Search Results (236)

Background: Maize shoot height is an important component of early vigor and plant architecture; however, its genetic basis during seedling development and its relationship with modern breeding remain insufficiently understood. This study aimed to investigate the genetic architecture of maize seedling shoot height across different breeding eras. Methods: Shoot height at 21 days after sowing was evaluated in 363 maize inbred lines representing three breeding eras in China. Genome-wide association analysis was performed to identify loci and candidate genes associated with shoot height variation, and selective sweep analysis was used to detect breeding-era differentiated genomic regions. Results: Modern breeding lines from the 2000–2010s exhibited significantly greater shoot height than lines from earlier breeding periods. Pearson’s correlation analysis revealed that 3-week shoot height showed highly significant positive correlations with plant height and ear height. Selective sweep analysis identified multiple differentiated genomic regions harboring previously reported height- and architecture-related genes, including ZmBR2, ZmLIL1, ZmNA1, ZmTE1, ZmSPL12, ZmBV1, ZmDIL1, ZmKN1 and ZmACS7. The GWAS identified 43 SNPs exceeding the GEC-derived suggestive threshold for shoot height, with the strongest and most continuous association signal located on chromosome 8. GWAS, together with LD analysis, haplotype analysis, and expression profiling, prioritized ZmGDCL (Zm00001d009163) as a promising candidate gene because of its strong association signal, local linkage disequilibrium support, broad expression profile, and significant haplotype effect on shoot height. Conclusions: Our results indicate that maize breeding has reshaped the genetic architecture of seedling shoot growth. ZmGDCL represents a promising candidate gene for future functional studies, while breeding-era differentiated regions provide useful genomic context for understanding maize architecture improvement. Full article

Climate change is intensifying extreme climatic events such as warming and drought. This study investigated the physiological and growth responses of Quercus variabilis, a major broadleaf plantation species in South Korea, to warming and drought under open-field conditions. From July to August 2024, one-year-old seedlings were exposed to factorial treatments of temperature (ambient: TC; +3 °C: T3; +5 °C: T5) and precipitation (ambient: PC; drought: DR). Gas exchange was measured twice (early: 12 July; late: 16 August) during the treatment period. In the early phase of the experiment, net photosynthetic rate (P_n) was 11.4% lower in DR than in PC, whereas differences were no longer significant in the late phase. Stomatal conductance (g_s) was significantly affected by the interaction between temperature and precipitation. These results suggest that the decline in photosynthesis was driven by non-stomatal limitations such as photosystem II impairment or reduced Rubisco activity, despite maintained or enhanced stomatal conductance. Consequently, intrinsic water-use efficiency (iWUE) during the late phase was 24.3% lower in T5 than in TC. Root collar diameter (RCD) was more sensitive to drought than height growth. Shoot (stem + leaf) biomass was 23.7% higher in T5 than in T3, and root biomass was 20.5% higher in T5 than in TC. However, the root-to-shoot (R/S) ratio did not differ significantly among temperature and precipitation treatments. These findings suggest that Q. variabilis seedlings exhibit physiological plasticity and maintain relatively stable biomass allocation under short-term warming and drought conditions. Full article

This study evaluated the morphological development of 23 Coffea canephora clones in Espírito Santo to identify materials with superior vigor and quality for commercial and breeding purposes. Seedlings from cuttings were arranged in a completely randomized design with ten replicates and assessed at the commercial dispatch stage. Shoot and root growth, biomass, leaf area (LA), Dickson Quality Index (DQI), structural ratios (shoot/root ratio, SRR; height/diameter ratio, HDR), and anatomical traits were measured. Data were analyzed using analysis of variance with Scott–Knott clustering, Pearson correlation, and Principal Component Analysis (PCA). Significant variability was observed among clones. Clones 88, VR3, 8, and LB33 showed the highest stem diameter (SD), total dry mass (TDM), LA, and DQI, with balanced shoot and root development. Leaf area correlated strongly with SD, number of leaves (NL), biomass, and DQI, confirming its role as a seedling quality indicator. PCA identified two groups: a high-performance group with greater vigor and biomass, and a lower-performance group including clones 7, MR04, and VR4. The convergence of methods confirms the robustness of the results. Overall, clones 88, VR3, 8, and LB33 demonstrate superior agronomic potential at the seedling stage, offering promising options for nurseries, growers, and clonal selection programs. Full article

The deterioration of the underwater light environment is a key driver of submerged vegetation decline in shallow lakes. However, previous studies have largely focused on the short-term light needs of plants, failing to capture their dynamic requirements across the entire growth period. To quantify these stage-specific dynamics, we investigated three common submerged macrophytes: the rosette-type Vallisneria natans, erect-type Hydrilla verticillata, and canopy-forming Myriophyllum spicatum. Using mesocosm enclosures, we established eight bottom light gradients (0–20% of ambient light intensity) during both seedling and rapid growth stages to assess growth responses. Key findings are as follows: (1) Light requirements varied by species: V. natans < H. verticillata < M. spicatum. (2) Growth traits exhibited distinct responses: shoot density and biomass increased progressively with light, while plant height showed a unimodal response (increasing then declining), reflecting a shift in energy allocation. (3) Light requirements increased with developmental stage: the light compensation point for V. natans, H. verticillata, and M. spicatum increased from 2.1%, 4.4%, and 4.7% (seedling stage) to 3.3%, 10.5%, and 24.1% (rapid growth stage), respectively. (4) An integrated light–biomass model showed that achieving specific biomass targets required 2.4 to 4.7 times more light during rapid growth than during the seedling stage. This study quantifies stage-specific light requirements for submerged macrophytes, providing a theoretical basis for vegetation restoration and light management in shallow lakes. Full article

Perennial groundcover (PGC) systems integrate perennial grasses with annual crops such as corn (Zea mays L.) to provide continuous soil cover and enhance soil health. However, the proximity to groundcover vegetation can alter light quality perceived by developing seedlings, inducing shade avoidance response (SAR), a phytochrome-mediated developmental response that modifies plant architecture and may compromise yield. Identifying the distance at which SAR is initiated and the extent to which management practices modulate this response is critical for optimizing PGC systems. This growth chamber study aimed to (1) identify the distance at which SAR occurs in corn seedlings, (2) determine whether the thiamethoxam seed treatment mitigates SAR expression, and (3) compare hybrid physiological responses to PGC-induced SAR. The experiment was arranged in a randomized complete block design with four replications across three periods and included two corn hybrids (P1185, P1197), two seed treatments (untreated and thiamethoxam at 0.25 mg seed⁻¹), and four perennial ryegrass (Lolium perenne L.) distances [0, 6, 25 cm, and a control (no-grass)]. Reduced red to far-red light ratios associated with closer proximity to ryegrass induced SAR responses. Corn plants at 6 cm from PGC exhibited significant stem and height elongation beginning at 8 days after planting (DAP), followed by reduced growth by 14 DAP, confirming an early SAR response. Plants grown at 0 cm exhibited reduced height and growth compared to other distances at all growth stages. Hybrid responses differed, and Hybrid P1197 showed enhanced stem elongation, a characteristic SAR response. The thiamethoxam seed treatment did not mitigate SAR. These results indicate that SAR causes stem elongation without altering root or shoot biomass. Full article

To explore the application potential of insect-derived functional microorganisms in short-cycle leafy vegetable production, we evaluated the effects of Serratia marcescens BRC-CXG2, isolated from larvae of Monochamus alternatus, on romaine lettuce in a pot experiment. Plant growth traits, biomass accumulation, nutritional quality, endogenous hormones, and rhizosphere microbial communities were systematically evaluated. The results demonstrated that inoculation significantly promoted seedling development. Plant height and root length increased by 48.7% and 29.1%, respectively, while shoot and root dry weights were 1.78- and 1.85-fold higher than those of the control. Vitamin C and total sugar contents increased by 76.4% and 98%, respectively. The levels of gibberellins (GA₃)-, indole-3-acetic acid (IAA)-, and abscisic acid (ABA)-immunoreactive equivalents increased by 1.5-, 1.29-, and 1.75-fold. High-throughput 16S rDNA gene and ITS amplicon sequencing further revealed that inoculation reshaped the composition of bacterial and fungal communities in the rhizosphere. Collectively, these findings demonstrate that insect-derived S. marcescens exhibits significant growth-promoting potential in short-cycle leafy vegetable systems, with effects associated with hormone regulation, enhanced total sugar accumulation, and shifts in rhizosphere microbial community structure. Full article

Salinity stress impairs maize growth by inducing osmotic stress, pigment degradation, and ionic imbalance, particularly during early seedling development. This study investigated the morpho-physiological and ionic responses of different maize genotypes exposed to increasing salinity levels (control, 3, 6, and 9 dS/m) at the seedling stage. Salinity caused a reduction in biomass accumulation (shoot fresh weight and shoot dry weight), plant height, and K⁺/Na⁺ ratio, with pronounced effects under severe stress. Significant genotypic variability was detected for photosynthetic pigments (chlorophyll a, chlorophyll b, total chlorophyll and carotenoids) growth traits, and ionic regulation, indicating diverse physiological adaptation strategies. Stress tolerance indices and multivariate analysis revealed that chlorophyll stability, carotenoid accumulation, and maintenance of ionic homeostasis (K⁺/Na⁺ ratio) were the dominant physiological determinants of salinity tolerance. Additionally, principal component analysis showed a shift from biomass-driven variation under non-stress conditions to pigment- and ion-driven variation under higher salinity. Based on the results, genotypes BML 6 and HKI 163 maintained higher pigment content and improved K⁺/Na⁺ balance, enabling better growth under saline conditions. These findings highlight key physiological traits underlying salinity tolerance and provide insight into early-stage adaptive mechanisms in maize. Full article

As climate change continues to alter rainfall patterns and precipitation regimes across the globe, waterlogging is emerging as a widespread and pressing issue that threatens agricultural productivity and food security. In this study, we investigated the potential of humic substances to mitigate waterlogging stress in cabbage (Brassica oleracea L.) seedlings. Specifically, humic acid and fulvic acid solutions were applied to the growth medium at weekly intervals both before and after a 10-day waterlogging period. The effects of humic acid and fulvic acid applications on waterlogging-induced stress were evaluated through various physiological and biochemical parameters, including shoot fresh weight, root fresh weight, shoot dry weight, root dry weight, plant height, stem diameter, chlorophyll a, chlorophyll b, total chlorophyll, proline, malondialdehyde, hydrogen peroxide, indole acetic acid, gibberellic acid, abscisic acid, and antioxidant enzyme activities including catalase, peroxidase, and superoxide dismutase. The results indicated that waterlogging stress significantly impaired plant growth parameters, but these adverse effects were mitigated by humic acid and fulvic acid applications. The humic substances contributed to stress tolerance by modulating key biochemical responses, including a shift in proline, hydrogen peroxide, malondialdehyde, abscisic acid, and antioxidant enzyme activity levels, which otherwise increased under stress conditions. Furthermore, the decline in indole acetic acid and gibberellic acid content due to waterlogging was alleviated by humic acid and fulvic acid treatments. Overall, the findings suggest that humic acid and fulvic acid can effectively reduce the detrimental effects of waterlogging stress in cabbage seedlings, demonstrating their potential as biostimulants with comparable protective effects. Full article

Ultrafine bubble (UFB)-enriched water promotes plant growth when nutrients are present. A key question is whether it can still encourage growth in the absence of nutrients. Therefore, this study examines how different UFB concentrations affect the early growth and development of rice seedlings under nutrient-free conditions where external nutritional application was excluded. The results showed that the examined morphological and physicochemical parameters were directly affected by the bubble concentration in the irrigation water. Higher bubble concentrations resulted in a significant increase in the fresh and dry weights of roots, primary and secondary root lengths, and specific root length. Similarly, higher bubble concentrations were also associated with greater shoot height, fresh weight, and dry weight. However, pigment concentrations were not clearly affected, except for anthocyanin. Hydrogen peroxide concentration increased proportionally with bubble concentration. Among the antioxidant enzymes assessed, peroxidase activity increased significantly with bubble concentration, whereas the other antioxidant enzymes showed no significant variation. Moreover, UFB irrigation significantly affected carbon metabolism, increasing soluble sugar content while reducing storage starch levels. In conclusion, the findings suggest that UFB-enriched irrigation can promote plant growth under nutrient-free external conditions by modulating stress-related molecules, activating antioxidant enzymes, and altering carbon metabolism. Full article

Cadmium (Cd) contamination and rising temperatures pose significant challenges to rice growth and food safety. Here, we investigated growth responses, Cd accumulation, physiological adaptations, and transcriptomic profiles of two rice cultivars, Yuzhenxiang (YZX) and Xiangwanxian 12 (XWX12), under combined Cd (0, 5, 20 μmol L⁻¹) and temperature (25 °C, 30 °C) stress. Moderate warming (30 °C) generally promoted seedling growth and enhanced Cd uptake, with YZX showing greater increases in plant height and biomass, whereas XWX12 developed longer roots. At maturity, the temperature-induced growth advantage persisted in YZX, accompanied by a 60% increase in root Cd concentration, compared with 36% in XWX12. Antioxidant enzyme activities (POD, SOD, CAT) were significantly induced under combined stress, with XWX12 exhibiting stronger enzymatic responses and broader activation of ABC transporter genes, supporting reduced Cd accumulation in shoots. Malondialdehyde content indicated milder oxidative damage in YZX despite higher Cd accumulation. Transcriptomic analyses revealed extensive early transcriptional reprogramming, with enrichment of antioxidant metabolism, ABC transporters, MAPK signaling, and Cd transport-related genes, demonstrating coordinated physiological and molecular responses. XWX12 favored intracellular Cd sequestration and sustained antioxidant activation, whereas YZX relied more on uptake and translocation processes. Overall, these results highlight genotype-specific strategies in coping with combined Cd and temperature stress, providing mechanistic insights for improving rice tolerance and safety under warming and contaminated environments. Full article

Salt stress is a severe threat to medicinal plants, adversely affecting their growth, yield, and quality. As a key antioxidant tripeptide, glutathione (GSH) confers salinity stress resilience in plants. However, how GSH shapes the plant tolerance to salt stress remains a mystery, especially in medicinal plants, including Pogostemon cablin. In this study, we investigated the regulatory effects of exogenous GSH on P. cablin seedlings under salt conditions. The results showed that GSH significantly improved seedling quality under both normal and salt conditions, evidenced by the increased shoot and root dry weight, plant height, and root length. Moreover, GSH effectively protected the photosynthetic system against salt-mediated damage via raised chlorophyll a, chlorophyll b, carotenoids, quantum yield of photosystem II [Y (II)], and PSII maximum efficiency (Fv/Fm). Furthermore, GSH stimulated the antioxidant defense system, including GSH, AsA, SOD, CAT, APX, POD, and GR, to restrain salt-induced malondialdehyde production and ROS burst. In addition, GSH treatment promoted the biosynthesis of secondary metabolites, including total polyphenol and flavonoid. RNA-seq analysis revealed that the activation of the flavonoid biosynthetic pathway significantly enhanced salt tolerance in P. cablin. Notably, several key regulatory genes within this pathway, including PAL, 4CL, C4H, CHI, ANS, F3′H, and CYP93, were significantly upregulated 24 h following GSH application under salt conditions. Therefore, exogenous GSH alleviates salt-induced oxidative stress in P. cablin via enhancing the antioxidant defense system and flavonoid biosynthetic activation. These findings provide valuable insights into the dual defense strategies of GSH for conferring salt resistance in plants. Full article

Soil salinization is a major threat to agricultural sustainability. Poly-gamma-glutamic acid (γ-PGA), a biopolymer produced by microbial fermentation, has received attention as a biostimulant due to its positive effects on crop performance. However, the function of γ-PGA in crop salt stress tolerance and its effect on the rhizosphere are unclear. This study explores the effects of γ-PGA application on rhizosphere soil nutrients and the soil–physical environment and examines the salt tolerance response of maize seedlings grown in saline–alkali soil under such an application regime. The results show a significant promotion of maize seedling growth and of nutrient accumulation with γ-PGA application under salt stress; plant dry weight, stem diameter, and plant height increased 121%, 39.5%, 18.4%, respectively, and shoot accumulation of nitrogen, phosphorus, potassium, and carbon increased by 1.38, 2.11, 1.50, and 1.36 times, respectively, under an optimal-concentration γ-PGA treatment (5.34 mg kg⁻¹ (12 kg ha⁻¹)) compared with the control. γ-PGA treatment significantly decreased rhizospheric pH and soil electrical conductivity and significantly increased nutrient availability in the rhizosphere, especially available nitrogen (AN) and available potassium (AK). Compared with the control, AN, available phosphorus (AP), and AK increased by 13.9%, 7.70%, and 17.7%, respectively, under an optimal concentration treatment with γ-PGA. γ-PGA application also significantly increased the activities of urease, acid phosphatase, alkaline phosphatase, dehydrogenase, and cellulose in rhizosphere soil by 35.5–39.3%, 35.4–39.3%, 5.59–8.85%, 18.9–19.8%, and 19.2–47.0%, respectively. γ-PGA application significantly decreased Na⁺ concentration and increased K⁺ concentration in shoots, resulting in a lowering of the Na⁺/K⁺ ratio by 30.5% and an increase in soluble sugar and soluble protein contents. Therefore, rhizosphere application of water-soluble and biodegradable γ-PGA facilitates the creation of an optimized rhizospheric environment for maize seedling and overcomes osmotic and ionic stresses, offering possibilities for future use in drip-irrigation systems in the cultivation of crops on saline-alkali land. Full article

Beauveria bassiana can colonize plants, acting against insect pests and promoting plant growth. This study evaluated how different fungal inoculation methods affected Eucalyptus grandis growth and the foraging behavior of ants. An isolate (LPP 139) was identified as B. bassiana based on ITS sequences. Seedlings were submitted to three inoculation methods using fungal suspensions at 1 × 10⁸ conidia mL⁻¹: (1) soil drenching at sowing (SD), (2) soil drenching 20 days after sowing (20SD), and (3) foliar spraying 20 days after sowing (20F) when compared to controls. SD treatment enhanced plant height (mean 25 cm with a 31.6% increase compared to the controls; p = 0.0353) and shoot fresh weight (mean 1.5 g, a 50% increase; p = 0.0154), while 20SD increased leaf number (141.4% increase; p = 0.0419). The 20F treatment increased leaf number (287.9% compared to the controls; p = 0.0006), shoot weight (mean fresh weight 1.5 g, a 50% increase; p = 0.0213 and mean dry weight 0.7 g, a 75% increase; p = 0.0236), and reduced leaf-cutting ant foraging (mean 26 cm², a reduction of 53.6%; p = 0.0134). These findings highlight the dual action of B. bassiana, promoting plant growth and reducing the activity of ants. Full article

Potato is globally recognized as the fourth most crucial staple food crop, trailing behind wheat, rice, and maize. Cadmium (Cd), a predominant heavy-metal pollutant in agricultural soils, demonstrates high biological toxicity and mobility. Therefore, exploring the genetic and molecular mechanisms underpinning cadmium tolerance in potato is of substantial theoretical and practical significance. In this research, an F₂ population composed of 170 families was established through the cross-breeding of homozygous diploid potato lines HD-5 (highly cadmium-tolerant) and M9 (cadmium-sensitive). Employing hydroponic cultivation, six traits, namely plant height (PH), root length (RL), shoot fresh weight (SFW), root fresh weight (RFW), chlorophyll content (SPAD), and nitrogen content (LNC), were measured in potato seedlings following a 9-day treatment with 40 mg·L⁻¹ CdCl₂. By utilizing the high-density genetic map of this population for QTL mapping, a total of 35 genetic loci associated with cadmium tolerance in potato seedlings were identified. Notably, loci21 and loci22 on chromosome 9, loci29 on chromosome 10, and loci31 and loci33 on chromosome 12 were consistently detected across multiple environmental conditions. This reproducibility across environments suggests the phenotypic stability of these five loci, which are thus considered reliable and robust genetic determinants. In addition, transcriptome sequencing analysis of roots from parental lines HD-5 and M9 after cadmium treatment revealed that significantly differentially expressed genes between the two parents were associated with glutathione metabolism and photosynthesis. By integrating QTL mapping, transcriptome analysis, and gene annotation, we screened four candidate genes involved in cadmium tolerance regulation: DM8C09G01000 (GST), DM8C09G01060 (GST), DM8C09G02130 (OXP1), and DM8C06G22960 (PsaH). These findings provide molecular targets and a genetic basis for molecular breeding of cadmium-tolerant potato varieties. Full article

The presence of Bacillus subtilis on tomato roots contributes to plant growth promotion, which depends on its ability to establish in the roots. Edible-film formulations have emerged as effective carriers for beneficial bacteria. In this study, we evaluated film formulations based on guar gum, glycerol, and candelilla wax incorporating B. subtilis for root application in tomato seedlings to stimulate plant development. Sixteen film formulations were prepared and applied to seedling by dipping root; plants were grown under a 16/8 h photoperiod. At 60 days, growth parameters (plant height, leaf number, chlorophyll content, fresh and dry weights) were measured, along with B. subtilis on roots, and the soil degradation of the selected film. Treatments were: seedlings with B. subtilis at two doses (10^6,12 CFU/mL (B6, B12), film without bacteria (P), films with B. subtilis (P1–P16), and untreated (TST). Among the films, formulation 9 (guar gum 0.6%, candelilla wax 0.15%, glycerol 0.15% and B. subtilis 20%, 1 × 10¹²) significantly increased shoot and root biomass and supported higher root colonization of B. subtilis (2.3 × 10⁷ CFU/g). The film degraded in soil within 15 days, while the inoculant maintained high viability (6.3 × 10⁸ CFU/mL) after 8 months at 4 °C. These results highlight film formulation 9 as a promising bioinoculant for tomato cultivation. Full article