فصلنامه زیست شناسی گیاهی ایران
سال یازدهم شماره 3 (پیاپی 41، پاییز 1398)

Limited data published about the effects of salinity on nitrogen assimilation of fruit trees such as almond. A greenhouse experiment was conducted to study the effect of sodium chloride (0, 75 and 150 mM NaCl) on nitrate reductase activity, accumulation of nitrate, proline and some ions in the seedlings of two almond rootstocks (Prunus dulcis L.). The results showed that application of 150 mM sodium chloride significantly decreased the total dry weight in the seedling of “Bitter Almond” (2.68 g). In the seedlings of “Sweet Almond” treated with 150 mM sodium chloride, the leaf proline content increased significantly (140 µg. g FW) after 14 days, however, the proline content in leaves of both rootstocks (“Sweet Almond” and “Bitter Almond”) was decreased after application of 150 mM for 21 days (43.66 and 47.8 µg. g FW, respectively). Also, sodium chloride decreased the leaf nitrate reductase activity in leaves of both rootstocks. The interaction of effect sodium chloride and salinity duration on Na+, K+ and Cl- concentration was significant. The results suggested that the changes in nitrate content and nitrate reductase activity in almond rootstocks after NaCl treatment is an important biochemical index during salinity treatment and may be resulted to disruption in nitrogen assimilation in almond seedlings.

Induction of soil acidity in the condition of waterlogging in rice fields increases the solubility and uptake of silicon and iron. In this research, the effects of 1.5 mM silicon (in the form of sodium silicate) and extra iron (150 mgL-1 as Fe-EDTA) on physiological parameters of the rice plants were evaluated. After 7 days, in plants treated with 1.5 mM silicon, the minimum and maximum of chlorophyll fluorescence in dark conditions, variable fluorescence and non-photochemical quenching of PSII increased by 27, 20, 19 and 8 percent respectively, but application of silicon in seedling treated with 150 mgL-1 Fe reduced the maximum fluorescence by 23% in light conditions and increased about 55% non-photochemical quenching of PSII. In plants treated with silicon, the amount of root and shoot Si, root and shoot iron and calcium of shoot were increased by 14, 20, 88, 33 and 8 percent, respectively, and the calcium content of root decreased by 11 percent. In the cross section of the root tip of plants treated with 150 mg L-1 iron, the ratio of cortex area to protoxylem area increased significantly compared to the control plants. This study showed that Si induced growth of plants by increasing of photosynthesis capacity and improving relative water content, however, Fe excess decreased growth due to the reduction of quantum yield, decline in water equilibrium and increase of cell wall components in younger parts of roots. Silicon application did not decrease Fe accumulation in plants and could not mitigate effects of iron toxicity on plant growth.

Salinity is an abiotic stress that reduces the growth and yield of plants. Citrus is categorized as a salt sensitive tree. Hence, a study was conducted to investigate the effect of chitosan on biochemical and nutritional features of two important citrus rootstocks in different sodium chloride levels under in vitro condition. The experiment was conducted as a factorial in a completely randomized design with three replications. The first factor was sodium chloride concentration at four levels (0, 50, 75 and 100 mM), the second factor was chitosan at three levels (0,50 and 100 ppm) and the third factor was rootstocks (citrange and sour orange). Murashige and Skoog media were used. The treatments were added to the medium during the first culture. According to the results, salinity, chitosan and citrus rootstocks interaction in the most tested parameters were significant. With increasing in salinity, the leaf number, shoot length and potassium and calcium content of sour orange and citrange leaf decreased significantly, while proline content, soluble sugar, leaf chloride and super oxide dismutase activity had shown increased significantly. Chitosan, as a growth promoter, was increased the number of leaf and shoot length compared to control treatment (chitosan-free) under stress. Due to the low absorption of chlorine ion, maintaining more potassium ion and the greater accumulation of proline and soluble sugars, in response to salt stress, sour orange had shown more tolerant than citrange. Finally, chitosan could be proposed as a combination to reduce the adverse effects of salinity stress by stimulating antioxidant enzymes and neutralizing reactive oxygen species.

Measuring the forest structural diversity is a useful and important way to predict the growth and the future development activities of the forest stands. Calculating structural indices are the most common methods for estimating the forest structure. These indices provide a quantitative estimation of the situation of stands variations. The aim of this study was to investigate the structural diversity of Acer campestre L. stands as one of the most important species in Arasbaran forests in order to identify the condition of this species and improve its structural diversity. The structural diversity index (S-index) was calculated by using summing three indices consist of uniform angle index, mingling index and diameter differentiation index in distance method. The results showed that the uniform angle index (Wt=0.36) indicated a uniform -random distribution. The diameter differentiation index (Dt=0.16) showed a low diameter differentiation among the reference trees and the neighbor trees species and mingling index (Mt=0.57) showed the high amount of species mixture in the study area. Finally, the structural diversity index showed high structural variation (0.479) in the study area. This study can be considered as the basic information for improving the conditions, recognizing the ecological relationships between tree species and a pattern for restoration activities.

Plant responses to elicitors are the result of a series of highly modulated consecutive changes in hormones or reactive oxygen species (ROS). In the present study, we examined growth index, chlorophylls and carotenoid content, H2O2 content, membrane lipid peroxidation, antioxidant enzymes (CAT, GPX, APX and SOD) activity and proline content in M. officinalis shoots culture that induced through the use of an elicitor, ABA. Mediums of M. officinalis were fed by different concentration of ABA (0, 5, 25, 50 and 100 µM) and 7 and 14 day after elicitation, biochemical and physiological parameters were measured in shoot cultures. Growth index of the treated samples decreased in all concentration of ABA compared to control. Content of chlorophyll a, b and total chlorophyll decreased in all concentrations of ABA compared to control. Content of carotenoid at 25 and 100 µM concentrations of ABA increased compared to control. ABA elicitor increased the amount of H2O2 at all concentration of ABA compared to control. Among the measured antioxidant enzymes APX enzyme and SOD enzyme increased at all concentrations of ABA. Content of lipid peroxidation increased only at 100 µM concentration of ABA compared to control. Content of proline increased at all concentration except at 5 µM concentration of ABA compared to control. ABA as a transmitter molecule seems to play an important role in the production of hydrogen peroxide and the production of antioxidant defense proteins such as catalase and peroxidases in shoot cultures of M. officinalis.

Salinity is one of the main osmotic stresses that limit plants growth and development through changes in osmatic and ionic balance. In order to locate genomic regions controlling quantitative traits locus (QTLs), related to salinity tolerance in the barley and evaluating the relevant indices at the experimental germination stage in 2016 and 2017 using 100 families of the Badia × Comino cross with their parents in a completely Three replications were Randomized and six treatments including normal and five levels of salinity (4, 8, 12, 15 and 20 dS/m). QTL analysis was performed by composite location method based on each of the six treatments. A total of three QTLs were identified under normal conditions and 23 QTLs under stress conditions. The total phenotypic variance explained by these QTLs varied from 9.1 to 15.4 percent, with the lowest and the most related to root length in terms of 20 dS/m. Sustained QTLs in each of the six environments and linked markers in the selection method can be used to improve germination traits under salt stress conditions after several years of testing and repeat.