Germination Research Articles

Dynamic Investigation of Auxin on Germination of Sesamum Indicum Seed by 1H Spectroscopy and Chemical Shift Selection Imaging

Ger mination of sesame seeds in acidic and indole-3-acetic acid (IAA) liquid mediums was investigated using single pulse 1H spectroscopy and chemical shift selection imaging. The spectra and images demonstrated high correlation and reliability. Chemical shift selection imaging allowed for an intuitive comprehension of the dynamic distribution of metabolites and structural changes during germination, leading to a clearer understanding of IAA’s regulation on sesame metabolites, when combined with 1H spectra. Results showed that exogenous hormones accelerated the decomposition of lipid macromolecules before rapid radicle growth, while IAA delayed sesame development at this stage. However, post-growth delay, the addition of IAA effectively accelerated germination. This study confirms that 1H spectroscopy and chemical shift selection imaging can interpret the metabolic response of plants to the change in their internal physiological state and help to determine the optimal time to add IAA.

Toxic risk evaluation of effluents from a swine biodigester in the plant models Lactuca sativa and Allium cepa.

Pig farming is recognized as an activity with great polluting potential. The aim was to investigate possible environmental risks of effluents from the stabilization pond (SP) and the raw effluent (RE) from the biodigestion process of swine residues, in different concentrations in the models Lactuca sativa and Allium cepa. Seeds were germinated in different dilutions, 100% (C1), 50% (C2), 25% (C3), 12.5% (C4), 6.25% (C5), 3.12% (C6), 0.78% (C7), and 0.39% (C8). Distilled water was used as the negative control (CN) and trifluralin (0.84 g/L-1) as the positive control. Germination (GR), root growth (RG), cell cycle, and oxidative stress (OS) were analyzed. To assess OS, the activity of the enzymes superoxide dismutase (SOD), catalase (CAT), and glutathione S-transferase (GST) and the quantification of glutathione (GSH) and lipid peroxidation (LPO) were analyzed. Data were submitted to ANOVA (one way), followed by the Kruskal-Wallis mean test (P ≤ 0.05). Chemical analysis showed high values of Cu, Fe, Mn, and Zn. Dilutions (C1, C2, C3 RE) and (C1 and C2 SP) inhibited GR and RG of L. sativa and A. cepa than other concentrations. The mitotic index showed a reduction in C5 (RE), C6, and C7 (SP) of L. sativa and C3 and C4 (SP) of A. cepa in relation to CN and higher frequencies of chromosomal alterations. Regarding the OS, only the concentrations of SP treatment showed statistical difference in relation to the NC: in L. sativa model, GSH at (C5 and C8) concentrations and LPO (C7); in A. cepa model, SOD (C3 and C4), GST (C4, C5 and C6), GSH (C5 and C8), and CAT (C3 and C7). The alterations in metabolism are possibly related to the metals, such as zinc and copper, observed in high amounts in the raw waste. The results allowed us to conclude that the raw and stabilization pond effluents offer environmental risks, requiring caution and monitoring in the use of these effluents.

Comparative study of different biological processing methods on nutritional composition and bioactivity of whole‐grain wheat

AbstractBackground and ObjectivesBiological processing is considered one of the most effective technologies used to eliminate adverse traits and improve the quality of cereal. To compare the effects of different biological processing methods on the nutritional value and bioactivity of whole‐grain wheat (WGW), solid‐state fermentation (SSF), germination (GT), solid‐state fermentation (SSF), germination (GT), and phytase treatment (PT) were performed.FindingsAfter biological processing, protein, insoluble dietary fiber, and bound flavonoid contents significantly increased, while phytate, bound phenolic, and free flavonoid contents obviously decreased. The molar ratio of phytate content to mineral content, including PA/Ca, PA/Fe, and PA/Zn, significantly reduced by 13.8%–42.0%, 8.4%–73.4%, and 17.9%–45.0%, respectively, suggesting the improvement of mineral bioavailability. The greatest reduction of phytate content was found in WGW after PT. In comparison to SSF and PT, GT significantly improved phenolic content and 2,2‐azinobis (3‐ethylbenzothiazoline‐6‐sulfonic acid) and 1, 1‐diphenyl‐2‐picrylhydrazyl free radical scavenging abilities of free phenolic extract in WGW. As compared to GT and PT, the ORAC of the free phenolic extract in WGW obviously improved after SSF with strains of Lactobacillus plantarum, Saccharomyces cerevisiae, and Monascus sp.ConclusionsOverall, SSF, GT, and PT showed high efficiency in phytate degradation, and GT and SSF, in particular, improved the nutritional value and bioactivity of WGW.Significance and NoveltyThis study provides data supporting the use of different biological processing methods based on different objectives when preparing WGW products.

Effect of genotype-environment interaction on soybean (Glycine max (L.) Merrill) germination, vigor index, and seed yield

The adverse edaphoclimatic conditions in the Orinoquía region affect the soybean crop cycle, deteriorating seed quality. The aim of this study was to investigate the effect of the genotype (G), the environment (E), and their interaction (GxE) on the yield and seed quality of six soybean varieties (Corpoica Superior 6, Orinoquía 3, Soyica P34, Corpoica Taluma 5, and Agrosavia Primavera 11 of Colombian origin and Barreira of Brazilian origin) in five environments of the Orinoquía Colombia region, two in the second half of 2020 (LIBB: La Libertad and TALB: Taluma) and three in the first half of 2021 (LIBA: La Libertad, TALA: Taluma, and LEONAS), to determine their adaptation domain. Highly significant differences (P<0.01) were observed between G, E, and GxE for germination (GER) and seed yield (SY). A similar situation was shown by the vigor index (VI), although without differences between environments. The GGE biplot for GER, and SY separated environments by year halves. Taluma during the first half was the most discriminating environment for the response variables, useful for genetic breeding programs with a seed quality approach. Only in La Libertad during the second half was GER above 80%. The most stable variety per environment was Soyica P34 in two response variables, and the best with specific adaptation were Corpoica Superior 6 and Orinoquía 3. These last two reached higher average values in GER (69.6%; 63.1%), VI (13.3; 13.4), and SY (1473 kg ha-1; 1404 kg ha-1).

Shade and no light explain Hovenia dulcis Thunb. invasiveness in subtropical forest fragments: A Greenhouse Microcosm Experiment

Hovenia dulcis is a non-native species with high capacity for invasion in subtropical forest fragments. In this study we used a greenhouse experiment simulating field abiotic and biotic conditions to investigate the germination and growth to determine the mechanisms associated with the high invasion potential of this species. We evaluated the effects of abiotic factors (light) and biotic factors (litter mass and litter type) on ecophysiological parameters: germination (GR), initial establishment (RR and ER) and shoot and root growth in a greenhouse experiment. Interactions between factors were compared using GLM, to select the best model and the factors that influence each parameter evaluated. GR, RR and ER were negative influenced by light intensities, when the low intensity presents more germination and establishment of individuals than intermediate intensity. Additionally, shoot height and root length were negatively influenced by the light intensity with a higher stem elongation in low light intensities. We found no interactions between the abiotic and biotic conditions tested. However, when evaluated individually, germination, establishment and growth were better in low light conditions regardless of the litter mass and litter type. These results challenge the classification of H. dulcis as an intolerant shade species.

Influence of Nitric oxide donor nanoencapsulation on Dyckia excelsa Lema (Bromeliaceae) germination

Bromeliads are used in landscaping due to the beauty of their leaves and flowers. The use of plant regulators such as nitric oxide (NO) promotes the stimulus of germination and it has been a way out to enhance production and reduce the search for plants in nature and nanoencapsulation aims to optimize its effect. The objective of this work was to evaluate the effect of using free and nanoencapsulated NO donor on the germination of D. excelsa. The treatments consisted of soaking the seeds for 5 minutes with s-nitrosoglutathione (GSNO), chitosan/sodium tripolyphosphate nanoparticles containing GSNO (NP CS/TPP-GSNO) and empty (NP CS/TPP) at doses: 15 mM and 20 mM. The control consisted of imbibition in distilled water. For each treatment, 4 replications of 50 seeds were used. The following variables were evaluated: percentage of germination (GER), first germination count (FGC), germination speed index (GSI), average germination time (AGT) in addition to the length (SL) and seedling dry weight (SDW). To characterize the seeds, water content and viability were evaluated. D. excelsa seeds had 9.9% water content and 64% viability. For GER, treatments with GSNO ranged from 43 to 60%. The application of GSNO stimulated the germination process of D. excelsa and the nanoencapsulation did not cause any difference in the results compared to the free GSNO. It was concluded that the application of 15 or 20 mM of the GSNO donor is recommended for stored seeds of D. excelsa.

Seed bio-priming with phosphate-solubilizing bacteria strains to improve rice (Oryza sativa L. var. FARO 44) growth under ferruginous ultisol conditions.

This study investigated the possibility of using phosphate-solubilizing bacteria (PSB) with plant-growth-promoting (PGP) capabilities to improve the growth properties of rice plants under ferruginous ultisol (FU) conditions through bio-priming. The following PSB with PGP properties were used in this study: Bacillus cereus strain GGBSU-1, Proteus mirabilis strain TL14-1, and Klebsiella variicola strain AUH-KAM-9, which were previously isolated and characterized based on 16S rRNA gene sequencing. Biosafety analysis of the PSB isolates was conducted using blood agar. The rice seeds were then bio primed with the PSB for 3, 12, and 24 h and then sown in a composite FU soil sample. Differences in germinat ion bioassay were investigated 15 weeks after bio-priming using scanning electron microscopy (SEM), morphology, physiology, and biomass parameters. The composite FU soil used in this study had high pH, low bioavailable phosphorus, low water-holding capacity, and high iron levels, which resulted in low growth properties of rice seeds without bio-priming in the FU soil. Germination parameters were improved in seeds bio primed with the PSB, especially after 12 h of priming, compared with seeds without priming. SEM showed higher bacterial colonization in bio primed seeds. Bio-priming of rice seeds with the studied PSB under FU soil conditions significantly improved seed microbiome, rhizocolonization, and soil nutrient properties, thereby enhancing the growth properties of rice. This indicated the ability of PSB to solubilize and mineralize soil phosphate and improve phosphorus availability and soil properties for optimum plant usage in phosphate-stressed and iron toxic soils.

Influence of delta-hexachlorocyclohexane (δ-HCH) to Phytophthora ×alni resistant Alnus glutinosa genotypes − Evaluation of physiological parameters and remediation potential

Hexachlorocyclohexanes (HCHs) are persistent organochlorine pesticides with the adverse effects on human health and the environment. The effect of delta-isomer of hexachlorocyclohexane (δ-HCH) on germination, growth parameters and physiological parameters was studied in different Alnus glutinosa (L.) Gaertn. progeny of resistant genotypes to pathogen Phytophthora ×alni. Two experiments were performed: a short-term experiment to determine the effect of δ-HCH on total germination (GT), germination energy (GE), speed of germination (SG), shoot length and biomass of seedlings, and a long-term experiment devoted to remediation aspects. In addition, changes in the hormonal system of alders were monitored in both cases. Significant differences were found between the treated and control group in most of the evaluated characteristics. Also, the content of studied phytohormones differs between groups. Furthermore, the obtained results indicate genetically determined variability in response to δ-HCH. Of the six tested, the Březové and Tuřany progeny seem to be suitable candidates for phytoremediation because of the adaptation to stress conditions or high remediation efficiency. The rest of tested progeny seems to be unsuitable due to higher mortality, lower remediation efficiency and higher levels of stress hormones resulting in significant decrease in biomass and plant height. Moreover, results indicate the role of the plant as a remediation accelerator, probably through released exudates, and a positive effect on the soil microbiome as the presence of plants increased the remediation efficiency by 20.85 – 35.89%. The obtained research findings may be helpful in better understanding the processes involved in removing these pesticides from the soil. Further research should be focused on rhizosphere microbiome, mechanism of in-plant isomerization and metabolites identification.

Growth, sporulation and germination of Verticillium alfalfae on media

Growth, sporulation and germination of Verticillium alfalfae on media

Physico-chemical changes and maturity evaluation of composts from wood residue mixed with sewage sludge and chicken manure

Purpose Using the effective approaches for modifying the recycled wood as a novel bulky agent improves the quality of soil amendment. This study aimed to compare the stability and maturity of the soil amendments produced by the compostation of forest industrial waste and sewage sludge on seed germination. Method Three materials, namely sawdust, sewage sludge, and chicken manure were mixed at different ratios (dry weight basis) to reach the initial bulk density of 0.40 Kg.L-1, the temperature of 30 °C, the C/N ratio of 25, and the moisture content of 60 %. A pilot-scale composting process was applied to monitor the aeration rate, temperature, and moisture contents during the process over time. The comparison of physico-chemical, phytotoxicity, and germination indices among the samples was performed in three repetitions. Results The results of this study indicated that the sustainable conditions (i.e., the temperature of 70 °C, aeration rate of 0.30 L.Kg-1DM.min-1, and moisture content of 50-60 %) can have a significant effect on the thermophilic stage for compost curing without any inhibitory repercussion. Increasing the germination index of cress (Lepidium sativum) up to 79 % proved that the toxicity of industrial sewage sludge was declined through the elimination of heavy metals. Conclusion This study revealed that the availability of bulky agents such as wood residue can reinforce the microbial activity by continuously decreasing the C/N ratio to the minimum value of 13.2.

Quality of wheat breads enriched with flour from germinated amaranth seeds.

Amaranth flour from germinated (GA) and non-germinated (A) seeds (0%-C, 5%, 15%, 25%) were mixed with wheat flour for breadmaking. Fermentation parameters of dough (time-tf, maximum volume-Vmax) were obtained. Specific volume (Vsp) of breads, crust color, texture and relaxation of crumb were analyzed. A high amount of germinated amaranth flour decreased Vmax and increased tf, obtaining breads with low Vsp and darkness crust. A firmed and chewy crumb, although with a more aerated structure (high area occupied by alveoli) was obtained. The GA25 bread presented the softer crumb. The elastic modulus-E1 of crumb increased and the relaxation time-T1 decreased with higher amounts of amaranth flour, suggesting the formation of a more structured crumb; mainly in the case of non-germinated amaranth flour. Wheat flour resisted the inclusion of 25% of germinated amaranth seeds (GA25) without substantial changes in bread quality.

Seed germination and morphological characterization of traditional leafy vegetables

Traditional leafy vegetables provide affordable sources of micronutrients to many people in Zimbabwe. They are produced by smallholder farmers with limited knowledge on the agronomic value of high-quality seed and the seed is rarely tested to determine its quality. This study was therefore conducted to evaluate the germination of seeds of three traditional leafy vegetables sourced from five different farmers and the morphological characteristics of the seedlings. The seeds were collected in the growing season of 2015 to 2016, stored at room temperature and tested for germination in the laboratory at regular monthly intervals during storage. Field germination tests were conducted only once. The seeds tested were classified as normal seedlings, abnormal seedlings, fresh non-germinated seeds or dead seeds. Morphological analysis was conducted at seedling stage, including seven qualitative characters and one quantitative character. Mean separation based on the least significance difference at 5% indicated that percentage germination, purity and 1000-seeds weight for all three species significantly differed among sources. The results showed that Cleome gynandra had lowest germination percentages, Amaranthus hybridus was intermediate and Bidens pilosa had highest values throughout the tests. C. gynandra seed exhibited dormancy, showing high levels of fresh non-germinated seed percentage after each test, which is potentially disastrous for the farmers. The combination of pre-chilling, light, potassium nitrate and alternating temperatures as a way of improving germination for C. gynandra needs further validation. Key words: Seed quality, purity, germination, morphological characteristics of seedlings.

THE POSSIBILITY OF USING DRILING WASTEWATER IN THE REMEDIATION OF DISTURBED LAND

The paper examines the possibility of using drilling wastewater in the remediation of disturbed land. The samples were examined using concentration meter, spectrophometer, and pH meter. Studies on the metal content were carried out by atomic emission spectrometry with inductively coupled plasma. It was found that the liquid drilling waste contains a complex of biophilic elements: N, Ca, Na, K, P, S, Cl, Fe, Cu, Co, Mn, Zn. Three soil plots for sowing grasses on liquid drilling waste were studied. The soil was furrowed and the grass mixture was sown using working solutions. The possibility of using drilling wastewater as a meliorant in the conditions of forest-tundra and tundra zones of the Krasnoyarsk Territory has been established. The results of experimental data indicate that the use of components of liquid drilling waste in the formulation of agrochemical preparations does not have a negative effect on seed germination and plant growth.

Physiological quality and seed storage potential of four soybean cultivars

The objective of this study was to evaluate physiological seeds quality of four soybean cultivars during storage, under controlled and uncontrolled conditions. Seeds of Brasmax Lança IPRO, Brasmax Raio IPRO (está diferente do Material e Médtodos), Pioneer 95y52 and TMG 7062 IPRO cultivars were stored in controlled (20 ± 1.2 °C) and uncontrolled (producer's warehouse) environments and the following traits were assessed: percentage of germination (GERM), germination speed index (GSI), germination speed (GS) and accelerated aging (AA) at 0, 60, 120 and 180 days of storage. Covariance matrices structure of storage time was tested through repeated measures analysis, adopting a bifactorial model. Data were submitted to ANOVA (α=5%) and when the means presented significant differences, regression analysis and Scott-Knott test (α=5%) were performed. Differences in soybean seeds physiological quality are not related to storage environment. Lança cultivar was the most tolerant to storage, while Ray and TMG 7062 cultivars were more sensitive.

Potensi Fungisida Perlakuan Benih terhadap Perenosclerospora sp. penyebab Penyakit Bulai Jagung

Jamur patogen Perenosclerospora sp. merupakan penyakit penting pada tanaman jagung. Dampak yang ditimbulkan dapat menimbulkan kerugian hingga 100%. Penelitian ini bertujuan untuk mengetahui pengaruh bahan aktif fungisida sebagai perlakuan benih dalam mengendalikan penyakit bulai (Perenosclerospora sp.) pada tanaman jagung. Penelitian dilaksanakan dengan diawali menanam tanaman jagung yang diinokulasi bulai sebagai tanaman spreader (sumber inokulum alami) dan pembatas antar perlakuan. Selanjutnya saat tanaman border sudah terinfeksi bulai baru ditanam benih perlakuan yang sudah dicampur dengan bahan aktif fungisida. Penelitian disusun dalam rancangan acak lengkap dengan delapan perlakuan dengan tiga ulangan. Perlakuan terdiri atas kontrol tanpa fungisida (P0), dimetomorf (P1), dimetomorf + piraklostrobin (P2), fenamidon (P3), fenamidon dan propamokarb hodroklorida (P4), metalaksil (P5), mefenoksam (P6), dan fluopikolid+propineb (P7). Hasil penelitian menunjukkan perlakuan kontrol lebih bagus dalam meningkatkan daya kecambah dibandingkan dengan menggunakan fungisida. Benih jagung yang diberikan perlakukan bahan aktif dimetomorf + piraklostrobin memiliki potensi yang paling tinggi dalam menekan keterjadian penyakit bulai pada jagung manis dan mampu meningkatkan pertumbuhan tinggi tanaman jagung yang dibandingkan perlakuan lainnya.

واکنش ژنوتیپهای چند جوانه چغندرقند به تنش شوری

با وجود توسعه کشت مکانیزه و استفاده از ارقام منوژرم چغندرقند در کشور، هنوز در برخی مناطق مانند اراضی دارای تنش شوری و خشکی، استفاده از ارقام چند جوانه به منظور کاهش اثرات سوء محیط و افزایش درصد سبز و استقرار توصیه می‌شود. لذا بررسی ژرم‌پلاسم چند جوانه‌ای چغندرقند تحت تنش شوری ضروری بوده تا بتوان در آینده به ارقام چند جوانه متحمل به شوری دست یافت. برای این منظور، 20 گرده افشان مختلف ابتدا در آزمایشگاه در شرایط بدون تنش و شوری 20 دسی زیمنس برمتر به صورت آزمایش فاکتوریل در قالب طرح کاملا تصادفی با چهار تکرار در دو آزمایش جداگانه از نظر درصد جوانه‌زنی بین کاغذ و روش سریع جوانه‌زنی در ارلن با هم مقایسه شده و سپس در محیط گلخانه در شرایط بدون تنش و شوری 16 دسی زیمنس بر متر با چهار تکرار مورد آزمون قرار گرفتند. نمونه‌برداری حدود دو ماه بعد از اعمال تنش در مرحله هشت برگی (استقرار) انجام وعملکرد تر و خشک اندام هوایی و ریشه و عناصر سدیم و پتاسیم و کربوهیدرات محلول اندازه‌گیری شد. از نظر شاخص پتانسیل ظهور در مزرعه، ژنوتیپ‌های 7233، AMP2 و PB13-S2-151-HSF-915 به ترتیب با مقادیر 0.176، 0.09 و 0.05 دارای بیشترین مقدار این شاخص بودند. شوری باعث کاهش وزن خشک کل، اندام هوایی و ریشه، پتاسیم و کربوهیدرات محلول به ترتیب حدود 20، 24و 6، 42 و 38 درصد و افزایش مقدار سدیم و فسفر برگ به ترتیب حدود 4 برابر و 11 درصد شد و در نهایت ژنوتیپ‌های PB13-S2-151-HSF-915، 7233، S1–930882، S1–931008، Poly8823، S1–930770، Gazale، S1–930910، 5RR-87-HS-28 و S1–930792 بر اساس مجموع صفات جوانه‌زنی به روش سریع و روش بین کاغذ، صفات عملکردی و بیوشیمیایی به عنوان ده ژنوتیپ برتر در تنش شوری انتخاب شدند

Direct defense of common bean accessions against two-spotted spider mite (Tetranychus urticae Koch.) attack

To find the direct defense of seedling resistance of common beans, by resistant mechanisms, morphological and physiological attributes of ten cultivars (Naz, Dorsa, Akhtar,KS41128, 65-062-107, 65-071-98, 65-071-306, 65-071-410, 65-071-400, and 65-071-405) were evaluated against two-spotted spider mite in 2017 at Bu-Ali Sina university, Hamedan, Iran. Among four kinds of resistant mechanisms such as antixenosis, antibiosis, tolerant tests and PRI index, both antixenosis and tolerance mechanisms determined to be the most accurate tests in the evaluating of common bean resistance against TSSM attack. Germination delay, development and fast growth, early maturity, erected posture, small cotyledon area, the more leaf thickness along with the dark-colored demonstrated were the escape mechanisms of common beans tolerant genotypes against TSSM attack. Some epidermal traits such as the first defense barrier on common bean like hook-shaped and high density of trichome especially on abaxial epidermis by having trapping behavior showed high relation with tolerant genotypes. In fact, in tolerant beans, related-traits to trichome on leaves entrapped the body parts of TSSM such as leg tarsi, mouthpart and ovipositor and prevented to move, feed and reproduction of mites and therefore, these features decreased damage to leaf area of Phaseolus vulgaris as well. The 65-071-98, 65-062-107 genotypes and NAZ, were certainly categorized as the most tolerant cultivars while Akhtar and 65-071-400 were introduced as the most susceptible accessions of common beans, respectively.

Efeito do extrato hidroalcoólico e do óleo de nim (Azadirachta indica) sobre o fungo Fusarium oxysporum f. sp. vasinfectum e na resistência induzida de quiabeiros à fusariose

O objetivo deste trabalho foi verificar o efeito do extrato hidroalcoólico e do óleo de nim sobre o crescimento micelial, esporulação, germinação e adesão de conídios do fungo F. oxysporum f. sp. vasinfectum e avaliar o efeito desses produtos na indução de resistência em quiabeiros tratados e, posteriormente, inoculados com o fungo, por meio da atividade de enzimas antioxidantes relacionadas com processos de defesa vegetal. Os resultados evidenciaram que tanto o extrato quanto o óleo de nim foram eficientes em inibir o crescimento micelial e esporulação do fungo. Além disso, houve inibição da germinação e fixação de conídios produzidos na presença dos produtos. O extrato e o óleo de nim reduziram a severidade da doença nos quiabeiros, medida pelo índice de infecção da doença. Além disso, incrementos significativos das enzimas guaiacol-peroxidase, polifenoloxidase, superóxido-dismutase e catalase foram observados nos quiabeiros tratados com os produtos, sendo estes aumentos, diretamente proporcionais aos aumentos das concentrações utilizadas. Assim, tanto o extrato quanto o óleo de nim têm efeitos diretos sobre o desenvolvimento do fungo F. oxysporum f. sp. vasinfectum e induzem resistência em quiabeiros a partir da formação de espécies reativas de oxigênio (EROs).

Effects of seed size and bract of Ceratoides arborescens on germination and seedling growth under drought stress.

Drought is a crucial factor affecting seed germination and seedling growth of desert plants. In the study, we examined the effects of seed size (large, small) and bract (without bracts, with bracts) on seed germination and seedling growth of Ceratoides arborescens, a perennial super xerophyte semi-shrub, under different drought levels (0, 100, 200, 300 and 400 g·L-1 PEG6000). The results showed that drought stress significantly inhibited seed germination and reduced shoot length of seedlings. Under the 100 and 200 g·L-1 PEG6000 stress conditions, root length of seedlings were significantly increased, whereas it was significantly reduced under the 300 and 400 g·L-1 PEG6000 stress intensities. The presence of bract significantly reduced seed germination percentage by 12%, germination index by 50.5%, and shoot length by 20.8%, but increased root length by 6.3%. Seed size did not affect seed germination index. Compared with small seeds, germination percentage of large seeds was 3% higher, shoot length and root length of seedlings were 20.5% and 33.0% higher, respectively. In summary, seed bract in C. arborescens through delaying seed germination and seed size through influencing the survival of the early state of seedling were the most important strategies to adapt extremely arid environment.

The effect of seed priming at different seed quality by melatonin on seedling emergence and growth characteristic of safflower (Carthamus tinctorius L.) under stress combination of salinity and drought.

IntroductionDrought and salinity are major environmental factors that influence crop productivity worldwide .Plants are normally subjected to a combination of various types of abiotic stresses in nature, such as the combined effects of drought and salinity .Studies have revealed that the physiological and biochemical responses of plants to the interaction of drought and salinity are unique and cannot be directly extrapolated from the responses to the two stresses individually.Storage of orthodox seeds for prolonged period induces their deterioration leading ultimately to loss of their viability. The rate of seed deterioration varies among plant species and seed lots, but high moisture content and high temperature accelerate this process. During long-term storage, all seeds undergo aging processes leading to deterioration in seed quality, especially in the humid tropical regions. However, the rate of seed deterioration can vary among various plant species. When aged seeds are sown, they show decreased viability, lower germinability performance, and produce weak seedlings which could not manage to survive in their habitat. Seed priming (osmoconditioning) has been successfully demonstrated to improve seed germination and seedling establishment for many field crops.The beneficial effects of priming have also been demonstrated on germination and seed emergence, as well as seedling establishment of many crops, particularly under drought and salt stress.Use of chemical compounds as priming agents has been found to improve plant tolerancesignificantly in various crop and non-crop species against a range of different individually applied abiotic stresses.Melatonin, due to its pleiotropic effects can play important roles in improving plant tolerance to adverse conditions.Safflower (Carthamus tinctorius L.) is one of the prospective oilseed crops because it yields about 32–40 % seed oil. However, due to its considerable salt resistance than commonly grown oilseed crops, it is cultivated in arid and semi-arid regions where soil salinity is one of the major threats to agriculture.Drought is very unpredictable among abiotic stresses in terms to occurrence, severity, timing. and duration and safflower can be a promising alternate crop in dryland agro-ecosystems due to its growth potential under water stress without a substantial reduction of oil and seed yields. Safflower cultivation constitutes a more profitable crop for the farmers in some countries, compared to other conventional crops such as barley, lentil, and chickpea.The fact that safflower can overcome environmental stresses such as extreme temperatures, drought, and salinity has facilitated its expansion in areas around the world, where soil and climatic restrictions have impeded the cultivation of conventional food and cash crops.In particular, safflower has demonstrated drought resistance with a slight decrease in crop yield and significant stability in water use efficiency Materials and methods In order to study the effect of seed priming of naturally aged seed by melatonin on seedling emergence and growth characteristic of safflower, three experiments were conducted at seed science technology laboratory, greenhouse and research farm of Aburaihan Campus, the University of Tehran in 2017. The experimental design for all experiment was factorial in completely randomized design (laboratory) and randomized complete block design (research farm and greenhouse) with 4 replicates. The main treatments that common between experiments consist of seed quality (1-naturally aged seed 2- new seed) and seed priming (1-without priming 2- hydropriming 3- Melatonin 0.1 mM 4- Melatonin 0.5 mM). Soil water was determined based on soil moisture release curve, which indicates the relationship between soil water potential andsoil moisture content. Prior to the pot experiments, three samples of wet soil (wet soil = drysoil ? soil moisture content) were dried and soil moisture content at the beginning of experiment was determined.Then pots were equally filled with wet soil. Two pots were considered as references and were weighted each day: one for drought stress and one for other abiotic stresses. The soil moisture content could be obtainable after weighing and it was possible to calculate soil water potential from soil moisture release curve. Results and discussionThe results of this research indicated that the highest percentage of seedling emergence of naturally aged seed obtained by hydropriming and melatonin priming at 0.1 mM by %54.50 and %57.50 that increased the seedling emergence up to %39.74 and %47 respectively, in comparison to control in the farm condition. Also, the results showed that highest percentage of seedling emergence under drought condition belong to melatonin priming at 0.1 mM concentration that increased the seedling emergence up to %154 in comparison to control in the greenhouse condition. The results of this experiment indicated melatonin priming at 0.1 mM concentration led to the highest rate and percentage of seedling emergence under salinity and combination of salinity and drought condition while melatonin priming at 0.5 mM concentration has decreased the rate of seedling emergence.ConclusionsIn general, using of seed priming as a cost-effective method also hydropriming and melatonin priming could enhance the seed quality for growth under salinity and drought conditions.