JOURNAL OF PLANT PROCESS AND FUNCTION
Year:2014 | Volume:3 | Issue:7|Papers Count:11

In this study, the ability of Dunaliella salina, strain Utex-200 in bioelimination of aluminium was investigated. First the alga was grown in the culture medium and then the effects of six concentrations of 0(control), 250, 500, 1000, 2000 and 4000 mM of aluminum on the growth rate and total chlorophyll content of alga were studied for duration of 27 days. The results indicated that an increase in the aluminum concentration in the medium caused decrease in the growth rate and chlorophyll content. It seemed that these effects are probably due to destruction of cell membrane and suppression of essential elements uptake, such as Ca2+ and Mg2+. The treatment of algal suspension by different concentrations of aluminum resulted in algal cells-Al3+ ions binding, cell agglutination and sedimentation, reduction of the algal cell number in supernatant of cell suspension and consequently removal of aluminum. The results of adding EDT A to algal suspension for binding of aluminum and prevention of cell sedimentation confirmed algal cells-Al3+ ions binding. Also, this study indicated that not only each cell of algal suspension had defmed capacity for sedimentation of aluminum, but just intact cells could bind to Al3+ ions and aluminum bioelimination. On the whole, the results ofthis study indicated that strong binding of algal cells- Al3+ ions resulted in reduction of growth rate and cell division, cell agglutination and sedimentation and aluminum bioelimination.

In this experiment, 36 accessions of seven species of Brassica genus were evaluated both under field condition (for study of genetic variation) and under laboratory condition (for study seedling drought tolerance) in 2012 at Isfahan university of technology research farm. The statistic design in the field was completely randomized block with three replications. Results of the field assessments were suggestive of considerable variation between accessions for all of the measured traits with better performance for B. carinata with respect to seed yield. The results of principal component analysis showed that three independent factors explained 71 percent of total variability. In second experiment, accessions were evaluated under three levels of water deficit treatment (zero, -3 and -6 bar caused by PEG) in germination stage according to a factorial experiment based on the completely randomized design with three replications. Results indicated that for most of the traits, effect of water deficit levels, genotypes and their interaction were significant. Rootlet length was the most sensitive trait and increased by decreasing drought stress. Results of drought tolerance indices (such as TOL and STI) also confirmed that wild species such as B. nigra, B. oleracea and B. juncea could tolerate drought at least in germination stage. According to principal component analysis, B. fruticulosa and B. napus were found to be the most sensitive and B. nigra, B. oleracea and B. juncea to be the most drought tolerant species; hence the latter species can be used as a good sources of genes for improving cultivated species in breeding programs.

One of the negative effects of water stress on growth and crop production is micronutrient uptake reduction by plant root. Therefore, to evaluate the effect of foliar application of Fe and Zn on some physiological and morphological characteristics of red bean (Akhtar cultivar) under drought stress this experiment was designed as a split plot in a completely randomized block design with three replications. Irrigation as the main plot at three levels: Irrigation after 50, 75 and 100 mm evaporation from pan evaporation, and foliar application of micronutrients as the sub-plot at four levels: foliar application with water (control), ferrous sulfate, zinc sulfate and a mixture of ferrous sulfate and zinc (each at a concentration 3.1000) were used. The results showed that delay in irrigation decreased leaf relative water content, chlorophyll content, plant height, number of lateral branches and seed yield and increased electrolyte leakage, leaf proline and soluble sugar content in compared to control treatment. The effect of foliar application treatments was significant on all traits except leaf soluble sugars and plant height. The foliar application of Fe and Zn increased leaf relative water content, chlorophyll content, number of lateral branches and grain yield, and decreased electrolyte leakage and leaf proline significantly. According to the results, the foliar application of Fe and Zn improved physiological characteristics and stress tolerance in plants. Therefore, the plants were delayed in encountering with water stress condition, and produced a better performance.

Nanomaterials are considered as one of the most important innovations of modern science. Nanoparticles are highly reactive. These properties are largely due to their size (from 1 to 100 nm), large surface area and high solubility. Among all the micronutrients, iron has the largest amount in plants. Iron is the catalytic component of many oxidization and redox enzymes and is needed for chlorophyll synthesis. In this study, iron oxide nanoparticles in six different concentrations (0, 5, 10, 20, 30 and 40 micromolar) and complete Hogland nutrient medium (include fe-chelate) as control environment was given to Catharanthus roseus plant for 70 days. The results have shown that iron oxide nanopartic1es significantly increased the leaf growth parameters and carbohydrate contents in comparison with control plants, but it had no effects on the amount of proline, antioxidants and the stomatal density of leaf. The highest amounts of leaf growth parameters was obtained in 30m1 iron oxide nanoparticles and the lowest values of these parameters was found with Om1 iron oxide nanopartic1es. The highest values of proline and antioxidants activity were measured in Om1 iron, since this concentration is considered as stress for plant. Therefore, use of iron oxide nanoparticles fertilizer is recommended, because it reduce the harmful effects of chemical fertilizers into the environment.

In order to evaluate morphological and physiological responses of sorghum (Pegah cultivar) to salt stress (0, 5, 10 and 15 dS/m) and different salicylic acid (SA) levels (0, 0.75 and 1.5 mM), an experiment was carried out in research green house of college of Agriculture Shiraz University during 2012 using a factorial as randomized complete block design with four replications. The results showed that salinity reduced stem length and leaf area of sorghum and the effect of salinity level at 15 dS/m was more pronounced. On the contrary, foliar application by SA increased these parameters. Moreover, salt stress and foliar SA increased the activity of catalase, superoxide dismutase, peroxidase and ascorbate peroxidase and chlorophyll content. In summary, it can be concluded that foliar application of sorghum by SA improved growth and enhanced salt tolerance in this plant. Indeed, SA stimulated sorghum growth under salinity stress via enhanced anti-oxidant defense system, reduced oxidative stress and increased photo synthetic pigments.

This study was conducted to evaluate the effects of water stress on growth indices and phenological traits of Thymus kotschyanus during 2010 and 2011 growing seasons. A field experiment was carried out with three irrigation regims (T20, T50 and T80 representing irrigation after 20, 50 and 80% soil water depletion, respectively) using a randomized complete block design with four replications at Experimental Station of Isfahan Agricultural and Natural Resources Research Center. Dry matter (DM), leaf area index (LAI), crop growth rate (CGR) and growth degree day (GDD) for each phonological step were decreased under water stress. DM in second year (152 gr m-2) was more than 2 times of the first year (67 gr m-2). The highest rate of CGR, LAI and DM were obtained at early blooming, 50 and 100% flowering stage, respectively. Phenological stages provoked 100-150 GDD under water stresses. DM was decreased 60% over increasing water stress from T20 to T80. The results suggested that for the highest yield production, 20% soil water depletion is recommended and harvesting should be done at fully flowering stage and prevention of water stress in early blooming stage is also recommended.

The present study was undertaken in order to evaluate native desiccation tolerance and its mechanism in wheat seedlings of different genotypes. At the first step, drought stress was applied by using different concentrations of polyethylene glycol (PEG) and mannitol. Due to the fact that these compounds (even in high concentrations) were not able to produce sever water stress, the experiment was carried out by stop irrigation method. The results of drought tolerance in different days of growth (3, 4 & 7 days) showed that four-day wheat seedlings had the most tolerance to serious drought stress and this toleration was similar to that of desiccation tolerant and resurrection plants. Also, it was intuitive, and irrespective of wheat genotypes. Four-day wheat seedlings were well able to tolerate drought stress up to more than 3weeks and produce new roots 3 days after re-watering. One Iranian cultivar which was sensitive to terminal drought stress, Marvdasht, was used for further analysis. Prolonged drought stress (10 to 30 days) showed that 4-day seedlings of this genotype tolerated desiccation and grew up very well. The results also showed that soluble sugars, e.g. glucose and mannose increased after stress but decreased after re-watering. Cessation of the growth of seedlings which were separated from seeds even in nutrient media indicated that connection to seeds is an inevitable condition for expression of drought tolerance by seedlings.

Because of water and soil salinity, there are many problems for turfgrass in Iran. Use of salt tolerant native plants is one of the appropriate ways for solving these problems. This study was undertaken to evaluate effects of four levels of salinity (less than 2, 4, 8 and 16 ds/m) on morphological and physiological characteristics in native grass, Wheatgrass (Agropyron desertorum). The experiment was performed based on randomized complete block design with three replications. The results showed that salinity stress decreased turf grass quality (TQ), fresh and dry weight of shoots and roots, relative water content (R We) and root and shoot potassium contents. Also, salinity stress increased shoot and root sodium contents, electrolyte leakage (EL), proline contents and activity of enzymes. According to reduction in TQ and RWC and increase in EL under salinity stress, it seemed that increasing in proline contents and enzymes activities was not be able to reduce the damage caused by stress. All of the measured parameters in this study showed the significant differences with control plant in 4 ds/m salinity level. The results showed the wheatgrass was salt-sensitive and its salt tolerance was less than 4 (ds/m).

In order to evaluate the effect of Arbuscular Mycorrhizal (AM) fungi species Glomus mosseae to salinity stress of three ecotypes of hemp, a study was carried out at a field in north-east of Isfahan city in 2012 growing season. The experimental design set as factorial based on randomized complete block design with three hemp ecotypes (Shiraz, Mashhad and Isfahan) and Arbuscular Mycorrhizal fungi species of Glomus mosseae and control under saline soil and saline water. The result showed that total dry weight, height, number of lateral shoots and grain yield of Mycorrhizal plants were higher than the non Mycorrhizal plants. The ecotype of Shiraz with Mycorrhizal had the highest percentage of potassium. AM fungi significantly enhanced the concentration of potassium. Hemp Mycorrhizal plants absorbed less amounts of sodium and inhibited its transfer to the shoots. It is suggested that mycorrhizal ecotype Shiraz is the most resistant to salinity under saline soil and water.

Different biological and environmental factors, harvesting methods, transportation, storage time and the methods of storage affect agricultural product properties. As a result of climacteric nature and continuous physiological life of apple fruit, the biochemical changes can be important economical consequence. This study was designed to assess these changes and to understand how they can affect apple quality. In the first week of Oct. 2012 the fruits of two apple cultivars were harvested and stored in cold house (Malekan city, East Azarbaijan). Independent factors, storage time (0, 45, 90, 135 days) and cultivar (Golden delicious and Red delicious), were tested with factorial analysis in completely randomized design for some apple fruit characteristics. Results showed significant differences between cultivars in most biochemical characteristics. With increasing storage time, protein, soluble sugars, reducing and non-reducing sugar contents and the juice pH were significantly increased; however, titratable acidity, total soluble solids and electrical conductivity were decreased. Cold storage did not significant change insoluble sugars content. It can be concluded that, time dependent biochemical changes may occur with cold storage of apple fruits that may induce changes in quality of fruits.

Chemical herbicides are the key component of weed control in agriculture but have adverse effects on environment. In order to evaluate the allelopatic potential of sunflower alcoholic extract against winter wild oat (Avena ludoviciana) at germination and vegetative growth stage, two experiments were conducted. Experiments were laid out according to Completely Randomized Design with five replications and treatments with various concentration of sunflower extract (0, 5, 10, 15 and 20 gr L-1). Results indicated that sunflower alcoholic extract application exhibited gradual rise inhibitory effect on seed germination, seedling weight, antioxidant enzymes activity and a-amylase enzyme activity but elevated the mean germination time and malondialdehyde concentration in winter wild oat seedlings. The lowest a-amylase enzyme activity was noted at higher levels of extract application (1.1 nmol seed-1 min-2), Likewise, seedling weight, antioxidant enzyme activities and sucrose synthetesis enzymes activity were declined with sunflower extract application but malondialdehyde concentration was increased. Minimum sucrose synthesis activity (1.36 nmol prot -1 min-2) and highest malondialdehyde concentration (0.96 nmol grfw-1) were noted at 20 grL-1 concentration of sunflower al c oholic extract application. In conclusion, sunflower alcoholic extract decreased seed germination, seedling growth, a-amylase enzyme and sucrose synthetesis enzymes activity of winter wild oat.