.31-1.37 tons per hectare.

Adaptive and Selective Seed Abortion Reveals Complex Conditional Decision Making in Plants

Behavior is traditionally attributed to animals only. Recently, evidence for plant behavior is accumulating, mostly from plant physiological studies. Here, we provide ecological evidence for complex plant behavior in the form of seed abortion decisions conditional on internal and external cues. We analyzed seed abortion patterns of barberry plants exposed to seed parasitism and different environmental conditions. Without abortion, parasite infestation of seeds can lead to loss of all seeds in a fruit. We statistically tested a series of null models with Monte Carlo simulations to establish selectivity and adaptiveness of the observed seed abortion patterns. Seed abortion was more frequent in parasitized fruits and fruits from dry habitats. Surprisingly, seed abortion occurred with significantly greater probability if there was a second intact seed in the fruit. This strategy provides a fitness benefit if abortion can prevent a sibling seed from coinfestation and if nonabortion of an infested but surviving single seed saves resources invested in the fruit coat. Ecological evidence for complex decision making in plants thus includes a structural memory (the second seed), simple reasoning (integration of inner and outer conditions), conditional behavior (abortion), and anticipation of future risks (seed predation).

Factors influencing the fruit crops and seed fates ofPistacia chinensis: the results of structural equation modeling

Seed production and quality are important factors influencing population regeneration in many seed plants. We used structural equation modeling to investigate how plant and fruit traits interact with each other to influence the fruit crops and seed fates of Pistacia chinensis. From May to September 2009, we sampled 45 fruiting female trees and measured plant traits (height, DBH and crown area), fruit traits (infructescence size, fruit size) and the fruit crop of each sampled tree in Jiyuan City of Henan Province, Central China. The fruit crops of P. chinensis were positively correlated with tree height, crown area and infructescence size but not significantly correlated with DBH or fruit size. The fruit crop of an individual tree had no negative direct effect on the infestation of seeds by wasps (Eurytoma plotnikovi). Such a direct effect would be predicted by the predator satiation hypothesis. Tree height and fruit size had a positive direct effect on the seed predation rate, but a significant negative correlation was found between the seed predation rate and the rate of seedlessness. Our results indicate that seedless fruits may serve as a defensive mechanism against insect seed predators. In addition, both seedless and insect-infested fruits had a negative direct effect on seed survival, and DBH, infructescence size and fruit crop had a positive indirect effect on seed survival. However, tree height and fruit size had negative indirect effects on seed survival. In conclusion, we have shown 第 2期 郭洪岭等: 应用结构方程模型解析影响黄连木果实产量和种子命运的因素 175 that both plant and fruit traits can strongly influence fruit crops and insect seed predation and subsequently determine the seed quality and population regeneration of P. chinensis.

Effects of fungicide, seeding date and seedling age on clubroot severity, seedling emergence and yield of canola

Hwang, S. F., Cao, T., Xiao, Q., Ahmed, H. U., Manolii, V. P., Turnbull, G. D., Gossen, B. D., Peng, G. and Strelkov, S. E. 2012. Effects of fungicide, seeding date and seedling age on clubroot severity, seedling emergence and yield of canola. Can. J. Plant Sci. 92: 1175–1186. The infestation of seeds by Plasmodiophora brassicae can result in the transmission of clubroot disease in canola. Five fungicides, including Dynasty 100 FS (azoxystrobin), Helix Xtra (thiamethoxam+difenoconazole+metataxyl+fludioxonil), NebijinTM5SC (flusulfamide), Prosper FX (clothianidin+carbathiin+trifloxystrobin+metalaxyl), and Vitavax RS (carbathiin+thiram), were evaluated under greenhouse conditions using artificially infested canola seeds for their efficacy in eliminating seed-borne inoculum. All of the fungicides significantly reduced clubroot relative to the non-treated control, but NebijinTM5SC and Dynasty 100 FS were the most effective. However, in field trials with Cruiser 5 FS (thiamethoxam), Helix Xtra, Dynasty, Prosper and Sedaxane (pyrazole anilide) applied alone or as a mixture, none of the treatments reduced clubroot severity or improved seedling emergence or yield compared with the insecticidal control (Cruiser 5 FS) in the susceptible cultivar. Clubroot severity was lower in early-seeded canola compared with the late-seeded crops in 2 site-years. The younger seedlings had greater disease severity and reduced plant height and yield than did older seedlings in both resistant and susceptible canola cultivars. We conclude that a combination of approaches including seed treatments and manipulation of seeding dates in conjunction with deployment of resistant cultivars is necessary for the sustainable management of clubroot in canola.

Treatment of lentil (Lens culinaris. L) seeds with various concentrations of salts to check their efficiency against seed-borne mycoflora during storage

Seed sample of lentil collected from the Swabi district were treated with NaCl and KCl at 0.01, 0.1 and 1.0% (w/w). Seed-borne mycoflora was observed at 0, 20, 40, 60 and 80 day intervals. Seed treatment with both the salts was found to be effective against storage fungi; however, KCl was more efficient against storage mycoflora such as Aspergillus species when compared with NaCl. With the passage of time, the incidence of deep-seated fungi was observed in salt-treated seed samples while untreated seed sample showed heavy infestation by the species of Aspergillus. Seed viability also remained unaffected in storage, except in seeds heavily infested with seed-borne mycoflora. Aspergillus spp. were the main cause of seed rot. Surface sterilisation of seeds with 1% Na(OCl)2 reduced the fungal infestation of seeds. Among various concentrations of salts, 0.1% (w/w) of both salts were better in controlling seed-borne mycoflora.

Direct evidence of surface infestation of seeds and tubers by Plasmodiophora brassicae and quantification of spore loads

Using quantitative PCR, DNA of Plasmodiophora brassicae, the causal agent of clubroot, was detected and quantified on canola, pea and wheat seeds, as well as on potato tubers, all harvested from clubroot‐infested fields in Alberta, Canada. Quantifiable levels of infestation were found on seven of the 46 samples analysed, and ranged from <1·0 × 103 to 3·4 × 104 resting spores per 10 g seeds; the vast majority (80–100%) of resting spores on these samples were viable, as determined by Evan’s blue vital staining. However, the levels of infestation found were generally lower than that required to cause consistent clubroot symptoms in greenhouse plant bioassays. While the occurrence of P. brassicae resting spores on seeds and tubers harvested from clubroot‐infested fields suggests that seedborne dissemination of this pathogen is possible, practices such as commercial seed cleaning may be sufficient to effectively mitigate this risk.

Seed-hoarding of Edward’s long-tailed rats Leopoldamys edwardsi in response to weevil infestation in cork oak Quercus variabilis

Abstract Seed hoarders show different hoarding and eating responses towards insect-infested seeds that can affect the fitness of both the seeds and insects. It remains unclear how seed hoarders adopt different strategies in eating and hoarding infested seeds with and without larvae concealed inside. Here we investigated hoarding and eating responses of Edward’s long-tailed rats Leopoldamys edwardsi (scatter hoarders) to weevil infestation of cork oak Quercus variabilis seeds within outdoor enclosures. We provided sound seeds, larvae-emerged seeds, (infested seeds where larvae have emerged) and larvae-concealed seeds (infested seeds with larvae concealed inside) to subjects independently (each seed type presented separately) and in pairwise combinations (sound and larvae-emerged seeds; sound and larvae-concealed seeds). We found that L. edwardsi removed, scatter hoarded and ate fewer larvae-emerged seeds than sound seeds. No difference was found between sound seeds and larvae-concealed seeds. These results suggest that sound and larvae-concealed seeds are more favored by L. edwardsi than larvae-emerged seeds. We posit that not only plants but also insects may benefit from the behavioral responses of hoarders to seed infestation under natural conditions.

Seed predation and defleshing in the agouti-dispersed palmAstrocaryum standleyanum

Abstract:The agouti (Dasyprocta punctata) meticulously defleshesAstrocaryum standleyanumpalm seeds before scatter hoarding. On Barro Colorado Island, Panama, we experimentally tested three hypotheses on how this behaviour could reduce seed predation to the mutual benefit of the tree and the rodent. The first and established hypothesis – that defleshing reduces seed predation by bruchid beetles by intercepting larvae – was rejected. Experiments in which manually defleshed seeds or entire fruits were incubated at different times showed that defleshing reduced bruchid infestation before fruit fall but not after fruit fall. The second hypothesis – that defleshing reduces cache pilferage by making seeds less conspicuous – was supported. An experiment in which intact fruits and manually defleshed seeds were placed in mimicked agouti caches and followed showed that seeds with flesh were pilfered at higher rates than defleshed seeds. The third hypothesis – that defleshing reduces post-dispersal infestation of cached seeds – was rejected. An experiment in which intact fruits and manually defleshed seeds were placed in mammal exclosures and later collected to assess infestation showed that burial reduced seed infestation but defleshing did not. Thus, seed defleshing reduced palm seed predation, but in a different way than previously believed. We also found that (1) bruchid beetles can be pre-dispersal rather than post-dispersal seed predators, (2) seed infestation by scolytid beetles may control bruchid larvae, and (3) scolytids rather than bruchids are the main invertebrate seed predators of this palm.

Vitality and Healthiness of Barley (Hordeum Vulgare L.) Seeds Treated with Plant Extracts

The aim of presented experiments was to determine the usefulness of plant extracts for dressing of cereal seeds. Water ex- tracts (macerations, infusions) prepared from different morphological parts of 39 plant species were used as dressing preparations. Non-disinfected seeds of two cultivars of barley (Hordeum vulgare L.): Rudzik (brewing barley) and Stratus (common barley) were used for the purpose of dressing. The experiment was conducted as a filter paper test (PN-94 R-65950) while determining the germina- tion viability (1st date) and the germination capacity (2nd date) as well as the healthiness of the seeds. A significant differentiation of the effect of the extracts on vitality and healthiness of seeds was demonstrated depending on the origin of the extract (plant species), the way it was prepared and an interaction between these factors. The germination viability of seeds of brewing barley was influenced mostly by infusions from fruits of Coriandrum sativum, from seeds of Linum usitatissimum, from bark of Quercus robur, from roots of Levisticum officinale, from roots of Arctium lappa and from flowers of Verbascum thapsiforme. The most favourable activity on germination capacity was revealed using the infusions from seeds of L. usita- tissimum, from roots of A. lappa, from fruits of C. sativum and macerations from roots of A. lappa, from fruits of C. sativum and from bark of Q. robur. The infestation of seeds by microflora was reduced by macerations from leaves of Betula verrucosa, from seeds of L. usitatissimum, from fruits of Juniperus communis, and infusions from flowers of Crataegus oxyacantha, from seeds of L. usitatissimum, from leaves of B. verrucosa. The most favourable impact on viability of the seeds of common barley was revealed for infusions from roots of L. officinale, from stig- mas of Zea mays, from flowers of C. oxyacantha and macerations from flowers of Lavandula vera, from leaves of Mentha piperita and from roots of L. officinale. A positive effect on the germination capacity was exerted by infusions from the stigmas of Z. mays, from flowers of C. oxyacantha, from rhizomes of Acorus calamus, from bark of Frangula alnus, and macerations from bark of F. alnus, from leaves of M. piperita, from flowers of C. oxyacantha and from herb of Marrubium vulgare. The contamination of the seeds by microflora was reduced most effectively with infusions from young sprouts of Pinus sylvestris, from roots of Inula helenium, from leaves of Juglans regia, from herb of M. vulgare, from stigmas of Z. mays and macerations from rhizomes of A. calamus, from herb of M. vulgare, from leaves of J. regia, from seeds of L. usitatissimum and from flowers of L. vera.