•Maize seeds vectored endophytic bacteria which are crucial for seedling development and protection.•Removal of bacteria from seeds compromised the seedling development and re-inoculation of ...bacterial isolates (Lysinibacillus sp. and Paenibacillus dendritiformis) restored the seedling growth.•Fifteen bacterial isolates inhibited the growth of tested fungal pathogens in dual plate culture assay.•Seeds inoculated with Bacillus velezensis protected seedlings from Fusarium infection.
Bacteria from different crops and plant varieties have been shown to possess enormous growth promotional attributes. The study aimed to investigate the role of the endophytic microbiome of seeds of corn in improving the growth of seedlings of two different varieties of maize crops (K-25 and baby corn). Furthermore, the study also assessed the role of these bacteria in the protection of seedlings from fungal pathogens. Total twenty-three endophytic bacterial strains were isolated from maize seeds and identified using 16S rDNA sequencing. Most of the isolates had the ability to synthesize auxin (70 %) and solubilize phosphate (74 %), while all the isolates showed nitrogen fixation ability. Some isolates also showed antagonistic activity against phytopathogenic fungi including Rhizoctonia solani and Fusarium sp. suggesting their biocontrol potential. The presence of different lipopeptide genes including bacillomycin D, fengycin, iturin A and surfactin was confirmed in some of the isolates. We observed that treating seeds with an antibiotic compromised the seedlings’ growth; however, re-inoculation with endophytic isolates (ZM1/Lysinibacillus sp. and ZM2/Paenibacillus dendritiformis) restored the growth of the seedlings in terms of improved root and shoot development in comparison to non-inoculated controls. The colonization of inoculated bacteria on the root surface was visualized using fluorescent microscopy. Seedling protection assay showed that treated seeds (with ZMW8/ Bacillus velezensis) were protected from fungal infestation (Fusarium verticillioides) even after 12 days of inoculation in comparison to the uninoculated control. The study concludes that indigenous seed-associated bacteria of maize play a major role during seed germination, seedling formation and protect them from phytopathogens.
•Bacterial seed endophytes of sorghum inhibited the growth of fungal pathogens.•The presence of surfactin (Sfp) gene was confirmed in Bacillus pumilus.•B. pumilus and its lipopeptide extract caused ...structural deformations in R. solani.•B. pumilus significantly protected the sorghum seedlings from R. solani infection.•B. pumilus up-regulated the expression of defense genes in sorghum seedlings.
The goal of this study was to evaluate the role of seed endophytic bacteria (SEB) in fungal disease protection in sorghum seedlings. Total six SEB, including two Bacillus spp. (SM1 and SM6), and four Paenibacillus spp. (SM2, SM3, SM4, and SM5) were isolated from sorghum seeds. All isolates produced auxin while only SM3 isolate showed phosphate solubilization activity. All SEB inhibited the growth of tested fungal pathogens. Bacillus pumilus (SM1) and Bacillus subtilis (SM6) showed positive drop collapse assay, and presence of surfactin gene was also screened in their genomes. Further, lipopeptides extracted from SM1 and SM6 strongly inhibited Rhizoctonia solani growth in disc diffusion assay. Live-dead staining and fluorescence microscopy revealed the structural deformations and cell death in R. solani by lipopeptides. In microcosm assay, seeds inoculated with B. pumilus significantly protected the seedlings from Rhizoctonia infection. B. pumilus inoculated seedlings showed significant increase in the levels of PAL and SOD enzymes and their gene expressions (2.76, 2.00 and 4.61, 2.25 folds, respectively) compared to control. PR1 gene expression was also increased by 2.68 folds compared to the control. Present study concludes that sorghum seeds inhabit SEB like B. pumilus which is crucial in protecting seedlings from R. solani by producing lipopeptides, enhancing antioxidant and defense enzymes level and their gene expressions. This study is significant in terms of its originality which presents a first report on SEB of sorghum roles in seedlings protection against soil borne fungal pathogen like Rhizoctonia solani.
•Bivariate generalized mixed model was used to predict feeding pressure and pine weevil feeding in seedlings.•Soil scarification with mineral soil cover is needed if seedlings are planted without ...insecticide treatment.•Soil splashed from the ground to the stem base protects seedlings from pine weevil feeding.
Several insecticides used against large pine weevil (Hylobius abietis (L.)) feeding have been prohibited due to environmental and health issues. Thus, there is a need to find other protection methods. We investigated whether spot mounding without insecticide protection could ensure high seedling survival in boreal conditions. In addition, we predicted pine weevil feeding and mortality by site, planting spot and seedling level factors. A generalized linear mixed model (GLMM) was used for predicting feeding pressure. Multivariate GLMM was used for modelling the effects of feeding pressure on lambda-cyhalothrin insecticide-sprayed and unsprayed seedlings. We planted Norway spruce (Picea abies (L.) Karst.) container seedlings for two different years in central Finland. Seedlings were planted with and without insecticide treatment in spot mounds. Untreated seedlings were also planted in unprepared humus to predict pine weevil feeding pressure. Pine weevil feeding pressure was explained only by the age of the clear cuts: feeding pressure was high in fresh clear cuts and decreased if there was one growing season between the clear cut and the planting. On average, 8% of unsprayed seedlings planted in mounds died within two years after planting, while 2% of sprayed seedlings died. Under high feeding pressure, mortality probability of an unsprayed seedling planted in a mound was less than 0.1 only when the seedling was surrounded by mineral soil and the stem base diameter of seedlings was at least 4mm. In mounds covered by mineral soil, especially if it was medium coarse, soil was splashed on the stem base and thereby protected seedlings from pine weevil feeding. Under lower feeding pressure, also thinner seedlings survived without insecticide treatment if mounds were covered by mineral soil. Thus, if Norway spruce seedlings are planted without insecticide treatment, they should have a relatively thick stem and need to be planted in mounds covered with mineral soil.
•Methyl jasmonate emerges as an attractive alternative to protect conifers against H. abietis.•MeJa treated seedlings were less attacked, less wounded, and showed higher survival.•Protection was ...long-lasting and remained effective during two growing seasons.•Results were consistent across species and environmental conditions.•Initial growth reductions were largely compensated by growth benefits due to reduced damage.
Herbivore damage commonly initiates an increased synthesis of chemical defensive compounds in attacked plants. Such induced defences are a vital part of plant defence systems, but when herbivore pressure is high, as frequently occurs in man-made ecosystems such as agricultural and forest plantations, plants may suffer considerable damage before adequate induced defences build up. To prepare the plants for such conditions their induced defence may be artificially triggered by the exogenous application of different phytohormones involved in damage signalling. This method is already employed in agriculture but within forestry systems it has so far been restricted to promising laboratory results. The pine weevil, Hylobius abietis, causes damage by feeding on the bark of young conifer plants and it is one of the main threats to successful regeneration in the Palaearctic region. Here we present results from a large scale field experiment where we triggered the induced defences of conifer seedlings using exogenous application of the chemical elicitor methyl jasmonate. To enhance the generality of the results different species were planted under extremely different environmental conditions; Maritime pine and Monterrey pine in Spain, and Scots pine and Norway spruce in Sweden. Weevil damage, chemical defences, and seedling growth were studied during the two growing periods following planting. In general, treated plants showed increased quantitative defences, and were less attacked, less wounded, less girdled and showed lower mortality rates than their untreated counterparts. Effects were mostly dose dependent, although some interactive effects with tree species were observed. The treatment initially caused a growth reduction but it was later compensated by the benefit, in terms of growth, of being less damaged. The measures that are currently taken to protect forest plantations against this harmful pest all around Europe have enormous economic costs and cause important environmental hazards. Elicitation of inducible defences in seedlings in the nursery appears to be an attractive alternative to these measures. To our knowledge, this is the first field study that explores the applicability of chemical elicitors of induced defences as a way to protect forest plantations against biotic threats.
The aim of this work was to evaluate the impact of soybean sowing in soil with low water availability, under two management systems, using seeds with and without chemical treatment, on the ...physiological quality of seeds and seedling emergence. For this, two experiments were set up, one under no-tillage system (NTS) and the other under conventional tillage system (CTS), in a randomized block design, both in a 2x6 factorial scheme, with two seed treatment conditions (with and without) and six periods of seed permanence in the soil (0, 24, 48, 72, 96 and 120 h), with four replications. Germination, vigor, percentage of abnormal seedlings and percentage of dead seeds were evaluated. Seed treatment made it possible to maintain germination at acceptable levels for up to five days of permanence of the seeds in the soil, even in CTS. Sowing in soils with low water availability can lead to reductions of 0.2 and 0.5 percentage points per hour of exposure to dry soil in germination and vigor of soybean seeds, respectively.
Resumo: O objetivo deste trabalho foi avaliar o impacto da semeadura da soja em solo com baixa disponibilidade hídrica, sob dois sistemas de manejo, utilizando sementes com e sem tratamento químico; sobre a qualidade fisiológica das sementes e emergência de plântulas. Para isso, instalou-se dois experimentos, um em sistema de plantio direto (NTS) e outro sob sistema de plantio convencional (CTS), em delineamento de blocos casualizados, ambos em esquema fatorial 2x6, com duas condições de tratamento de sementes (com e sem) e seis períodos de permanência das sementes no solo (0, 24, 48, 72, 96 e 120 h), com quatro repetições. Foram avaliadas a germinação, o vigor, o percentual de plântulas anormais e o percentual de sementes mortas. O tratamento de sementes possibilitou a manutenção da germinação em níveis aceitáveis até cinco dias de permanência das sementes no solo, mesmo em CTS. A semeadura em solos com baixa disponibilidade hídrica pode acarretar reduções de 0,2 e 0,5 ponto percentual por hora de exposição ao solo seco na germinação e no vigor das sementes de soja, respectivamente.
Abstract
Yellow leaf curl disease caused by pepper yellow leaf curl virus (PepYLCV) and transmitted by the whitefly (
Bemisia tabaci
), becomes the main problem in major horticultural crops, ...including chili pepper. The control of the insect vector is crucial to overwhelm the diseases. The experiment was designed to verify the efficacy of integrated vector and virus control focused on barrier crops and healthy seedling techniques on chili pepper to reduce whitefly crowdedness, the prevalence of the virus, and crop yield. This experiment used a randomized block design. The treatments were two kinds of seedlings, with and without seedling cover, combined with four kinds of borders i.e., maize, Sunn–hemp, screen (chiffon), and control (non-border). The result indicated that the use of protected seedlings was able to defend against the attack of
B. tabaci
and delay virus infection for about 2 weeks. The use of protected seedlings together with barrier crops (maize and sunn-hemp) reduced the number of pests, and PepYLCV damage up to 49.94 – 50.80%, and gave the highest yields. The positive correlation (r) between the population of
B. tabaci
and disease incidence was 0.925, whereas the correlation between disease incidence and yield crop was negative (r = -0.8886). These results will provide an advance of more valuable and practical methods for safeguarding chili pepper production.
► Seedling mortality due to pine weevil was reduced by silvicultural and other measures. ► Soil scarification followed by planting in mineral soil reduced damage substantially. ► A fallow period of 2
...years gave less damage than a one-year fallow period. ► Seedlings with a larger stem diameter were less frequently attacked and killed. ► Successful regeneration can be achieved in boreal forests without reliance on insecticides.
Successful regeneration of conifer forests by planting is, in large parts of Europe, highly dependent on the effective suppression of damage caused by the pine weevil
Hylobius abietis. We investigated the effectiveness of various combinations of control measures against pine weevil damage under boreal forest conditions in Sweden. In particular, we aimed to determine whether satisfactory regeneration could be obtained without the use of insecticides. The experimental study was established on ten new clear-cuts in each of three consecutive years. We studied the use of chemical and physical methods to protect seedlings directly, and investigated the influence of seedling type, age of clear-cut, and a number of soil factors as affected by preparation of the planting site, on the mortality and level of damage suffered by protected and unprotected seedlings. After two seasons, mortality due to pine weevil was 16% among unprotected seedlings, 6% for seedlings treated with the insecticides cypermethrin or imidacloprid, and less than 1% for those physically protected by a coating of Conniflex. However, the Conniflex, which consists of fine-grained sand embedded in a flexible acrylate matrix, was applied manually, and this may have enhanced its effectiveness compared to that achieved during large-scale, commercial application. Two types of containerized Norway spruce seedlings, which differed mainly in their stem diameter (average 2.6
mm and 3.5
mm), were used in the experiments. Among the unprotected seedlings, the narrower stemmed type was more frequently attacked (34% vs. 28%) and killed (19% vs. 12%) by pine weevil. Mortality caused by pine weevil among unprotected seedlings was higher on 1-year-old than on 2-year-old clear-cuts (20% vs. 12%). Soil preparation around unprotected seedlings had a substantial effect on the proportion attacked and killed by pine weevil as well as on the total mortality, with the highest level of feeding damage and mortality occurring on seedlings in undisturbed humus, and the lowest levels occurring on seedlings planted in pure mineral soil (26% vs. 7% for unprotected seedlings). This study demonstrates that acceptable levels of seedling survival can be achieved in regenerations of North European boreal forest without the use of insecticides. Mortality of unprotected seedlings can be reduced to acceptable levels if they are mostly planted in pure mineral soil. Damage can be further reduced by using seedlings with a somewhat larger stem diameter. Insecticides or a physical barrier of Conniflex alone appear to provide a sufficient level of protection.
This study concludes an extensive investigation of antifeedants for the pine weevil, Hylobius abietis (Coleoptera: Curculionidae), an economically important pest of planted conifer seedlings. ...Building on the previously reported antifeedant effects of benzoates and phenylpropanoids (aromatic compounds with one- or three-carbon-atom substituents on the benzene ring), we here report the antifeedant effects of compounds with two-carbon-atom side chains (i.e., phenylacetates). We also present new results; the best antifeedants from the benzoate class were tested at 10-fold lower concentrations in order to find the optimal antifeedants. Generally, for all three compound classes, efficient antifeedants were found to have one or two methyl, chloro, or methoxy substituents on the aromatic ring. For monosubstituted phenylpropanoids, the substituent preferably should be in the para-position. In the search for synergistic antifeedant effects among the three compound classes, combinations of compounds from the three classes were tested in binary and ternary mixtures.
U ovom stručnom članku detaljno su opisani svi čimbenici koji utječu na uzgoj kvalitetne šumske sadnice poljskog jasena za umjetnu obnovu i pošumljavanje. Do sada se pozornost nije poklanjala ...kvaliteti sadnica s obzirom na nove i potpuno promijenjene nepovoljne ekološke i biološke čimbenike koji se događaju sa sastojinama poljskog jasena u Hrvatskoj. Kvaliteta sadnica poljskog jasena određivala se isključivo jednim morfološkim čimbenikom, a to je najčešće visina izbojka što nije dobro. U radu su definirani pojmovi morfološke i fiziološke kvalitete sadnica. Opisane su metodologije za mjerenje morfoloških i fizioloških svojstava šumskih sadnica i njihov značaj na preživljenje, rast i prirast nakon sadnje na terenu. Morfološka svojstva su: visina izbojka, promjer stabljike, odnos visine izbojka i promjera stabljike, duljina pupa, volumen korijena i stabljike, težina sadnica, odnos volumena izbojka i korijena te boja, forma i oštećenja. Fiziološka svojstva su: otpornost na hladnoću, potencijal rasta korijena (PRK), dormantnost pupa i koncentracija hranjiva u lišću. Opisana su tri stresna čimbenika koja utječu na smanjenje kvalitete šumskih sadnica, preživljenje, rast i prirast na terenu, a to su: stres zbog vlage u biljci (PMS), stres zbog temperature i fizički stres (padanje, gnječenje, vibracije, površinsko oštećivanje i trganje korijena). Definirani su i svi ostali stresni čimbenici koji utječu na pad kvalitete šumske sadnice koji se događa u razdoblju od vađenja u rasadniku do sadnje na terenu. Razjašnjena je uloga pojedinog stresnog čimbenika na sadnice, kao i kumulativan utjecaj više stresnih čimbenika. U članku se govori o ispravnom rukovanju sadnicama od vađenja u rasadniku do pošumljavanja. Prikazane su novije patentirane mogućnosti zaštite sadnica od trenutka vađenja iz rasadnika ili kamiona-hladnjače do sadnje na terenu.
This expert article describes in detail all the factors that affect the cultivation of quality forest seedlings of narrow-leaved ash for artificial regeneration and afforestation. So far no attention has been paid to the quality of the seedlings given the new and completely changed adverse ecological and biological factors occurring in narrow-leaved ash stands in Croatia. The quality of field ash seedlings was determined solely by one morphological factor, which is usually the shoot height, which is not good. The paper defines the concepts of morphological and physiological quality of seedlings. Methodologies for measuring the morphological and physiological characteristics of forest seedlings and their importance for survival, growth and growth after field planting are described. Morphological features include shoot height, stem diameter, height: diameter ratio, bud length, root and stem volume, weights, shoot: root ratio, and colour, form, and damage. Physiological properties are: cold hardiness, root growth potential (RGP), bud dormancy and foliar nutrient concentration. Three stress factors that affect the decrease in forest seedling quality, survival, growth, and field gains are described, namely: plant moisture stress (PMS), temperature stress, and physical stress (falling, crushing, vibration, surface damage, and root tearing).All other stress factors that affect the decline in the quality of forest seedlings, which occurs during the period from the nursery to field planting, have been identified. The role of an individual stress factor on seedlings is clarified, and so is the cumulative influence of multiple stress factors. The article deals with the correct handling of seedlings from harvesting in the nursery to afforestation. Recent patented protection options for seedlings from the time of removal from the nursery or cold storage truck to planting in the field are presented.
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