Germinating Maize Seeds Research Articles

IAA production and maize crop growth promoting potential of endophyte Aspergillus niger (AO11) under salt stress

Maize is cultivated under a broad range of soil conditions and environments. Maize is slightly vulnerable to salt stress and therefore it is seriously affected by soil salinity all over the world. Recognizing the responses of maize to salt stress and making a good strategy to overcome this problem could aid to develop solutions in saline areas to improve maize productivity. We investigated in this research the impacts, tolerance and salt stress management in corn. Many endophytic fungi can produce the Indole-3-acetic acid (IAA) is known for their role in plant growth and development both with and without salt stress conditions. The current study was focused on the production of IAA by endophytic fungi (Aspergillus niger) and maize seeds germination and promotion of seedling growth and vigor. In order to evaluate the defense response of maize plant, in relation to A. niger, an experiment was designed with three replications of treatments (control, salt stressed, salt stressed inoculated with A. niger, and only A. niger inoculated plants. It was determined that A. niger has the ability to produce the IAA in NaCl and KCl stress peaking 53 μg/ml and was not significantly by alternating the nitrogen and carbon sources in the nutrient broth but increasing the tryptophan concentration raised its production level. High concentration stress of sodium chloride and potassium chloride decrease maize plant seeds germination percentage, shoot and root length also affected the fresh and dry weight of maize. A. niger improves salt resistance in maize and also increased the germination percentage up to 30%, also improved the chlorophyll level and it was proved an effective approach for improving maize germination and growth under salt stress.

Effects of Waterlogging On Maize Seedling Growth during Seed Germination

In order to understand the resistance of maize seed germination characteristics, to varying degrees of early germination of maize seeds flooding stress, explore the seed germination of maize seedling vigor and growth period of flooding stress, help to understand inverse resistant mechanism of corn seed germination period, to help agricultural production results show that the seeds of waterflooded development, continue to develop at a young age, compared with control, corn seedling variety of enzyme activity and soluble sugar and soluble protein in different degree of change Compared with the control group, the chlorophyll content of Lu yu 36 maize seedlings decreased, while the chlorophyll content of Zheng Dang 958 showed a trend of first decreasing and then increasing. Peroxidase (POD), malondialdehyde (MDA) and soluble sugar all showed an increasing trend. These results provided a basis for better understanding of the waterlogging stress tolerance of maize seeds during germination.

Variations in growth and genetic properties of Zea mays L. germinants exposed to cold shock

BackgroundAbiotic stresses like low temperatures are contributory factors to the variations observed among species during plant germination, growth, and development. The present study evaluated the morphological and genetic responses of maize (Zea mays L.) seedling to cold shock induced by a one-time exposure to low temperature. Seeds were originally exposed to distilled water at room temperature for 48 h before they were completely submerged in buckets of ice for 0.5, 1.5, 3, 6, and 12 h, respectively, and then transferred into Petri dishes. The set up was left on the laboratory bench for an additional 5 days, and plant germination parameters were measured. DNA was extracted and this was followed by RAPD—polymerase chain reaction.ResultsSignificant growth impairment upon exposure to cold shock corresponding to the length of time of exposure was shown. The length of the prominent root significantly reduced upon exposure to a cold shock from 141.8 mm to as low as 91.4 mm in those plants exposed at 1.5 h. The length of the prominent leaf also significantly reduced from 100.6 mm in the control to between 62.6 and 85.5 mm in low-temperature-exposed plants (p < 0.05), notwithstanding the time of exposure. There were significant reductions in final germination percent in the low-temperature-exposed germinants (35.8–60.5%) when compared to the control (88.5%). The RAPD marker (OPA04) revealed variations in germinated maize seeds after treatment with different duration of low temperatures. The test plantlets treated for 0, 0.5, and 1.5 h have an unrecognizable complementary sequence to the primer OPA04, whereas the primer amplified regions of the genome of test plantlets treated for 3, 6, and 12 h. Primer OPA05 also presented diversity among maize seedlings stressed for various durations of cold shock.ConclusionThe existence of genetic variations in the present study has far-reaching effects on the development of maize exposed to varying degrees of cold stress. Though restricted to germination only, they are important because the development of plants begins at the germination stage. These changes may affect the characteristics of economic importance or perhaps impact on the physiology of the maize plant eventually.

Osmolyte accumulation and antioxidant metabolism during germination of vigorous maize seeds subjected to water deficit

The objective of this work was to evaluate the alterations of antioxidant enzyme reserves and antioxidant enzymes during germination under water deficit in maize hybrids and to associate with seed vigor, determining the mechanisms related to tolerance for this stress. Two three-way maize hybrids were characterized by their vigor at different levels of water deficit induced by polyethylene glycol 6000. Next, the seeds were hydrated at different osmotic potentials (0.0, -0.3, and -0.9 MPa) and removed at different times to assess the levels of the total soluble protein, total soluble sugars, proline, starch, and antioxidant enzymes, such as superoxide dismutase, catalase and ascorbate peroxidase. The analysis of variance, Tukey test at 5% and principal component analysis (PCA) were used. The vigorous hybrid (HT1) was more efficient than the low vigor hybrid seeds (HT2) in mobilizing the total soluble protein during the initial stages of germination and the total soluble sugars before and after root protrusion under water deficit in addition to increasing the catalase activity at the different osmotic potentials that were assessed.

Using isothermal calorimetry and FT-Raman spectroscopy for step-by-step monitoring of maize seed germination: case study

Thermoanalytical methods are widely used to study seed germination processes. Our research aimed to use them in order to monitor the germination of maize seeds. To this end, we employed—for the first time—the isothermal calorimetric method with full oxygen access. Dry seeds were placed in ampoules with threaded caps, filled with distilled water. Heat flow was recorded in microwatts at 20 °C for 72 h in order to determine changes in thermal power associated with germination. In parallel with these measurements, in the same time regime, we measured FT-Raman spectra, which allowed us to analyze how endosperm and embryo changed their chemical compositions during imbibition and germination. Spectra obtained for endosperm reflected chemical changes resulting from catabolic processes. We also analyzed variations in the secondary structure of proteins in the embryo accompanying germination. Decomposition of amide I bands proved that during germination and protein hydrolysis, the content of helical and β-sheet structures decreased. Furthermore, in the embryos of dry seeds, S-S linkages were in both gauche–gauche-trans and trans-gauche-trans conformations, but after imbibition, only gauche–gauche-trans conformation can be identified.

Metabolic Status during Germination of Nano Silica Primed Zea mays Seeds under Salinity Stress

Priming is a safe, easy, and effective way to increase plant tolerance against stress. This research aims to study the metabolic status of the nano-silica-primed germinated maize seeds under salinity stress. We prepare the nano-silica solution (10 mg/ml) from rice straw. We primed group maize seeds with nano-silica solution and the other group remained dry. The two seeds group germinated under different concentrations of NaCl (0, 50, 150 mM). Nano-silica primed seeds showed a higher germination rate and seedling vigor index. Priming helps the maize seeds to germinate under salinity stress through increasing the antioxidant enzymes activity which in turn suppresses the increase in the reactive oxygen species and so decreases the lipid peroxidation. Also, priming increases the gibberellin content and therefore activates the amylase and lipase activities which ensured the availability of the simple compounds needed for energy releasing through respiration. Besides that, priming enhances the activity of the respiration enzymes such as aldolase and iso citrate lyase. Finally, nano-silica priming enhanced the metabolic status of maize seeds under salinity stress.

Plant Growth Promoting Potential of Phormidium sp. ISC108 on Seed Germination, Growth Indices and Photosynthetic Efficiency of Maize (Zea mays L.)

Cyanobacteria are oxygenic, photosynthetic prokaryotes with unique potential to enhance plant growth, development, and productivity. The effects of Phormidium sp. ISC108 was evaluate on seed germination, seedling growth criteria and photosynthetic efficiency of maize. Phormidium sp. ISC108 was applied to soil via irrigation whereas control group was irrigated via sterilized water. A significant promotion in seed germination was observed in Phormidium sp. ISC108 treated maize seeds. Similarly, seedling growth indices of treated plants including biomass production, plant heights and leaf area significantly enhanced. Chlorophyll content as well as chlorophyll a fluorescence kinetics was also positively influenced by Phormidium sp. ISC108 application. Quantum yield of photosynthesis, primary photochemical reactions, rate of exiton transfer to electron transport chain, yield of electron transport and performance index of photosynthetic apparatus significantly increased in response to Phormidium sp. ISC108 application in soil. However, values of thermal dissipation of absorbed light showed a significant reduction as a result of Phormidium sp. ISC108 treatment. Considering remarkable growth promoting properties, Phormidium sp. ISC108 may offer a feasible economical and environmental-friendly candidate as bio-fertilizer in sustainable maize production..

Seed Priming with Melatonin Improves the Seed Germination of Waxy Maize under Chilling Stress via Promoting the Antioxidant System and Starch Metabolism

Chilling stress is one of the major abiotic stresses affecting waxy maize plant growth. Melatonin (MT) is able to improve tolerance to abiotic stress in plants. To investigate the effects of seed priming with MT on tolerance to chilling stress in waxy maize, the seed germination characteristics and physiological parameters were tested with varied MT concentrations (0, 50, 100 µM) and treatment times (12, 24 h) at ambient (25 °C) and chilling (13 °C) temperature. MT primed seeds significantly enhanced the germination potential (by 20.29% and 50.71%, respectively), germination rate (by 20.88% and 33.72%), and increased the radicle length (by 90.73% and 217.14%), hypocotyl length (by 60.28% and 136.14%), root length (by 74.59% and 108.70%), and seed vigor index (46.13%, 63.81%), compared with the non-priming seeds under chilling stress. No significant difference was found in priming time between primed and non-primed seeds. In addition, lower H2O2 and malondialdehyde concentrations, increased antioxidant enzyme activities (superoxide dismutase, peroxidase, catalase and ascorbateperoxidase), and promoted starch metabolism were found in primed seeds compared to non-primed ones. It was suggested that seed priming with MT improved waxy maize seed germination under chilling stress through improving antioxidant system and starch metabolism, which protected from oxidative damage.

Comparison of Seed Germination, Root and Shoot Length of Maize and Wheat Crops with Compost Leachate and Commercial Fertilizer

The increasing public concern about municipal solid waste (MSW) due to its impact on health and environment induces people to think about more ways of recycling this waste. These days, people strive to find more appropriate methods and processes to treat MSW for its proper management and disposal. Composting process is the most appropriate method of recycling used to get rid of organic fractions. The most important concern is the production of compost leachate. This study was designed to check the potential of compost leachate as a chemical fertilizer and to compare it with commercial fertilizer. Different dilutions of compost leachate and commercial fertilizer were used to check their effects on seed germination of wheat and maize crop and the initial root and shoot length measurement of these crops. Germination index, germination inhibition and germination rate were also evaluated in different experimental trials with variation in leachate dilution. The results showed best root, shoot length and seed germination at low quantity of leachate sample. The obtained results showed that leachate has better fertilizer qualities as compared to commercial fertilizer. Moreover, it is more economical and environment friendly. It also helps in maintaining the structure of soil and conditions the soil.

Effects of Exhaust Pollutants and Garden Soil on Seed Germination and Seedling Growth of Maize (Zea mays L.) and Sunflower (Helianthus annuus L.)

Aim: This study was conducted to examine the effects of exhaust pollutants and garden soil extract on seed germination and seedling growth of some economically important crops, maize and sunflower.&#x0D; Study Design: The in-vitro experimental design was completely randomized.&#x0D; Place and Duration of Study: The experimental site was Department of Botany, University of Karachi, Pakistan and the experiment was lasted for 10 days in Ecology laboratory.&#x0D; Methodology: The seeds of maize and sunflower were placed in front of the generator to exposed exhaust pollutants daily, 10 minutes, for 10 days. After the exposure of exhaust gas seeds were shifted into Petri dishes. The garden soil was obtained from mini garden of the Department of Botany, University of Karachi. The different concentrations of garden soil with distilled water were made and filtered. This filtered solution was assumed as the standard solution, which was 100%. From this standard solution, further dilution of 25%, 50% and 75% were made. Distilled water was used as a control for the experiment. Three best seedlings were selected from each Petri dish for the determination of mean values of seed germination (percentage), root, shoot and seedling length and seedling dry weight. &#x0D; Results: This publication will help to understand the importance of exhaust pollutant impact and soil on crop growth and productivity. The soil quality influences plant growth and identifies the impact of exhaust emission on plant growth. The effects of exhaust pollutants of the generator and different concentration of garden soil on seed germination and seedling growth of two important crops Zea mays (L.) maize and sunflower Helianthus annuus (L.) were recorded. The treatment of different concentration of garden soil extract (0, 25, 50, 75, and 100%) affected seed germination percentage, root, shoot, and seedling length and seedling dry weight of both crop species. The soil extract at 25% significantly (p&lt;0.05) affected the seed germination percentage of H. annuus as compared to control. The treatment of soil extract also decreased seedling growth performance of Z. mays and H. annuus as compared to control. A significant (p&lt;0.05) decrease in seedling length of Z. mays becomes evident that exhaust treatment affected the seedling dry weight performance of maize as compared to control. Similarly, exposure of exhaust pollutant affected the seedling dry weight of Z. mays and H. annuus as compared to control treatment. The effects of garden soil extract on seed germination and seedling growth of Z. mays was found higher as compared H. annuus.&#x0D; Conclusion: It was concluded that the treatment of exhaust emissions from a portable power generator fueled negatively affected the seed germination and seedling growth performance of maize and sunflower as compared to control treatment. A comparison between the seed germination percentage, seedling growth and biomass production performance of maize was found highly affected as compared to sunflower.

Moisture adsorption isotherms and quality of seeds stored in conventional packaging materials and hermetic Super Bag.

Seed moisture content (SMC) is an important attribute to seed quality. Maintaining seed dryness throughout supply chain (The Dry Chain) prevents seed germination and quality losses. Ambient relative humidity (RH) and temperature affect seed moisture and thereof seed moisture isotherm. Present study was conducted to compare the moisture adsorption isotherms of wheat, maize, cotton and quinoa seeds packed in hermetic Super Bag and traditional packaging materials including paper, polypropylene (PP), jute and cloth bags. Seeds were incubated at 60, 70, 80 and 90% static RH. Nearly straight line moisture isotherms for all crop seeds were obtained in Super Bag. Seed moisture contents increased in traditional packaging materials with increasing RH. At higher level of RH, moisture contents increased slightly (1–2%) in Super Bag, whereas this increase was much higher in traditional packaging materials (≈9% higher than original SMC at 90% RH). In second study, seeds were dried to 8 and 14% initial seed moisture contents using zeolite drying beads and were stored in hermetic and conventional packaging materials for a period of 18 months. For all crop seeds, germination was severely affected in all packaging materials both at 8 and 14% initial SMC except storage in Super Bag at 8% SMC. Wheat seed stored in Super Bag at 8% SMC almost maintained initial germination while germination of cotton, maize and quinoa seeds declined 7%, 14% and 30% respectively in Super Bag at 8% SMC. Seed storage in Super Bag can help to prevent the significant increase in seed moisture at higher RH as is evident from moisture isotherm study, thus helps to preserve quality of maize, wheat, cotton and quinoa seeds by maintaining The Dry Chain throughout the storage period.

Development of biodegradable coatings for maize seeds and their application for Azospirillum brasilense immobilization.

The objective of this study was to develop biodegradable coatings for agriculture crop seeds based on starch, gelatin, and polyvinyl alcohol (PVA). Developed materials were characterized according to their microstructures, barrier properties, influence on germination of maize seeds, and ability to sustain Azospirillum brasilense Ab-V5 viability in coated maize seeds. The coatings were obtained employing different proportions of starch, gelatin, and PVA, ranging from 0 to 3.0g/100g of each material, respectively. Samples formulated with the pure polymers showed the highest values of water absorption capacity, solubility, and water vapor permeability, and the ternary mixtures showed the lowest values. Single polymer formulations and the binary starch-gelatin mixture (CS50GL50) favored maize seeds germination compared to the uncoated maize seeds. In addition, seed coating obtained from CS50GL50 formulation resulted in A. brasilense Ab-V5 viability in coated seeds up to 15days after bacterial immobilization, being considered a promising low-cost, biodegradable, and renewable source material to be used in agriculture.

Drought Stresses on Seed Germination and Early Growth of Maize and Sorghum

Seeds of maize (Zea mays L.) and sorghum [Sorghum bicolor (L.) Moench.] were submitted to different osmotic potential levels induced by polyethylene glycol (PEG) with the objective of evaluating the effects of drought stress on seed germination and early seedling growth. Seeds were arranged in paper rolls and soaked in PEG solutions prepared with osmotic potentials 0.0 (control), -0.2, -0.4, and -0.8 MPa and kept into a seed germinator, at 25 &amp;deg;C for 18 days. A completely randomized design in a 2 &amp;times; 4 factorial scheme with four replications of 50 seeds each was used. The results showed that by increasing of the osmotic potential level, germinated seed number, germination rate index, root and shoot length, shoot and root dry matter, and seedling vigor index (SVI) decreased, while mean germination time (MGT) and root: shoot ratio (RSR) increased in both crops. Additionally, the maize was more susceptible than sorghum to drought stress, with germination response declining more rapidly with decreasing osmotic potential. Sorghum crop tolerates water stress of up to -0.2 MPa, without reducing germination of the seeds; however, the growth of shoots and roots are inhibited. Drought stress limits the process of seed germination and early growth of maize seedlings.

Signaling Molecule Hydrogen Sulfide Improves Seed Germination and Seedling Growth of Maize (Zea mays L.) Under High Temperature by Inducing Antioxidant System and Osmolyte Biosynthesis.

Hydrogen sulfide (H2S) is a novel type signaling molecule in plants. Seed germination is a key stage of life cycle of plants, which is vulnerable to environmental stress including high temperature. However, under high temperature stress, whether pre-soaking of maize seeds with NaHS (a H2S donor) could improve seed germination and seedling growth and the possible mechanisms are not completely clear. In this study, maize seeds pre-soaked with NaHS enhanced germination percentage, sprout length, root length, and fresh weight compared with the control without NaHS treatment, illustrating that H2S could improve maize seed germination and seedling growth under high temperature. In addition, in comparison to the control, NaHS pre-soaking stimulated antioxidant enzymes [ascorbate peroxidase (APX), glutathione reductase (GR), guaiacol peroxidase (GPX), superoxide dismutase (SOD), and catalase (CAT)] activities and the contents of water soluble non-enzymatic antioxidants [ascorbic acid (AsA) and glutathione (GSH)], as well as the ratio of reduced antioxidant to oxidized antioxidant. Moreover, pre-soaking with NaHS activated Δ1-pyrroline-5-carboxylate synthetase (P5CS) and ornithine aminotransferase [OAT; both are rate-limiting enzymes in proline (Pro) synthesis], betaine aldehyde dehydrogenase [BADH; a key enzyme in glycine betaine (GB)], and trehalose (Tre)-6-phosphate phosphatase (a key step in Tre synthesis), which in turn accumulated Pro, GB, and Tre in germinating seeds compared with the control. Also, an improved germination by NaHS under high temperature was reinforced by the above osmotic adjustment substances (osmolytes) alone, while deteriorated by the inhibitors of osmolyte biosynthesis [gabaculine (GAB), disulfiram (DSF), and sodium citrate (SC)]. These results imply that H2S could improve maize seed germination and seedling growth under high temperature by inducing antioxidant system and osmolyte biosynthesis.

Effect of Cold Atmospheric Pressure Plasma on Maize Seeds: Enhancement of Seedlings Growth and Surface Microorganisms Inactivation

Cold atmospheric pressure ambient air plasma generated by Diffuse Coplanar Surface Barrier Discharge (DCSBD) was investigated for inhibition of native microbiota and potentially dangerous pathogens (Aspergillus flavus, Alternaria alternata and Fusarium culmorum) on the maize surface. Moreover, the improvement of germination and growth parameters of maize seeds was evaluated. Maize (Zea mays L.; cv. Ronaldinio), one of the most important cultivated crops worldwide, was selected as the research material. Electrical measurements confirmed the high volume power density (80 W cm−3) of DCSBD plasma. Non-equilibrium plasma state evaluated using optical emission spectroscopy showed values of vibrational and rotational temperature (2700 ± 300) K and (370 ± 75) K, respectively. Changes on the plasma treated seeds surface were studied by water contact angle measurement, scanning electron microscope analysis and Fourier transform infrared spectroscopy. A complete devitalisation of native microbiota on the surface of seeds was observed after a short treatment time of 60 s (bacteria) and 180 s (filamentous fungi). The plasma treatment efficiency of artificially contaminated maize seeds was estimated as a reduction of 3.79 log (CFU/g) in F. culmorum after a 60-s plasma treatment, 4.21 log (CFU/g) in A. flavus and 3.22 log (CFU/g) in A. alternata after a 300-s plasma treatment. Moreover, the obtained results show an increase in wettability, resulting in a better water uptake and in an enhancement of growth parameters. The investigated DCSBD plasma source provides significant technical advantages and application potential for seed surface finishing without the use of hazardous chemicals.

Evaluating the Potential Effect of Seed Priming Techniques in Improving Germination and Root Shoot Length of Maize Seed

Abstract The present research was conducted under laboratory conditions. The purpose of research was to investigate the potential of priming with press mud, peat moss, sand, gunny bags, compost, farm yard manure and moringa leaf extract (MLE) on seedling growth and germination capacity of maize seed. Untreated or non-primed seeds were used as a control treatment. Priming treatments improved germination capacity, stand establishment and seedling vigor, compared with control. Priming with moringa leaf extract enhance germination and seedling vigor of maize seed, compared with the control and other seed primed treatments. In moringa leaf extract primed seeds, root and shoot growth was improved. Overall, moringa leaf extract primed maize seeds performed better than all other treatments and it could be related by seedling vigor enhancement and lowering the mean germination time, due to imbibition of higher quantity of water and earlier enzymatic activity. The results propose that moringa leaf extract priming treatment had the potential to enhance germination, stand establishment and early growth of maize seeds.

Toxicity evaluation of process water from hydrothermal carbonization of sugarcane industry by-products.

Hydrothermal carbonization (HTC) is a thermochemical process carried out in an aqueous medium. It is capable of converting biomass into a solid, carbon-rich material (hydrochar), and producing a liquid phase (process water) which contains the unreactive feedstock and/or chemical intermediates from the carbonization reaction. The aim of this study was to evaluate the characteristics of process water generated by HTC from vinasse and sugarcane bagasse produced by sugarcane industry and to evaluate its toxicity to both marine (using Artemia salina as a model organism) and the terrestrial environment (through seed germination studies of maize, lettuce, and tomato). The experiments showed that concentrated process water completely inhibited germination of maize, lettuce, and tomato seeds. On the other hand, diluted process water was able to stimulate seedlings of maize and tomato and enhance root and shoot growth. For Artemia, the LC50 indicated that the process water is practically non-toxic; however, morphological changes, especially damages to the digestive tube and antennas of Artemia, were observed for the concentration of 1000mgCL-1.

Effect of seed priming with hormonal combinations on morphological and biochemical attributes of maize seedlings

Maize (Zea mays L., the third most important cereal crop after wheat and rice, is the major kharif (summer) crop of rainfed areas in Pakistan. The yield per hectare and total production of maize in Pakistan is low versus an exponentially increasing population. The objective of this work was to study the interactive effects of phytohormones [Gibberellic acid (GA), Sodium nitroprusside (SNP), Abscicic acid (ABA) and kinetin (KIN)] on morphological, physiological and biochemical parameters during the germination of maize seeds. Seeds were presoaked in different hormones, separately or in combinations. Priming with GA+SNP+ABA+KIN enhanced the total fresh (TFW) and dry weights (TDW) of the seedlings in comparison to the control. Similarly, exogenous application of GA+KN, GA+SNP, GA+SNP+ABA+KIN, SNP+KIN+ABA increased the oxidative enzymes [catalase (CAT) and ascorbateperoxidase (APX)] of the maize seedlings. Sugar and proteins concentrations were increased in response to the exogenous application of GA+SNP+ABA+KN, KN+ABA, GA+SNP+KIN, SNP+KIN+ABA, GA+ABA and SNP+KIN. A combination of hormones for presoaking seeds is recommended to improve the germination characteristics which will ultimately enhance grain yield.

Amelioration of Salinity Stress in Maize Seed Germination and Seedling Growth Attributes through Seed Priming

Germination of seeds and growth of seedling respond to seed priming as priming can guard the damage of salinity stress. A study conducted in the net house of the Department of Agronomy, BAU, Mymensingh during the period from November 2012 to April 2013 investigated the ameliorative effect of seed priming on seed germination and seedling attributes of maize under various salinity stress conditions. The experiment consisted of five seed priming and four salinity levels (NaCl) and laid out in a Completely Randomized Design (CRD) with three replications. Seed germination and seedling attributes of maize varied due to salinity stress and priming. The highest seed germination (95.7%) was recorded when no stress was imposed under hydropriming (48 hours). The germination of seeds performed even well (92.3%) when treated with hydropriming (48 hours) and NaCl@0.25 dS&#183m-1 which was followed by hydropriming (24 hours) under no salinity imposed and NaCl@0.25 dS&#183m-1 salinity. Hydropriming for 48 hours without salt stress performed the best on number of leaves seedling-1 (8), shoot length (28.2 cm), root length (14.5 cm), fresh weight (100.8 g) and dry weight of seedling (50.3 g). The germination and seedling growth parameters were reduced with the increase in salinity levels irrespective of priming while all seed priming treatments showed ameliorative effects. However, reduction in seed germination and seedling attributes were minimal with hydropriming for 48 hours. The results revealed that priming of maize seeds could be used for amelioration of salinity stress and hydropriming for 48 hours appeared as the best seed priming treatment.

Influence of salicylic acid pretreatment on seeds germination and some defence mechanisms of Zea mays plants under copper stress

The study was focused on the influence of salicylic acid (SA) on maize seeds germination and on some physiological and biochemical processes in maize plants growing in the hydroponic culture under copper (Cu) stress. A significant influence of SA pretreatment on the advanced induction of the maize seeds metabolic activity and the level of the endogenous SA in germinated seeds and developing roots have been stated. Although, the ability of maize seeds to uptake SA and accumulate it in the germinated roots was confirmed, the growth inhibition of Cu-stressed maize seedlings was not ameliorated by SA seeds pretreatment. Cu-stressed plants exhibited a decrease in the photosynthetic pigment concentration and the increase in non-photochemical quenching (NPQ) - an indicator of an excess energy in PSII antenna assemblies lost as a heat. The amelioration effect of SA application was found only for carotenoids content which increased in stressed plants. It was also shown that maize roots growing in stress conditions significantly differed in the chemical composition in comparison to the roots of control plants, but the SA pretreatment did not affect these differences. On the other hand, it was found that SA seed pretreatment significantly influenced the ability of stressed plants to accumulate copper in the roots. It was stated that a higher level of exogenous SA application led to a lower accumulation of Cu ions in maize roots. Cu-stressed plants exhibited higher oxidative stress in roots than in leaves which was manifested as an increase in the concentration of hydrogen peroxide due to stress factor application. We observed an increase in catalase (CAT) activity in leaves of Cu-stressed plants which corresponded with a lower H2O2 content when compared with roots where the hydrogen peroxide level was higher, and the inhibition of the CAT activity was found. Furthermore, we found that the SA seed pretreatment led to a decrease in the H2O2 content in the roots of the Cu-stressed plants, but it did not influence the H2O2 level in leaves. The increase in hydrogen peroxide content in the roots of Cu-stressed plants correlated with a higher activity of the MnSODI and MnSODII isoforms. It was found that SA pretreatment caused a decrease in MnSODII activity accompanied by the decrease in H2O2 concentration. Achieved results indicated also that the changes in the chemical composition of the root tissue under copper stress constituted protection mechanisms of blocking copper flow into other plant organs. However, it might be assumed that the root tissue remodelling under Cu stress did not only prevent against the Cu ions uptake but also limited the absorption of minerals required for the normal growth leading to the inhibition of the plant development.