Search Results (174)

Chilli (Capsicum annuum) is a popular spice and vegetable crop of significant economic importance that is cultivated worldwide in warm and humid climatic zones. Although chilli is a thermophilic crop, its quality and yield potential are significantly affected due to various abiotic factors, including extremely fluctuating temperatures beyond the optimum temperatures (18–30 °C). Global warming and anthropogenic activities lead to adverse climatic changes, imposing severe stress on growth, development, and productivity. High temperatures above 43–45 °C adversely affect chilli crops, especially during the reproductive stages, by causing immature fruit dropping, poor seed vigour, reduced number of flowers, flower abscission, aborted reproductive organs, reduced fruit set, and significant yield loss by 50%. Therefore, to reduce quantitative and qualitative losses, heat management is necessary from April to June in Pakistan, when the temperature rises beyond 40 °C. For heat management, the hybridisation of heat-resilient and high-yielding genotypes to develop heat-tolerant high-yielding hybrids appears to be a rational approach. These genetically improved hybrids inherit such characteristics that assist in maintaining vigorous growth, fruit quality, and stable yield without significant yield losses even under heat-stressed conditions. Hence, the thermotolerant chilli hybrids developed through hybridisation help to satisfy the escalating demand for chilli and guarantee the financial stability of farmers. Full article

Background/Objectives: Evidence links children’s health-related quality of life (HRQoL) to overall diet, but data on specific, actionable habits are limited. We tested whether vegetable intake ≥2 portions/day and fish intake ≥2–3 times/week were associated with risk of low HRQoL (KIDSCREEN-10 Index score <40) and assessed their joint effect and robustness to overall diet quality. Methods: In three waves (2020–2023) in Madrid (Spain), 1127 observations from 771 children (8–12 years) were analysed. Logistic Generalised Estimating Equations (GEE) adjusted for age, sex, socioeconomic status (four levels), moderate-to-vigorous physical activity (MVPA), screen time, body mass index (BMI) z-score, wave and school ownership. Marginal predicted probabilities were computed for four exposure combinations (neither, vegetables only, fish only, both). Sensitivity models added school area and the Mediterranean Diet Quality Index (KIDMED; KIDMED_wo_FV and total); hybrid within–between GEE and a linear mixed model for continuous KIDSCREEN-10 were also fitted. Results: Vegetables ≥2/day and fish ≥2–3/week were inversely associated with low HRQoL (odds ratio (OR) 0.49 (95% confidence interval (CI) 0.30–0.82) and 0.61 (0.43–0.87)). The interaction was positive (OR 2.50 (1.39–4.53)). Adjusted probabilities were 40.1% (neither), 25.8% (vegetables only; −14.3 percentage points (p.p.)), 29.7% (fish only; −10.5 p.p.), and 34.0% (both; −6.1 p.p.). Findings persisted with KIDMED_wo_FV and attenuated with total KIDMED. MVPA related inversely and screen time directly to risk. Conclusions: Vegetables ≥2/day and fish ≥2–3/week were associated with lower odds of low HRQoL, with non-additive combined effects. These simple targets may complement physical-activity promotion and reduced screen time; longitudinal/experimental studies should test causality and dose–response. Full article

Potassium (K) is a vital macronutrient for plant growth and yield, yet most soil K occurs in insoluble mineral forms, limiting availability to crops. Reliance on chemical K fertilizers is unsustainable due to cost and environmental concerns. Microbial solubilization of mineral K, particularly by purple nonsulfur bacteria (PNSB), offers an eco-friendly alternative. This study focused on isolating mica-potassium-solubilizing purple nonsulfur bacteria (MK-PNSB) from in-dyke alluvial soil and assessing their effects on hybrid maize germination and seedling growth. Among the isolates, the results showed that strain M-Wa-19 released the highest amount of soluble K under microaerobic light conditions (27.4 mg∙L⁻¹). Under aerobic dark conditions, M-Wa-24 and M-Wa-26 released 20.1–21.0 mg∙L⁻¹ of soluble K. Strains M-Wa-21, M-Wa-25, and M-Sl-13 solubilized K in the range of 14.3–25.1 mg∙L⁻¹ and 12.9–24.4 mg∙L⁻¹ under both incubation conditions. The selected strains were identified by 16S rRNA as Rhodopseudomonas palustris strain M-Sl-13 (PX588604), Rhodoplanes pokkaliisoli strain M-Wa-19 (PX588605), Afifella marina strain M-Wa-21 (PX588606), Rhodocista pekingensis strain M-Wa-24 (PX588607), Rhodocista pekingensis strain M-Wa-25 (PX588608), and Rhodocista pekingensis strain M-Wa-26 (PX588609). None exhibited toxicity to maize seeds; instead, all enhanced seed vigor indices by up to 99.7% and improved plant height and root biomass by 19.0–26.2% and 14.4–22.9%, respectively, under static hydroponic conditions. At a 1:1000 (bacteria and distilled water) dilution rate, strains M-Wa-26, M-Wa-25, M-Sl-13, M-Wa-24, M-Wa-19, and M-Wa-21, along with the six-strain mixture, improved seed vigor index by 3.96–7.91%. These findings suggest that MK-PNSB, individually or in mixtures, hold promise as biofertilizer candidates for sustainable K management in crop production. Full article

Limited annotated data often constrain accurate yield prediction in underrepresented crops. To address this challenge, we developed a cross-crop deep transfer learning (TL) framework that leverages potato (Solanum tuberosum L.) as the source domain to predict sweet potato (Ipomoea batatas L.) yield using multi-temporal uncrewed aerial vehicle (UAV)-based multispectral imagery. A hybrid convolutional–recurrent neural network (CNN–RNN–Attention) architecture was implemented with a robust parameter-based transfer strategy to ensure temporal alignment and feature-space consistency across crops. Cross-crop feature migration analysis showed that predictors capturing canopy vigor, structure, and soil–vegetation contrast exhibited the highest distributional similarity between potato and sweet potato. In comparison, pigment-sensitive and agronomic predictors were less transferable. These robustness patterns were reflected in model performance, as all architectures showed substantial improvement when moving from the minimal 3 predictor subset to the 5–7 predictor subsets, where the most transferable indices were introduced. The hybrid CNN–RNN–Attention model achieved peak accuracy ($R^2\approx 0.64$ and RMSE ≈ 18%) using time-series data up to the tuberization stage with only 7 predictors. In contrast, convolutional neural network (CNN), bidirectional gated recurrent unit (BiGRU), and bidirectional long short-term memory (BiLSTM) baseline models required 11–13 predictors to achieve comparable performance and often showed reduced or unstable accuracy at higher dimensionality due to redundancy and domain-shift amplification. Two-way ANOVA further revealed that cover crop type significantly influenced yield, whereas nitrogen rate and the interaction term were not significant. Overall, this study demonstrates that combining robustness-aware feature design with hybrid deep TL model enables accurate, data-efficient, and physiologically interpretable yield prediction in sweet potato, offering a scalable pathway for applying TL in other underrepresented root and tuber crops. Full article

Developing reliable in vitro propagation methods for rowanberry genotypes is essential for their use in breeding and horticultural programs. While different rowanberry species and cultivars are primarily valued for their ornamental and forestry properties, poor seed germination and the low success rate of conventional vegetative techniques constrain their propagation. Micropropagation offers a practical approach to obtaining uniform, disease-free plant material for selection, hybridization, and the subsequent horticultural use of particular valuable genotypes. Shoot multiplication of a prospective sweet rowanberry cultivar ‘Discolor’ was studied on a Murashige and Skoog (MS) medium supplemented with 6-benzylaminopurine (BAP) at concentrations of 1, 2, and 4 mg L⁻¹, thidiazuron (TDZ) at concentrations of 0.5 and 1 mg L⁻¹, and 6-(γ,γ-dimethylallylamino)purine (2iP) at a concentration of 10 mg L⁻¹. Root induction was evaluated on a half-strength MS medium (50% MS) supplemented with 1 mg L⁻¹ of naphthaleneacetic acid (NAA), indole-3-butyric acid (IBA), or indole-3-acetic acid (IAA). TDZ at 1 mg L⁻¹ yielded the highest multiplication coefficient. However, media with TDZ at a lower concentration (0.5 mg L⁻¹) or BAP (2–4 mg L⁻¹) provided the best balance between proliferation rate and shoot quality. These media promoted the growth of vigorous, well-elongated shoots with minimal callus formation. In contrast, the phytohormone 2iP did not elicit physiological response in the in vitro multiplication of explants. The best rooting results were obtained using a 50% MS medium supplemented with 1 mg L⁻¹ IAA, which provided the highest rooting percentage and root quality. IBA produced slightly lower, though comparable, results, while NAA resulted in weak, sporadic root formation. The established protocol enables the efficient in vitro propagation of the studied cultivar. This system supports its application in breeding and fruit production programs, as well as in maintaining valuable genetic resources within the genus Sorbus. Full article

Background: Heterosis (hybrid vigor) is a fundamental phenomenon in plant breeding, but its molecular basis remains poorly understood in perennial crops such as tea (Camellia sinensis). This study aimed to elucidate the molecular mechanisms underlying heterosis in tea and its hybrids by performing integrated transcriptomic and metabolomic analyses of F₁ hybrids derived from two elite cultivars, Fuding Dabaicha (FD) and Baojing Huangjincha 1 (HJC). Methods: Comprehensive RNA sequencing and widely targeted metabolomic profiling were conducted on the parental lines and F₁ hybrids at the one-bud-one-leaf stage. Primary metabolites (including amino acids, nucleotides, saccharides, and fatty acids) were quantified, and gene expression profiles were obtained. Transcriptomic and metabolomic datasets were integrated using KEGG pathway enrichment and co-expression network analysis to identify coordinated molecular changes underlying heterosis. Results: Metabolomic profiling detected 977 primary metabolites, many of which displayed non-additive accumulation patterns. Notably, linoleic acid derivatives (9(S)-HODE, 13(S)-HODE) and nucleotides (guanosine, uridine) exhibited significant positive mid-parent heterosis. Transcriptomic analysis revealed extensive non-additive gene expression in F₁ hybrids, and upregulated genes were enriched in fatty acid metabolism, nucleotide biosynthesis, and stress signaling pathways. Integrated analysis demonstrated strong coordination between differential gene expression and metabolite accumulation, especially in linoleic acid metabolism, cutin/suberine biosynthesis, and pyrimidine metabolism. Positive correlations between elevated fatty acid levels and transcript abundance of lipid metabolism genes suggest that the transcriptional remodeling of lipid pathways contributes to heterosis. Conclusions: These findings provide novel insights into tea plant heterosis and identify potential molecular targets for breeding high-quality cultivars. Full article

Although purple non-sulfur bacteria (PNSB) have been studied as good biofertilizers, their direct effects on maize seed vigor remain unclear. Additionally, the seedling stage is a vital factor for the later growth of maize. This study was conducted to evaluate the effectiveness of potassium-solubilizing PNSB (K-PNSB) in enhancing the vigor of hybrid maize seeds. A completely randomized design was employed, incorporating single strains, Luteovulum sphaeroides M-Sl-09, Rhodopseudomonas thermotolerans M-So-11, and Rhodopseudomonas palustris M-So-14, as well as a mixture of all three strains. Each was tested at bacterial suspension dilution ratios with sterile distilled water of 1:2000; 1:2250; 1:2500; 1:2750; and 1:3000 (v/v), with three replications per treatment. Each replicate consisted of a Petri dish containing 10 hybrid maize seeds of each hybrid of LVN 10, C.P. 511, and NK7328 Gt/BT, and was incubated for five days. The results showed that K-PNSB significantly enhanced root and shoot development compared to the control (p < 0.05). The 1:2500 dilution of the individual strains and the mixture notably improved germination rate, root length, shoot length, and seedling vigor index compared to the control. At the 1:2500 dilution, the improved vigor index increased by 73.5% for L. sphaeroides, 48.7% for R. thermotolerans, 47.4% for R. palustris, and 78.5% for the mixed inoculum in the LVN 10 hybrid. Similar trends were observed for C.P. 511 and NK7328 hybrids, confirming strain- and hybrid-specific responses. The findings highlight that K-PNSB can serve as effective bio-priming agents to enhance maize seed vigor through mechanisms related to potassium solubilization and phytohormone production. Field-scale validation is recommended to assess their long-term agronomic potential. Full article

Potassium (K) is present in soils mainly in minerals, including feldspar. However, most of it is unavailable to plants. In the in-dyked alluvial soils of the Mekong Delta, available K is typically low despite the abundance of K-bearing feldspar, leading to nutrient imbalances and yield constraints. This study aimed to (i) select potential feldspar-potassium-solubilizing purple nonsulfur bacteria (K-PNSB), (ii) determine their ability to enhance hybrid maize seed vigor (Zea mays L.), and (iii) evaluate their effects on the growth of maize seedlings. Fifty-eight K-PNSB strains were isolated from maize-cultivated in-dyked alluvial soils, with soluble K concentrations ranging from 0.108 to 15.0 mg L⁻¹. Among these, strain M-Sl-03 released the highest K concentration under microaerobic light conditions, whereas strains M-Sl-01 and M-Sl-06 produced best under aerobic dark conditions. In addition, two more strains, M-Sl-02 and M-Wa-06, were also selected for their K solubilization ability. The selected strains were identified as Cereibacter sphaeroides strains M-Sl-01 and M-Sl-02, Rhodopseudomonas palustris strain M-Sl-03, and Rhodoplanes pokkaliisoli strains M-Sl-03 and M-Wa-06, according to their 16S rDNA region. None of them exhibited toxicity to germinating maize seeds. Both individual strains and the five-strain mixture significantly improved seed vigor. At a 1:1000 dilution, individual and mixed inoculants increased the vigor index of maize seeds by 47.5–68.8%. In addition, the selected PNSB strains contributed to improving the growth of maize seedlings, particularly plant height and root dry biomass. These promising strains have potential for application as biofertilizers to support hybrid maize cultivation. Full article

The Lower Cambrian Niutitang Formation was deposited precisely during the Cambrian Explosion period, a short-lived interval marked by drastic shifts in oceanic chemistry and climate. This stratigraphic sequence preserves a comprehensive record of early-ocean evolution and constitutes a world-class reservoir for rare and precious metals, widely termed the “poly-metallic enrichment layer”. Despite its metallogenic prominence, the genetic model for metal enrichment in the Niutitang Formation remains contentious. In this study, we employed inductively coupled plasma mass spectrometry (ICP-MS), carbon and sulfur analyzer, and X-ray fluorescence spectrometry (XRF) to quantify trace-metal abundances, redox-sensitive element distribution patterns, rare-earth element signatures, and total organic carbon contents. Results reveal that metal enrichment in the Niutitang Formation was governed by temporally distinct mechanisms. Member I records extreme enrichment in As, Ag, V, Re, Ba, Cr, Cs, Ga, Ge, Se and In. This anomaly was driven by the Great Oxidation Event and intensified upwelling that oxidized surface waters, elevated primary productivity and delivered abundant organic matter. Subsequent microbial sulfate reduction generated high H₂S concentrations, converting the water column to euxinic conditions. Basin restriction imposed persistent anoxia in bottom waters, establishing a pronounced redox stratification. Concurrent vigorous hydrothermal activity injected large metal fluxes, leading to efficient scavenging of the above metals at the sulfidic–anoxic interface. In Members II and III, basin restriction waned, permitting enhanced water-mass exchange and a concomitant shift from euxinic to anoxic–suboxic conditions. Hydrothermal metal fluxes declined, yet elevated organic-matter fluxes continued to sequester Ag, Mo, Ni, Sb, Re, Th, Ga, and Tl via carboxyl- and thiol-complexation. Thus, “organic ligand shuttling” superseded “sulfide precipitation” as the dominant enrichment mechanism. Collectively, the polymetallic enrichment in the Niutitang Formation reflects a hybrid model controlled by seawater redox gradients, episodic hydrothermal metal supply, and organic-complexation processes. Consequently, metal enrichment in Member I was primarily governed by the interplay between vigorous hydrothermal flux and a persistently sulfidic water column, whereas enrichment in Members II and III was dominated by organic-ligand complexation and fluctuations in the marine redox interface. This study clarifies the stage-dependent metal enrichment model of the Niutitang Formation and provides a theoretical basis for accurate prediction and efficient exploration of polymetallic resources in the region. Full article

Recent advances in hyperspectral imaging (HSI) and multimodal deep learning have opened new opportunities for crop health analysis; however, most existing models remain limited by dataset scope, lack of interpretability, and weak cross-domain generalization. To overcome these limitations, this study introduces Agri-DSSA, a novel Dual Self-Supervised Attention (DSSA) framework that simultaneously models spectral and spatial dependencies through two complementary self-attention branches. The proposed architecture enables robust and interpretable feature learning across heterogeneous data sources, facilitating the estimation of spectral proxies of chlorophyll content, plant vigor, and disease stress indicators rather than direct physiological measurements. Experiments were performed on seven publicly available benchmark datasets encompassing diverse spectral and visual domains: three hyperspectral datasets (Indian Pines with 16 classes and 10,366 labeled samples; Pavia University with 9 classes and 42,776 samples; and Kennedy Space Center with 13 classes and 5211 samples), two plant disease datasets (PlantVillage with 54,000 labeled leaf images covering 38 diseases across 14 crop species, and the New Plant Diseases dataset with over 30,000 field images captured under natural conditions), and two chlorophyll content datasets (the Global Leaf Chlorophyll Content Dataset (GLCC), derived from MERIS and OLCI satellite data between 2003–2020, and the Leaf Chlorophyll Content Dataset for Crops, which includes paired spectrophotometric and multispectral measurements collected from multiple crop species). To ensure statistical rigor and spatial independence, a block-based spatial cross-validation scheme was employed across five independent runs with fixed random seeds. Model performance was evaluated using $R^2$, RMSE, F1-score, AUC-ROC, and AUC-PR, each reported as mean ± standard deviation with 95% confidence intervals. Results show that Agri-DSSA consistently outperforms baseline models (PLSR, RF, 3D-CNN, and HybridSN), achieving up to $R^2=0.86$ for chlorophyll content estimation and F1-scores above 0.95 for plant disease detection. The attention distributions highlight physiologically meaningful spectral regions (550–710 nm) associated with chlorophyll absorption, confirming the interpretability of the model’s learned representations. This study serves as a methodological foundation for UAV-based and field-deployable crop monitoring systems. By unifying hyperspectral, chlorophyll, and visual disease datasets, Agri-DSSA provides an interpretable and generalizable framework for proxy-based vegetation stress estimation. Future work will extend the model to real UAV campaigns and in-field spectrophotometric validation to achieve full agronomic reliability. Full article

Triploid breeding is a promising approach for developing seedless varieties, but the long juvenile phase of perennial fruit trees necessitates efficient early selection. In loquat (Eriobotrya japonica), a fruit crop with high demand for seedlessness, the relative contributions of hybridity, ploidy level, and parent-of-origin effects (POEs) to triploid seedling vigor remain elusive. To dissect these factors, we established a comprehensive experimental system comprising reciprocal diploid (2x), triploid (3x), and tetraploid (4x) hybrids from two genetically distinct cultivars. The ploidy, hybridity and genetic architecture of hybrid and parental groups were verified using flow cytometry, chromosome counting, newly developed InDel markers and genome-wide SNP analysis. Phenotypic evaluation of eight vigor-related traits revealed that plant height and soluble starch content were the most robust indicators of triploid heterosis in loquat. Notably, paternal-excess triploids [3x(p)] consistently outperformed all other groups. Quantitative analysis revealed POE as the main positive driver of triploid heterosis (+10.37% for plant height), far exceeding the negative impacts of hybridity (−12.75%) and ploidy level (−20.87%). These findings demonstrate that POE predominantly drives seedling vigor heterosis in triploid loquat. We propose a practical breeding strategy that combines prioritizing paternal-excess crosses with novel InDel markers for rapid verification of superior seedless progeny. Full article

Although heterosis plays a crucial role in enhancing crop yield and stress resistance, its underlying genetic mechanism remains not yet fully understood. Previous studies have shown that heterosis tends to increase with greater genetic distance in the absence of reproductive isolation barriers. However, whether variation in parental genome size alone can generate heterosis under near-isogenic backgrounds has not been thoroughly explored. Here, we used a rapeseed double haploid (DH) inducer line to generate progeny from the Pol CMS three-line hybrid Rongyou 18 (RY18). Although the progeny maintained the same ploidy level as the parents, their genome sizes showed notable variation (818.99–1024.88 Mb). To eliminate genetic distance effects, multiple DH progeny carrying restorer genes were crossed as paternal parents with the female parent 0068A of RY18, creating novel F₁ hybrids. Using RY18 as the control, we observed a marked reduction in the genetic distance between the newly induced restorer line and the female parent (0068A). Correlation analysis further revealed a significant negative correlation (r = −0.310 *) between the paternal genome size and heterosis for thousand-seed weight (TSW). Furthermore, the genomic expansion in hybrid offspring relative to the male parent showed that significant correlations were observed between paternal genome size and heterosis over the standard for both TSW (r = 0.300, p < 0.05) and plot yield (r = 0.326, p < 0.05). Resequencing of high-and low-yielding F₁ hybrids identified SNP sites, indicating that under an identical genetic background, heterosis for yield was more pronounced on chromosome A and chromosome C04. The doubled haploid (DH) induction line facilitates the generation of parental lines with distinct genome sizes, potentially providing a potential novel approach for studying heterosis research in Brassica napus. Full article

Background: Studying the genetic characteristics and molecular mechanisms of immune regulation in horses is of great significance for protecting their genetic resources, improving breeding strategies, and enhancing their disease resistance, thereby ensuring their healthy performance in both sports and production. Aims/objectives: This study investigates the genetic characteristics and molecular mechanisms underlying immune regulation in Yili horses, comparing them with Thoroughbreds and Kazakh horses. Methods: Blood samples from each breed were analyzed for physiological, biochemical, and immune indices alongside transcriptome sequencing to identify differentially expressed genes (DEGs). Results: The results revealed significant differences in neutrophil counts, monocytes, red blood cell parameters, glucose levels, and immunoglobulins (IgA, IgG, IgM) among breeds. Yili horses exhibited intermediate values for most parameters, aligning more closely with Thoroughbreds. Transcriptomic analysis identified 3574 DEGs, enriched in immune-related pathways such as platelet activation, antigen processing, and cytokine signaling. Key genes, including TNFRSF14, IFIT3, and IL21R, correlated with immune traits, highlighting hybrid vigor in Yili horses. Functional enrichment underscored pathways like IL-17 signaling and NF-κB regulation, linking genetic differences to immune adaptability. Conclusions: These findings provide molecular insights into breed-specific immune traits, supporting strategies to enhance disease resilience in Yili horses while preserving their athletic performance. This study underscores the importance of integrating transcriptomic and phenotypic data for informed breeding practices in equine conservation and improvement. Full article

Rose of Sharon (Hibiscus syriacus L.) is an important perennial deciduous ornamental plant, featured by the daily flowering habit and a prolonged flowering period. However, the genetic relationships of the elite germplasmare largely unclear, which hampers the breeding programs of H. syriacus. Here, we analyzed the genetic diversity andstructure of 46 cultivars by employing a combination of 10 simple sequence repeat (SSR) and 5 inter-simple sequence repeat (ISSR) polymorphicmarkers. On average, 1.251 effective alleles per locus were detected for the SSR markers, in contrast to 1.321 for ISSR. Consistently, these elite accessions were grouped into five clades when using either marker or a combination of both, albeit with some differences. In the combined topology, clade II contains three relatively less multiple-petaled accessions, “Notwoodone” and its branch mutant “Bricutts”, as well as H. syriacus var. Shigyoku. By contrast, “Duc de Brabant” and “Mindour1” are both pink multiple-petaled accessions in clade III, in addition to a solo single-petaled “Oiseau Bleu” in clade I. Clade V was the largest group of 34 accessions, which account for 73.9% of the evaluated Hibiscus varieties and cluster into six subclasses. Overall, these varieties have some morphological variances in both patterns and colors of flowers. They show similarities in subclass scale, as exemplified by “Lady Stanley” and its branch mutant, “America Irene Scott”. The distantly related varieties, like in clade I and clade V, would benefit for breeding new varieties of high-hybrid vigor. Together, we updated a pilot study of the genetic diversity andstructure in elite varieties of H. syriacus, which could provide new insights into marker-assisted selection and genetic breeding of new varieties. Full article

Breeding improvement in alfalfa (Medicago sativa L.) is often constrained by the complexity of agronomic traits and trade-offs among yield-related characteristics. Conventional single-trait selection rarely captures the full range of phenotypic variation or the interactions among traits. To address this, we developed a principal component analysis (PCA)-based framework for multivariate selection in hybrid breeding. Six yield-related traits—plant height, branch number, fresh/hay yield ratio (FHR), leaf/stem ratio (LSR), multifoliolate leaf frequency, and dry weight per plant—were quantified in two parental lines and their F₁/F₂ generations. PCA identified three principal components (PC1–PC3) with eigenvalues >1, explaining 71.14% of the total phenotypic variance: PC1 (32.43% variance) was predominantly loaded with positive contributions from dry weight per single plant, height, and branches, biologically representing overall plant vigor and biomass accumulation; PC2 (21.77% variance) showed strong negative loadings for LSR, capturing architectural trade-offs between stem dominance and leaf production; PC3 (16.94% variance) had positive loadings on multifoliolate leaf rate and fresh/dry ratio, embodying quality and physiological resilience traits. Based on PCA scores, a composite selection index was constructed, and the top 31.1% of F1 hybrids were selected. Their F₂ progeny showed significant improvements in dry weight (+15.56%, p < 0.01), multifoliolate leaf frequency (+74.78%, p < 0.001), and reduced FHR (–8.2%, p < 0.05), accompanied by lower yield decline (−7.2% versus −14.1% in controls). These results show that PCA-based multivariate selection effectively balances trait trade-offs, enhances intergenerational stability, and improves selection efficiency. This framework offers a practical tool for alfalfa breeding. Full article