Young wheat plants (Triticum aestivum L. cv. Mv Béres) were exposed to 0 or 25 mM NaCl for 11 days (salt acclimation). Thereafter the plants were irrigated with 500 mM NaCl for 5 days (salt stress). Irrigating the plants with a low concentration of NaCl successfully led to a reduction in chlorotic symptoms and in the impairment of the photosynthetic processes when the plants were exposed to subsequent high-dose salt treatment. After exposure to a high concentration of NaCl there was no difference in leaf Na content between the salt-acclimated and non-acclimated plants, indicating that salt acclimation did not significantly modify Na transport to the shoots. While the polyamine level was lower in salt-treated plants than in the 2 control, salt acclimation led to increased osmotic potential in the leaves. Similarly, the activities of certain antioxidant enzymes, namely glutathione reductase, catalase and ascorbate peroxidase, were significantly higher in salt-acclimated plants. The results also suggest that while SOS1, SOS2 or NHX2 do not play a decisive role in the salt acclimation processes in young wheat plants; another stress-related gene, WALI6, may contribute to the success of the salt acclimation processes. The present study suggested that the responses of wheat plants to acclimation with low level of salt and to treatment with high doses of salt may be fundamentally different.

No abstract

The effect of seed treatments of common bean plants (cv. Nebraska) with Bion, Salicylic Acid (SA) and Paenibacillus polymyxa on infection with Rhizoctonia solani under greenhouse and field conditions was investigated. In greenhouse experiment, all treatments decreased percentages of pre and post-emergence damping-off compared with control grown in infested soil by R. solani. The highest percentage of survival plants was achieved from treatment with Bion 5mM (80%) followed by each of Bion 3mM and SA 5mM (76.7%) compared with control (40.1%). Meantime, significant increases in the values of shoot length, shoot dry weight and root dry weight over the control treatment were achieved. Under field experiments during summer 2009 and 2010 growing seasons, all the tested treatments significantly increased the percentage of survived plants compared with the control. There were no significant differences between the treatments with Bion 3mM and fungicide (Rhizolex-T 3g/Kg seeds) 89.4% and 89.3 %, respectively compared with untreated control 67.9% calculated as means of the two seasons. Also, the treatments with salicylic acid and P. polymyxa were less effective regarding survival plants in 2009 and 2010 growing seasons. Moreover, all treatments significantly increased all the studied vegetative characteristics, i.e. stem length, number of leaves/plant as well as fresh and dry weight of leaves/plant compared with untreated control. Meanwhile, higher increase pe in seed yield (kg/feddan) was estimated with bion and fungicide treatments (86% and 87.7%, respectively) followed by salicylic acid and P. polymyxa (66.8% and 55.4 %, respectively) increasing over the untreated control calculated as means of the two seasons. Laboratory studies indicated that, all treatments were effective in eliciting the activities of peroxidase and polyphenol oxidase. Peroxidase activity was higher with Bion followed by SA treatments; they showed 77.7% and 41.2 % increase over the untreated control, respectively. Meantime, elevation of the polyphenol oxidase activity was showed with Bion followed by SA treatments as 97.7% and 58.0% increasing over the untreated control, respectively. However, Bion treatment resulted in the highest increase in total phenols contents over the untreated control (94.3%) followed by SA and P. polymyxa treatments (57.9% and 52.6%) over the untreated control, respectively.

No abstract

Two field experiments were carried out at Sids Agric. Res. Station, Beni-Suef Governorate, in 2007 and 2008 seasons, to study response of growth, fruiting and yield of the Egyptian cotton cultivar Giza 80 (G. barbadense L.) to foliar application with indole acetic acid (IAA) and Kinetin (a synthetic cytokinin). Besides the control treatment, two concentrations of each of IAA (25 and 50 ppm) and kinetin (10 and 20 ppm) and their combinations were application twice, at the start and peak of flowering stages. Results revealed that, cotton plants treated with various treatments of IAA and/or kinetin showed higher leaves content of chlorophyll a, b and total chlorophylls than those of untreated ones. However, only some treatments of IAA and/or kinetin significantly increased plant height, numbers of fruiting branches/plant and open bolls/plant in both seasons; number of main stem nodes and seed cotton yield/fad., in 2007 season only; and total fruiting sites/plant and seed index in 2008 season only, but they significantly decreased fruit shedding% and earliness% in 2007 season only. Application 50 ppm IAA alone significantly decreased earliness% in 2007 season, and either alone or with kinetin at both levels gave the highest values of plant growth parameters, but their effects on fruit shedding and yield did not reach the significant level. In general, the most consistently positive effects on plant fruiting and seed cotton yield were given by application 25 ppm IAA alone or 20 ppm kinetin alone or both.