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A field experiment was conducted from September 2010 to July 2011 at Research Station Farm of Higher Institute of Agronomy, Chott Mariem, Sousse (Tunisia) in order to evaluate the performance of seven onion varieties: ‘GIZA 6’, ‘Red Amposta’, ‘Z6’, ‘Morada de Amposta’, ‘Yellow Dessex’, ‘Early Yellow Texas Grano 502’ and ‘Keep Red’ against the commonly grown variety ‘Blanc Hâtif de Paris’ under field conditions. The experiment was conducted in a randomized complete block design with three replications. Results obtained showed that onion varieties were significantly different when it comes to the plant and bulb morphological characteristics. Variety ‘Morada de Amposta’ recorded the highest leaf length (68.06 cm), pseudostem diameter (8.63 cm), number of leaves (8.71), plant height (76.95 cm), in addition to the greatest yields (32.88 t/ha) which were significantly (p≤0.05) increased by respectively 66.2, 88.8, 2.1, 61.2, 63, 27.9 and 28.4% compared to those obtained from the regular variety ‘Blanc Hâtif de Paris’. Variety ‘Blanc Hâtif de Paris’ was the earliest to maturity and recorded the most preferment bulb weight (155.02 g) and diameter (8.21 cm). ‘Keep Red’ variety had the highest height of the bulb (7.19 cm). Variety ‘Z6’ recorded the minimum data in all measured parameters.

Seed priming is a simple pre-germination method to improve seed performance and to attenuate the effects of stress exposure. The objective of this study was to determinate an optimal priming protocol for three pepper cultivars (Capsicum annuum L.): ‘Beldi’, ‘Baklouti’ and ‘Anaheim Chili’. Seeds were primed with three solutions of NaCl, KCl and CaCl2 (0, 10, 20 and 50 mM) for three different durations (12, 24 and 36h). Control seeds were soaked in distilled water for the same durations. After that, all seeds were kept to germinate in laboratory under normal light and controlled temperature. Results indicated that priming depends on concentration, duration and cultivar. The best combinations that we obtained were: KCl priming (10 mM, 36h) for ‘Beldi’ cultivar, CaCl2 priming (10 mM, 36h) for ‘Baklouti’ cultivar and finally NaCl priming (50 mM, 24h) for ‘Anaheim Chili’ cultivar. Generally, priming had an effect on total germination percentage, mean germination time, germination index and the coefficient of velocity compared to control seeds. The beneficial effect of seed priming could be used for improving salt tolerance on germination and early seedling growth for pepper cultivar.

Tuberisation under salt stress of potato vitroplants (Solanum tuberosum L.). In Chott-Mariem (Tunisia), potato plants of Claustar variety, regenerated in vitro from a salt-adapted cal (3 g.l-1 of NaCl) and cultivated in presence of NaCl concentration of 4 g.l-1 have tuberised. These adapted plants were as outstanding as plants regenerated from a control cal and irrigated with NaCl-free water, relating to the number of tubers per plant and the average fresh weight of tuber. However, tubers of NaCladapted plants have shown a reduction in diameter and bud number, and they were affected by a deep fissuring when grown under irrigation with saline water. These results suggest that increasing the level of organic matter above 1 % in soil can be recommended in order to overcome such abnormalities, caused by salinity and saline water use (3 to 4 g.l-1 of NaCl) in the Sahel region (Mahdia, Monastir and Sousse).

Sodic soils reduce growth and production of most vegetables, including sesame (Sesamum indicum L.), and NaCl interferes with the nutrient balance of the rhizosphere. A greenhouse experiment was undertaken to investigate the effects of calcium nitrate fertigation and NaCl concentration on growth and development of sesame. The NaCl concentrations applied in the irrigation water were 0, 30, 70, or 100 mM, and the calcium nitrate levels were 0 or 100 mg·L−1. Leaf area and shoot dry weight did not change with addition of calcium nitrate (100 mg∙L−1) at all NaCl levels. At 100 mM, plants supplemented with 100 mg∙L−1 calcium nitrate produced 51% and 136% more chlorophyll (a) and carotenoids, respectively, and enhanced proline content by 45% and total soluble proteins by 25%. Calcium nitrate supplemented plants accumulated more Na+ ions at roots (+26%) and less Na+ ions at leaves (−20%). These plants generally had higher K+ content at roots (+30%) and at leaves (+94%) owing to 100 mM NaCl. Calcium nitrate (100 mg·L−1) enhanced catalase activity (+43%) and phenolic compounds. Calcium nitrate supplemented plants (100 mg∙L−1) accumulated less malondialdehyde (−50%) and had the highest antioxidant activity compared to 0 mg·L−1. Calcium nitrate may be used to moderate some adverse physiological effects of NaCl for sesame in sodic soils. However, the calcium nitrate concentration was not sufficiently high to benefit yield. [ABSTRACT FROM AUTHOR]

Many research studies have shown the importance of seaweed extract (SWE) in alleviating stress damage to plants. In this study, we examined the effect of liquid SWEs made from brown seaweed,Fucus spiralis, on germination, growth, antioxidant enzymes and some biochemical attributes of durum wheat under different levels of NaCl concentrations. Application of SWE at different concentrations (5, 10, 25, and 50%) significantly enhanced seed germination and growth parameters under salt stress, especially with 25% of seaweed liquid extract. Results show that the activity of antioxidant enzymes increased with increasing the algal extract concentration to 50%. Therefore, algal treatment is proved to be an effective technique to improve the growth of wheat seedlings under salt stress conditions. This study provides important information on the identification and utilization of seaweed resources for agriculture and it is the first study to report on the uses of this macroalgae as biostimulants in agriculture. AbbreviationsTG: total germination (%); SL: shoot length (cm); SFW: seedling fresh weight (g); SDW: seedling dry weight (g); TC: total carotenoids (mg/g.FW); TSP: total soluble proteins (mg/g.FW); SSC: soluble sugars content (mg/g.FW); TPC: (µg equivalent AG/mg DW); CAT: catalase (U mg−1protein); SOD: superoxide dismutase (U mg−1protein); APX: ascorbate peroxydase (U mg−1protein). [ABSTRACT FROM AUTHOR]

Seeds of ten accessions of carrot (Daucus carota L.) collected from seven areas in the region of Sidi Bouzid, Lessouda (three accessions: L1, L2 and L3) Faid (one accession: F4), El Ogla (one accession: E5), Regueb (two accessions: R7 and R8), Lahweze (one accession: L10) Garet Hdid (one accession: G11) and Souk Jedid (one accession: S12) were germinated at 20° C in the dark and in the presence of NaCl (0, 2, 4, 6, 8, 10, 12, 14 and 16 g/l) during 14 days. The results obtained showed that germination is possible until the highest concentration of salt (16 g/l) but germination and speed of germination decrease according to the concentration, so the accession L3 was the most tolerant and accessions L1, L2 and S12 was the most sensitive.

The present work has focused on the assessment of the tolerance of ten accessions of carrot (L1, L2, L3, F4, E5, R7, R8, L10, G11 and S12) to salt stress, grown in the region of Sidi Bouzid. The tests were carried out under plastic greenhouse (during 5 months). The results obtained show that the salt stress reduced the parameters of growth and production. However, a difference in the response to salt stress was recorded between the accessions studied. A reduction in yield of up to 70 % with the concentration 3 g / l of NaCl, for different accessions studied is recorded. However, the accession L1 who has given the longer roots and dry matter yield and the largest root shows the most tolerant accessions unlike L10, G11 and S12 which are the most sensitive.