Modulation of germination physiology and biochemical metabolism in rice (Oryza sativa L.) through microbial seed biopriming

Wild Ber Seed Germination as Affected by Bio-stimulants and Growth Regulators under in-vivo Conditions

Wild ber (Ziziphus rotundifolia Lamk.) is an adaptable fruit-tree species of ecological and economic importance in arid and semi-arid regions. This study evaluated the effectiveness of biostimulants and plant growth regulators in improving seed germination, seedling vigour and survival under nursery conditions. The experiment was conducted during 2021–22 at the Fruit Nursery, Department of Horticulture, CCS Haryana Agricultural University, Hisar. Twelve treatments comprised an untreated control, five bio-stimulant treatments and gibberellic acid (GA3), 1-naphthaleneacetic acid (NAA) and indole-3-butyric acid (IBA), each at 50 and 100 mg/L. The experiment followed a completely randomized design with three replications. Among the treatments, GA3 at 100 mg/L produced the highest germination percentage (73.0%, compared with 45.7% in the control), the highest relative seed germination value (159.9%), and the shortest time to germination (3.3 days, compared with 8.7 days in the control). This treatment also recorded the highest survival percentage at 120 days after sowing (98.7%), mean seedling length (27.7 cm, compared with 18.3 cm), mean fresh weight per seedling (9.36 g, compared with 4.16 g), and mean dry weight per seedling (3.91 g, compared with 1.53 g). GA3 at 50 mg/L recorded the highest relative water content. Selected bio-stimulants also improved early seedling performance. These findings indicate that pre-sowing treatment with GA3, particularly at 100 mg/L, can improve the nursery propagation of wild ber.

Biochemical and microbial interactions of Sargassum wightii extract and plant growth-promoting rhizobacteria consortia enhance growth and yield of tomato (Solanum lycopersicum L.)

The increasing need for sustainable agricultural practices has intensified interest in seaweed-based biostimulants and plant growth-promoting rhizobacteria (PGPR) as eco-friendly alternatives to chemical fertilisers. This study examined the individual and combined effects of Sargassum wightii extract and PGPR strains (Azospirillum lipoferum TSA-6 and Bacillus megaterium TSB-3) on the growth and yield of tomato (PKM-1) under pot culture conditions. Seaweed extracts obtained through hot-water and solvent extraction were screened for phytochemicals and endogenous growth hormones (IAA, GA₃ and cytokinin). Among the six species analysed, S. wightii exhibited the highest levels of auxin (3.7 mg L-1) and cytokinin (4.9 mg L-1). Preliminary screening using crude extract showed that a 2.5 % concentration significantly enhanced germination, seedling vigour, root and shoot length and leaf area index. In the pot experiment, the integrated treatment comprising 75 % recommended dose of fertilisers (RDF) + 2.5 % S. wightii extract + A. lipoferum + B. megaterium (T8) recorded superior growth and yield attributes, including increased dry matter production, fruit number, fruit weight and total fruit yield, comparable to 100 % RDF. The results demonstrate that the combined application of  S. wightii extract and PGPR can effectively enhance tomato productivity while reducing fertiliser usage by 25 %. This integrated biostimulant strategy offers a sustainable approach to improving crop performance and reducing chemical fertiliser dependence.  

Efficacy of seed priming through different plant extracts on seed germination of Naga-King Chilli (Capsicum chinense Jacq.)

Biopriming with plant growth-promoting bacteria enhances germination and stress tolerance of Pinus nigra seeds under drought and salinity stress

Climate change has intensified drought and soil salinity, posing significant constraints to seed germination, seedling establishment, and afforestation success in forest tree species. Seed biopriming with plant growth-promoting bacteria (PGPB) has emerged as a sustainable strategy to enhance plant tolerance to abiotic stress; however, its effectiveness in Pinus nigra remains poorly understood. This study evaluated the effects of seed biopriming with eight PGPB strains ( Lactobacillus paracasei , L. paraplantarum , Paenibacillus amylolyticus , P. pabuli , Bacillus subtilis , B. megaterium , B. licheniformis , and Pseudomonas chlororaphis ), individually and in two bacterial consortia on the germination performance of black pine ( Pinus nigra Arnold.) under simulated drought (PEG-6000) and salinity (NaCl) stress. Germination percentage, mean germination rate, relative germination percentage, mean germination time, germination index, and germination value were evaluated under four levels of each stress. Biopriming significantly mitigated the adverse effects of both drought and salinity, resulting in higher germination performance than untreated controls. Bacillus megaterium consistently maintained the highest germination percentage and germination index under drought stress, whereas Bacillus licheniformis exhibited superior performance under high salinity. Lactobacillus paraplantarum and Paenibacillus amylolyticus markedly accelerated germination by reducing mean germination time and maintaining stable germination rates across increasing stress intensities. Principal component analysis further demonstrated distinct stress-specific responses among bacterial treatments, with Bacillus species showing the strongest association with improved germination under severe abiotic stress. Overall, the findings demonstrate that PGPB-mediated seed biopriming effectively enhances germination resilience of P. nigra under drought and salinity stress. This environmentally sustainable approach has considerable potential to improve nursery production, afforestation success, and climate-resilient forest restoration in water-limited and salt-affected environments.

Germination and Growth Responses of Trifoliate Orange (Poncirus trifoliata L.) Seeds to Glycerol-Chitosan-Based Biostimulant Treatments

Trifoliate orange (Poncirus trifoliata L.), a citrus rootstock valued for its cold hardiness and resistance to broad biotic stress, produces desiccation-sensitive seeds whose successful germination requires optimized pre-sowing treatments for reliable sexual propagation. This study investigated whether chitosan-based coating systems, incorporating glycerol as a plasticizer combined with either an amino acid biostimulant (betaine-proline) or gibberellic acid (GA3), could improve germination kinetics and seedling establishment. Seeds from mature fruits were subjected to 18 treatments across Petri dish and soil bioassays. In Petri dishes, the germination percentage remained uniformly high (86.67–100%), with GA3-containing formulations promoting shoot elongation and proline-betaine combinations favoring root development. In soil, treatments primarily modulated germination kinetics: GA3 combined with chitosan (1.5–2%) increased the germination speed by approximately 3.0–3.4 times relative to the control, while 1.5% chitosan with proline-betaine and glycerol yielded the fastest germination overall. Biomass responses were strongly formulation-dependent: 2% chitosan with GA3 maximized shoot and total dry weight, whereas 2% chitosan with proline-betaine and glycerol substantially improved root dry biomass and overall seedling quality. Glycerol exerted context-dependent effects, enhancing amino acid formulations while reducing performance in GA3 mixtures. These findings support the use of optimized chitosan-based treatments as effective tools for accelerating emergence and improving seedling robustness in rootstock production.

Independent Effects of Seed-Priming Treatments and Seed Mass Class on Germination and Early Seedling Performance of Silphium perfoliatum L.

Silphium perfoliatum L. is a promising perennial bioenergy and forage crop; however, its agricultural expansion is severely hindered by primary physiological dormancy and non- uniform seedling emergence This study evaluated the effects of chemical priming treatments (distilled H2O, H2O2, GA3, KNO3, ethephon, and sodium nitrophenolate (SNP)) and the seed mass classification (small: 0.011–0.015 g; medium: 0.016–0.019 g; large: 0.020–0.024 g) on germination dynamics, allometry, and seedling vigor. Under controlled conditions, priming agents demonstrated highly differentiated morpho-regulatory capacities. Gibberellic acid (GA3) significantly overcame physiological dormancy, maximizing the final germination percentage (77.33%), germination index (2.54), and seedling vigor index II (SV II) (4.62) compared to the control (23.33%, 0.99, and 1.11, respectively). Conversely, KNO3 and ethephon optimized germination synchrony (Z) (0.27 and 0.29) and suppressed early fragile shoot etiolation to enhance dry matter accumulation (0.064 g). Furthermore, multivariate morphometric analysis of seed mass categories revealed a distinct transverse allometric expansion in larger seeds (length-to-width ratio decreasing from 1.58 in small seeds to 1.50 in large seeds). While the ultimate germination capacity remained statistically unaffected by seed size (37.60% to 47.20%), large seeds exhibited a pronounced early kinetic divergence, achieving a developmental head start (23.2% cumulative germination by day 8 versus (7.2%) for small seeds. Larger seed mass directly translated into superior structural biomass accumulation, yielding significantly robust seedlings with elevated fresh weight (1.059 g vs. 0.789 g in small seeds), dry weight (0.073 g vs. 0.041 g), and total seedling length (91.32 mm vs. 73.70 mm), without altering the radicle-to-shoot allocation ratio (0.89 vs. 0.76). We conclude that early crop establishment in S. perfoliatum is driven by dormancy-breaking chemical signaling and reserve-dependent physical seed quality.