Iranian Journal of Plant Physiology
Volume:6 Issue: 2, Winter 2016

The concept of source and sink strength is presently well-recognized and accepted by the scientific community as a pertinent approach describing the mechanisms of carbohydrate partitioning into the different and competing organs at a whole plant or canopy scales. Sink–source relationships have a clear role in the size of sink organs. Besides the effect on organ size, sink/source ratio might also affect photosynthesis. Crop biomass productivity is closely related to source and sink capacities and the balance between them. Determination of the carbon balance of a whole plant and relation between source and sink were studied by carbon isotopic labeling techniques. Techniques using 14C or 13C have been used for many years to study the allocation of carbohydrates produced by photosynthesis between different parts of the plant. This method also allows calculation of the proportion of the total carbon accumulated in each sink that was supplied by all source leaves, as well as the growth contribution from each source leaf to the main plant sinks. These data are vital to determine the productivity of each source leaf.

Nanoparticles are atomic or molecular particles with at least 1–100 nanometer diameters. They have entered vastly into the world of agriculture and biology; this is because of their special effect and their unique features. Their unknown impact on living things and the ecosystems has caused a lot of concern. This research was done in order to study the effects of nano-TiO2 and nano aluminium on wheat (Triticum aestivum). Both Nano titanium dioxide and nano aluminium were used in four concentrations {(0, 100, 1000, 2000 mgL-1) and (0, 500, 100, 1000, 2000 mgL-1) respectively}. The experiment was done as factorial in a completely randomized design in 3 replications. The seeds were sterilized and transferred into pots containing sand. When the plants reached four leaves stages, the nanoparticles were sprayed on plants two times in a week internal. The results revealed that nano aluminium decreased the length of root and shoot and the content of chlorophyll; however, it increased the content of proline and malondialdehyde in shoot and root. The treatment of plants in different levels of nano aluminium with nano titanium dioxide especially in 100 mgL-1 concentration increased the length of both the root and shoot. Nano titanium dioxide in 1000 and 2000 mgL-1 increased the MDA and proline content. Generally the application of nano titanium dioxide in low concentration can moderate the damage effects of nano aluminium in the range of 100 mgL-1.

This study evaluated the effect of mycorrhizal inoculation on growth characteristics and gel quality of Aloe Vera. Research was conducted as a randomized complete block design with three replications. Eight treatment of experiment were plant inoculation by different strains of mycorrhiza, namely, Glomus fassiculatum, G. interaradise, G. mosseae, combination of two strains of G. fasiculatum and G. mosseae, combination of two strains of G. Fasiculatum and G. interaradise, combination of two strains of G. Interaradise and G. mosseae, combination of three strains of G. fasiculatum, G. interaradise, and G. mosseae, and control treatment (without inoculation). The research results indicated mycorrhizal inoculation decreased gel pH and leaf area index, whereas mycorrhiza fungi increased the content of vitamin C, aloin and barbaloin content, relative growth rate, and ratio of mature leaf gel to weight of mature leaf skin compared to control treatment. Results of the present research revealed highest and lowest effects on studied traits was seen in combination of three strains and control treatment, respectively.

In order to investigate the effect of seed pretreatment with growth regulators on biochemical characteristics of red bean genotypes, a factorial experiment was carried out in a randomized complete block design with three replications. In this research, seed pretreatment with growth regulators namely salicylic acid (SA) and naphthalene acetic acid (NAA) were applied at four levels including P0: control (pretreated with distilled water); P1: pretreated with NAA hormone (0.5 mM/lit); P2: pretreated with SA hormone (0.7 mM/lit); P3: pretreated with combination of NAA hormones (0.5 and 0.7 mM/lit) and two genotypes of red beans (KS31169 and D81083). The ANOVA results showed that the simple effects and the interactive effects of genotypes × priming with growth regulators on all traits were significant except the relative chlorophyll content. The results of mean comparison for the interactive effect of genotypes and priming with growth regulators showed that application of SA increased the amount of chlorophyll a in D81083 genotype. The highest rate of chlorophyll b and total chlorophyll belonged to D81083 genotype with application of NAA. The rates of flavonoids and carotenoids decreased by using growth regulators, therefore the highest rates of these traits were observed in control × D81083 genotype. Seed priming with combined treatments (NAA) led to the highest stability of cytoplasmic membrane in KS31169 genotype. In general, the results of the present study indicated that the use of growth regulators as seed pretreatment will increase the main pigments of photosynthesis and cytoplasmic membrane stability.

Drought is one of the major environmental problems in agricultural field worldwide. The present study investigated the effects of water deficit caused by exogenous application of polyethylene glycol (PEG) on cabbage (Brassica oleracea var. capitata) grown in hydroponic culture. Root length, shoot length, dry weight, and relative water content of the seedlings significantly decreased in dose dependent manner. Significant reduction in chlorophyll, sugar and protein content, and nitrate reductase activity were recorded. The increase in proline content was recorded as the concentration of PEG increased. Increasing concentration of PEG affected the antioxidant enzymes viz. superoxide dismutase, catalase, and peroxidase activity of the seedlings through the production of reactive oxygen species (ROS) in stress condition. PEG at higher concentrations significantly enhanced the activities of antioxidant enzymes. The cabbage seedlings induced antioxidative defense system to mitigate the adverse effect resulting from altered environmental condition.

Chromium is a heavy metal toxic for plants that due extensive industrial applications over the last decade, has become a serious environmental pollution. On the other hand, chelator dissolution and absorption of metal by the plant increase and their use in phytoremediation is important. The aim of this study was to evaluate the effect of different concentrations of chromium and ethylene diamine tetra acetic acid (EDTA) chelator on sunflower (Heliantus annuus L.) through the study of growth parameters, chlorophyll, and soluble sugar amounts and Cr accumulation in plants under hydroponic culture. In order to plant sunflower were treated with different concentrations of Cr (1, 2, 4 and 6 ppm) and EDTA (0, 1 and 3 mg/L) in the medium Hoagland. The results showed that the use of chromium reduced the length of shoots and roots, and chlorophyll, while it increased soluble sugars. Addition of EDTA to the metal increased the shoot and root length and chlorophyll content while it reduced soluble sugars. According to the results, the use of chromium heavy metal in medium increased the amount of it in shoot and root. EDTA application, particularly with higher levels of chromium led to its accumulation in shoot and root. This research suggested positive role of application of EDTA in the presence of chromium heavy metal in increasing the power of phytoremediation of sunflower.

Bitter melon (Colocynth) is a species of herbs, annual medicinal plant of family Cucurbitaceae which are mainly grown in warm regions of Iran. Fatty acids of the seeds of this plant are considered as important materials, medicinally. In this study, essential fatty acids of seed collected from nine different regions of Iran were evaluated. The composition of fatty acids such as oleic, linoleic, stearic and palmetic acid were measured by GC (Gas Chromatography). The total fatty acid content in the seed was varied from 35% to 40%. The highest content of linoleic fatty acid was found in seeds of Orzooiyeh accessions (72.4%) and the maximum amount of oleic acid was in Khorasgan (13.8%%). Kerman accession was important in case of phenolic content which was 8810.9 mg GAE/g based on results fatty acids contents were significantly differed among different accessions and there were valuable accessions considering unsaturated fatty acids and total phenolic compounds. These plant materials could be used for improving breeding programs and selection to plant as valuable accessions.

Salinity is one of the most important limiting factors for growth and product of plants around the world. Identification of salt tolerant varieties and improvement of plants tolerance are the most effective way to increase its performance. Experiments were conducted in a hydroponic system in order to study the reaction of borage (Borago officinalis L.) to salinity in terms of developmental changes and pigment content. Salinity was applied by 100 mM Sodium Chloride and Sodium Sulfate salts by the ratio of two to one on borage at the 4-leaf stage. Wet and dry weights of shoots and roots, chlorophyll, protein, proline, anthocyanins, soluble carbohydrate, and reducing carbohydrates were determined. Decrease in fresh and dry weights of shoots and roots was observed in the salinity condition and the fresh weight loss in shoots was significant (p