Low Germination Rate Research Articles

Mutation of the K+ transporter SlHAK5 of tomato alters pistil morphology, ionome, metabolome and transcriptome in flowers.

K+ accumulation in plant tissues is a crucial factor for plant growth and development. The tomato high-affinity K+ transporter SlHAK5 is essential for root K+ acquisition from low external concentrations. It is also involved in K+ accumulation in pollen and plant fertility as slhak5 KO plants show a low rate of pollen germination, impaired pollen tube growth and parthenocarpic fruits. Here, we present a thorough analysis of slhak5 flowers, which showed relevant defects at the anatomic, ionomic, metabolomic and transcriptomic levels. First, slhak5 flowers exhibited shorter styles and enlarged ovaries that, together with a low number of seeds in fruits from slhak5 X WT crosses, indicated an effect of the slhak5 mutation on female fertility. Second, a lower accumulation of Ca2+, as well as of several metabolites such as amino acids, citric acid and sugars, was observed in mutant flowers, whereas indole-3-acetic acid content was increased when compared to the wild-type. Third, RNAseq conducted on pistils and stamens of wild-type and slhak5 plants revealed that transport and signalling pathways are significantly enriched in the gene expression analyses of stamens. Thus, it can be concluded that a functional SlHAK5 transporter is required to maintain appropriate Ca2+, metabolite and gene expression levels in flowers, and its absence leads to important reductions in both male and female fertility.

OsNAL11 and OsGASR9 Regulate the Low-Temperature Germination of Rice Seeds by Affecting GA Content

Low temperatures cause serious threat to rice seed emergence, which has become one of the main limiting factors in the production of direct seeding rice. It is of great importance to study the genes controlling low-temperature tolerance during seed germination and to mine the possible regulatory mechanism for developing new rice varieties with immense low-temperature germination ability. In the current research study, two types of mutants of nal11 and gasr9, derived from the WT (wild type) ZH11, were used for the analysis of low-temperature germinability. The results showed that the nal11 and gasr9 mutants displayed no significant difference in germination rate with ZH11 at room temperature, but the mutants showed significantly lower germination rates, germination potential and germination index, and slowed seedling growth in the simulated direct seeding experiments at low temperatures compared to ZH11. Additionally, the activity of POD, SOD, CAT, and anti-superoxide anion radial activity were significantly reduced, but the levels of MDA and H2O2 were significantly higher in the nal11 and gasr9 mutant seeds that were germinated at low temperatures compared to ZH11. Further analysis revealed that the levels of total active GA, especially GA4 and GA7, were significantly lower in the nal11 and gasr9 mutants than that in ZH11 during low-temperature germination. Based on qRT-PCR analysis, the expression levels of some GA synthesis-related genes were higher, whereas some were lower in the nal11 and gasr9 mutants than those in ZH11, however, the GA metabolism-related genes OsGA2ox8 and OsGA2ox10 and the GA signaling negative regulator gene SLR1 were significantly up-regulated in both nal11 and gasr9 mutants at several time points during low-temperature germination. This may explain the lower GA levels in the nal11 and gasr9 mutants. Furthermore, the interaction between the OsNAL11 and OsGASR9 proteins was confirmed by Y2H, LUC, and Co-IP assays. This study provides preliminary insights into the regulatory mechanism of the OsNAL11 and OsGASR9 genes, which control the low-temperature germination of rice seeds by affecting the GA pathway. Our study will provide the basis for further mining the molecular mechanisms of low-temperature germination in rice and valuable theoretical reference for breeding varieties with strong low-temperature germinability.

Optimizing germination dynamics in seven key industrial and medicinal hemp varieties through seed priming techniques: An initial study for hemp cultivation in Pakistan

Seed germination is crucial for studying factors influencing production conditions since it represents the initial physiological stage of the plant's life cycle. Hemp seeds are grown to obtain cannabinoids; however, these varieties, hybrids, and feminized seeds are costly in the market with low germination rates. Therefore, optimizing the germination of hemp seeds can play an important role in maintaining plant populations and crop establishment and can reduce seed costs. This study was aimed at evaluating the germination potential of seven hemp varieties/cultivars (Cannabis sativa L.) in response to priming with Indole Butyric Acid (IBA), moringa leaf crude extract, hydro-priming, and a control. Results showed that IBA at 1000 ppm significantly improved germination rates; while the hydro-priming exhibited the fastest germination across all varieties/cultivars. Two cultivars viz., Santhica-70 and Fedora-17 exhibited the highest germination percentages of 83% and 77%, respectively with IBA treatment; while CBD Pink Kush exhibited a germination rate of 63%. This study represents the first comprehensive investigation into seed germination and seedling growth of hemp varieties, offering insights into optimized priming agent selection for industrial and medicinal hemp crop cultivation in Pakistan, highlighting the importance of variety-specific traits and priming techniques for maximizing crop yield.

Factors affecting early red oak (Quercus rubra L.) regeneration near its northern distribution limit in Quebec

Red oak is an important species within the North American landscape, with climate change projections indicating a potential northward shift in its distribution. However, understanding the factors influencing its regeneration success at the northern limit remains limited. Site conditions and seed provenance adaptability may play critical roles. To bridge this knowledge gap, we conducted a seed transfer study in two northern red oak stands in Quebec. We firstly investigated stand regeneration history through dendrochronological characterization. Then, we monitored the survival and growth of saplings for four red oak provenances across a south-to-north gradient in field and greenhouse settings, with varying soil nutrient levels due to fertilization, and with or without protection from large herbivores. Results indicated that stands have similar age structures with red oak establishment coinciding with the last major fire disturbance in the early 1920s. However, tree species composition and density differed, suggesting differences in fire disturbance regime or ecological succession status prior to fire. Site had the largest influence on red oak regeneration, with the highest tree density and soil water availability site exhibiting a 29% higher survival rate. Protection against large herbivores also significantly impacted red oak seedling performance, leading to a 16% higher survival rate. Germination, survival and growth also significantly differed between provenances. The local (northernmost) provenance exhibited the poorest overall performance with 28 to 42% lower germination, survival and growth rates, while the two southernmost provenances exhibited superior germination and sprout survival. An increase in soil nutrient availability was beneficial to red oak in the greenhouse, but only marginally benefited survival and growth in the field, suggesting that this factor is of less importance than other factors (e.g., water and light availability) for red oak early regeneration. The findings of this study suggest that silvicultural efforts to favor red oak should focus on site and provenance selection, and that water availability is currently limiting red oak regeneration success at acorn and early seedling life stages (i.e., 1 year old seedlings) near its northern distribution limit.

A Proteomic Study on Seed Germination of Nitraria roborowskii Kom.

Owing to the dormancy of the seeds of Nitraria roborowskii Kom., which results in a low germination rate in nature, germination takes a long time, and natural regeneration is difficult. Therefore, there is a need to study the molecular mechanism by which the seeds of N. roborowskii release dormancy. In this study, the differentially expressed proteins of N. roborowskii seeds before and after dormancy and germination were quantitatively and qualitatively analyzed via two-dimensional high-performance liquid chromatography tandem mass spectrometry (LC–MS) and TMTTM. Differentially expressed proteins from dormant and germinated seeds were characterized and enriched via bioinformatics to determine the functions and pathways of the differentially expressed proteins. The results revealed that seed dormancy was regulated by multiple metabolic pathways, including protein synthesis, nutrient utilization and phytohormone signal transduction pathways. A comparison of the dormant and germinated N. roborowskii seed samples revealed 1082 differentially expressed proteins with FC ≥ 1.5 and p values ≤ 0.05, among which 191 proteins were upregulated and 891 proteins were downregulated in the seeds of the germinated group, and proteins more closely related to the key genes of the germinated N. roborowskii seeds were involved in the activity of D-threo-aldose 1-dehydrogenase. Four proteins (WD40, cystatin, AMP binding protein, and helicase) were involved in the positive regulation of seed germination. The release of N. roborowskii seed dormancy is a complex biological process involving cell differentiation, formation, cellular transport, signaling and resistance, etc. The interactions of multiple metabolic pathways, such as carbon fixation, glycolysis/gluconeogenesis, the pentose phosphate pathway, endoplasmic reticulum protein processing and pyruvic acid metabolism in photosynthetic organisms, constitute a complex regulatory mechanism for dormancy release.

Diversity of Treatments in Overcoming Morphophysiological Dormancy of Paeonia peregrina Mill. Seeds.

Paeonia peregrina Mill. is a protected, herbaceous species native to Southeastern Europe and Turkey. Due to its vulnerability, it has to be protected both in its natural habitats and through cultivation. Peonies are known to have a low potential for natural regeneration due to their seed dormancy, low germination rate, and long germination period. In this study, treatments with gibberellic acid (GA3 150, 200, 250, 300, and 350 mg L-1 GA3) and warm (at 20/16 °C day/night regime) and cold stratification (at 4 °C) were used to accelerate dormancy release and increase the germination rate. The seeds of P. peregrina from four natural habitats in Serbia and the Institute's collection were collected and analyzed. They showed an underdeveloped embryo that needs to grow inside the seed before it can germinate. The application of GA3 accelerated each stage of germination (seed coat rapturing, hypocotyl dormancy release, and epicotyl dormancy release) for approximately 10 days compared to the control. It was also found that two-day imbibition with 200 mg L-1 GA3 significantly accelerated and equalized germination. Higher GA3 concentrations had a more pronounced impact on each stage but also resulted in greater seed infection after the seed coat rupture, elongated and weak seedlings, while lower concentrations did not result in obtaining uniform seedlings. There were no significant differences observed between localities. Restoring P. peregrina through seeds and nursery-produced plants is crucial for conserving the genetic diversity of the tested species.

Achieving hybridisation between Miscanthus species: Commercially-scalable methods to manipulate flowering synchronisation and maximise seed yield

Miscanthus is a high-yielding lignocellulosic perennial biomass crop. The low multiplication rate of clonal rhizome propagation is a bottleneck to upscaling plantation areas of feedstock needed to supply and expand the bioeconomy. Novel seeded Miscanthus hybrids are currently being developed to overcome this bottleneck by increasing annual multiplication rates from approximately 10 to over 1000 times. We describe a series of field experiments in southern Italy using agronomic methods to optimise multiplication rates through (i) planting configurations and densities, (ii) ratio of seed parents to pollen parents (iii) supplemental pre-dawn misting to increase humidity during pollination. In these trials the seed-bearing M. sinensis started flowering 2–3 weeks earlier than the M. sacchariflorus pollen parent. Earlier experiments indicated that flowering in M. sacchariflorus was mostly determined by photoperiod while in M. sinensis it was modulated by endogenous signals. Consequently, a second set of experiments were conducted to delay flowering time in M. sinensis: (iv) mid-season stem cut back, (v) oversupply of nitrogen, and (vi) undersupply of water. Across all treatments and years, the multiplication rates varied from 140 to 1300 seeds m². Reducing the proportion of the pollen parent plants (M. sacchariflorus) from 50 % to 25 % did not reduce seed yield per plant. This therefore increases the seed yield per m² and reduces seed production upscaling costs. Flowering time and duration in M. sinensis was significantly impacted by mid-season cutting and water stress, but not by nitrogen supply rates. Mid-season shoot cutting reduced number of flowers per plant (77 %), seed quantity (47 %), seed size (46 %), and resulted in seeds with a low germination rate of 39 %. High M. sinensis planting densities produced higher seed yields in the first year. However, in subsequent years higher density plots were more susceptible to autumn lodging lowering seed production by loss of panicles. Pre-dawn misting to prolong pollen life and stigma receptivity had no significant effects on seed production. This study demonstrates the importance of flowering time synchronization in the open field for commercial seed production. The limited effect of agronomic efforts to reduce the interspecies flowering time gap emphasises the importance of genetic factors in controlling flowering time. The most impactful intervention to change flowering time and improve parental synchronisation was mid-season cutting, while this method reduced seed production when applied to the seed parent it could be ideal for pollen parents.

The Effect of Boxwood Leaf Volatiles on Conidial Germination of Calonectria pseudonaviculata, the Causal Agent of Boxwood Blight.

The fungal pathogen Calonectria pseudonaviculata causes boxwood blight and is a significant threat to the boxwood industry, as well as historic boxwood gardens. The pathogen produces conidia in sticky masses that are splash dispersed, which germinate and infect through stomata on the leaves or stems, causing leaf spots and stem lesions. Despite its ability to cause severe infections on boxwood plants, the pathogen often has a low germination rate on artificial media under lab conditions. To identify cues that stimulate germination, we explored whether host factors could induce high germination rates. In this study, we demonstrate that C. pseudonaviculata spores achieve high germination rates when they are placed on detached leaves of boxwood and other known hosts, compared to potato dextrose agar and glass coverslips. We also demonstrate that germination is induced by volatiles from detached leaves of boxwood, as well as the nonhost Berberis thunbergii. When C. pseudonaviculata spores were exposed to volatiles from boxwood leaves in the presence of ethylene scrubber packs that contained potassium permanganate, the stimulatory effect on spore germination was reduced. However, ethylene, a regulator of leaf senescence, did not stimulate germination of C. pseudonaviculata spores. This suggests that the pathogen may have evolved to recognize one or more host volatiles, other than ethylene to induce germination, thus limiting its growth until it senses the presence of a host plant.

Direct shoot regeneration from cotyledonary node of Uraria picta (Jacq.) Desv. ex DC., an important plant of dashmula drugs, and assessment of genetic fidelity, metabolic profiling, and anti-diabetic activity

Uraria picta root is used in the polyherbal product ‘Dashmula’. Its exploitation for formulation preparation has depleted its availability, leading to medicine adulteration. Direct shoot regeneration from the cotyledonary node holds promise as a source of raw material. This study aimed to develop a regeneration protocol for U. picta and validate its genetic and metabolic fidelity. The seeds of U. picta showed low germination rates, prolonged dormancy, and poor viability. Root exploitation in the wild poses a threat to its availability in nature. Seedling’s derived cotyledonary nodes cultured on B5 medium supplemented with BAP (0.5–3 mg L−1), Kinetin (0.5–3 mg L−1), Thidiazuron (0.01–1 mg L−1), and meta-Topolin (0.1–4 mg L1). To address hyperhydricity in regenerated shoots, cotyledonary nodes were cultured on high-agar concentration media. Microshoots were exposed to IBA solution (50–800 mg L−1) pulse treatment for rooting. Tissue-cultured plants genetic fidelity was assessed using ISSR and SCoT markers, while metabolic fidelity was studied with HRMS. The chlorophyll content, antioxidant, and antidiabetic activity of micropropagated plants were evaluated. The highest shoot regeneration frequency, with a maximum of 6.57±0.278 shoots per explant, was achieved using 2 mg L−1meta-Topolin. The shoots were elongated, had expanded leaves, and were hyperhydrated. BAP (2 mg L−1) induced a maximum of 9.83±0.333 shoot buds per explant. BAP caused explant browning, profuse callus formation, dwarfing, and hyperhydric shoots. Hyperhydricity was alleviated with a higher agar concentration (1 %). IBA (400 mg L−1) induced a maximum of 2.18±0.090 roots per shoot and a root length of 9.23±0.033 cm. Tissue-cultured and mother plants exhibited clonal fidelity, similar metabolite and chlorophyll content, strong antioxidant activity, and equal efficacy for inhibiting α-amylase and α-glucosidase. This method can propagate elite clones of U. picta and offer its improvement via genetic transformation.

Variation in Seed Morphological Traits Affects the Dispersal Strategies of Chromolaena odorata Following Invasion.

Seed germination and dispersal have an important impact on the establishment and spread of invasive plants. Understanding the extent of intraspecific seed trait variations can enhance our understanding of how invasive plants respond to environmental change after introduction and help predict the dynamic of invasive species under future environmental conditions. However, less attention has been given to the variation in seed traits within species as opposed to among species. We compared seed production, seed morphological traits, dispersal ability, and seedling performance of Chromolaena odorata from 10 introduced populations in Asia and 12 native populations in America in a common garden. The results showed that range (introduced vs. native) and climate affected these traits. Compared with the native population, the introduced populations had higher seed numbers per capitula, lighter seeds, and higher potential dispersal ability seeds (lower terminal velocity) but lower germination rates and seedling lengths. Climatic clines in seed numbers per capitula and pappus length were observed; however, the clines in pappus length differed between the introduced and native populations. Trait covariation patterns were also different between both ranges. In the native populations, there was a trade-off between seed numbers per capitula and seed mass, while this relationship was not found for the introduced populations. These results indicate that C. odorata alters the ecological strategy of seed following invasion, which facilitates its establishment and fast dispersal and contributes to successful invasion in the introduced ranges.

Can Photoselective Nets' Influence Pollen Traits? A Case Study in 'Matua' and 'Tomuri' Kiwifruit Cultivars.

The increasing use of photoselective nets (PNs) raises the question of their influence on pollen traits. We aimed to evaluate the effect of PNs (yellow, pearl, and grey) on the pollen of 'Matua' and 'Tomuri' Actinidia deliciosa cultivars. The pollen size and the exine were studied with a light microscopy and a scanning electron microscopy, and the fertility was analysed by a viability assay and in vitro germination. The total soluble proteins (TSPs) and sugars (TSSs) were quantified by colorimetric assays. The molecular structure of the pollen grain's wall was analysed by a Raman spectroscopy. The pollen from the plants under the PNs had a larger width and area and a lower germination rate. No significant changes were observed in the exine's microperforations. The TSP and TSS contents were influenced by the cultivar and PNs (particularly the pearl PN). The Raman spectra of the pollen from the plants grown under the nets presented some bands that significantly shifted from their original position, indicating differences in the vibration modes of the molecules, but no overall changes at their structural or organisation level were found. Our study showed that the PNs could influence several pollen traits, with the pearl PN inducing greater modifications. Our results also support the idea that cultivars affect the outcome of some characteristics.

An Economic Analysis of Market Acceptance and Performance of Rice Varieties Grown in Northern Telangana Zone

This study aims to conduct an economic analysis of market acceptance and performance of rice varieties grown in the Northern Telangana Zone, where diverse rice cultivars face cultivation and marketing challenges. The objectives are to identify and document rice cultivars released by PJTSAU, study technological attributes preferred by stakeholders, and document constraints faced by stakeholders. A purposive sampling technique was used to select 90 farmers, 30 traders, and 30 consumers, totaling 150 participants. Data were collected using well-developed schedules and analyzed using tabular analysis, Rice Preference Index (RPI), Garrett ranking technique, and other suitable methods. The results showed that Telangana Sona (RNR 15048) is highly favored for its long grain size, high head rice recovery, and strong market demand, despite its susceptibility to stem borer and higher fertilizer requirements. Pranahitha (JGL 11727) is appreciated for its good rice quality but faces significant challenges, including high susceptibility to lodging, pests, and diseases, and lower germination rates. Kunaram Rice-1 (KNM 733) showed acceptable profitability but struggled with low market demand, poor grain quality, and higher water requirements. The study concludes that while Telangana Sona excels in market appeal and profitability, Pranahitha and Kunaram Rice-1 need targeted interventions to overcome their specific constraints. Enhancing pest resistance, improving grain quality, and reducing input requirements are essential for optimizing the potential of these varieties. Addressing these challenges through improved management practices and technology adoption can significantly benefit farmers and boost the marketability of these paddy varieties.

Comparative transcriptome analysis reveals the potential mechanism of GA3-induced dormancy release in Suaeda glauca black seeds.

Suaeda glauca Bunge produces dimorphic seeds on the same plant, with brown seeds displaying non-dormant characteristics and black seeds exhibiting intermediate physiological dormancy traits. Previous studies have shown that black seeds have a very low germination rate under natural conditions, but exogenous GA3 effectively enhanced the germination rate of black seeds. However, the physiological and molecular mechanisms underlying the effects of GA3 on S. glauca black seeds are still unclear. In this study, transcriptomic profiles of seeds at different germination stages with and without GA3 treatment were analyzed and compared, and the TTF, H2O2, O2 -, starch, and soluble sugar contents of the corresponding seed samples were determined. The results indicated that exogenous GA3 treatment significantly increased seed vigor, H2O2, and O2 - contents but decreased starch and soluble sugar contents of S. glauca black seeds during seed dormancy release. RNA-seq results showed that a total of 1136 DEGs were identified in three comparison groups and were involved mainly in plant hormone signal transduction, diterpenoid biosynthesis, flavonoid biosynthesis, phenylpropanoid biosynthesis, and carbohydrate metabolism pathway. Among them, the DEGs related to diterpenoid biosynthesis (SgGA3ox1, SgKAO and SgGA2ox8) and ABA signal transduction (SgPP2Cs) could play important roles during seed dormancy release. Most genes involved in phenylpropanoid biosynthesis were activated under GA3 treatment conditions, especially many SgPER genes encoding peroxidase. In addition, exogenous GA3 treatment also significantly enhanced the expression of genes involved in flavonoid synthesis, which might be beneficial to seed dormancy release. In accordance with the decline in starch and soluble sugar contents, 15 genes involved in carbohydrate metabolism were significantly up-regulated during GA3-induced dormancy release, such as SgBAM, SgHXK2, and SgAGLU, etc. In a word, exogenous GA3 effectively increased the germination rate and seed vigor of S. glauca black seeds by mediating the metabolic process or signal transduction of plant hormones, phenylpropanoid and flavonoid biosynthesis, and carbohydrate metabolism processes. Our results provide novel insights into the transcriptional regulation mechanism of exogenous GA3 on the dormancy release of S. glauca black seeds. The candidate genes identified in this study may be further studied and used to enrich our knowledge of seed dormancy and germination.

Оценка посевных качеств семян и сезонного развития многолетних травянистых растений, интродуцированных в Полярно-альпийском ботаническом саду-институте

The study investigated the phenorhythms and sowing qualities of seeds from eight herbaceous perennial plant species (Arnica unalaschcensis, Aster bellidiastrum, Cirsium spinosissimum, Doronicum glaciale, Erigeron glacialis,Geum rhodopeum, G. virginianum and Rheum tataricum) introduced in Polar-Alpine Botanic Garden-Institute.Aster bellidiastrum, Doronicum glaciale, and Erigeron glacialis exhibited the earliest seed ripening, while Arnica unalaschcensis, and Rheum tataricum displayed a somewhat delayed ripening process. Notably, these species demonstrated high laboratory germination rates ranging from 92 % to 100 %, indicating their successful adaptation to the local environmental conditions. Conversely, Cirsium spinosissimum exhibited an extended period of seed maturation, with a lower germination rate of 37 %.

Small but strong: herbivory by sap-feeding insect reduces plant progeny growth but enhances direct and indirect anti-herbivore defenses.

The transmission of resistance traits to herbivores across subsequent generations is an important strategy employed by plants to enhance their fitness in environments with high herbivore pressure. However, our understanding of the impact of maternal herbivory on direct and indirect induced chemical defenses of progeny, as well as the associated costs, is currently limited to herbivory by leaf-chewing insects. In this study, we investigated the transgenerational effects of a sap-feeding insect, the green peach aphid Myzus persicae, on direct and indirect chemical defenses of bell pepper plants (Capsicum annuum), and whether the effects entail costs to plant growth. Aphid herbivory on parental plants led to a reduced number of seeds per fruit, which exhibited lower germination rates and produced smaller seedlings compared to those from non-infested parental plants. In contrast, the progeny of aphid-infested plants were less preferred as hosts by aphids and less suitable than the progeny of non-infested plants. This enhanced resistance in the progeny of aphid-infested plants coincided with elevated levels of both constitutive and herbivore-induced total phenolic compounds, compared to the progeny of non-infested plants. Furthermore, the progeny of aphid-infested plants emitted herbivore-induced plant volatiles (HIPVs) that were more attractive to the aphid parasitoid Aphidius platensis than those emitted by the progeny of non-infested plants. Our results indicate that herbivory by sap-feeding insect induces transgenerational resistance on progeny bell pepper plants, albeit at the expense of vegetative growth.

Rapid detection of turtle cracks in corn seed based on reflected and transmitted images combined with deep learning method

Cracks in corn seeds greatly affect their storage tolerance and germination ability. These cracks are categorized as single, double, and turtle cracks. The vigor experiment showed that turtle cracks lead to the poorest seed vigor, with significantly lower germination rates after artificial aging. Traditional methods to detect turtle cracks, like lightboxes, staining, and colorimetry, are inefficient or costly. Therefore, a detection method for turtle cracks of corn seeds based on reflected light and transmitted light images combined with deep learning was proposed. The transmitted and reflected light images on embryo and endosperm surfaces of 2000 corn seeds with different crack were collected. A Based on Self-Attention Modul Convolutional Neural Support Vector Networks (SACNSVN) model was proposed to detect the turtle cracks seeds, and compared with the model established by LSTM, CNN, BLR, SVM, and MLP. The effects of embryo surface, endosperm surface, varieties and maturity on turtle crack detection were investigated. The results showed that: (1) The transmitted light image had a significant correlation with 62 and 58 indicators of cracks and turtle cracks, respectively, which better reflected the crack and turtle crack seeds than reflected light image; (2) The accuracy of turtle cracks detection model based on embryo endosperm surface combined dataset were higher than embryo surface, endosperm surface, and embryo endosperm surface mixed dataset; (3) The SACNSVN model provides the optimal accuracy with 82.6%; (4) Variety greatly affects turtle crack detection in corn seeds, while maturity level has a minor impact, and SACNSVN exhibits strong generalization ability. This study provides significant technical support for optimizing the seed processing process and improving the seed quality.

Effective techniques to break seed dormancy in Rhodomyrtus tomentosa (Aiton) Hassk. for seed germination enhancement

Rhodomyrtus tomentosa is a valuable plant for medical and pharmaceutical uses. The plant reproduces through seeds; however, the seeds become dormant, resulting in low germination rates. The industrial demand for this plant is expanding, making sustainable propagation a major challenge. The present study aims to evaluate different techniques for breaking the dormancy of R. tomentosa seeds. A randomized design was used to evaluate different techniques for breaking the dormancy of R. tomentosa seeds, including de-operculum, chemical scarifications, and exogenous gibberellic acid (GA3), in both laboratory conditions at ambient temperature (25 ± 2 °C) and field conditions. The characteristics of R. tomentosa fruit and seeds were assessed. The average mass, width, and length of fruits were 1.90 g, 13.78 g, and 15.27 g, respectively. The average seed/ripe fruit contained 57 seeds, and the mass of 1000 seeds was 2.64 g. Seed viability (100 %) was achieved in the treatment with 0.075 % tetrazolium at 45 °C for 3 h, but a germinated seed was only 13.00 %. The study of breaking seed dormancy in laboratory conditions revealed that de-operculum significantly enhanced seed germination up to 83.00 % within 15 days, compared with control treatment of 13.00 % within 34 days (p ≤ 0.01). In contrast, 10 % KNO3 for 24 h under field conditions resulted in the highest seed germination rate of 91.00 % within 34 days, while de-operculum treatment showed 63.00 % of seed germination within 15 days. In addition, the seed water imbibition rate between control and de-operculum seeds was evaluated. The results demonstrated that the control seeds absorbed water more slowly than the de-operculum seeds, indicating that de-operculum promoted faster germination. The findings concluded that breaking seed dormancy is important for R. tomentosa seed germination. De-operculum and KNO3 were discovered to be effective ways of breaking seed dormancy in R. tomentosa.

The fungal protease BbAorsin contributes to growth, conidiation, germination, virulence, and antiphytopathogenic activities in Beauveria bassiana (Hypocreales: Cordycipitaceae)

The fall armyworm, Spodoptera frugiperda (Lepidoptera: Noctuidae), is one of the most destructive agricultural pests. The entomopathogenic fungus Beauveria bassiana (Hypocreales: Clavicipitaceae) is a biopesticide widely used for biocontrol of various pests. Secreted fungal proteases are critical for insect cuticle destruction and successful infection. We have previously shown that the serine protease BbAorsin in B. bassiana has entomopathogenic and antiphytopathogenic activities. However, the contribution of BbAorsin to fungal growth, conidiation, germination, virulence and antiphytopathogenic activities remains unclear. In this study, the deletion (ΔBbAorsin), complementation (Comp), and overexpression (BbAorsinOE) strains of B. bassiana were generated for comparative studies. The results showed that ΔBbAorsin exhibited slower growth, reduced conidiation, lower germination rate, and longer germination time compared to WT and Comp. In contrast, BbAorsinOE showed higher growth rate, increased conidiation, higher germination rate and shorter germination time. Injection of BbAorsinOE showed the highest virulence against S. frugiperda larvae, while injection of ΔBbAorsin showed the lowest virulence. Feeding BbAorsinOE resulted in lower pupation and adult eclosion rates and malformed adults. 16S rRNA sequencing revealed no changes in the gut microbiota after feeding either WT or BbAorsinOE. However, BbAorsinOE caused a disrupted midgut, leakage of gut microbiota into the hemolymph, and upregulation of apoptosis and immunity-related genes. BbAorsin can disrupt the cell wall of the phytopathogen Fusarium graminearum and alleviate symptoms in wheat seedlings and cherry tomatoes infected with F. graminearum. These results highlight the importance of BbAorsin for B. bassiana and its potential as a multifunctional biopesticide.

Narrow mycorrhizal specialization and its effect on early development in the Mediterranean orchid Orchis italica

Abstract The contribution of individual orchid mycorrhizal (OrM) fungi to orchid germination is poorly understood. We isolated Tulasnella OrM fungi from 11 populations representing nine Italian regions associated with the orchid Orchis italica. We performed in vitro germination experiments using both single and two OrM isolate combinations of Tulasnella and Ceratobasidium isolates found in O. italica and co-occurring orchids. We performed an in situ reciprocal translocation experiment of O. italica seeds in two populations and we experimentally planted seeds into two unoccupied sites to test whether the presence of suitable OrM may limit its distribution. In vitro, Tulasnella isolates initiated germination, but only two isolates resulted in seedling development, while seeds did not germinate in the presence of Ceratobasidium isolates. Combinations of two Tulasnella isolates had lower germination rates compared to single isolates. Reciprocal translocations revealed that seeds from the same population had higher germination rates. Protocorms developed in one unoccupied site, with the associated fungus identified as Tulasnella spp. These results suggest that Tulasnella vary in their efficacy in seed germination and O. italica has a narrow specialization on Tulasnella. Such information is important for understanding the range limits of orchids and their ecological dependency on OrM fungi.

Losses of low-germinating, slow-growing species prevent grassland composition recovery from nutrient amendment.

Nutrient enrichment often alters the biomass and species composition of plant communities, but the extent to which these changes are reversible after the cessation of nutrient addition is not well-understood. Our 22-year experiment (15 years for nutrient addition and 7 years for recovery), conducted in an alpine meadow, showed that soil nitrogen concentration and pH recovered rapidly after cessation of nutrient addition. However, this was not accompanied by a full recovery of plant community composition. An incomplete recovery in plant diversity and a directional shift in species composition from grass dominance to forb dominance were observed 7 years after the nutrient addition ended. Strikingy, the historically dominant sedges with low germination rate and slow growth rate and nitrogen-fixing legumes with low germination rate were unable to re-establish after nutrient addition ceased. By contrast, rapid recovery of aboveground biomass was observed after nutrient cessation as the increase in forb biomass only partially compensated for the decline in grass biomass. These results indicate that anthropogenic nutrient input can have long-lasting effects on the structure, but not the soil chemistry and plant biomass, of grassland communities, and that the recovery of soil chemical properties and plant biomass does not necessarily guarantee the restoration of plant community structure. These findings have important implications for the management and recovery of grassland communities, many of which are experiencing alterations in resource input.