Search Results (120)

Passion fruit (Passiflora edulis), a commercially vital tropical crop, faces flowering instability due to photoperiod-sensitive flowering patterns, particularly under the cloudy, rainy climates of subtropical regions. To mitigate floral suppression during unfavorable light conditions, this study implemented a dual-modality strategy combining 16 h daily supplementary lighting (460 nm blue + 630 nm red spectrum) and foliar application of a high-phosphorus-containing nutrient, the Plant-Prod (nitrogen–phosphorus–potassium = 10:52:10) grown in field ‘Qinmi No. 9’. The treatment significantly stimulated lateral branch formation, internode elongation, flower retention, stage IV flower bud development, and enhanced photosynthetic efficiency. Physiological analyses revealed that the treatment increased the net photosynthetic rate (Pn), reduced the intercellular carbon dioxide concentration (Ci), and enhanced stomatal conductance (Gs), indicating the improvement of carbon assimilation. Controlled seedling trials further confirmed these effects, with treated groups exhibiting accelerated lateral branching and stress resilience. This integrated approach, combining optimized supplemental lighting and precision phosphorus fertilization, offers a practical and scalable strategy to stabilize passion fruit yields in climate-variable regions, with immediate potential for commercial orchards and greenhouse production. Full article

Hop latent viroid (HLVd), a 256-nucleotide RNA strand with complementary base-pairing and internal stem loop structures, forms circular or rod-shaped molecules within diseased plants. RT-PCR/RT-qPCR was used to assess HLVd transmission, spread and longevity. The viroid was detected in asymptomatic stock plants and in rooted vegetative cuttings, as well as in recirculated nutrient solution sampled from propagation tables and nozzles. Plant-to-plant spread through root infection in hydroponic cultivation was demonstrated. The viroid survived for 7 days and 4 weeks, respectively, in crushed leaf extracts (sap) or dried leaves/roots at room temperature. Following stem inoculation with infectious sap, HLVd was detected in root tissues within 2–3 weeks and in the foliage within 4–6 weeks. Plants grown under a 12:12 h photoperiod to induce inflorescence development showed more rapid spread of HLVd compared to 24 h lighting. The viroid was subsequently detected in inflorescence tissues, in trichome glands, in dried cannabis flowers and in crude resinous oil extracts. Anthers and pollen from infected male plants and seeds from infected female plants contained HLVd, giving rise to up to 100% infected seedlings. Artificially inoculated tomato and tobacco plants supported viroid replication in roots and leaves. Infected cannabis leaf and root tissues treated with UV-C for 3–5 min or temperatures of 70–90 °C for 30 min contained amplifiable HLVd-RNA. Infectious plant extract treated with 5–10% bleach (0.825% NaOCl) or 1000 ppm hypochlorous acid yielded no RT-PCR bands, suggesting the RNA was degraded. Meristem tip culture from HLVd-infected plants yielded a high frequency of pathogen-free plants, depending on the genotype. Full article

Rhodomyrtus psidioides (G.Don) Benth. (Myrtaceae) is a critically endangered rainforest species from the east coast of Australia, where populations have severely and rapidly declined due to the effects of repeated myrtle rust infection. With very limited material available in the wild and freezing-sensitive seeds that have prevented storage in a seed bank, ex situ conservation of this exceptional species has proven difficult. Material from a seed orchard grown at the Australian Botanic Garden Mount Annan was successfully used to initiate three new accessions into tissue culture from cuttings, and to undertake cryopreservation experiments using a droplet-vitrification (DV) protocol for both seeds and cultured shoot tips. Use of seedling material for tissue culture initiation was very effective, with a 94–100% success rate for semi-hardwood explants and a 50–62% success rate for softwood explants. Although no survival of seeds after cryopreservation was observed, seeds of R. psidioides showed some tolerance of desiccation and exposure to cryoprotective agents. Regeneration after cryopreservation using a DV protocol was demonstrated in only one shoot tip precultured on basal medium containing 0.4 M sucrose and incubated in PVS2 for 20 min prior to immersion in liquid nitrogen. These results demonstrate the value of living collections in botanic gardens for conservation research, highlight the importance of germplasm choice for tissue culture initiation, and demonstrate the potential of cryobiotechnologies for the ex situ conservation of exceptional plant species. Full article

To produce plug seedlings with uniform growth and which are suitable for high-speed transplanting operations, it is essential to sow seeds precisely at the center of each plug-tray hole. For accurately determining the position of the seed covered by the substrate within individual plug-tray holes, a novel method for detecting the growth points of plug seedlings has been proposed. It employs an adaptive grayscale processing algorithm based on the differential evolution extra-green algorithm to extract the contour features of seedlings during the early stages of cotyledon emergence. The pixel overlay curve peak points within the binary image of the plug-tray’s background are utilized to delineate the boundaries of the plug-tray holes. Each plug-tray hole containing a single seedling is identified by analyzing the area and perimeter of the seedling’s contour connectivity domains. The midpoint of the shortest line between these domains is designated as the growth point of the individual seedling. For laboratory-grown plug seedlings of tomato, pepper, and Chinese kale, the highest detection accuracy was achieved on the third-, fourth-, and second-days’ post-cotyledon emergence, respectively. The identification rate of missing seedlings and single seedlings exceeded 97.57% and 99.25%, respectively, with a growth-point detection error of less than 0.98 mm. For tomato and broccoli plug seedlings cultivated in a nursery greenhouse three days after cotyledon emergence, the detection accuracy for missing seedlings and single seedlings was greater than 95.78%, with a growth-point detection error of less than 2.06 mm. These results validated the high detection accuracy and broad applicability of the proposed method for various seedling types at the appropriate growth stages. Full article

Citrus nurseries significantly increase production costs due to the application of strictly technical and sanitary protocols. The growth media used are generally based on peat, a limited resource that is becoming increasingly scarce and consequently more expensive. Among the alternatives to peat is biochar, which could constitute a valid growing medium component for citrus seedling production. Three growth media were compared, each containing 50% sandy volcanic soil and the remaining 50% being: (i) biochar 50%; (ii) black peat 25% + biochar 25%; and (iii) black peat 25% + lapillus 25% as the control. The impact on the agronomic performance of citrus seedlings was assessed, and the involvement of specific genes in macronutrient uptake was evaluated. Destructive and molecular analyses were performed on leaves and roots during two different periods of the year: February and April. Based on physicochemical parameters and seedling growth, it can be assumed that peat can be partially substituted by conifer wood biochar in a total amount of 25 or 50%. A general comparison of the averages from the sampling and the various analyzed substrates revealed that in February, the evaluated genes involved in the absorption and transport of nutrients were differentially expressed in both leaves and roots, while in April, the expression was not consistent. Additionally, a general comparison between the analyzed tissues showed that, in most cases, expression was higher in the roots than in the leaves. Overall, a comparison among plants grown in different substrates indicated that the medium with 50% biochar displayed the highest expression levels. Full article

Most commercial citrus fruits are grown in acidic soils with high copper (Cu) and low organic matter levels in China. Sweet orange (Citrus sinensis (L.) Osbeck cv. Xuegan) seedlings were treated with 0 (HA0), 0.1 (HA0.1), or 0.5 (HA0.5) mM humic acid (HA) and 0.5 (Cu0.5) or 400 (Cu400 or Cu excess) μM CuCl₂ for 24 weeks. The purpose was to validate the hypothesis that HA reduces the oxidative injury caused by Cu400 in roots and leaves via the coordination of strengthened antioxidant defense and glyoxalase systems. Copper excess increased the superoxide anion production rate by 27.0% and 14.2% in leaves and by 47.9% and 33.9% in roots, the malonaldehyde concentration by 199.6% and 27.8% in leaves and by 369.4% and 77.4% in roots, and the methylglyoxal concentration by 18.2% and 6.6% in leaves and by 381.8% and 153.3% in roots, as well as the H₂O₂ production rate (HPR) by 70.5% and 16.5% in roots, respectively, at HA0 and HA0.5. Also, Cu400 increased the leaf HPR at HA0, but not at HA0.5. The addition of HA reduced the Cu400-induced production and accumulation of reactive oxygen species and methylglyoxal and alleviated the impairment of Cu400 to the antioxidant defense system (ascorbate-glutathione cycle, antioxidant enzymes, sulfur-containing compounds, and sulfur-metabolizing enzymes) and glyoxalase system in roots and leaves. The HA-mediated amelioration of Cu toxicity involved reduced oxidative injury due to the coordination of strengthened antioxidant defense and glyoxalase systems. These findings highlight the promise of HA for sustainable citrus cultivation in heavy metal (Cu)-polluted soils. Full article

An important issue in container nurseries is the production of seedlings of appropriate quality. These seedlings must meet specific biometric parameters and possess traits that ensure their suitability for later use in forest cultivation. One such traitis the ease of pulling the seedling out of the container cell, characterized by the pulling resistance. This resistance depends on many factors, including theseedling parameters, substrate, and container. In this work, a prototype measuring station was used to record seedling pull-out resistance as a function of their vertical displacement. Tests were conducted on 30 seedlings of each species: pine, beech, and oak. These were grown in polystyrene containers with cell volumes of 150 cm³ for pine (Pinus sylvestris L.) and 300 cm³ for beech (Fagus sylvatica L.) and oak (Quercus robur L.). Significant differences were observed in seedling extraction resistance between species, as well as between resistances associated with containers of different cell volumes. The maximum pull-out resistance of pine seedlingswas the lowest at 12.4 ± 8.58 N, followed by 22.5 ± 1.87 N for beech, and 33.5 ± 18.08 N for oak (extraction speed of 2.5 cm·s⁻¹).Similarly, the total energy required to extract pine seedlings was 0.358 ± 0.196 J, compared to 0.502 ± 0.316 J for beech and 1.479 ± 0.774 J for oak. The pattern of pull-out resistance regardingvertical displacement was consistent across all species. A correlation was found between the maximum pull-out resistance and the total energy required to extract the seedlings, along with biometric parameters such as root collar diameter, shoot height, dry mass of seedling parts, root volume, the extent of root ball overgrowth, and the volumetric density of the substrate within the cell.These relationships should be considered when designing devices for the automatic extraction of seedlings from polystyrene containers. Full article

As a result of climate change, drought and the unequal distribution of rainfall is a worldwide problem. Drought stress on plants affects not only the yield, but also the amount and ratio of bioactive components in tomato fruit. The aim of the present work was to investigate the effect of a new soil biodegradable water-retention agent (Water and Soil’s Water Retainer^®, Water and Soil Ltd., Budapest, Hungary) containing natural ingredients during the seedling period and under different irrigation conditions on the product volume, dry matter content and on some characteristic secondary metabolites in tomato fruits. The study was conducted to screen four different irrigation and soil treatment combination treatments for production and quality characteristics (polyphenols, tocopherols, carotenoids, vitamin C) to check the effect of seedling-stage stress on the tomato yield and bioactive components. Significant differences were found among the treatment and the cultivation seasons for the phytochemical content of fruits. The average yield and BRIX value did not change as a result of the Water Retainer^® compared to the irrigated samples, but the amount of lycopene, Vitamin C, antioxidant capacity, and total polyphenol content increased significantly with the use of the Water Retainer^®. In the two cultivation seasons, the highest concentration of lycopene and Vitamin C (114.30 ± 3.18 μg.g⁻¹ and 338.10 ± 13.70 μg.g⁻¹ fwt, respectively) was determined in fruits of 50% irrigation + 1.5 mL/m² WR^®-treated plants. The highest measured antioxidant capacity and total polyphenol content were 21.54 ± 0.17 mMTr/kg and 504 ± 44 mg GAE/kg, respectively, in the same treated samples. We found that seedlings exposed to drought stress, and after planting, when grown under ideal conditions in the field, can be distinguished from each other, despite the fact that there was only a difference between their cultivation during the seedling period. This may prove that rehydration is not sufficient to completely restore the metabolomic processes of stressed plants. Full article

Dianthus cruentus Griseb. (Caryophyllaceae) is an herbaceous perennial native to Greece with a strong ornamental potential when used as a pollinator-friendly component of xeric gardens and green roofs, where it is valued for its tolerance of poor, dry soils, and its showy colorful inflorescences. Aiming to develop an efficient mass propagation protocol appropriate for the introduction of the species as a novel floricultural crop, the in vitro seed and clonal propagation of a Greek native xeric ecotype were investigated in this paper for the first time. A total of 90–100% of the seeds, after being stored in the dark at room temperature for 12 months, germinated when incubated at 10 to 25 °C after their surface sterilization and transfer in vitro. Sixty-day-old seedlings grown in vitro were then used as a source of nodal explants for the initial establishment of micropropagation cultures, more efficiently on MS medium with 0.1 mg L⁻¹ 6-benzylaminopurine (BA). In the multiplication stage, either normal or hyperhydric micro-shoots were used as explant sources, assessing the possibility of incorporating usually discarded material in the propagation procedure. Different solid media were tested, with the highest multiplication indices (5.1) recorded in an MS medium containing 0.1 mg L⁻¹ BA and 0.05 mg L⁻¹ NAA, regardless of explants’ hyperhydricity, while an MS medium containing 0.1 mg L⁻¹ BA and 12 g L⁻¹ agar proved optimal for the effective reversal of hyperhydric explants (MI: 5.2). Despite higher hyperhydricity and reaction rates being observed when hyperhydric explants were used, modifications in the multiplication medium proved to be highly effective in controlling hyperhydricity, with the highest number of normal shoots (2.4–2.6) produced in BA-containing media. Micro-shoots rooted readily in ½ MS medium (60–100%), with rooting rates and quality positively affected by the presence of 0.5 mg L⁻¹ IBA in the rooting medium and the absence of cytokinins in the multiplication one. Rooted micro-shoots were successfully acclimatized ex vitro at high rates (65–100%), their origin influencing their acclimatization and morphology. Thus, the concurrent use of normal and hyperhydric shoots in the proposed micropropagation protocol is proven to be both feasible and desirable, as it is able to significantly increase efficiency and facilitate the sustainable exploitation and dissemination of D. cruentus as a promising multivalent horticultural crop. Full article

Pseudomonas jordanii strain G34 is a moderately halophilic endophytic bacterium isolated from the root tissue of durum wheat plants growing in the saline environment of the Jordan Valley’s Ghor Sweimeh region. Microscopic and biochemical analyses of P. jordanii strain G34 revealed that it is a Gram-negative, non-motile rod. It also exhibits capsule formation, catalase and oxidase positive reactions, indole positivity, citrate utilization, and non-glucose fermenting capability. Pseudomonas jordanii strain G34 showed growth-promoting effects on durum wheat seedlings grown under severe salinity stress conditions up to a 200 mM NaCl concentration. The draft genome of P. jordanii strain G34 comprises 5,142,528 base pairs (bp) and possesses a G + C content of 64.0%. It contains 57 RNA coding genes and is predicted to encode a total of 4675 protein-coding genes. Putative genes linked to various aspects of the bacterial endophyte lifestyle were identified including ion transport, motility, secretion, adhesion, delivery systems, and plant cell wall modification. Performing a comprehensive phylogenomic analysis identified P. jordanii as a new species, with its closest relative being P. argentinensis LMG 22563, sharing only around 40.2% digital DNA-DNA hybridization identity. Pseudomonas jordanii strain G34 holds great potential for future use as a biofertilizer in saline environments. Full article

Frass generated during the production of black soldier fly larvae is attracting the interest of scientists and horticultural producers because it is a material made from the biotransformation of organic waste, it contains several nutrients that can be used by plants, and it has a biostimulant capacity that has become a recent focus. Thermal composting is a stabilization process that improves the physical and chemical properties of treated wastes, allowing better performance in plants compared to the waste in its fresh state. In this research, thermocomposted frass was evaluated as a germination substrate for kale seeds (Brassica oleracea). To achieve this, the phytotoxicity of increasing concentrations of frass was evaluated by examining the germination of kale seeds, and seedlings were grown for 30 days in germination substrates mixed with 20, 40, 60, 80, and 100% frass under greenhouse conditions. The treatment with 20% frass showed the highest values of seedling height, stem diameter, number of leaves, length and width of the first true leaf and length and width of cotyledons, and reduced the contents of phenols, tannins and antioxidants. However, the content of flavonoids increased compared to the control and the rest of the mixtures. Full article

The objective of this study was to evaluate the effect of weed placement on the growth of container-grown ornamental plants. Additionally, it also assessed the safety of applying herbicides beneath and on the slits of air-pruning containers using four common container-grown ornamental plants. The study was divided into three experiments, with uniform liners of pentas (Pentas lanceolata (Forssk.) Deflers) and golden dewdrop (Duranta erecta L.) in the first experiment and pentas in the second. The weed seedlings, consisting of either ageratum (Ageratum houstonianum Mill.) or eclipta (Eclipta prostrata L.), were positioned in one of three locations within the container, either directly beside the rootball of the ornamental plant, 2.5 cm away from the rootball, or inside the drain hole of the container. The third experiment involved four ornamental species, which were utilized to assess the safety of herbicide application either beneath or on the slits of air-pruning containers. The overall results of the first two experiments revealed that weeds growing either at the center or the sides of the ornamental plant rootball had significant competitive effects on the growth of the ornamental species. In case of the third experiment, no herbicide injury was observed on the ornamental species, with a minor decrease in the growth of loropetulam (Loropetalum chinensis ‘Ruby’). Full article

Deep sowing is an efficient strategy for maize to ensure the seedling emergence rate under adverse conditions such as drought or low temperatures. However, the genetic basis of deep-sowing tolerance-related traits in maize remains largely unknown. In this study, we performed a genome-wide association study on traits related to deep-sowing tolerance, including mesocotyl length (ML), coleoptile length (CL), plumule length (PL), shoot length (SL), and primary root length (PRL), using 255 maize inbred lines grown in three different environments. We identified 23, 6, 4, and 4 quantitative trait loci (QTLs) associated with ML, CL, PL, and SL, respectively. By analyzing candidate genes within these QTLs, we found a γ-tubulin-containing complex protein, ZmGCP2, which was significantly associated with ML, PL, and SL. Loss of function of ZmGCP2 resulted in decreased PL, possibly by affecting the cell elongation, thus affecting SL. Additionally, we identified superior haplotypes and allelic variations of ZmGCP2 with a longer PL and SL, which may be useful for breeding varieties with deep-sowing tolerance to improve maize cultivation. Full article

To reveal genetic diversity for effective resistance to five foliar diseases and toxic aluminum ions, the entire collection of wheat species from the N.I. Vavilov All-Russian Institute of Plant Genetic Resources (VIR) originating from Ethiopia and Eritrea were studied regarding their traits. The collection contains 509 samples of four wheat species (Triticum aestivum—122 samples; T. aethiopicum—340 samples; T. polonicum—6 samples; and T. dicoccum—41 samples). The majority of accessions are new entries of landraces added to the Vavilov collection as a result of the Russian–Ethiopian expedition in 2012. Wheat seedlings were inoculated with causal agents of leaf rust (Pt), powdery mildew (Bgt), Septoria nodorum blotch (SNB), and dark-brown leaf spot blotch (HLB). The types of reaction and disease development were assessed to describe the levels of resistance. All samples of T. aethiopicum were also screened for seedling and adult resistance to Pt, Bgt, and yellow rust (Pst) under field conditions after double inoculation with the corresponding pathogens. To study tolerance to abiotic stress, seedlings were grown in a solution of Al³⁺ (185 µM, pH 4,0) and in water. The index of root length was used to characterize tolerance. Seedlings belonging to only two accessions out of those studied—k-68236 of T. aethiopicum and k-67397 of T. dicoccum—were resistant to Pt at 20 °C but susceptible at 25 °C. Specific molecular markers closely linked to the five genes for Pt resistance effective against populations of the pathogen from the northwestern region of Russia were not amplified in these two entries after PCR with corresponding primers. Four entries of T. dicoccum—k-18971, k-18975, k-19577, and k-67398—were highly resistant to Bgt. All samples under study were susceptible to HLB and SNB. Under field conditions, 15% of the T. aethiopicum samples were resistant to Pst, both at the seedling and the flag leaf stages, but all were susceptible to the other diseases under study. Among the evaluated samples, 20 entries of T. aestivum, 1 of T. polonicum (k-43765), and 2 of T. dicoccum (k-18971, k-67397) were tolerant to aluminum ions. The identified entries could be valuable sources for the breeding of T. aestivum and other wheats for resistance to biotic and abiotic stresses. Full article

Selenium (Se) and nitrate have the potential to modify rice root architecture, but it is unclear how Se is linked to changes in the rice seedlings nitrate status. Thus, rice seedlings were grown in nutrient solutions containing either 0- or 10-µM Se that were supplemented with 0.05 (low nitrate condition) or 5.0 mM nitrate (high nitrate condition). Se application to seedlings treated with low nitrate led to sugar accumulation in shoot and root and increased cytokinin concentrations in root, while decreasing cytokinin concentrations in shoot compared with seedlings in 0.05 mM nitrate alone. This, in turn, resulted in decreased shoot growth, while downregulation of OsXTH and OsEXP negatively affected root expansion. On the other hand, Se combined with 5.0 mM nitrate did not affect sugar concentration in tissues compared with seedlings in 5.0 mM nitrate. Moreover, Se negatively regulated the cytokinin biosynthesis in shoot and root of seedlings grown under 5.0 mM nitrate. The reduction in cytokinin concentrations by Se under high nitrate condition decreased shoot growth, but increased root growth through induction of OsXTH and OsEXP. Thus, many of the effects of Se in shoot and root growth are due to a shift in nitrate status of the seedlings. Full article