Salinity is one of the major abiotic stress factors affecting series of morphological, physiological, metabolic and molecular changes in plant growth. The effect of different concentrations (0, 25, 50, 100 and 150 mM) of NaCl on the vegetative growth and some physiological parameters of karkade (Hibiscus sabdariffa var. sabdariffa) seedling were investigated. NaCl affected the germination rate, delayed emergence and retarded vegetative growth of seedlings. The length of seedling as well as the leaf area was significantly reduced. The fresh weight remained lower in NaCl treated seedlings compared to control. NaCl at 100 and 150 mM concentrations had significant effect on the dry matter contents of the treated seedlings. The chloroplast pigments in the treated seedlings were affected, suggesting that the NaCl had a significant effect on the chlorophyll and carotenoid biosynthesis. The results showed that the salt treatments induced an increase in proline concentration of the seedlings. The osmotic potential (ψs) of NaCl treated seedlings decreased with increasing NaCl concentrations. Salt treatments resulted in dramatic quantitative reduction in the total sterol percent compared with control ones. Salt stress resulted in increase and decrease of Na+ and K+ ions, respectively. NaCl salinity increased lipid peroxidation. SDS-PAGE was used to evaluate protein pattern after applying salt stress. High molecular weight proteins were intensified, while low molecular weight proteins were faint. NaCl at 100 and 150 mM concentration distinguished with new protein bands. Salt stress induced a new peroxidase bands and increased the band intensity, indicating the protective role of peroxidase enzyme.
Aggressiveness variation among 16 isolates of four Fusarium species (F. culmorum, F. solani, F. verticillioides and F. equiseti) causing Fusarium head blight (FHB) was studied in vitro. Evaluation of three aggressiveness criteria involved in a Petri-dish test: germination rate reduction, standardized area under disease progress curve (AUDPCstandard), and coleoptile length reduction was carried out on the barley cultivar Arabi Aswad. Results showed differences between barley plants inoculated with FHB isolates and control for the three tested aggressiveness criteria. Regarding AUDPCstandard and Petri-dish aggressiveness index which is calculated from the mean value of three aggressiveness criteria, within and among variation was detected. Intra- and inter-species variability was not distinguished for the other two aggressiveness criteria. However, pathogenic level observed among 16 isolates can not be differentiated within the four FHB species. Significant correlation was detected only between AUDPCstandard and Petri-dish aggressiveness index. The results were comparable with those previously obtained using the same fungal isolates on wheat cultivar in vitro. It seems that FHB isolates recovered from wheat spikes and tested on wheat plants showed a similar range of aggressiveness on a barley cultivar, Arabi Aswad.
Salinity reduces plant growth and yield by affecting morphological and physiological processes. To alleviate the harmful effects of salt stress various approaches involving plant hormones are used. In this study several parameters involving the measurement of cell membrane injury were used to observe whether stress tolerance could be enhanced in Chinese cabbage (B. oleracea capitata L. Chinensis group) by soaking the seeds for 10 h in distilled water (control), or in 100, 150 or 200 mg l−1 gibberellic acid (GA3). The NaCl concentrations were 0 (control), 50, 100 and 150 mM. Seed treated with GA3 showed increased water uptake and decreased electrolyte leakage as compared to that of distilled water-primed seeds even 24 h after soaking under control conditions. Seed priming with GA3 increased the final germination and the germination rate (1/t50, where t50 is the time to 50% germination) under salt stress conditions. Seed priming also alleviated the harmful effect of salt stress on cabbage in terms of fresh and dry weights. Leaf area was higher in plants raised from seeds primed with the higher GA3 concentrations as compared with those raised from seeds treated with distilled water under control conditions (without NaCl) or at 50 mM NaCl stress. The chlorophyll content increased with the NaCl concentration, especially in plants grown from seeds primed with GA3. Plants grown from GA3-primed seeds also suffered lower cellular injury both under control conditions and under NaCl stress.
Concerns about the vulnerability of agricultural production to climate change are increasing. The establishment of seedlings at early growth stages of crop plants, one of the most important determinants of high yield, is severely affected by extreme temperatures. Therefore, efforts must be made to achieve high germination rate and vigorous early growth under extreme temperature conditions.Alfalfa is a perennial forage crop with high yield, good quality and high protein content, but is frequently exposed to extreme temperature conditions. The primary purpose of this investigation was to test the hypothesis that L-ascorbic acid (AsA) and pyridoxine (B6) pretreatment can completely or partially alleviate the effect of extreme temperature stress on seed germination and other physiological activities of alfalfa seedlings. Such treatment could be of importance for the establishment of alfalfa seedlings under temperature conditions colder or hotter than the optimum.Several parameters were studied in alfalfa seedlings primed before germination with 50 ppm ascorbic acid or 50 ppm pyridoxine for 6 h and then subjected to various temperatures (10, 15, 20, 25, 30, 35 and 40°C) for 7 days.The germination percentage of alfalfa seeds was negatively affected by extreme temperature. The vitamin treatments failed to alleviate the depressive effect of extreme temperature stress on seed germination. Extreme temperature also induced a reduction in the growth, total water content and respiration rate of alfalfa seedlings. Seed soaking in vitamins modified the stress-induced changes in respiration rate and growth criteria. Temperatures above or below the optimum stimulated the accumulation of soluble carbohydrates in alfalfa seedlings. Treatment with AsA or B6 partially or completely retarded the stimulatory effects of extreme temperature on soluble carbohydrate accumulation in the seedlings except in the case of 40 °C, where a significant stimulation was detected. However, extreme temperature stress and its interactive effects with AsA or B6 induced an inhibitory effect on the accumulation of free amino acids and soluble proteins in the test seedlings.
Authors:Brigitta Tóth, Dr. Szilvia Veres, Nóra Bákonyi, Éva Gajdos, Marianna Marozsán, and Dr. László Lévai
Környezetünk védelme közös feladat. Minden szennyezés, ami földjeinket, növényeinket, a szűkebb, vagy a tágabb értelemben vett környezetünket éri, előbb-utóbb megjelenik az élelmiszerlánc valamelyik tagjában, végül a piramis csúcsán álló emberben.
Munkánk célja egy átlátható képet adni néhány ipari hulladék – cementpor, mészpor, mészhidrátpor – növényekre gyakorolt fiziológiai hatásáról. A vizsgált anyagok a növények számára sok létfontosságú elemet tartalmaznak (pl.: vas, kálium, magnézium, foszfor, cink), de mindezek mellett alumínium, ólom, króm és kobalt is megtalálható bennük. Ezek figyelembevételével vizsgáltuk a csírázásra gyakorolt hatást, a növények elemfelvételét, a száraz anyag felhalmozást és a relatív klorofill tartalmat. A laboratóriumi kísérletek során bizonyítottá vált a cementpor, a mészpor és a mészhidrátpor kedvező és kedvezőtlen fiziológiai hatása. Kétségtelen, hogy a laboratóriumban a környezet kompenzáló hatása kizárt, azonban a környezeti terhelések semlegesítése természetes körülmények között sem végtelen.
Authors:D. Paquin, K. Yanagihara, W. Grannis, and Q. Li
There are millions of acres of chemically contaminated lands on which biofuel crops can be planted for dual purposes of biomass production and land reclamation. Phytoremediation is a proven technology for environmental cleanup, particularly in tropical and sub-tropical environments. There are advantages in that multiple growing seasons and increased soil temperature accelerate the clean-up processes. Seeds of 13 tropical and temperate plant species were germinated and grown for 10 days in petroleum contaminated soil containing 3148 μg/g of polycyclic aromatic hydrocarbons (PAHs). The results indicate that the presence of PAHs enhanced both emergence and early seedling growth with some of the species tested. Kiawe tree germination rate was 7-fold higher in PAH soils than that in the control media. The potential biofuel grasses sugarcane, banagrass, switch grass, vetiver and miscanthus showed degradation of PAHs in at least one of the amended PAH-contaminated soils in 35 days of growth. Banagrass biomass production in all the treatments was far greater than the other four species. No plant control pots were most effective to reduce PAHs in the un-amended PAH soil. Vetiver degraded all PAHs when planted in the PAH soil amended with 1/3 of the Promix soil (a 2/3 PAH soil volume). Among five biofuel crops tested, banagrass produced a tripled amount or more of biomass than all the other species in the LF-14 un-amended PAH soil or its amended soils. The dry weight (dw) biomass of banagrass averaged ∼3 g/day/3-L pot in all PAH soils and 6 g/day/3-L pot in Promix as harvested at the ground level. Banagrass in 90-cm spacing could produce approximately 30 tons/ha/yr of dry matter in a 70-day crop season. The results warrant further investigation of biofuel crops for phytoremediation and biomass production purposes. Future plantings may be considered using these and other crops in combination with applicable contaminants to help clean up the contaminated environment and reduce petroleum dependency.
Anthocyanins are natural antioxidants able to scavenge free radicals, which appear in plant cells under various environmental stresses. In wheat, anthocyanin pigments can be synthesized in vegetative and reproductive organs. The objective of the current study was to estimate the significance of these substances for wheat seedlings protection under irradiation stress (after treatment of dry seeds with moderate doses of gamma-irradiation, 50, 100 and 200 Gy). For this goal a set of near-isogenic lines (8 NILs) carrying different combinations of the Pp (purple pericarp) and Rc (red coleoptile) alleles were used. The effect of gammairradiation on the growth parameters and anthocyanin content in coleoptiles was studied at the 4th day after germination. The germination rate was not affected, while roots’ and shoots’ lengths and fresh weights as well as root number decreased significantly under irradiation treatment. The effect was deeper under higher doses. Irradiation treatment also induced change of root morphology (‘hairy roots’). The effect of treatment on coleoptile anthocyanin content depended on allelic combination at the Rc loci. At the presence of ‘weak’ Rc-A1 allele anthocyanin content decreased, while it did not change in lines with Rc-A1 + Rc-D1 combination (NILs with intensively colored coleoptiles). Factors ‘pericarp color’ and ‘coleoptile color’ influenced vigor of the seedlings under 50 Gy, whereas under higher doses (100 and 200 Gy) these factors did not contribute to growth parameters changes. Statistically significant positive effect of anthocyanins synthesized in coleoptile (in the presence of Rc-A1 + Rc-D1 dominant alleles) on root growth of seedling germinated from 50 Gy-treated seeds was observed.
Covell, S., Ellis, R. H., Roberts, E. H. and Summerfield, R. J. (1986): The influence of temperature on seed germinationrate in grain legumes. I. A comparison of chickpea, lentil, soyabean and cowpea at constant temperatures. —
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