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Mutants lacking functional HYD2 homoeologs showed improved seedling growth, but comparable or increased susceptibility to salt stress in tillering plants, suggesting a developmentally restricted role of HYD2 in salt response. Salinity stress threatens global food security by reducing the yield of staple crops such as wheat (Triticum ssp.). Understanding how wheat responds to salinity stress is crucial for developing climate resilient varieties. In this study, we examined the interplay between carotenoid metabolism and the response to salt (NaCl) stress, a specific form of salinity stress, in tetraploid wheat plants with mutations in carotenoid β-hydroxylase 1 (HYD1) and HYD2. Our investigation encompassed both the vulnerable seedling stage and the more developed tillering stage of wheat plant growth. Mutant combinations lacking functional HYD2 homoeologs, including hyd-A2 hyd-B2, hyd-A1 hyd-A2 hyd-B2, hyd-B1 hyd-A2 hyd-B2, and hyd-A1 hyd-B1 hyd-A2 hyd-B2, had longer first true leaves and slightly enhanced root growth during germination under salt stress compared to the segregate wild-type (control) plants. Interestingly, these mutant seedlings also showed decreased levels of neoxanthin and violaxanthin (xanthophylls derived from β-carotene) and an increase in β-carotene in roots. However, tillering hyd mutant and segregate wild-type plants generally did not differ in their height, tiller count, and biomass production under acute or prolonged salt stress, except for decreases in these parameters observed in the hyd-A1 hyd-B1 hyd-A2 hyd-B2 mutant that indicate its heightened susceptibility to salt stress. Taken together, these findings suggest a significant, yet developmentally restricted role of HYD2 homoeologs in salt-stress response in tetraploid wheat. They also show that hyd-A2 hyd-B2 mutant plants, previously demonstrated for possessing enriched nutritional (β-carotene) content, maintain an unimpaired ability to withstand salt stress.

Numerous studies have shown reduced performance in plants that are surrounded by neighbours of the same species1,2, a phenomenon known as conspecific negative density dependence (CNDD)3. A long-held ecological hypothesis posits that CNDD is more pronounced in tropical than in temperate forests4,5, which increases community stabilization, species coexistence and the diversity of local tree species6,7. Previous analyses supporting such a latitudinal gradient in CNDD8,9 have suffered from methodological limitations related to the use of static data10-12. Here we present a comprehensive assessment of latitudinal CNDD patterns using dynamic mortality data to estimate species-site-specific CNDD across 23 sites. Averaged across species, we found that stabilizing CNDD was present at all except one site, but that average stabilizing CNDD was not stronger toward the tropics. However, in tropical tree communities, rare and intermediate abundant species experienced stronger stabilizing CNDD than did common species. This pattern was absent in temperate forests, which suggests that CNDD influences species abundances more strongly in tropical forests than it does in temperate ones13. We also found that interspecific variation in CNDD, which might attenuate its stabilizing effect on species diversity14,15, was high but not significantly different across latitudes. Although the consequences of these patterns for latitudinal diversity gradients are difficult to evaluate, we speculate that a more effective regulation of population abundances could translate into greater stabilization of tropical tree communities and thus contribute to the high local diversity of tropical forests.

Breeding perennial tree crops often requires prediction of mature performance from juvenile data. To assess the utility of juvenile screens to predict salinity tolerance of mature pistachio trees, we compared performance of 3-month ungrafted seedlings and 4-year-old grafted rootstocks under salinity stress. The QTL allele associated with higher salt exclusion from seedling leaves conferred lower growth in saline field conditions, suggesting that mapping QTL in seedlings may be easier than discerning the optimal allele for field performance.

BACKGROUND AND AIMS: Understanding shifts in the demographic and functional composition of forests after major natural disturbances has become increasingly relevant given the accelerating rates of climate change and elevated frequency of natural disturbances. Although plant demographic strategies are often described across a slow-fast continuum, severe and frequent disturbance events influencing demographic processes may alter the demographic trade-offs and the functional composition of forests. We examined demographic trade-offs and the shifts in functional traits in a hurricane-disturbed forest using long-term data from the Luquillo Forest Dynamics Plot (LFPD) in Puerto Rico. METHODS: We analysed information on growth, survival, seed rain and seedling recruitment for 30 woody species in the LFDP. In addition, we compiled data on leaf, seed and wood functional traits that capture the main ecological strategies for plants. We used this information to identify the main axes of demographic variation for this forest community and evaluate shifts in community-weighted means for traits from 2000 to 2016. KEY RESULTS: The previously identified growth-survival trade-off was not observed. Instead, we identified a fecundity-growth trade-off and an axis representing seedling-to-adult survival. Both axes formed dimensions independent of resprouting ability. Also, changes in tree species composition during the post-hurricane period reflected a directional shift from seedling and tree communities dominated by acquisitive towards conservative leaf economics traits and large seed mass. Wood specific gravity, however, did not show significant directional changes over time. CONCLUSIONS: Our study demonstrates that tree demographic strategies coping with frequent storms and hurricane disturbances deviate from strategies typically observed in undisturbed forests, yet the shifts in functional composition still conform to the expected changes from acquisitive to conservative resource-uptake strategies expected over succession. In the face of increased rates of natural and anthropogenic disturbance in tropical regions, our results anticipate shifts in species demographic trade-offs and different functional dimensions.

Abstract Dazomet is a dry powder formulation that releases toxic gas containing methyl isothiocyanate, which controls soil-borne pests and weeds, improving crop yields when applied to moist soils. To explore the efficacy of dazomet fumigation in the cultivation of the perennial herb Codonopsis pilosula, four typical cultivars (G1, G2, W1 and TCK) in Gansu Province were selected for seedling cultivation after soil fumigation (F) by dazomet, and non-fumigated soil was used as a control (CK). The experiments took 2 years to complete. The functional diversity of the soil enzymes and microorganisms, seedling emergence and physiological characteristics, and the quality and yield of Codonopsis seedlings and Radix were assessed. The results showed that the seed emergence rate, seedling re-green rate and several antioxidant enzymatic activities improved in the treatments involving soil fumigation with dazomet, and membrane lipid peroxidation in the seedlings decreased. On average, compared with those of the respective controls, the root viability and yield of the seedlings of the tested cultivars also increased by 34.87% and 42.4%, respectively, and the incidence of root rot in the seedlings was reduced by 83.9%, compared with their respective controls. After harvest, the yield increased by 23.9%, the incidence of root rot decreased by 61.3%, increase in yield and a 61.3% reduction in incidence, and the medicinal materials were determined to be safe and residue-free. The effects of fumigation were cultivar-specific and were especially prominent in G2. Therefore, soil fumigation with dazomet could improve the quality and productivity of Codonopsis pilosula seedlings. Taken together, these findings suggest that when herbs are bred by seedling transplantation, especially cultivars of good quality but poor resistance or species with rare germplasm resources, soil fumigation provides a way to improve cultivation effectiveness and, more importantly, ensures the probability of successfully breeding the species.

The use of mycorrhiza and seaweed are becoming significant and complementary applications in different production systems because organisms increased quality of seedlings and crop yield. This study has been conducted under growth chamber conditions to determine some of the seedling growth parameters (length (cm), stem diameter (mm), fresh weight (g plant −1), dry weight (g plant −1), root fresh weight (g plant −1), root dry weight (g plant −1), leaf area (cm2 plant−1), SPAD, photosynthesis rate (%) and color parameters). As a plant material, Cuma F1 and Mert F1 genotype seeds were sown. Endo Roots Soluble (Mycorrhiza (ERS)) and MC-Extra (Seaweed) were applied in different doses (0, 250 and 500 mg kg−1) to seedling growing vessels at a rate of 10 ml per plant. Treatment effects in tomato were found statistically significant (p ≤.01**) on stem diameter, fresh weight, dry weight. Seedling length, leaf area and SPAD results were also statistically significant (p ≤.01**), and the results of these parameters were higher in ERS. ERS increases the leaf area and SPAD measurements in tomato seedlings. The results of pepper measurements were found to be statistically significant at p ≤.05* on root fresh weight, SPAD and photosynthesis rate. The highest values of root fresh weight, SPAD were obtained from 250 mg kg−1 doses of ERS; the highest value of photosynthesis rate was measured from 500 mg kg−1 doses of ERS on pepper. The effect of 500 mg kg−1 ERS on seedling growth was found statistically significant in pepper. [ABSTRACT FROM AUTHOR]

Background: Cadmium (Cd) pollution has declined crop yields and quality. Selenium (Se) is a beneficial mineral element that protects plants from oxidative damage, thereby improving crop tolerance to heavy metals. The molecular mechanism of Se-induced Cd tolerance in rice (Oryza sativa) is not yet understood. This study aimed to elucidate the beneficial mechanism of Se (1 mg/kg) in alleviating Cd toxicity in rice seedlings. Results: Exogenous selenium addition significantly improved the toxic effect of cadmium stress on rice seedlings, increasing plant height and fresh weight by 20.53% and 34.48%, respectively, and increasing chlorophyll and carotenoid content by 16.68% and 15.26%, respectively. Moreover, the MDA, ·OH, and protein carbonyl levels induced by cadmium stress were reduced by 47.65%, 67.57%, and 56.43%, respectively. Cell wall metabolism, energy cycling, and enzymatic and non-enzymatic antioxidant systems in rice seedlings were significantly enhanced. Transcriptome analysis showed that the expressions of key functional genes psbQ, psbO, psaG, psaD, atpG, and PetH were significantly up-regulated under low-concentration Se treatment, which enhanced the energy metabolism process of photosystem I and photosystem II in rice seedlings. At the same time, the up-regulation of LHCA, LHCB family, and C4H1, PRX, and atp6 functional genes improved the ability of photon capture and heavy metal ion binding in plants. Combined with proteome analysis, the expression of functional proteins OsGSTF1, OsGSTU11, OsG6PDH4, OsDHAB1, CP29, and CabE was significantly up-regulated under Se, which enhanced photosynthesis and anti-oxidative stress mechanism in rice seedlings. At the same time, it regulates the plant hormone signal transduction pathway. It up-regulates the expression response process of IAA, ABA, and JAZ to activate the synergistic effect between each cell rapidly and jointly maintain the homeostasis balance. Conclusion: Our results revealed the regulation process of Se-mediated critical metabolic pathways, functional genes, and proteins in rice under cadmium stress. They provided insights into the expression rules and dynamic response process of the Se-mediated plant resistance mechanism. This study provided the theoretical basis and technical support for crop safety in cropland ecosystems and cadmium-contaminated areas. Highlights: Se could improve the growth inhibition of rice under Cd stress. Se mediated the increase of photosynthetic pigment content. Se up-regulates functional genes and proteins involved in the photosynthetic system. Se-mediated decreased the content of MDA, ·OH, and protein carbonyl. Se-mediated plant hormone signal transduction plays a vital role in Cd detoxification. [ABSTRACT FROM AUTHOR]

In February 2021, damping off and collar and root rot on coriander (Coriandrum sativum L.) became widespread in the municipality of Vitória da Conquista, Bahia, Brazil. An oomycete was isolated from root and collar segments of affected seedlings and caused the same symptoms in inoculated seedlings. Based on morphological features and DNA sequences from the ITS and cox2 region, the pathogen was identified as Pythium aphanidermatum. To the best of our knowledge, this is the first report of the occurrence of P. aphanidermatum on coriander plants in Brazil. [ABSTRACT FROM AUTHOR]

This study characterizes seedling exudates of peas, tomatoes, and cucumbers at the level of chemical composition and functionality. A plant experiment confirmed that Rhizobium leguminosarum bv. viciae 3841 enhanced growth of pea shoots, while Azospirillum brasilense Sp7 supported growth of pea, tomato, and cucumber roots. Chemical analysis of exudates after 1 day of seedling incubation in water yielded differences between the exudates of the three plants. Most remarkably, cucumber seedling exudate did not contain detectable sugars. All exudates contained amino acids, nucleobases/nucleosides, and organic acids, among other compounds. Cucumber seedling exudate contained reduced glutathione. Migration on semi solid agar plates containing individual exudate compounds as putative chemoattractants revealed that R. leguminosarum bv. viciae was more selective than A. brasilense, which migrated towards any of the compounds tested. Migration on semi solid agar plates containing 1:1 dilutions of seedling exudate was observed for each of the combinations of bacteria and exudates tested. Likewise, R. leguminosarum bv. viciae and A. brasilense grew on each of the three seedling exudates, though at varying growth rates. We conclude that the seedling exudates of peas, tomatoes, and cucumbers contain everything that is needed for their symbiotic bacteria to migrate and grow on. [ABSTRACT FROM AUTHOR]

Drought has a direct impact on rice growth performance at various stages. Nevertheless, the impact of nanoparticles on the rice seedlings under drought stress remained limited. Thus, a laboratory experiment was conducted to investigate the effects of different concentrations (300, 600, and 900 mg/L) of silica nanoparticles (SiNPs) on morpho-histological and biochemical features of two rice varieties (UMT-R and MR219) under drought stress (15 % PEG). The findings indicated a substantial reduction due to drought stress in the growth, protein, and antioxidant enzymes, while increasing the proline, malondialdehyde (MDA), and hydrogen peroxide (H 2 O 2) content, and negatively affecting the root histology. Results showed that SiNPs at 600 mg/L were managed to improve plant growth, root vigour, and enzymatic antioxidant levels. Under SiNPs treated plants, among UMT-R and MR219, the proline (1.947 and 1.748 in leaves, 2.010 and 1.890 U/mg protein in roots), peroxidase (POD) (2.850 and 3.512 in leaves, 2.521 and 2.952 U/mg protein in roots), superoxide dismutase (SOD) (3.958 and 4.558 in leaves, 4.296 and 4.606 U/mg protein in roots), and catalase (CAT) (2.171 and 2.289 in leaves, 1.897 and 2.050 U/mg protein in roots) were higher than the drought stress conditions. Meanwhile, the nonenzymatic antioxidant, MDA (0.974 and 0.812 in leaves, 0.842 and 0.778 U/mg Protein in roots), and H 2 O 2 (1.378 and 1.229 in leaves, 1.280 and 1.054 U/mg Protein in roots) showed an opposite trend. SiNPs application noticeably enhanced the histological features of roots under drought conditions. The current findings suggested that SiNPs at 600 mg/L can mitigate the adverse impacts of drought stress and enhance the plant's resistance. Further study should be carried out on the reproductive stage and post-harvest performance of drought-stress rice treated with SiNPs. [Display omitted] • SiNPs treatment significantly increased plant growth under drought conditions. • SiNPs have a significant effect on the root histological traits. • SiNPs significantly enhance protein, proline, SOD, POD, and CAT content. • UMT-R was more sensitive to drought stress as compared to MR219. [ABSTRACT FROM AUTHOR]

In light of the environmental pollution resulting from the excessive use of chemical fertilizers, several methods, including the analysis of morphological and cultural characteristics as well as ITS rDNA sequencing, were utilized to identify the strain and evaluate its phosphate solubilizing capacity. A controlled greenhouse pot experiment was then conducted to assess the effects of the phosphate solubilizing bacteria strain Y-5 on crop growth and soil fertility. The identification results revealed that the phosphate solubilizing strain, Y-5, belongs to Pseudomonas donghuensis. Under liquid culture for 5 days, the ratio of the phosphate solubilizing ring's diameter to the colony's diameter (D/d) was 3.51. Notably, strain Y-5 exhibited exceptional phosphate solubilization efficiency, with a maximum phosphate solubilizing amount of calcium phosphate reaching 432.25 mg/L. Furthermore, the highest phosphate soluble content of lecithin was 116.37 mg/L, highlighting its robust phosphate solubilizing capacity. The pot experiment results revealed that the modified biochar of strain Y-5 effectively enhances the content of available phosphate and organic matter in soil. Additionally, the modified biochar of the Y-5 strain exerted a significant growth-promoting effect on corn seedlings. Based on the indices of maize seedling growth and soil property changes, it was determined that the optimal application ratio of Pseudomonas donghuensis modified biochar was approximately 10 g/kg. This research result significantly reduced the cost of popularizing and applying phosphate solubilizing bacteria modified biochar and served as a new agricultural material with good prospects for popularization and application, potentially contributing to the green and sustainable development of agriculture in the future. [ABSTRACT FROM AUTHOR]

Salt stress causes deleterious impacts on the germination, growth, and productivity of various crop plants. Screening new cultivars regarding salt stress tolerance could enhance the growth and productivity of sorghum. In this regard, an experiment was conducted at the laboratory of the Department of Agronomy, Hajee Mohamad Danesh Science and Technology University (HSTU), Bangladesh, in October 2018 to find out salt tolerance based on seed germination and seedling growth traits. The experiment consisted of seven sorghum varieties, viz. Adan Gab, Karmici, Debuday, ESP/S01, Green Jambuplus, Jambo, and Elmi Jama, and three levels of salt stress, viz. 0, 100, and 200 mM NaClinduced salt stress, laid out completely randomized design (CRD) with three replications. The seeds of the seven sorghum varieties were placed in plastic trays (20 cm x 10 cm) on a sand bed irrigated with tap water (control) and NaCl (100 and 200 mM salinity levels) solutions. Data were collected on germination character and seedling growth at parameters. The collected data were analyzed statistically and means were adjudged by DMRT at 1 and 5% level of probability. The results of the experiment revealed that salinity stress significantly reduced the germination percentage (GP) and germination rate (GR) of sorghum in all sorghum varieties, and the variety Debuday showed the highest values of GP and GR, while Karmici showed the lowest values under 100 and 200 NaCl stress. Moreover, the root and shoot lengths, fresh weights, and dry weights gradually decreased with salinity levels, and the minimum reduction was recorded in Debuday, whereas the maximum reduction was in the Karmici variety. Higher Na and lower K accumulation of the Debuday genotype can be treated as salt tolerant. Contrary, the salt tolerance index (STI) based on the root and shoot dry weight in the Debuday variety exhibited the highest values, and the Karmici variety exhibited the minimum values under salt stresses. The inhibition of GP and GR, and lengths and biomass weight of root and shoot, were at the minimum level, while, on the contrary, the values declined superficially in the Karmici variety. Therefore, it can be concluded that the variety Debuday is indorsed as a salt-tolerant sorghum variety, and Karmici is a more susceptible one, based on the seed germination and seedling growth properties. [ABSTRACT FROM AUTHOR]

The aim of the present study was to assess the selectivity of herbicides applied in the pre and post-planting of pre-sprouted seedlings (PSS). The experiment was conducted in a greenhouse, using a completely randomized design, with nine treatments and four repetitions. The IACSP95-5000 cultivar was used. The treatments consisted of herbicides applied in five doses as follows: in pre-planting: sulfentrazone, diclosulam, imazapic, and imazapyr, in post-planting: ethoxysulfuron, halosulfuron, 2,4-D and MSMA, and a control treatment without herbicide. Injury symptoms were assessed at 7, 15, 30, 45, 60, 75, and 90 days after application (DAA), height, diameter, number of tillers, chlorophyll A, B, and total chlorophyll at 30, 60, and 90 DAA, leaf area, shoot and root dry mass at 90 DAA. The post-emergent herbicides were considered selective. Pre-planting herbicides reduced the variables assessed at 90 DAA, observed by linear regression for diclosulam and imazapic, and exponential regression for imazapyr. Treatments with sulfentrazone caused few injury symptoms, with subsequent recovery. In addition, all the variables analyzed were equal to control, with the sulfentrazone considered selective for the IACSP95-5000 cultivar. [ABSTRACT FROM AUTHOR]

Our experiments explored the effects of far-red (FR) light on cucumber (Cucumis sativus L. 'Zhongnong No. 26') seedling growth. Our results indicated that FR light significantly promoted the growth of cucumber seedlings. Specifically, it promoted the accumulation of shoot biomass and the elongation of internodes and leaves (except the first leaf at the bottom). Further analysis showed that FR light had no effect on the accumulation contents of abscisic acid (ABA) and auxin (IAA) in seedling leaves. Still, it significantly caused the increase of the gibberellin (GA3, GA4, and GA7) contents and the decrease of GA1 content, which suggested that the leaf expansion progress under FR light may be primarily related to GA. Therefore, the cucumber seedling leaf expansion response to GA was evaluated under different light sources. The exogenous spraying of different GA4/7 contents significantly promoted the leaf expansion of cucumber seedlings under white light, while the GA biosynthesis inhibitor paclobutrazol (PAC) significantly promoted the expression of GA hydrolytic genes (GA2ox2 and GA2ox4) and decreased the content of endogenous active GA, which inhibited the leaf expansion induced by FR light. As expected, the combination of exogenous GA4/7 and PAC restored the growth promotion effect of FR light on cucumber seedling leaves. It increased the contents of endogenous active GA (GA1, GA3, GA4, and GA7), and the expression trend in GA synthetic/hydrolytic-related genes was the opposite of that of PAC was applied alone. All of the above results indicated that FR light regulates leaf expansion progress in cucumber seedlings through GA. [ABSTRACT FROM AUTHOR]

Among the several factors limiting sugarcane production, the occurrence and severity of diseases such as orange rust is one of the reason for replacing cultivars and the use of silicon (Si) can reduce the intensity of diseases caused by pathogens. This study was carried out to evaluate the effect of a preventive application of Si to suppress the intensity of orange rust caused by Puccinia kuehnii on sugarcane seedlings. Three experiments under house conditions have been conducted using a Randomized Block Design with two in a 2x5 factorial scheme (soil with and without Si application x five foliar treatments), with variety RB92-579 and SP81-3250, and a third study with 13 treatments (soil and foliar treatments) with variety SP-015503. RB92-579 showed higher dry mass without Si application in the soil whereas higher levels of Si content in plants and soil with soil treated with Si was verified. Foliar treatments showed higher values of height, dry mass, and Si uptake. The severity level of orange rust on SP81-3250 with soil treated with Si was lower than on untreated soil. SP-015503 showed a dry mass and Si uptake increase with foliar treatments, especially with silicic acid. K silicate and silicic acid showed lower severity of orange rust than the control and fungicide. Si was able to reduce the severity of orange rust and improve plant development even though it does not have effectiveness as a preventive treatment to control orange rust in one of the studied varieties. [ABSTRACT FROM AUTHOR]

Ascochyta blight and Fusarium root rot are the most serious fungal diseases of pea, caused by D. pinodes and F. avenaceum, respectively. Due to the lack of fully resistant cultivars, we proposed the use of biologically synthesized silver nanoparticles (bio-AgNPs) as a novel protecting agent. In this study, we evaluated the antifungal properties and effectiveness of bio-AgNPs, in in vitro (poisoned food technique; resazurin assay) and in vivo (seedlings infection) experiments, against D. pinodes and F. avenaceum. Moreover, the effects of diseases on changes in the seedlings' metabolic profiles were analyzed. The MIC for spores of both fungi was 125 mg/L, and bio-AgNPs at 200 mg/L most effectively inhibited the mycelium growth of D. pinodes and F. avenaceum (by 45 and 26%, respectively, measured on the 14th day of incubation). The treatment of seedlings with bio-AgNPs or fungicides before inoculation prevented the development of infection. Bio-AgNPs at concentrations of 200 mg/L for D. pinodes and 100 mg/L for F. avenaceum effectively inhibited infections' spread. The comparison of changes in polar metabolites' profiles revealed disturbances in carbon and nitrogen metabolism in pea seedlings by both pathogenic fungi. The involvement of bio-AgNPs in the mobilization of plant metabolism in response to fungal infection is also discussed. [ABSTRACT FROM AUTHOR]

Allelopathy is the chemical interactions between plants that might lead to either stimulation or inhibition of growth, community structure, and plant invasions. Lantana camara L. is a noxious invasive weed that negatively affects seed germination, seedling growth, and increases the mortality of the crop plant. The objective of this work was to assess allelopathic effect of L. camara leaf aqueous extract on germination and seedling growth of Capsicum annuum (pepper) and Daucus carota (carrot). The aqueous extract of Lantana leaf samples was used as a source of allelopathic effects. Data were collected for germination and seedling growth parameters. The result indicated that the highest concentration of the allelopathic extract (20 mg/L) has demonstrated significantly the highest germination inhibition rate GIR (60.00%), germination speed V (2.54 U/day) for D. carota as GIR (70.00%), mean germination time MGT (0.36 days), and GI (0.67%) for C. annuum seeds. The highest concentration of the allelopathic extract (20 mg/L) has recorded the highest plumule inhibition rate PIR (59.63%) and radical inhibition rate RIR (48.95%) for D. carota seeds, as well as PIR (27.47%) and RLR (79.49%) for C. annuum. The largest negative allelopathic index (−60.00% or allelopathic intensity of 60.00%) was recorded for D. carota seeds, whilst (−63.43% or allelopathic intensity of 63.43%) was recorded for C. annuum seed germination. For D. carota seed germination, the first principal component (PC1) has got high positive loads from GI (0.36), RLR (0.31), GR (0.34), allelopathic index AI (0.34), relative length of plumule RLP (0.24), and V (0.30). By contrast, PC1 for D. carota seed germination has got the highest negative component loads recorded by GIR (−0.34), PIR (−0.24), MGT (−0.35), and RIR (−0.31). In allelopathic effect on C. annum seed germination, the first principal component (PC1) has got high positive scores from relative length of radical RLR (0.31), RLP (0.33), germination rate GR (0.33), V (0.33), and AI (0.33). Likewise, the high negative component loads were recorded by GIR (−0.33), PIR (−0.33), RIR (−0.31), and MGT (−0.32). The result of the present study demonstrated that GIR, PIR, and RIR were directly related to negative allelopathic activity. [ABSTRACT FROM AUTHOR]

Using Cinnamomum saxatile as the material, a four-factor and four-level orthogonal design was adopted to explore the effects of proportional fertilization of N, P, K, Ca on the growth of one-year-old C. saxatile seedlings. The purpose of the study was to provide scientific basis for fertilization of C. saxatile. The results showed that the diameter and height of C. saxatile increased in general when the application time of N, P, K and Ca fertilizers was 30-150 d. The average value was 1. 11-1. 61 times and 1. 23-2. 17 times than the first fertilization. The effects of different fertilization treatments on the diameter and height of C. saxatile seedlings were significantly different. The best performance of growth was the combination of T8(N1P3K2Ca1 ). The effect of N fertilizer on the diameter and height of C. saxatile seedlings was significant, but the effect of P and K fertilizer was not. The effect of Ca fertilizer on height was significant, but not on diameter. The diameter growth reached the maximum at N1(100 mg / plant N) level. In conclusion, N1P3K2Ca1(100 mg / plant N+80 mg / plant P+40 mg / plant K)was the most suitable fertilizer combination to promote the growth of C. saxatile seedlings under the study conditions. [ABSTRACT FROM AUTHOR]

Seed germination is an important development process in plant growth. The phytohormone abscisic acid (ABA) plays a critical role during seed germination. However, the mechanism of rapeseed in response to ABA is still elusive. In order to understand changes of rapeseed under exogenous ABA treatment, we explored differentially expressed metabolites (DEMs) and the differentially expressed genes (DEGs) between mock- and ABA-treated seedlings. A widely targeted LC-MS/MS based metabolomics were used to identify and quantify metabolic changes in response to ABA during seed germination, and a total of 186 significantly DEMs were identified. There are many compounds which are involved in ABA stimuli, especially some specific ABA transportation-related metabolites such as starches and lipids were screened out. Meanwhile, a total of 4440 significantly DEGs were identified by transcriptomic analyses. There was a significant enrichment of DEGs related to phenylpropanoid and cell wall organization. It suggests that exogenous ABA mainly affects seed germination by regulating cell wall loosening. Finally, the correlation analysis of the key DEMs and DEGs indicates that many DEGs play a direct or indirect regulatory role in DEMs metabolism. The integrative analysis between DEGs and DEMs suggests that the starch and sucrose pathways were the key pathway in ABA responses. The two metabolites from starch and sucrose pathways, levan and cellobiose, both were found significantly down-regulated in ABA-treated seedlings. These comprehensive metabolic and transcript analyses provide useful information for the subsequent post-transcriptional modification and post germination growth of rapeseed in response to ABA signals and stresses. [ABSTRACT FROM AUTHOR]

Summary: The dimensions and distribution pattern of bordered pits are critical to the xylem water transport function of trees. However, studies on the three-dimensional distribution pattern of pits across xylem growth rings are still limited. Here, Micro-Computed Tomography (Micro-CT) was used to acquire xylem images of two-year-old Platycladus orientalis seedlings. We analyzed the tracheid lumen diameter of 665 tracheids, pit volume, and pit diameter of 11 810 inter-tracheid pits from three radial profiles. The volume ratio of inter-tracheid pits was about 0.90–0.96%. The average pit diameter was 6.8 μm and the average pit volume was 58.9 μm3, and more than 80% of the pits had a diameter of 5–8 μm and a volume of 20–90 μm3. Both the pit diameter and the pit volume increased gradually in the radial direction from the second-year growth ring to the current-year growth ring, and the pit diameter and volume were significantly higher in earlywood than in latewood. The distribution pattern of the tracheid diameter was similar to that of the pit diameter, and the wider the tracheids, the larger the pits. The distribution of bordered pits in P. orientalis may be a critical trait explaining the xylem embolism spread pattern in this species. [ABSTRACT FROM AUTHOR]

The giant sequoia, a serotinous conifer naturally occurring in mixed‐conifer forests of the southern and central Sierra Nevada, California, USA, is the world's largest tree species. Giant sequoia reproduction has been severely lacking over the past century, due to fire exclusion, creating a significant conservation threat. Previous research on postfire sequoia reproduction in high‐severity fire areas, relative to low‐ and moderate‐severity areas, is limited. At 6 years postfire, we investigated giant sequoia reproduction in a high‐severity fire area, and nearby low‐/mixed‐severity fire areas, in the Nelder Grove, which burned in 2017 in the Railroad fire. Postfire giant sequoia reproduction was positively correlated with fire severity in terms of density, height (growth), and proportion (relative to other conifer species), and sequoia seedling/sapling density was positively correlated with percent shrub cover. There was no correlation between distance to live sequoia seed source and density of sequoia reproduction. More research is needed in other mixed‐severity fire areas, with larger high‐severity fire patches, to determine whether a similar postfire response occurs elsewhere. [ABSTRACT FROM AUTHOR]

Epiphytic orchids comprise 68% of vascular epiphytes globally; nevertheless, many are endangered. One such epiphytic orchid is Phalaenopsis japonica, which is widely used in the floricultural industry. This study aimed to identify the mycorrhizal fungi of adult P. japonica and their roles in seed germination and seedling development. Root samples were collected from 32 adults across 4 sites in southern Japan, and mycorrhizal fungi were identified using Sanger and high-throughput sequencing (HTS). The results show phylogenetically diverse mycobionts, mainly Ceratobasidiaceae (CE) and Tulasnellaceae (TU), with dominant OTUs designated CE6 and CE22. Sanger sequencing found 9 OTUs, 4 CE, and 5 TU; HTS detected 22 OTUs, 4 CE, 16 TU, and 2 Serendipitaceae. Seeds inoculated with CE6 improved germination and protocorm development compared with other strains. In addition, asymbiotic seedlings inoculated with CE6, CE22, and TU18 displayed varying effects in growth, with CE6 being the most notable. While TU18 did not promote seed germination, it effectively promoted leaf development in seedlings. Overall, Ceratobasidiaceae was predominantly associated with seed germination, seedling growth, and the adult stages, with CE6 and CE22 becoming the primary partners throughout the life history of P. japonica. Our findings illuminate mycorrhizal symbiosis in epiphytic habitats, offering conservation and commercial production insights. [ABSTRACT FROM AUTHOR]

Drought stress poses significant productivity challenges to wheat. Several studies suggest that lower malondialdehyde (MDA) content may be a promising trait to identify drought-tolerant wheat genotypes. However, the optimal polyethylene glycol (PEG-6000) concentration for screening seedlings for drought tolerance based on MDA quantification is not clear. The aim of this study was to verify whether a 10% (w/v) PEG-6000 concentration-induced water stress was reliable for discriminating between twenty-two drought-susceptible and drought-tolerant tetraploid wheat (Triticum turgidum spp. durum, turanicum, and carthlicum) accessions based on MDA quantification. To do so, its correlation with morpho-physiological traits, notoriously related to seedling drought tolerance, i.e., Seedling Vigour Index and Seedling Water Content, was evaluated. Results showed that MDA content was not a reliable biomarker for drought tolerance, as it did not correlate significantly with the aforementioned morpho-physiological traits, which showed, on the contrary, high positive correlation with each other. Combining our study with the cited literature, it clearly emerges that different wheat genotypes have different "water stress thresholds", highlighting that using a 10% PEG-6000 concentration for screening wheat seedlings for drought tolerance based on MDA quantification is not reliable. Given the conflicting results in the literature, this study provides important insights for selecting appropriate methods for evaluating wheat seedling drought tolerance. [ABSTRACT FROM AUTHOR]

Due to intense ash dieback, this research tested the bioactivity of Thymus vulgaris, Lavandula angustifolia, and Cupressus sempervirens essential oils (EO) against Hymenoscyphus fraxineus. In vitro testing showed that EOs had a pronounced fungitoxic effect on H. fraxineus. The most effective EO was extracted from T. vulgaris, while EOs obtained from L. angustifolia and C. sempervirens were less effective and showed the same effect. At a concentration of 1%, all tested EOs inhibited mycelial growth, while 0.01% and 0.1% concentrations of EO extracted from T. vulgaris also inhibited the growth of H. fraxineus. The in planta test of EO extracted from T. vulgaris conducted on three‐year‐old Fraxinus angustifolia seedlings showed a reduction in the size of necrotic lesions and a better crown condition compared to untreated seedlings. This research demonstrates, for the first time, the efficiency of EOs in suppressing ash dieback making a path for the development of new biological protection measures against H. fraxineus. [ABSTRACT FROM AUTHOR]

Intercropping soybean in tea plantations is a sustainable cultivation system that can improve the growing environment of tea plants compared to monoculture tea. However, the effects of this system on the photosynthesis activity of tea seedlings have yet to be reported. Therefore, we used tea cultivar 'Zhongcha108' as experimental materials to investigate the effects of intercropping soybean on the canopy spectral parameters and photosynthesis activity of tea seedlings. Canopy spectral reflectance data showed that soybean–tea intercropping (STS) improved the reflectance of 720, 750 and 840 nm bands in tea seedlings' canopy. The vegetation indexes (VIs) value related to photosynthetic pigments in STS was obviously higher than monoculture tea (T). In addition, the Fv/Fm and SPAD value in STS were also clearly higher. Transcriptome analysis data indicated that STS induced the expression of light-harvesting complex (LHC) genes, photosystem subunit (Psbs and Psas) genes and dark reaction biological process genes (FBP1, RPE, Calvin cycle protein CP12-1 and transketolase). These results indicate that STS enhanced the photosynthesis activity. The metabolome analysis showed that STS promoted the accumulation of carbohydrate metabolites, which further provided evidence for the enhancement of photosynthesis in the leaves of tea seedlings. This study enhanced our understanding of how intercropping soybeans in a young tea plantation improves the photosynthesis activity to promote tea seedlings' growth and development. [ABSTRACT FROM AUTHOR]

Salt stress exerts adverse effects on yield by inhibiting or delaying seed germination and impeding seedling growth. Additionally, different salt concentrations have adverse effects on plant wet and dry weight and stem and shoot development. Crotalaria juncea L., the fastest-growing species within the Crotalaria genus, demonstrates a high degree of adaptability to both tropical and subtropical climates. To assess the tolerance of sunn hemp to salinity during the germination and early seedling stages, several indicators were determined at different (0, 50, 100, 150, 200, 250, and 300 mM) salt concentrations. Germination was conspicuously absent at salt concentrations of 250 mM and 300 mM. Notably, seedling characteristics, such as shoot length, root length, root fresh weight, seedling fresh weight, retention capability of the shoot, and the relative water content, experienced adverse effects with escalating salt concentrations. Intriguingly, the apex of seedling and root dry weights manifested at the pinnacle of salt concentration at 200 mM. Despite the discernible influence of heightened salt concentrations during the nascent seedling stage, the tolerance index was quantified at 100 mM, 150 mM, and 200 mM. Analyzing the study results through the lens of macro-minerals revealed an augmentation in Na and Cl content concomitant with increasing salt concentrations. [ABSTRACT FROM AUTHOR]

To address the lack of effective monitoring, evaluation, and prediction methods for water stress in citrus seedlings, we conducted 10 sets of water stress gradient experiments. Based on the experimental dataset, we constructed, trained, and improved an MLP classification model for citrus seedling water stress. In addition, we developed a monitoring, evaluation, and prediction system based on this model. The experiments demonstrated that 7 days of slight water stress can induce changes in overall root wilting and growth stagnation, and the chlorophyll content in the leaves can decrease by up to 11.78%. Furthermore, the optimal VWC for seedlings was [45%, 50%], the boundary of drought was [20%, 25%], and the boundary of waterlogging was [50%, 55%]. We validated the effectiveness of the system in assessing the growth status of seedlings over the past 7 days and predicting it after 7 days through testing sets and experiments on slight water stress. We found that the system achieved non-destructive remote monitoring, evaluation, and prediction of slight water stress in citrus seedlings, thus enhancing seedling quality. These research findings provide valuable insights into water stress management in citrus seedlings and other crops. [ABSTRACT FROM AUTHOR]

Plant growth and physiology can be affected by environmental and chemical factors that have the potential to influence yields. Among the factors that influence plant growth, neonicotinoid seed treatments have shown significant effects on plant growth, particularly in cotton. The dual benefits seen from neonicotinoids on plant growth and insect control show promise in improving cotton yields but little is known about how different seed treatments affect seedling physiology. A greenhouse experiment was undertaken to investigate how three neonicotinoid seed treatments (clothianidin, thiamethoxam, and imidacloprid) affect the physiology and growth of cotton seedlings in controlled environmental conditions. A randomized complete block design was used to examine seed treatments and an untreated control. Cotton seeds were treated, grown, and evaluated for physiological changes until the fifth true leaf-stage and measurements were taken at each of these stages. Data were collected on plant height, shoot fresh weight, leaf area, root length, and root biomass. In addition, chlorophyll pigments and nutrient analysis were performed on cotton seedlings. The seedlings of imidacloprid treated seeds had greater height, shoot fresh mass, leaf area, and relative growth rate by the fifth true leaf stage compared to other treated plants; however, clothianidin showed comparative performance at earlier stages in plant development that equilibrated over time. While all neonicotinoid seed treatments showed positive effects, imidacloprid showed the most potential as a bioactivator on plant growth. [ABSTRACT FROM AUTHOR]

The tolerance of Moringa oleifera plants to excess K may be linked to nutritional mechanisms, but studies are lacking. The present study was conducted to analyze the tolerance of Moringa oleifera to nutritional imbalance and its importance in the growth of plants submitted to high doses of K in the absence and presence of N. The experiment was conducted in pots with 9 dm3 of Oxisol in a 4 × 2 factorial scheme, with potassium doses of 0, 110, 190, and 265 mg dm−3 combined with nitrogen doses of 0 and 100 mg dm−3. The increase in K uptake by moringa is enhanced by N supply but decreases the uptake of Ca and Mg. Notwithstanding, this was of little importance as the soil cultivated had adequate Ca and Mg contents and was sufficient for adequate plant nutrition without impairing plant growth. The moringa plant is tolerant to nutritional imbalances when grown in environments with high K content probably because N favors an increase in Mg use efficiency, avoiding biological disturbances. The results of this study contributed to our understanding of how moringa induces nutritional mechanisms of action to deal with excess K in crops. [ABSTRACT FROM AUTHOR]

The plant growth regulator gibberellic acid (GA) and the herbicide glyphosate were examined for their possible interactions with growth and phenolic metabolism in soybean [Glycine max (L.) Merr. Cv. Hill] seedlings. GA caused increases in phenylalanine ammonia-lyase activity (PAL) (per axis basis) above those of the control seedling levels 48 h after treatment in light-grown seedlings. This effect increased to two-fold greater than control levels by 72 and 96 h after treatment. In dark-grown plants, GA had no effect on PAL levels at 24 h, reduced levels at 48 and 72 h, and increased PAL at 96 h. Early studies in our lab reported that glyphosate increased PAL levels, and also reduced hydroxyphenolic compound accumulation in both light- and dark-grown soybean seedlings. Treatments of GA plus glyphosate caused additive increases in PAL activity in light-grown seedlings, but GA lowered glyphosate's increase in PAL levels at 48–96 h after treatment in dark-grown seedlings. GA had little effect on hydroxyphenolic compound levels in either light- or dark-grown seedlings. GA treatment alone did not significantly affect root elongation, but stimulated hypocotyl and epicotyl elongation and caused marginal reversal of glyphosate inhibition of elongation in roots, hypocotyls, and epicotyls in light-grown plants. These results show some differential effects of GA and glyphosate on growth and phenolic metabolism, and their interactions that are dependent on plants grown in light or darkness. [ABSTRACT FROM AUTHOR]

Zelkova schneideriana Hand.-Mazz is a valuable ornamental tree and timber source, whose seedling breeding and large-scale cultivation are restricted by low seed germination and seedling rates. The regulatory mechanisms underlying seed germination and seedling establishment in Z. schneideriana remain unknown. This study conducted metabolomic and transcriptomic analyses of seed germination and seedling establishment in Z. schneideriana. Regular expression of genes and metabolite levels has been observed in plant hormone signal transduction, starch and sucrose metabolism, linoleic acid metabolism, and phenylpropanoid biosynthesis. The reduction in abscisic acid during seed germination may lead to seed release from dormancy. After the seed is released from dormancy, the metabolic levels of auxin, cytokinins, brassinolide, and various sugars are elevated, and they are consumed in large quantities during the seedling establishment stage. Linoleic acid metabolism is gradually activated during seedling establishment. Transcriptome analysis showed that a large number of genes in different metabolic pathways are upregulated during plant establishment, and material metabolism may be accelerated during seedling establishment. Genes regulating carbohydrate metabolism are altered during seed germination and seedling establishment, which may have altered the efficiency of carbohydrate utilization. In addition, the syntheses of lignin monomers and cellulose have different characteristics at different stages. These results provide new insights into the complex mechanisms underlying seed germination and seedling establishment in Z. schneideriana and other woody plants. [ABSTRACT FROM AUTHOR]

Drought is a major threat to alfalfa (Medicago sativa L.) production. The discovery of important alfalfa genes regulating drought response will facilitate breeding for drought‐resistant alfalfa cultivars. Here, we report a genome‐wide association study of drought resistance in alfalfa. We identified and functionally characterized an MYB‐like transcription factor gene (MsMYBH), which increases the drought resistance in alfalfa. Compared with the wild‐types, the biomass and forage quality were enhanced in MsMYBH overexpressed plants. Combined RNA‐seq, proteomics and chromatin immunoprecipitation analysis showed that MsMYBH can directly bind to the promoters of MsMCP1, MsMCP2, MsPRX1A and MsCARCAB to improve their expression. The outcomes of such interactions include better water balance, high photosynthetic efficiency and scavenge excess H2O2 in response to drought. Furthermore, an E3 ubiquitin ligase (MsWAV3) was found to induce MsMYBH degradation under long‐term drought, via the 26S proteasome pathway. Furthermore, variable‐number tandem repeats in MsMYBH promoter were characterized among a collection of germplasms, and the variation is associated with promoter activity. Collectively, our findings shed light on the functions of MsMYBH and provide a pivotal gene that could be leveraged for breeding drought‐resistant alfalfa. This discovery also offers new insights into the mechanisms of drought resistance in alfalfa. [ABSTRACT FROM AUTHOR]

Drought is a major obstacle to the development of naked oat industry. This work investigated mechanisms by which exogenous Streptomyces albidoflavus T4 and Streptomyces rochei D74 improved drought tolerance in naked oat (Avena nuda) seedlings. Results showed that in the seed germination experiment, germination rate, radicle and hypocotyl length of naked oat seeds treated with the fermentation filtrate of T4 or D74 under PEG induced drought stress increased significantly. In the hydroponic experiment, the shoot and root dry weights of oat seedlings increased significantly when treated with the T4 or D74 fermentation filtrate under the 15% PEG induced drought stress (S15). Simultaneously, the T4 treatment also significantly increased the surface area, volume, the number of tips and the root activity of oat seedlings. Both T4 and D74 treatments elicited significant increases in proline and soluble sugar contents, as well as the catalase and peroxidase activities in oat seedlings. The results of comprehensive drought resistance capacity (CDRC) calculation of oat plants showed that the drought resistance of oat seedlings under the T4 treatment was better than that under the D74 treatment, and the effect was better under higher drought stress (S15). Findings of this study may provide a novel and effective approach for enhancing plant defenses against drought stress. [ABSTRACT FROM AUTHOR]

Allelopathy is a process whereby a plant directly or indirectly promotes or inhibits growth of surrounding plants. Perennial sugarcane root extracts from various years significantly inhibited Bidens pilosa, Digitaria sanguinalis, sugarcane stem seedlings, and sugarcane tissue-cultured seedlings (P < 0.05), with maximum respective allelopathies of − 0.60, − 0.62, − 0.20, and − 0.29. Allelopathy increased with increasing concentrations for the same-year root extract, and inhibitory effects of the neutral, acidic, and alkaline components of perennial sugarcane root extract from different years were significantly stronger than those of the control for sugarcane stem seedlings (P < 0.05). The results suggest that allelopathic effects of perennial sugarcane root extract vary yearly, acids, esters and phenols could be a main reason for the allelopathic autotoxicity of sugarcane ratoons and depend on the type and content of allelochemicals present, and that allelopathy is influenced by other environmental factors within the rhizosphere such as the presence of old perennial sugarcane roots. This may be a crucial factor contributing to the decline of perennial sugarcane root health. [ABSTRACT FROM AUTHOR]

Nitrogen (N) is an essential element for plant growth and development. The identification and utilization of N use efficiency (NUE) loci are essential for breeding high NUE cultivars. In this study, 15 NUE traits were measured in a recombinant inbred line population containing 121 lines derived from the cross between a cultivated barley (Baudin) and a wild barley (CN4027). The hydroponic culture was conducted with normal N and low N treatments in one‐time frame, and field trials were conducted with N sufficiency and N deficiency treatments in two growing seasons. Twenty‐two quantitative trait loci (QTLs) and four clusters were detected. Of them, the five stable QTLs Qgna.sau‐3H for grain N concentration, Qtna.sau‐3H for total N accumulation per plant, Qnhi.sau‐3H for N harvest index, Qnutegy.sau‐3H for N utilization efficiency for grain yield and Qanutedm.sau‐3H.1 for N utilization efficiency for aboveground dry matter were co‐located on chromosome 3H flanked by the markers bpb6282426 and bpb4786261. These two novel QTL clusters simultaneously controlled NUE traits at the seedling and maturity stages. Some genes related to NUE traits in intervals of the major QTLs were predicted. The significant relationships between NUE traits and agronomic and physiological traits were detected and discussed. In conclusion, this study uncovers the most promising genomic regions for the marker‐assisted selection of NUE traits to improve NUE in barley. [ABSTRACT FROM AUTHOR]

SUMMARY: The development of photosynthetically competent seedlings requires both light and retrograde biogenic signaling pathways. The transcription factor GLK1 functions at the interface between these pathways and receives input from the biogenic signal integrator GUN1. BBX14 was previously identified, together with GLK1, in a core module that mediates the response to high light (HL) levels and biogenic signals, which was studied by using inhibitors of chloroplast development. Our chromatin immunoprecipitation‐Seq experiments revealed that BBX14 is a direct target of GLK1, and RNA‐Seq analysis suggests that BBX14 may function as a regulator of the circadian clock. In addition, BBX14 plays a role in chlorophyll biosynthesis during early onset of light. Knockout of BBX14 results in a long hypocotyl phenotype dependent on a retrograde signal. Furthermore, the expression of BBX14 and BBX15 during biogenic signaling requires GUN1. Investigation of the role of BBX14 and BBX15 in GUN‐type biogenic (gun) signaling showed that the overexpression of BBX14 or BBX15 caused de‐repression of CA1 mRNA levels, when seedlings were grown on norflurazon. Notably, transcripts of the LHCB1.2 marker are not de‐repressed. Furthermore, BBX14 is required to acclimate plants to HL stress. We propose that BBX14 is an integrator of biogenic signals and that BBX14 is a nuclear target of retrograde signals downstream of the GUN1/GLK1 module. However, we do not classify BBX14 or BBX15 overexpressors as gun mutants based on a critical evaluation of our results and those reported in the literature. Finally, we discuss a classification system necessary for the declaration of new gun mutants. Significance Statement: A picture is emerging in which BBX proteins have multifaceted functions in plant development, acting as receivers of chloroplast signals as well as playing a role in responses to acute stress. [ABSTRACT FROM AUTHOR]

Seedling establishment is crucial for the development of self-regenerating tree populations. Determinants of tree establishment vary widely and may compound in their effects. Using a factorial experiment, we manipulated invasive shrubs, downed woody debris (DWD), and rodent access to evaluate factors limiting the establishment of six woody species (five native trees, one invasive shrub). Our results suggest these factors independently contribute to tree seedling establishment. Exclusion of rodents increased establishment threefold. Invasive shrub removal (Elaeagnus umbellata; Lonicera maackii) and the presence of DWD promoted establishment of two native trees (Pinus strobus; Sassafras albidum). Notably, the presence of DWD halved L. maackii establishment. In identifying rodents as drivers of seed limitation, our results support findings that seed additions will likely promote woody seedling establishment when rodents are not abundant (e.g., low populations) or when seeds are physically or chemically protected (e.g., via taste deterrents). Management plans vary in DWD retention; results from our experimental cohort indicate retaining or introducing DWD promotes native tree recruitment and limits invasive shrub establishment. Future studies exploring the species-specific effects of invasive shrub removal and DWD amendments across multiple cohorts will help determine which woody species benefit most from these management practices. [ABSTRACT FROM AUTHOR]

Roadside vegetation in Central Europe is mostly species‐poor and dominated by a few grass species. Hemiparasitic plant species, including Rhinanthus spp., might effectively restrict grass growth, thereby making space for light‐dependent herb species. Despite the significance of abiotic site conditions for plant establishment in general, their effects on Rhinanthus establishment are less well known. We investigated combined effects of water availability, litter amount and seed position within litter on Rhinanthus seedling emergence and growth.Two parallel greenhouse experiments were conducted with R. angustifolius and R. minor. In these, we tested the impact of 200 or 400 g litter·m−2 with seeds sown beneath or on top of a litter layer under constantly humid or intermittently dry conditions on seedling emergence and biomass production of Rhinanthus.Presence of litter positively affected Rhinanthus seedling emergence when sown beneath the litter layer and reduced negative effects of water deficiency. Sowing beneath a litter layer increased seedling emergence by 157%, with similar effects at 200 and 400 g litter·m−2. Water level did not affect biomass production. Compared to R. minor, R. angustifolius had higher mean biomass, and its seedlings emerged earlier and in higher numbers.Our results indicate that Rhinanthus spp. react similarly to litter as non‐hemiparasitic plant species from temperate grasslands. Litter presence positively influenced Rhinanthus seedling emergence and growth under intermittently dry conditions. Its hemiparasitic characteristics might reduce drought impacts on biomass production. To ensure seed contact with the soil surface, seeds should be sown when no litter is present, or mulching should occur post‐sowing. [ABSTRACT FROM AUTHOR]

Ammonium nitrogen (NH4+‐N) is essential for fruit tree growth, but the impact of excess NH4+‐N from fertilizer on evergreen citrus trees is unclear.In a climate chamber, 8‐month‐old citrus plants were exposed to five different hydroponic NH4+‐N concentrations (0, 5, 10, 15 and 20 mm) for 1 month to study effects of NH4+‐N on growth characteristics, N uptake, metabolism, antioxidant enzymes and osmotic regulatory substances.Application of 10 mm NH4+‐N adversely affected root plasma membrane integrity, root physiological functions, and plant biomass. MDA, CAT, POD, APX and SOD content were significantly correlated with leaf N metabolic enzyme activity (GOGAT, GDH, GS and NR). GDH was the primary enzyme involved in NH4+‐N assimilation in leaves, while the primary pathway involved in roots was GS‐GOGAT.Under comparatively high NH4+ addition, roots were the main organs involved in NH4+ utilization in citrus seedlings. Our results demonstrated that variations in NH4+ concentration and enzyme activity in various organs are associated with more effective N metabolism in roots than in leaves to prevent NH4+ toxicity in evergreen woody citrus plants. These results provide insight into the N forms used by citrus plants that are important for N fertilizer management. [ABSTRACT FROM AUTHOR]

• Smoke–water (1:2500 v/v) foliar application was tested on radish, spinach and turnip seedlings. • Essential mineral elements were determined in the leaves of seedlings of these vegetables. • Smoke–water significantly stimulated the length and weight of seedlings of examined vegetables. • Potassium and zinc levels were markedly improved in leaves with smoke–water. • Smoke–water, a promising technology for growing vigorous vegetable seedlings. Smoke–water, a smoke-saturated solution derived from the smoke generated by burning plant materials, promotes seed germination and growth of various plant species. There are many reported studies where seeds are treated and soils are drenched with smoke–water to explore the beneficial effects of smoke. However, little information is available on the influence of foliar spraying of smoke–water on the seedlings of commercial vegetable crops for better growth prospects. This study, therefore, investigated the effects of standardized smoke–water (1:2500 v/v) foliar application on the seedling growth of radish (Raphanus sativus L.), spinach (Spinacia oleracea L.) and turnip (Brassica rapa L.), and determined the mineral elemental composition of leaves. Smoke–water foliar treatment significantly enhanced the length and weight of seedlings compared to the seedlings sprayed with water (control). Mineral elements, potassium and zinc, were increased notably in the leaves of all smoke–water foliar-treated seedlings. This can be attributed to increased photosynthetic activity that resulted in longer and heavier seedlings. The results of the present study provide an opportunity to incorporate the use of smoke–water for raising vigorous and healthier vegetable seedlings for better yield. Moreover, it can minimize the input of conventional chemical sprays that are detrimental to the environment. [ABSTRACT FROM AUTHOR]

Understanding the emergence patterns of agricultural weeds is paramount for effective management practices. This study investigates the emergence dynamics of feral radish (Raphanus sativus L.), a widespread weed in the Americas, unravelling the intricate interplay of seed attributes—low or no dormancy, darkness requirement, and indehiscent siliques—on seedling emergence. To explore this, we (1) buried isolated seeds and intact siliques at six increasing depths (0–16 cm) under controlled conditions, and (2) evaluated seedling emergence from both isolated seeds and intact siliques placed on the soil surface and buried at 10 cm under field conditions over 3 years. Our findings reveal that seedlings emergence was about five‐fold higher from shallow‐buried than from surficial isolated seeds, and from isolated seeds than from seeds inside siliques, suggesting strong effects of burial depth and the pericarp. Even isolated seeds buried at 12 cm depth outperformed surface isolated seeds. The burial depth influenced emergence patterns; isolated seeds exhibited rapid emergence, with rates five times higher at 10 cm deep compared to those on the soil surface, showing no emergence after year 1. Conversely, the pericarp delayed and staggered seedlings emergence, contributing to the formation of a persistent seed bank for at least 3 years in both burial depths. Seedlings emergence from seeds inside siliques buried at 10 cm begins in year 1 and in those placed on the soil surface year 2, with emergence peaks predominantly in autumn. These findings enrich our understanding of feral radish seedling emergence, providing valuable insights for the development of sustainable and efficient management practices. [ABSTRACT FROM AUTHOR]

The highly invasive weed Parthenium hysterophorus flowers during both hot, humid summers and cold, dry winters in Nepal, yet it remains unknown if there are differences in seed germination and seedling growth during these contrasting seasons. We analysed seed germination and seedling growth of summer and winter cohorts of P. hysterophorus in Kathmandu Valley. Seeds were germinated at low (25/15°C) and high (30/20°C) temperatures, 12/12 h photoperiod and complete dark, and at different levels of water stress. Seedlings were grown in a greenhouse to determine biomass allocation and relative growth rate (RGR). Winter seeds had higher seed biomass than summer seeds, and both seed types germinated under complete dark and 12/12 h photoperiod. Summer seeds germinated at significantly lower rates and percentage than winter seeds at the low temperature, but this difference in germination was not present when summer and winter seeds were incubated at the high temperature. Winter seeds had higher germination (percentage and rate) and took a longer time to reach maximum germination than summer seeds at different levels of water stress. Seedling emergence of both seed types declined with increasing soil depth. Seedling RGRs were nearly equal (summer: 73 mg g−1 day−1, winter: 77 mg g−1 day−1). Biomass allocation to stem and leaves were similar in both cohorts but root biomass allocation was higher in the winter than in the summer cohort. Overall, the maternal environmental effect was moderate on seed germination, and weak on seedling growth. Lack of a pronounced difference in the germination and seedling growth of summer and winter cohorts of P. hysterophorus suggests a wide environmental tolerance of the species, and this could be one of the reasons for the species' ability to invade diverse climatic and geographic regions globally. [ABSTRACT FROM AUTHOR]

Seedlings of two species of mangroves, Bruguiera gymnorrhiza and Rhizophora apiculata, were monitored for 8 years on the Pacific island of Kosrae, Federated States of Micronesia, to determine the effects of canopy cover and hydrogeomorphic zone on long-term survival and growth. Annual rainfall is high with little seasonality. Study plots with seedling subplots were in fringe, riverine, and interior hydrogeomorphic zones along four small rivers. The height of each seedling was measured each year and was designated each time as being under an open, partially closed, or closed canopy. Growth rates of both species were slow, and no seedling that was newly established during the study became a sapling (2 m). Many seedlings stopped growing for long periods of time. Bruguiera seedlings were more numerous than Rhizophora seedlings. They grew faster than Rhizophora seedlings except in riverine zones. Predicted growth rates of Bruguiera were fastest under an open canopy and slowest under a closed canopy, but Rhizophora was not affected by canopy status. Overall mortality rates for the two species were similar, averaging 36% year−1. El-Niño-Southern Oscillation events did not affect growth or mortality but may have caused some defoliation. [ABSTRACT FROM AUTHOR]

Nowadays, the applications of nanotechnology are increasing in various fields such as information technology, energy, the medical sector, and agriculture. Nanotechnology has proved its ability to solve problems in agriculture and related industries. Establishing the impact of nanoparticles on various ecosystems has become a primary research topic, but studies on forest ecosystems and trees are quite limited. This study examined the effects of silver nanoparticles on the germination parameters of oriental beech seeds and established their toxic threshold values. Silver nanoparticles were applied at concentrations of 200, 400, 600, 800, and 1000 mg/L to oriental beech (Fagus orientalis) seeds collected from 10 different populations in order to identify the germination rate, germination percentage, seedling height, root collar diameter, plumula length, radicle thickness, and radicle length parameters. The results revealed that silver nanoparticles have a negative effect on germination and seedling parameters of oriental beech seeds, and that this effect is clearly seen in the germination rate at 20 mg/L levels and in seedling characters starting from 60 mg/L dose, causing a decrease of 13% in germination rate, 24% in germination percentage, 40% in plumula length, and 30% in radicle length. The Kahramanmaras-Andirin population was found to be the most affected by nanoparticles, while the Bursa-Inegol and Ordu-Akkus populations were the least affected. [ABSTRACT FROM AUTHOR]

Temperature is one of the most important environmental factors for plant growth, as low-temperature freezing damage seriously affects the yield and distribution of plants. The Lanzhou lily (Lilium davidii, var. unicolor) is a famous ornamental plant with high ornamental value. Using an Illumina HiSeq transcriptome sequencing platform, sequencing was conducted on Lanzhou lilies exposed to two different temperature conditions: a normal temperature treatment at 20°C (A) and a cold treatment at −4°C (C). After being treated for 24 hours, a total of 5848 differentially expressed genes (DEGs) were identified, including 3478 significantly up regulated genes and 2370 significantly down regulated genes, accounting for 10.27% of the total number of DEGs. Quantitative real-time PCR (QRT-PCR) analysis showed that the expression trends of 10 randomly selected DEGs coincided with the results of high-throughput sequencing. In addition, genes responding to low-temperature stress were analyzed using the interaction regulatory network method. The anti-freeze pathway of Lanzhou lily was found to involve the photosynthetic and metabolic pathways, and the key freezing resistance genes were the OLEO3 gene, 9 CBF family genes, and C2H2 transcription factor c117817_g1 (ZFP). This lays the foundation for revealing the underlying mechanism of the molecular anti-freeze mechanism in Lanzhou lily. [ABSTRACT FROM AUTHOR]

Auxin plays a crucial role in regulating root growth and development, and its distribution pattern under environmental stimuli significantly influences root plasticity. Under K deficiency, the interaction between K+ transporters and auxin can modulate root development. This study compared the differences in root morphology and physiological mechanisms of the low-K-tolerant maize inbred line 90-21-3 and K-sensitive maize inbred line D937 under K-deficiency (K+ = 0.2 mM) with exogenous NAA (1-naphthaleneacetic acid, NAA = 0.01 mM) treatment. Root systems of 90-21-3 exhibited higher K+ absorption efficiency. Conversely, D937 seedling roots demonstrated greater plasticity and higher K+ content. In-depth analysis through transcriptomics and metabolomics revealed that 90-21-3 and D937 seedling roots showed differential responses to exogenous NAA under K-deficiency. In 90-21-3, upregulation of the expression of K+ absorption and transport-related proteins (proton-exporting ATPase and potassium transporter) and the enrichment of antioxidant-related functional genes were observed. In D937, exogenous NAA promoted the responses of genes related to intercellular ethylene and cation transport to K-deficiency. Differential metabolite enrichment analysis primarily revealed significant enrichment in flavonoid biosynthesis, tryptophan metabolism, and hormone signaling pathways. Integrated transcriptomic and metabolomic analyses revealed that phenylpropanoid biosynthesis is a crucial pathway, with core genes (related to peroxidase enzyme) and core metabolites upregulated in 90-21-3. The findings suggest that under K-deficiency, exogenous NAA induces substantial changes in maize roots, with the phenylpropanoid biosynthesis pathway playing a crucial role in the maize root's response to exogenous NAA regulation under K-deficiency. [ABSTRACT FROM AUTHOR]

BACKGROUND: Adjusting nitrogen (N) input based on actual seedling density (ASD) and plant N status is a practical approach for improving the yield stability of direct‐seeded rice. However, the adjustment of topdressing N rates has been empirical in the past. This study aimed to establish a quantitative approach for determining N topdressing rates during tillering (Ntil) and panicle development (NPI) based on ASD and crop N status in direct‐seeded rice. Field experiments were conducted involving 12 treatments, consisting of four Ntil and three seeding rates in 2017, and eight treatments combining seeding rate, Ntil, and NPI in 2020. RESULTS: Linear regression analysis revealed that the tiller number at panicle initiation (TILPI) was predominantly influenced by ASD and Ntil. The determination coefficients (R2) of the regression models ranged from 0.887 to 0.936 across the four‐season experiments. The results indicated that Ntil could be determined accurately using ASD and the target maximum tiller number. Similarly, grain yield was influenced significantly by the N uptake at panicle initiation (NUPPI) and NPI, with R2 of 0.814 and 0.783 in the early and late seasons of 2020, respectively. This suggested that NPI could be calculated based on NUPPI and the target grain yield. CONCLUSION: The findings offer a quantitative method for establishing N topdressing rates for tillering and panicle development, relying on the monitoring of actual seedling density and plant N status in direct‐seeded rice production. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]