Iranian Journal of Plant Physiology
Volume:3 Issue: 2, winter 2013

Water potential is amongst the most useful parameters for the measurement of the degree of water stress in plants. With the objective of mitigating adverse effects of moisture stress on water potential, osmotic potential and pressure potential of wheat variety Inquilab-91, a greenhouse experiment was conducted using two moisture levels viz., normal moisture supply and moisture stress at crown root stage. The moisture levels were randomized in main plots and growth substances including distilled water, Ethephon @ 400 mg l-1, Paclobutrazol @300 mg l-1, SADH @ 2000 mg l-1 and Triadimefon @ 200 mg l-1 were kept in sub-plots. Whereas, stages of growth substances application, i.e., pre-sowing seed treatment and foliar spray at crown root development, heading and grain filling were randomized in sub-plots. Water stress at crown root development stage was imposed simply by withholding irrigation. Moisture stress significantly lowered water potential and pressure potential and enhanced osmotic potential while growth substances application ameliorated all the traits under study; however, stages of application showed a varied response in this regard. Ethephon application @ 400 mg l-1 had pronounced effect with higher water potential (-1.584 MPa), osmotic potential (-1.781 MPa) and turgor potential (0.217 MPa) values. Amongst the stages of growth substances application, pre-sowing seed soaking in different growth substances was found to be the most effective in maintaining plant water balance. Interaction of moisture levels, growth substances treatments and stages of their application was highly significant. Thus, Ethephon application @ 400 mg l-1 as pre-sowing seed treatment under moisture stress conditions depicted the highest values of water potential (-2.080 MPa), osmotic potential (-2.268 MPa) and turgor potential (0.186 MPa).

The potential of three arbuscular mycorrhizal fungi (AMF) - Glomus mosseae, G. fasciculatum and G. intraradices- to enhance the production of essential oil and plant growth parameter was investigated in sweet basil (Ocimum basilicum). The AMF inoculation significantly increased plant height, fresh and dry matter yield, oil content and oil yield as compared to non-inoculated basil plants. Essential oil content in plants inoculated with G. mosseae and G. fasciculatum was significantly higher than other treatments. Shoot fresh weight significantly increased by all three mycorrhiza fungi species, but only inoculation with G. intraradices and G. fasciculatum increased root dry weight. Also oil composition improved with AMF inoculation and linalool and methyl chavicol that enhance the essence quality, increased in inoculated plant compared to control plants. These results demonstrate that AMF concomitantly increase essential oil production and biomass in an herbaceous species rich in commercially valued essential oils. Therefore, AMF potentially represent an alternative way of promoting growth of this important medicinal herb, as natural ways of growing such crops are currently highly sought after in the herbal industry.

In this study the effects of drought stress on proline, protein, chlorophyll a/b, ascorbate and dehrydroascorbate were investigated in Akri and Mobil cultivars of tomato species. The seeds were cultured at 23 °C with 15-16 hours light period and irrigation was done based on field capacity control (FC), mild drought stress (⅔ FC) and severe drought stress (⅓ FC) under greenhouse conditions. After nine weeks of sowing, leaf, stem and root were isolated and studied for various indices. The results indicated that amount of proline increased significantly in mild and severe stresses in root, but in stem and leaf proline increased only under severe drought stress. Chlorophyll a and b and total protein decreased significantly in mild and severe stress in leaf, stem and root. Ascorbic acid (ASC) increased but dehydro ascorbate decreased significantly in both species. It could be concluded that in both cultivars proline and ASC content increased under severe and mild drought stress although soluble protein and chlorophyll a/b decreased under severe stress. Therefore, in tomato plants osmolyte such as proline and also ASC as an antioxidant compound increased against drought stress. Protein accumulation has protecting role under mild stress.

aerial parts of the plantwere investigated spectrophotometrically and their antioxidant activitieswere obtained byTotal Antioxidant Capacity (TAC) method and then compared with standards such as butylatedhydroxyanisole, butylatedhydroxytoluene. Findings demonstrated that the TP content of aerial parts of Nasturtium officinalewere 8.03 to 9.35 mgGAE in vegetative period and 6.5 to 7.65 mgGAE in generative period. Also, TF contents were 26.5 to 31.11 mgQuE in vegetative period and 36.89 to 42.65 mgQuE in generative period. The highest secondary metabolitescontentsof TP were found in vegetative period. Aerial parts in high altitudes (1400 m) hadalso high amount of phenolic and flavonoid compounds. IC50 contents in aerial parts of the plant were 932 to 1494 μg/mlin TAC method.The highest antioxidant activity and radical scavenging effects were observed in vegetative period with the lowest IC50, 932 to 1227.5 μg/ml, whereas generative period with the highest amount of IC50 had the weakest antioxidant activity. Findings showeda positive correlation between antioxidant activity and the most important secondary metabolites,which explains why this plant is used by the rural healers in north of Iran for nutritionand anti-inflammation.

Avena fatua and Phalaris minor are narrow-leaved weeds that pose problems for many crops. In order to study the effects of sodium chloride (NaCl) and polyethylene glycol (PEG) on germination and initial seedling growth of Avena fatua and Phalaris minor, an experiment was conducted based on a completely randomized design with 4 replications under laboratory conditions during 2011-2012. Eight levels of NaCl: 0 (control), 50, 100, 150, 200, 250, 300, and 350 mM, and 8 PEG concentrations: 0 (control), 15.6, 100.7, 151.4, 190.5, 223.6, 279.3, and 326.2 g/L were used. The findings suggested that in both weed plantlets, increase in NaCl and PEG concentrations resulted in reduced seed germination, and seedling shoot and rootlet length, as compared with the control with no drought stress. In the treatments with high concentrations of NaCl and PEG, seed germination in both weeds approached zero which suggests their sensitivity to salt and drought stress. Overall, it seems that Avena fatua was more tolerant to salt and drought stress in comparison with Phalaris minor.

In order to study the effects of biofertilizers on yield quantity and quality of Capsicum annuum L., an experiment was conducted in completely randomized block design with three replications in 2011. All plants were treated before transplanting in pots in greenhouse condition by biological fertilizers including nitroxin and biophosphates. Treatments included 3 concentrations of nitroxin (1:3, 1:5 and 1:7) diluted by water, 2 levels of biophosphate fertilizer (inoculated and non- inoculated plants) and NPK (2:6:1.5 g per pot) fertilizer. The control group had no treatment of chemical and biofertilizer. Results revealed that the highest yield (3177.85 g/plant) dry weight and fresh weight (5.43 g and 120 g) respectively, were obtained by nitroxin 1:5 combined with phosphate solubilizing bacteria treatment. This combination of biofertilizers (nitroxin 1:5 and biophosphate) significantly improved leaf phosphorous and nitrogen content, 0.27% and 2.16%, respectively. Calcium content of fruits treated by nitroxin and biophosphate also showed considerable increase (0.33%). Vitamin C content was enhanced in combined treatments of nitroxin 1:5 and 1:3 with biophosphate. Application of low concentrations of nitroxin and biophosphate made no significant difference with control plants. Based on this investigation the best fertilizer concentration and combination for sweet pepper production in greenhouse condition was nitroxin 1:5 together with biophosphate fertilizer.

Some populations of Gundelia tournefortii were compared based on chemotaxonomical characteristics. In this study, some biochemical compounds such as total protein and storage proteins of shoot were studied. The populations were compared on the basis of biochemical characteristics using statistical methods. Different populations were collected from mountains of west Azarbaijan province. Total protein content was assayed through Lowry method and storage proteins content was determined by through electrophoresis via silver nitrate staining method. The results of electrophoresis showed that populations could be classified in 3 clusters. Orumieh, Ghushchi and Shahindej populations were included in cluster 1. Also cluster 2 comprised population of Bukan and the remaining populations including Mahabad and Takab were classified in cluster 3. The results of total protein showed the maximum total protein in Shahindej population (739 mg/100 g) and minimum total protein in Takab population (465 mg/100g).

Temperature changes occur in nature faster than other stressors. Plants due to inability to move and change their position, are exposed to extensive variations in daily or seasonal temperature, and therefore, should quickly and effectively adapt to temperature stress. In order to study the effects of heat stress on physiological traits of forage maize hybrids, a factorial split plot experiment was carried out in a completely randomized block design with three replications in 2011. Treatments consisted of two maize varieties Ks 704 and N 504, 2 concentrations of salicylic acid (0 mM and 1 mM) and 2 different planting dates (July 5th and 26th). The plant height, stem diameter, plant dry weight, dry matter production (DMP) and protein content (CP) were measured. Results showed that plant height was affected under the interaction of three factors of the study, i.e., planting date, hybrid and spraying salicylic acid. Plant height in the variety N 504, treated with 1 mM salicylic acid and the planting date of July 26th was 64.76% more than in the treatment including 0 mM salicylic acid and the planting date of July 5th. Maximum dry weight per plant was observed in the plants treated with 1 mM salicylic acid planted on July 26th. Dry matter production (DMP) in Ks 704 sprayed with 1 mM salicylic acid and the planting date of July 26th was 73.71%. On the other hand, the protein content (CP) in shoots with 0 mM salicylic acid was 15.68%.