Search

Various approaches are used to improve crop production. Seed priming is one of the simplest and least expensive methods currently used to ensure rapid and uniform yields. Our study highlights the role of priming and imbibition in improving seed germination. The objective of this study was to investigate the effect of seed imbibition and hormopriming with 0.1 mM gibberellic acid (GA3) on germination performance and biochemical changes in fenugreek (Trigonella foenum-graecum L.) radicles. The results showed that hydropriming and imbibition with GA3 significantly improved germination performance and radicle growth. Concurrently, treatments induced stimulation of the antioxidant activities of superoxide dismutase, ascorbic peroxidase, catalase and guaiacol peroxidase, and decreased lipid peroxidation, stimulated an increase in total non-enzymatic antioxidant capacity and reduced glutathione content. Accumulation of hydrogen peroxide and cytochemical analysis of reactive oxygen species (ROS) in situ confirmed the role of imbibition in stimulating ROS. Interestingly the effects of imbibition with gibberellic acid were more effective then hormopriming, probably due to the partial degradation of GA3 during dehydration process. [ABSTRACT FROM AUTHOR]

Herbicides are used in agriculture to increase crop yield. However, their use often prompts concern about the consequences safety of crop production. Salicylic acid (SA) is a phenolic compound considered a phytohormone that confers plant resistance to different stresses. To determine the influence of SA on the reduction of herbicide-induced toxicity, we used young bean (Phaseolus vulgaris L.) seedlings treated with 1 mM of SA, 100 µM of prometryne or combined treatments. After 30 days of culture, prometryne treatment resulted in plant growth inhibition (shoot height, leaf area, fresh and dry weight) and decreased photosynthetic pigments content. It increased malondialdehyde (MDA) and hydrogen peroxide (H2O2) levels. Meanwhile, the activities of enzymatic antioxidants, catalase (CAT) and ascorbate peroxidase (APX), as well as herbicide detoxification enzyme glutathione S‑transferase (GST), were significantly improved. Furthermore, herbicide enhanced proline amount and decreased that of glutathione. These findings reflect the presence of stress status. An exogenous supply of SA seemed to reduce the deleterious effects caused by prometryne and appeared to overcome this stress status. Such positive effect was reflected by enhancement of growth and leaf pigments contents, regulating antioxidant enzyme activities (CAT, APX, GST), and decreasing oxidative stress indices. This study demonstrates that exogenous application of SA to young bean plants reversed and/or minimized the damage caused by prometryne through the protection and improvement of some morpho-biochemical characters. [ABSTRACT FROM AUTHOR]

Soil contamination by heavy metals is considered as one of the major environmental issues in recent years as it poses a threat to agricultural production due to their adverse effects on plant growth, food quality and environmental health. Pollution by heavy metals involves metal ions which are not always essential to plants as they affect growth and development. The application of a chelating agent, EDTA, increases the absorption of heavy metals by increasing their phytoavailability. Our results showed that lead and nickel have a negative impact on peas (Pisum sativum) as they affect their germination rate, plant growth and protein content. EDTA itself also causes the same negative effects as heavy metals since it represents a toxic xenobiotic substance. The combination of this chelator with Ni or Pb amplified the action of these heavy metals on the various parameters studied. The Oxidative stress is manifested through the accumulation of reactive oxygen species and MDA which is an indication of cellular membranes alteration. The enzymatic activities of catalase, ascorbate peroxidase and superoxide dismutase were stimulated by EDTA, heavy metals or a combination of the two. In addition, the activity of the glutathione S-transferase was greatly increased in response to EDTA and both heavy metals. [ABSTRACT FROM AUTHOR]

Seed treatment is often used for improving germination performance, growth parameters and tolerance to abiotic stresses. Thus, the seeds can undergo chemical pretreatments by imbibition in the presence of certain molecules such as sodium nitroprusside (nitrogen monoxide donor) and calcium chloride (Ca2+ being involved in signaling). Hydropriming is a pregermination treatment which helps in stopping imbibition before the end of the reversible phase of germination, i.e before the start of the lengthening of the radicle. Our results showed an improvement in the germination performance and growth of fenugreek (Trigonella foenum-greacum L.) seedlings when treated in the same manner. These improvements were accompanied by the formation of reactive oxygen species (hydrogen peroxide and superoxide). Measurements of the antioxidative activities of catalase, ascorbate peroxidase, superoxide dismutase and guaiacol peroxidase showed strong stimulation in the radicles of pre-treated or hydroprimed seeds. This activity was stronger in hydroprimed seeds compared to the control and chemical treatment. Thus the improvement in germination performance and growth seems to be linked to the oxidative stress observed during germination. [ABSTRACT FROM AUTHOR]

For a long time, it has been known that seed priming allows the improvement of plant production and tolerance to abiotic stresses. However, a negative effect on the longevity of the seeds thus primed was observed; these mechanisms are still poorly understood. In addition, it has been shown by several authors that seed ageing is associated with the oxidation and particularly with carbonylation of protein. Our work consisted in studying the AOPP and carbonyl protein at the different parts of the embryo from freshly primed seeds and from those that have been primed for 4 years (after storage). We subjected Vigna unguiculata (L.) Walp. seeds to a single or double hydropriming. Our study showed that hydropriming, and more particularly a double cycle of hydration-dehydration, makes it possible to attenuate the oxidation of the protein while it favours a certain threshold of carbonylation in the freshly dehydrated seeds in order to better trigger the germination process. On the other hand, after a storage period of 4 years, these dehydrated seeds are characterised by a strong accumulation of the products of oxidation and especially carbonylated protein, compared with the untreated seeds, which could explain the decrease of the longevity of these seeds. Germination and drought tolerance of plants can be improved by pre-germination treatment (seed priming). However, a negative effect on the longevity of the primed seed is observed and we have shown that proteins oxidation, and particularly carbonylation, is a marker of the primed seed ageing. So better knowledge of seed ageing will allow a longer conservation of primed seeds. [ABSTRACT FROM AUTHOR]

Durum wheat, Triticum turgidum subsp. durum (Desf.) Husn., is one of the most salt-sensitive cereal crops, but the physiological responses of different cultivars to salt stress vary. Cultivars that are suited to arid conditions like in Algeria may not necessarily be tolerant to increased salinity. When 10-day seedlings of Algerian durum wheat varieties Hedba 3 (HD3) and Mohamed Ben Bachir (MBB) were subjected to salt stress, they accumulated proline and expressed stress-related and proline metabolism genes in a classic salt-stress response. Expression of the selective sodium transporter genes HKT1;4-1 and -2 was found to be organ-specific and modulated by salt stress in both cultivars. Adding proline to the salt-containing growth medium alleviated some salt stress effects such as decrease in water content, ion leakage and expression oxidative stress markers while growth parameters were partially rescued to different extents in the two cultivars. Durum wheat seedlings accumulated sodium ions (Na+) at the expense of potassium ions (K+) under salt stress which lowered the in planta K+/Na+ ratio. The two durum wheat cultivars studied here respond differently to salt stress in terms of responsiveness to proline, HKT1;4 gene expression, and Na+ and K+ accumulation. Notably, salt stress can be partially alleviated by proline in the drought-resistant cultivar MBB, even though it is relatively salt sensitive. [ABSTRACT FROM AUTHOR]

Norflurazon 100 µM alone or in combination with α-tocopherol (0.25 mM) was applied in pre-emergence of peanut seedlings (Arachis hypogaea L.). Norflurazon treatment allowed to partially or totally photobleach plants which were noticeably smaller than the control. Norflurazon impaired the photosynthetic activity by decreasing photosynthetic pigments (carotenoids and chlorophylls) and by reducing quantities of soluble sugar. The determination of malondialdehyde (MDA) showed that its content was higher in treated plants in relation with enhancement of reactive oxygen species by the herbicide and decreased the endogenous α-tocopherol. The addition of exogenous a-tocopherol reduced the damage done by the herbicide at the membrane level because of the MDA content was less important than in norflurazon treated seedlings. Furthermore, the norflurazon decreased the glutathione S-transferase (GST) activity in the leaves and the roots of peanut seedlings, while it increased the level of reduced glutathione. This activity decreased even more with the application of exogenous α-tocopherol in combination with the herbicide. The herbicide alone or in association with the antioxidant α-tocopherol increased ascorbic acid content. The supplementation of α-tocopherol did not decrease the phytotoxicity of norflurazon although we observed a decrease in MDA content. [ABSTRACT FROM AUTHOR]

Pre-germination treatments represent the physiological methods that improve plant production by modulating the metabolic activities of germination before the emergence of the radicle. It was suggested that reactive oxygen species (ROS) play a crucial role in signalling seed germination. Our work consisted in studying changes in the redox status in the embryonic axis (radicle and plumule) and in cotyledons of Vigna unguiculata (L.) Walp. non-primed, osmoprimed (30% PEG6000), hydroprimed or twice hydroprimed seeds, by estimating antioxidant activities and production of ROS. Some antioxidant enzymatic activities as well as total non-enzymatic antioxidant capacity were measured. The production of hydrogen peroxide (H2O2) and superoxide anion (O2–) was also assessed by 3,3′-diaminobenzidine (DAB) and nitroblue tetrazolium (NBT) respectively. The results obtained showed, on the one hand, that priming allows activation of antioxidant enzymes, especially in the plumule. On the other hand, these results showed that priming caused an accumulation of ROS in embryonic tissues. This may explain the improvement of seed germination performance according to the oxidative window model. Priming induced changes in the redox environment at the seed level. These changes were closely related to the pre-germination treatments. Indeed, a double cycle of hydration-rehydration induced the broadest spectrum of modifications of the redox status, which would explain the improvement of the seed vigour. Seed priming allows an improvement of germination performances as well as a tolerance to abiotic stress and higher yields. We have hypothesised that Vigna unguiculata seed priming is related to redox status of different parts of the embryo. We showed that priming allows activation of antioxidant enzymes, especially in the plumule, and that it causes an accumulation of ROS in radicle and the meristematic zones of the plumule. [ABSTRACT FROM AUTHOR]

This experiment was conducted to determine the effect of exogenous proline (20 mM) on the physiological and biochemical behavior of durum wheat seedlings subjected to a salt constraint (10 g/l NaCl). This effect was evaluated through the estimation of plant water status (leaf relative water content), photosynthetic pigments, sugars content, water soluble proteins content, the osmotic adjustment (endogenous proline and glycine betaine), the lipid peroxidation (the membrane integrity and the malondialdehyde content) and the activity of the antioxydant enzyme catalase in wheat plantlets. Results obtained show that the saline stress affects the majority of the studied parameters. However, exogenous application of proline seems to attenuate the negative effects of the saline stress by the improvement of the content of total chlorophyll, proteins, glycine betaïne and the relative electrolyte leakage. These results suggest the capacity of the exogenous application of proline to improve the tolerance of the saltstressed wheat plants. [ABSTRACT FROM AUTHOR]

Plant Growth Promoting Rhizobacteria (PGPR) can play important role in agriculture. The objective of this study was to assess the ability of the isolated strain Pseudomonas putida to improve physiological and biochemical parameters of durum wheat seedlings (Triticum durum Desf. Var. Mohamed Ben Bachir) and helped them to withstand bleaching herbicide the norflurazon. At 10-4 M, the norflurazon induced the bleaching of seedlings (photobleaching). At the physiological level, it caused the inhibition of carotenoids (0.03±0.01 mg g-1), chlorophylls (0.15±0.03 mg g-1) and carbohydrates (0.28±0.07 mg g-1) contents. At the cellular level, carotenoids defiency angendred by the norflurazon induced oxidative stress which manifested by an increase of MDA content (32.33±2.08 mmoles g-1), a lipid peroxidation marker, as well as a sharp increase in the electrolytes leakage (63.7±6.01 %) sign of membrane systems deterioration. The norflurazon also decreased the catalase (7.13 μmol H2O2 mn-1mg -1of proteins) and glutathion S-transferase (2 nanomol min-1mg-1 of proteins) activities in the leaves of durum wheat seedlings. The strain of Pseudomonas putida with inherent phosphate solubilizing activity, auxins (IAA) synthesis and EPS production was inoculated to the wheat seedlings in the presence and absence of norflurazon. It had eased phytotoxic effects of norflurazon on wheat seedlings and improving theirs physiology and their antioxidant mechanisms. The bacteria strain used would so represent a valuable partner in the future agriculture by its bioprotective and biostimulating properties. [ABSTRACT FROM AUTHOR]

Copyright of Acta Agriculturae Slovenica is the property of Biotechnical Faculty of the University of Ljubljana and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)