JWSS - Journal of Water and Soil Science

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In vitro salt tolerance of 28 cultivars of durum wheat with native and exotic origins was investigated, using MS medium containing sodium chloride. The resulting calli were subjected to 8 salinity levels including 0, 0.3, 0.6, 0.9, 1.2, 1.5 and 1.8 percent NaCl (w/v). Donor plants of explant (immature embryo) were grown in a recirculating hydroponics and pots in a greenhouse as well as in the field. Assessment of calli was conducted after 0, 8 and 16 days after subculture of calli into the NaCl-contained medium. Callus growth rate, relative callus growth rate and percentages of callus necrosis were measured, using a 8 × 28 factorial experiment layout in a completely randomized design with 3 observations per treatment and 3 replications. Results of analysis of variances showed that among the criteria, relative growth rate of callus was the most reliable, while callus growth rate as not being quantitatively measured, was less devoted. Results of this study revealed that 'PI 40100' and 'Dipper-6' were superior genotypes for in vitro salt tolerance. The high relative callus growth rate and less callus necrosis of these cvs. may indicate their superior genetic potential for in vitro salinity tolerance.

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To determine the effects of salinity and boron excess in irrigation water on relative growth rate (RGR), net assimilation rate on a leaf weight basis (NAR), and leaf weight ratio (LWR) of pistachio, three pistachio rootstocks (Badami -Zarand, Sarakhs and Ghazvini) were used. Rootstocks were grown in soil in eight-liter polyethylene pots. Sodium chloride treatments were 0, 75,150 and 225 mM NaCl and boron treatments were 0, 20 and 40mg liter^-1. Treatments were applied to the one-year old pistachio rootstock seedlings in three-day intervals with irrigation water. Some plants were randomly selected and destructively harvested before (day 0) and after applying treatments (30 and 60 days after treatments started). Growth and physiological characters were then measured as follows: number of leaves, leaf area, plant height and root length, fresh and dry weights of stem, root and leaf, proline accumulation in the leaf, total chlorophyll, and leaf relative water content (RWC). Results indicated that relative growth rate decreased with time for all treatments and in all rootstocks. Salt treatment significantly reduced both RGR and NAR, whereas LWR showed no significant differences. In all rootstocks, NAR, but not LWR, was significantly correlated with RGR, indicating that NAR was an important factor underlying the salinity-induced differences in RGR among the pistachio rootstocks. Salinity did not affect leaf water potential (ψ), chlorophyll content, and Fv:Fm ratio but increased NaCl concentration and time correspondingly increased proline accumulation in leaves. In addition, Ghazvini rootstock accumulated more proline compared to other rootstocks and was more resistant to salinity treatments. Different boron treatments did not show any significant effect on growth rate nor on measured parameters after two months of exposure to treatments.

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One of the main criteria for salt tolerance is cell membrane stability under stress. Reactive oxygen species (ROS), activity of lipoxygenase (Lox) and lipid peroxidation are considered to be destructive to cell membrane under salt stress. In this study, the effects of 0, 75 and 150 mM NaCI, over a period of 14 days on the activity of lipoxygenease, the amount of hydrogen peroxide (H₂O₂) and malon dialdehyde (MDA. as a lipid peroxidation) in the leaves of Pistacia vera L. (cv. 'Qazvini' and wild 'Sarakhs' pistachio) and 'Mastic' (P. mutica F. & M.) were studied. The results indicated that by increasing salinity Lox activity increased in the leaves of all the three rootstocks. This activity reached a climax on the 7^th day and then decreased on the 14^th day. Among the three species, Mastic reached the highest amount of the Lox activity on the 14^th day with the lowest amount of Lox reduction. The amounts of H₂O₂ in the leaves of all the three rootstocks increased, on the 14^th day the highest amount of hydrogen peroxide was found in 'Mastic' and 'Sarakhs' after treating them with 150 mM NaCl. The amounts of MDA were also reached the highest level in all three rootstocks on the 7^th and 14^th days. The results also indicated the possibility of the use of lipid peroxidation index and Lox activity for selecting salt tolerant Pistacia rootstocks. More studies are needed for understanding the biochemical changes and enzyme activities in Pistacia rootstocks under salt stress.