Seedling Mortality Research Articles

Combined Application of Bio-agents and Novel Fungicides for Management of Collar Rot of Chickpea

Background: The chickpea, scientifically known as Cicer arietinum L., is a significant legume crop that serves as a valuable source of vegetable protein. The chickpea crop is susceptible to various pests and illnesses. Collar rot, induced by the fungal pathogen Sclerotium rolfsii, is a highly significant and extremely damaging disease that affects chickpea crops. The disease causes seedling mortality ranging from 54.7 to 95 per cent and field conditions result in yield decrease ranging from 22 to 50 per cent. The present study aimed to investigate the effectiveness of using a combination of fungicides, bio-agents and organic amendments for the management of collar rot in chickpea. Methods: The investigations were conducted in the Rabi seasons of 2019-20 and 2020-21. The experiments involved the integration of fungicides, fungal biocontrol agents (Trichoderma spp.), FYM and Vermicompost to control Collar rot disease in Chickpea caused by S. rolfsii. Six indigenous fungal antagonists (Trichoderma spp.) were assessed in a laboratory setting against S. rolfsii using both dual culture and non-volatile (culture filtrate) methods. The efficacy of the fungicides was assessed using the poison food technique. Nine fungicides were assessed in a laboratory setting to determine their effectiveness against a pathogen and Trichoderma harzianum-2. The fungicides were tested at four different concentrations: 50, 100, 500 and 1000 ppm. The goal was to identify fungicides that are extremely toxic to S. rolfsii at lower concentrations, while being less harmful to the bioagent Trichoderma spp. Pot culture studies were conducted using a completely randomised design (CRD), while field experiments were conducted using a randomised block design (RBD). Result: Trichoderma harzianum-2 (TH-2) was found to be highly efficient against the pathogen. It reduced the growth of the pathogen by 75.18% in the dual culture technique and by 61.85% in the culture filtrate approach. Among the nine fungicides tested, four of them, specifically propineb, mancozeb, captan 70% + hexaconazole 5% WP and penflufen 13.28% w/w + trifloxystrobin, showed lower inhibitory effects on Trichoderma harzianum at doses ranging from 50 to 1000 ppm. The treatment that resulted in the highest seed germination rate (100%) and the lowest occurrence of collar rot was the one where the seeds were treated with captan 70% + hexaconazole 5% WP and the soil was supplemented with Trichoderma harzianum through vermicompost application.

Mechanisms linking river flow regime and riparian hardwood establishment

AbstractThe dominant conceptual model for how river flow affects when and where riparian hardwood trees establish (the “recruitment box model”) considers streamflow recession and a survivable rate of stage decline to predict survival of seedling desiccation. However, to become established, plants must also survive the pre‐seedling life stages and avoid inundation and scour mortality in high flows. We examine the relative importance of these flow‐dependent mechanisms by representing them in a two‐dimensional simulation model. Analysis of the model as applied to a low‐gradient reach of a large mountain river indicates that the soil characteristic determining moisture elevation (the “capillary fringe” height) is the most important process driving establishment rates; also important are the dates of seed deposition, inundation mortality, and the time needed for sprouted seeds to develop roots. Root growth rate had only moderate effect on seedling survival. These results indicate that the conventional conceptual model of establishment is incomplete. At our site, natural rates of decline in soil moisture elevation exceeded root growth rates, so widespread establishment required periods of near‐steady flows. Further, under both reservoir‐controlled and unimpaired flow regimes, establishment was strongly determined by post‐deposition flow increases: seeds deposited at elevations low enough to support rooting were often killed via inundation or scour in flow fluctuations that occurred under both reservoir‐regulated and unregulated flow scenarios. When soil moisture dynamics are represented even simply, the survivable rate of stage decline is not constant but depends on capillary fringe height, seed elevation, and the duration of stage decline. A more complete conceptual model of hardwood establishment considers that seeds need to be deposited where soil is moist long enough to develop roots but far enough from the water's edge to avoid mortality in flow fluctuations; for soil moisture to remain within reach of roots, which could require unusually steady flows, a high capillary fringe, or favorable groundwater gradients; and to avoid mortality due to scour or inundation in winter high flows. Model sensitivity and lack of literature suggest the time and moisture requirements for seeds to develop roots and inundation mortality of seedlings as research priorities.

Field establishment of Cenchrus grass pasture through seed pelleting

Sowing the individual seeds of grasses at proper depth and spacing is a great challenge. Low germination and high seedling mortality at an early stage is a general problem in the establishment of pasture. Spikelets (seed) of Cenchrus ciliaris were used for the formation of seed pellets viz. round shaped and cube-shaped and cloth pouch. Pelleting materials consisted of farm soil, clay and farm yard manure in a 2:1:1 ratio. The weight of one pellet ranged from 5 to 7 g which embedded 8-10 spikelets. Two sowing methods viz. dry sowing and normal sowing, were evaluated. Significant differences were observed in germination and other growth parameters for both sowing methods and types of pellets. The number of seedlings/pellet in dry sowing ranged from 2.5-4.5, while in normal sowing it ranged from 3.8-5.5. The highest plant stand per plot was recorded in cloth pouch (84.5) followed by cube-shaped pellet (75.7) and round-shaped pellet (71.1). Seedling mortality was high in the dry sowing method, irrespective of the type of pellets. Cloth pouches had an advantage over both types of pellets for plant stands, while cube-shaped pellets were found to be better when compared to round-shaped pellets.

Characterization and Pathogenicity of Soilborne Pathogens in Gloriosa superba: Effects of Single- and Multiple-Pathogen Coinfection on Disease Responses.

Glory lily (Gloriosa superba), an ornamental climbing plant, contains the bioactive compound colchicine, attracting attention from the pharmaceutical industry. However, soilborne pathogens have emerged as a serious threat to the cultivation of glory lily, leading to substantial economic losses in the southern parts of India. Among these, the three major pathogens are Macrophomina phaseolina, Fusarium oxysporum, and Agroathelia rolfsii, causing dry root rot (also referred to as charcoal rot), wilt, and stem rot, respectively. Here, we characterized these pathogens using morphological characteristics and phylogenetic analysis of DNA sequences related to the internal transcribed spacer of ribosomal DNA, calmodulin (CAL), and translation elongation factor 1-alpha (TEF-1α). Furthermore, in the pathogenicity tests, the inoculation of M. phaseolina alone resulted in lesions measuring 7.54 ± 0.01 mm on tubers and 90% seedling mortality. This severity was comparable to the simultaneous inoculation of all three pathogens, indicating the prominence of dry root rot among soilborne diseases. This study marks the first detailed investigation of soilborne pathogens combined infection in G. superba, contributing to the understanding of fungal disease complexity in medicinal plants.

Short‐term survival and growth of 32 native boreal plants on treated oil sands tailings

AbstractThe consolidation of oil sands tailings is a cost‐ and time‐consuming process that requires treatment via active (e.g., centrifugation) and passive (e.g., self‐weight consolidation) methods. The use of plants to dewater tailings is a promising concept and has previously been evaluated using agronomic grass species in greenhouse studies. This greenhouse study evaluated the short‐term survivorship and growth of 32 upland and lowland native plant species (12 forbs, 14 graminoids, and six woody plants) in centrifuged tailings and benchmarked their performance against reclamation soil and undisturbed forest soil. All plant species were propagated from seed and transplanted as seedlings into containers filled with one of the three substrates. After 42 days, the height (woody species only) and total aboveground biomass were determined for all living plants. As expected, the mortality of seedlings in tailings was higher than plants grown in the other two substrates. Graminoid species, regardless of species community type (wetland or upland), had higher survival probabilities and growth compared to forb or woody species across all substrates. Of forbs and woody species evaluated, Geum aleppicum and Populus tremuloides showed the most promise amongst the upland species, and Rumex occidentalis was the wetland equivalent.

BUMDes Strategies for Successful Banana Planting Programs

General Background: Village-Owned Enterprises (BUMDes) are essential for enhancing local economies through agricultural initiatives. Specific Background: In Krembung Village, Sidoarjo Regency, a banana planting program has been implemented to improve productivity and income. Knowledge Gap: However, challenges like high seedling mortality and inadequate practices hinder success. Aims: This study analyzes BUMDes strategies in executing the banana program, focusing on community involvement and resource management. Results: While strength and progress indicators are optimal, the value aspect is suboptimal due to significant seedling losses. Community support for banana cultivation has been strong. Novelty: The research highlights practical challenges and strategic approaches in managing BUMDes agricultural programs. Implications: Findings emphasize the need for better resource allocation and community engagement to enhance agricultural initiatives, providing insights for improving BUMDes operations and promoting sustainable rural development. Highlights: Community Involvement: Strong local support is crucial for the success of the banana planting program. Resource Management: Effective allocation and management of resources are necessary to mitigate seedling mortality. Strategic Approaches: Implementing targeted strategies can enhance agricultural productivity and economic benefits for the village. Keywords: BUMDes, Banana Planting, Community Engagement, Agricultural Productivity, Village Potential

Development of a qPCR Assay for the Detection and Quantification of the Fungal Pathogen Calonectria canadiana on Conifers

ABSTRACTA real‐time PCR TaqMan assay was developed for the detection of Calonectria canadiana, a fungal pathogen responsible for damping off, root rot and seedling blight in conifer forest nurseries in central and eastern North America. While highly significant in Quebec Forest nurseries, coniferous seedling mortality decreased significantly when nurseries transitioned from bare root to container seedling production. However, over the past few years, this pathogen has re‐emerged as a threat and millions of container white spruce seedlings were culled in two nurseries in eastern Quebec. A sensitive detection and quantification assay for C. canadiana was essential to investigate the biological and environmental factors driving this new epidemic. We designed primers and a TaqMan probe targeting the internal transcribed spacer (ITS) of C. canadiana. The resulting Ccan TaqMan assay successfully differentiated C. canadiana from other soil‐borne pathogens of the Nectriaceae encountered in Quebec Forest nurseries. The limit of detection of the assay was established at eight copies of C. canadiana ITS. The Ccan TaqMan assay quickly identified the presence of the pathogen in both symptomatic and asymptomatic white spruce (Picea glauca) seedlings. Furthermore, we demonstrated that the pathogen was more easily detected when DNA was extracted from necrotic needles at the base of the stem rather than from necrotic roots. This molecular tool will greatly aid in understanding the biology and epidemiology of C. canadiana.

Effect of shade management practice on cocoa seedling mortality: micro evidence from the Amansie-West district of Ghana

Effect of shade management practice on cocoa seedling mortality: micro evidence from the Amansie-West district of Ghana

Plant, bacteria and fungi crosstalk: Direct and indirect biocontrol mechanisms of sugarcane rhizoplane Pseudomonas species against Fusarium wilt

Plant, bacteria and fungi crosstalk: Direct and indirect biocontrol mechanisms of sugarcane rhizoplane Pseudomonas species against Fusarium wilt

The rates of starch depletion and hydraulic failure both play a role in drought-induced seedling mortality

Key messageThe elapsed times to deplete starch concentrations and to reach a null hydraulic safety margin were related to tree seedling mortality under experimental drought. Starch concentration showed an accelerated decline across all species during the early stages of dehydration, while the concentrations of soluble sugars and total nonstructural carbohydrates remained stable. Concomitant carbohydrate depletion and hydraulic failure drive seedling mortality under drought.ContextCurrent upsurges of drought events are provoking impacts on tree physiology, resulting in forest mortality. Hydraulic dysfunction and nonstructural carbohydrate (NSC) depletion have been posited as the main mechanisms leading to plant mortality under drought.AimsThis study explores the dynamics of the two mortality-inducing processes during drought stress using an experimental approach with 12 evergreen tree species.MethodsSeedlings were subjected to drought until 100% mortality was observed. Midday (ΨMD) and predawn (ΨPD) water potentials, xylem pressure leading to a 50% loss of hydraulic conductivity (Ψ50), along with NSC concentrations in different organs (leaves, stems, and roots) were measured regularly during drought.ResultsTotal NSC concentrations and soluble sugar pools did not decline during drought. However, starch pools showed strong reductions early during drought stress as ΨPD decreased, and the time leading to starch depletion emerged as a strong mortality predictor. Ψ50 alone did not provide an accurate estimate of mortality, while the elapsed time to reach a null hydraulic safety margin (ΨMD—Ψ50 = 0) was related to seedling mortality.ConclusionAdopting a dynamic approach by estimating the times to consume both starch reserves and hydraulic safety margins is highly relevant to improve predictions of tree mortality under the current context of increasing global drought.

Winter and spring frost events delay leaf-out, hamper growth and increase mortality in European beech seedlings, with weaker effects of subsequent frosts.

The persistence of plant populations depends crucially on successful regeneration. Yet, little is known about the effects of consecutive winter and spring frost events on the regeneration stage of trees from different seed sources, although this will partly determine the success of climate warming-driven poleward range shifts. In a common garden experiment with European beech (Fagus sylvatica) seedlings from winter 2015/2016 to autumn 2017, we studied how simulated successive spring and winter frost events affect leaf-out dates, growth performance, and survival rates of 1- to 2-year-old seedlings from provenances differing in climate at origin. We further investigated the combined effects of successive frost events. The first spring frost after germination led to a mortality rate up to 75%, resulting in reduced seedling numbers but better frost tolerance of the survivors, as reflected in a weaker impact of the following winter frost event in the survivors compared to the non-acclimated control. Final plant height was most strongly reduced by the spring frost in the second year. The winter frost event delayed leaf-out by up to 40 days, leading to severe growth impairment in 2017. Our results indicate partly successful frost acclimation and/or the selection of frost-hardier individuals, because the negative growth effects of consecutive frost events did not add up after exposure to more than one event. Both mechanisms may help to increase the frost tolerance of beech offspring. Nevertheless, mortality after the first spring frost was high, and frost exposure generally caused growth reductions. Thus, achieving higher frost tolerance may not be sufficient for beech seedlings to overcome frost-induced reductions in competitive strength caused by winter frost damage and delayed leaf enfolding.

Seedling development of Schizolobium parahyba var. amazonicum inoculated with Rhizoglomus clarum in different doses of phosphorus

This work aimed to evaluate the growth and phosphorus uptake of Schizolobium parahyba var. amazonicum (Huber ex Ducke) Barneby (pinho-cuiabano) seedlings inoculated with Rhizoglomus clarum (T.H.Nicolson & N.C.Schenck) Sieverd., G.A.Silva & Oehl at different doses of phosphorus. The treatments consisted of five levels of phosphorus (0, 25, 50, 100 and 200 mg dm-³) and inoculation or not with R. clarum. After 45 days of seedling inoculation, we analyzed: height, root fresh and dry matter, shoot fresh and dry matter, number of leaves, survival, stem diameter, root volume, Dickson quality index, mycorrhizal colonization, relative water content, leaf tissue density, phosphorus content, efficiency of phosphorus uptake and efficiency of phosphorus utilization. Inoculation with R. clarum and the lowest doses of phosphorus resulted in lower seedling mortality rates. R. clarum did not increase the phosphorus content, efficiency of phosphorus uptake, efficiency of phosphorus utilization, relative water content and the Dickson quality index of the seedlings, but it was efficient in increasing the shoot fresh and dry matter as well as leaf tissue density. Inoculation with R. clarum and phosphate fertilization had a significant joint effect on seedling height and root fresh matter. Thus, it can be concluded that R. clarum may represent an important sustainable technology for the production of pinho-cuiabano seedlings, increasing seedling growth, even at low levels of phosphate fertilization.

Virtual Reciprocal Garden Assessment of Germination Syndromes for Elymus elymoides ssp. brevifolius and Elymus multisetus

Virtual Reciprocal Garden Assessment of Germination Syndromes for Elymus elymoides ssp. brevifolius and Elymus multisetus

Distinct effects of phyllosphere and rhizosphere microbes on invader Ageratina adenophora during its early life stages.

Microbes strongly affect invasive plant growth. However, how phyllosphere and rhizosphere soil microbes distinctively affect seedling mortality and growth of invaders across ontogeny under varying soil nutrient levels remains unclear. In this study, we used the invader Ageratina adenophora to evaluate these effects. We found that higher proportions of potential pathogens were detected in core microbial taxa in leaf litter than rhizosphere soil and thus leaf inoculation had more adverse effects on seed germination and seedling survival than soil inoculation. Microbial inoculation at different growth stages altered the microbial community and functions of seedlings, and earlier inoculation had a more adverse effect on seedling survival and growth. The soil nutrient level did not affect microbe-mediated seedling growth and the relative abundance of the microbial community and functions involved in seedling growth. The effects of some microbial genera on seedling survival are distinct from those on growth. Moreover, the A. adenophora seedling-killing effects of fungal strains isolated from dead seedlings by non-sterile leaf inoculation exhibited significant phylogenetic signals, by which strains of Allophoma and Alternaria generally caused high seedling mortality. Our study stresses the essential role of A. adenophora litter microbes in population establishment by regulating seedling density and growth.

Distinct effects of phyllosphere and rhizosphere microbes on invader Ageratina adenophora during its early life stages

Microbes strongly affect invasive plant growth. However, how phyllosphere and rhizosphere soil microbes distinctively affect seedling mortality and growth of invaders across ontogeny under varying soil nutrient levels remains unclear. In this study, we used the invader Ageratina adenophora to evaluate these effects. We found that higher proportions of potential pathogens were detected in core microbial taxa in leaf litter than rhizosphere soil and thus leaf inoculation had more adverse effects on seed germination and seedling survival than soil inoculation. Microbial inoculation at different growth stages altered the microbial community and functions of seedlings, and earlier inoculation had a more adverse effect on seedling survival and growth. The soil nutrient level did not affect microbe-mediated seedling growth and the relative abundance of the microbial community and functions involved in seedling growth. The effects of some microbial genera on seedling survival are distinct from those on growth. Moreover, the A. adenophora seedling-killing effects of fungal strains isolated from dead seedlings by non-sterile leaf inoculation exhibited significant phylogenetic signals, by which strains of Allophoma and Alternaria generally caused high seedling mortality. Our study stresses the essential role of A. adenophora litter microbes in population establishment by regulating seedling density and growth.

Post-fire resurveys reveal predictability of long-term conifer recruitment in severely burned California dry forests

Post-fire resurveys reveal predictability of long-term conifer recruitment in severely burned California dry forests

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.

Effect of drought and pine weevil damage on mechanically protected Norway spruce seedlings

Effect of drought and pine weevil damage on mechanically protected Norway spruce seedlings

Innovative fertilizers with added plant extracts in the cultivation of Valeriana officinalis and Raphanus sativus and in the control of Botrytis and powdery mildew

Research objective: The main objective of this article is to report the results obtained from the use of innovative fertilisers with added plant extracts in agriculture. In particular, this article will deal with two important topics: i) study of the effect of innovative fertilisers on the biomass of vegetable plants; ii) possible control on mortality due to diseases such as Botrytis and powdery mildew. The information reported in this research work can support the design of cultivation systems in which agricultural sustainability is fundamental due to the presence of plant extracts as an alternative to synthetic plant protection products. Materials and Methods: The plants were grown in pots under controlled conditions; 30 seedlings per thesis, divided into 3 replications of 10 plants each, were planted in early January 2024. The plants used in the trial were Valeriana officinalis L. and Raphanus sativus. The five experimental groups in cultivation were: i) group control, irrigated with water and previously fertilised substrate; ii) group with Aktigen, irrigated with water and previously fertilised substrate, (3 ml per plant once a week); iii) group with Lifegen, irrigated with water and previously fertilised substrate, (3 ml per plant once a week); iv) group with QI-gen, irrigated with water and previously fertilised substrate, (3 ml per plant once a week); v) Group with Ecklonia maxima (EK): (peat 70% + pumice 20%), irrigated with water and previously fertilised substrate, (3 ml per plant once a week). On 5 May 2024, plant height, number of leaves, primary root length (mm), biomass of the aerial and root system, and number of dead plants (Botrytis and powdery mildew) were recorded. Results and Discussion: The experiment showed that the use of innovative fertilisers enriched with plant extracts can indeed significantly improve the vegetative and root growth of Valeriana officinalis L. and Raphanus sativus. All treatments showed a significant improvement over the untreated control and the commercial Ecklonia maxima treatment for the agronomic parameters analysed, but the Qi-gen treatment was significantly the best for increasing vegetative and root biomass. Improvements were also found in plant height, leaf number and root length. The trial also revealed the significant effect on Botrytis control of the product Aktigen and on powdery mildew of the product Lifegen, in fact they reduced the mortality of Valeriana officinalis and Raphanus sativus seedlings. Conclusions: A number of scientific studies have shown that the application of biofertilizers can improve plant growth, productivity, quality, and tolerance to biotic and abiotic stresses. Because of their multiple properties, they have become increasingly important as advanced agricultural techniques in global agriculture. This type of product, which includes natural substances, will contribute significantly to ecologically and economically sustainable agricultural production systems in the coming years, as well as serving as the foundation for large-scale sustainable agriculture in the future.

Evaluation of Endophytic Microorganisms (Trichoderma hazianum and Bacillus subtilus) as Biofungicides against Bayoud Disease (Fusarium oxysporum f. sp. albedinis) on Date Palm (Phoenix dactylifera L.)

Backgraound: Date palm disease named Bayoud, is the major constraint caused by the soil fungus Fusarium oxysporum f. sp. albedinis (Foa) in Algeria. This work has the objective to in vivo biocontrol on bayoud disease incidence on three date palm varieties (Deglet-Nour, Feggous and H-mira), using two antagonistic microorganisms, one fungus (Trichoderma harzianum) and one bacterium (Bacillus subtilus). Methods: Foa strains obtained from isolation of the spines carrying the typical symptoms of Bayoud disease. Two strains used T. harzianum and B. subtilus, are isolated from rhizosphere soils of the date palm. Using the greenhouse screening test, the in vivo biocontrol test is carried out on 3-4 month-old date palm seedlings at the rate of 5 ml of inoculum suspension. Result: A significant (P less than 0.01), difference of date palm seedlings reactions against Foa isolate and antagonistic microorganisms was observed. All three date palm varieties present a high susceptibility against Foa until the total mortality of date palm seedlings. The biocontrol test showed that two antagonists showed different reaction, with the complete resistance of three varieties treated by T. harzianum, while, the antagonist B. subtilus protect just two varieties (Deglet-Nour and H-mira) and can’t protect Feggous variety when showed the susceptibility reaction by presentation of typical symptoms of bayoud disease. We can apply of these antagonistic microorganisms to protect our groves contaminated by Bayoud disease and contain just susceptible commercial cultivars of date palm.