Iranian Journal of Plant Physiology
Volume:1 Issue: 4, Summer 2011

The present study investigates the effects of Glomus mosseae and Glomus intraradices on the resistance of green basil plants to salinity stress. The findings suggested that there was an interaction of effects between mycorrhiza fungi inoculation and salt stress on the physiological characteristics of Ocimum basilicum L. On one hand, salinity decreased percentage of root colonization, root length, fresh and dry weight of shoot and root and content of photosynthetic pigments in inoculated basil plants. On the other hand, mycorrhiza fungus – inoculated plants experienced increase in root length, dry and fresh weights of shoot and content of photosynthetic.

Salinity is a major abiotic‐stress worldwide which decreases crop growth productivity. The objective of the present study was to investigate whether salt stress has adverse effects on growth, photosynthetic efficiency, biochemical properties and nutrient status of maize. An experiment was carried out with seeds of four varieties of maize which were allowed to germinate for one week. Afterwards, one‐week old maize seedlings of each variety were subjected to 0, 150 mM NaCl for four weeks. Significant decreasing effect by salinity was found in shoot‐root fresh and dry biomass, chlorophyll contents, total soluble proteins and macronutrients of all maize varieties. From the results, it is obvious that amino acids concentration increased under salinity as compared to control in all maize varieties.

In order to improve seed and seedling quality indices of two carrot cultivars (Nantes and Forto), a hormonal priming technique was used. A factorial experiment was carried out on the basis of randomized complete block design (RCBD) with 3 replications and 16 hormonal priming treatments such as gibberellin and salicylic acid in four concentrations including 0, 50, 100 and 150 ppm. The interaction of cultivar ×hormone × concentration was significant for emergence percentage. The results showed that emergence rate, vigor index and root and shoot length were affected by treatments. The fastest and slowest emergence were observed in N‐0 (Nantes hydro‐primed seed) and F‐GA50 (Forto primed with Gibberellin 50 ppm) respectively. The highest vigor index was N‐0 (Nantes primed with distilled water) and least vigor index was N‐GA50 (Nantes primed with Gibberellin 50 ppm). In both cultivars, emergence rate, vigor index and root and shoot length of hydro‐priming were more than hormonal priming. Comparison of the two cultivars suggests that Forto has a more positive response to priming than Nantes.

With the objective of mitigating adverse effects of moisture stress on germination and seedling growth of wheat, four growth substances viz. ethephon, paclobutrazol, succinic acid, triademifon with varying concentrations and distilled water were used as seed treatment in a lab experiment. Moisture stress of ‐0.4 MPa induced with the application of mannitol significantly reduced speed of germination and suppressed root, shoot and coleoptile elongation. However, due to less adverse effect of water stress on root growth, root‐shoot ratio was increased. Thus, decline in speed of germination, root elongation, shoot growth and coleoptiles length was 51, 5.70, 58 and 2.85 percent, respectively. Eventually, maximum speed of germination (23.98), root length (10.00 cm), shoots length (24.57 cm) and coleoptiles (5.09 cm) were found in case of control; whereas values of these parameters were minimum under moisture stress with no treatment. Pre‐sowing seed treatment in ethephon, paclobutrazol, succinic acid, Triademifon and distilled water considerably accelerated speed of germination. Different concentrations of growth substances exhibited varied effect on these parameters. Seedling growth was further checked by the application of growth substances but seedlings were healthier than the untreated ones. Ethephon application @ 400 mg l‐ 1 under moisture stress had more pronounced and ameliorating effect on speed of germination.

This study was carried out to determine the pretreatment effect of gamma irradiation and salt stress on improvement of germination and physiological factors, protein and proline contents in rice cultivar Taroom Hashemi. Mature and healthy seeds irradiated with 4 doses (0, 100, 200, 300 Gy) and under 3 salinity doses (0, 5, 15 and 25 mmosh/lit NaCl) were cultured. After one week, radicle length was assayed in control and treatment of MS culture. After 1 month proline and protein contents were measured. The obtained data were analyzed by SPSS using ANOVA and Duncan test. The results showed that the lowest percentage of germination and shoot length was observed in treatments under 300 Gy gamma irradiation and salinity, 15 mmosh/lit. Also minimum length of radicle was observed in treatments under 300 Gy gamma irradiation in all salinity treatments. Moreover, the lowest percentage of callus regeneration was recorded in the treatments of various doses of gamma radiation in the salt concentration 25 mmosh/lit. The callus length of 100 Gy seedlings in 5, 15 and 25 mmosh/lit salinity was highest compared to other group. With increasing irradiation and salt concentration proline content was increased. The protein content on the other hand, decreased with increasing irradiation and salinity concentration. These results show that the up‐regulation of some physiological characteristics and seedling growth of rice following gamma radiation treatment may be used to control abiotic stresses such as drought and salt.

Algae are highly taken into consideration because of their nutritional value and different applications in environment cleaning. Also nowadays, algae are considered as an energy source. Efficient photobioreactors are used for increasing the mass of micro‐algae. However, one of the limiting factors in suitable nutrient application in cultivation of micro‐algae is biomass movement. Sodium nitrate and carbon dioxide are important restrictive factors in microalgae growth. In this research, the performance of a designed tubular photobioreactor in Islamic Azad University, Varamin branch was compared with that of a channel photobioreactor under various CO2 and NaNO3 quantities. Therefore, by varying the amount of CO2 and NaNO3 on microalgae growth while keeping factors such as temperature, pH and light intensity constant, the performance of two different photobioreactors were compared. A factorial experiment with three replications was carried out with different amounts of NaNO3 (0.75, 1.5 and 3 mM) and CO2 (0.2, 0.35 and 0.5 L /min). Results showed that the growth of microalgae increased significantly by increasing CO2 and NaNO3 quantities (p

If a seed could germinate earlier and form bigger and stronger seedlings, this would positively affect its yield. Seed size affects the features and quality of seedlings of crop; therefore, farmers can select suitable and favorite size of seed and increase performance and stability of the crop. In the present study, we considered effects of three seed sizes on seedling characteristics of five barley cultivars. The study was carried out in a randomized design with four replications in Horticulture Laboratory of Faculty of Agriculture, Islamic Azad University, Saveh Branch, Iran. The variables considered in the study included five cultivars of barley and three seed sizes (2, 2.5 and 3 mm in width). Results suggested that the speed of germination, percentage of germination, speed of growth, root length, shoot length and seedling dry and fresh weight were generally influenced by cultivars and seed size. Seed size did not affect percentage of germination, speed of germination, root and shoot length in most of the cultivars. However, in 3 variables, namely, seedling growth rate, fresh weight and dry weight meaningful changes were observed in 3 cultivars.

The reclamation of saline ‐ sodic soils is an important issue in agriculture and agronomy programs. In arid and semiarid areas, rainfall is not sufficient for leaching of salts from root zone and excess of soluble salts in the soil root zone can reduce water uptake of the plant. This is due to the decrease in the osmotic potential of soil solution and also degradation of soil structure because of sodium which could be toxic to the plant. In this field study reclamation of saline‐sodic soils at four stations in Minab, south of Iran was investigated. The experimental design of the study was double‐ring. The leaching was investigated up to 100 cm depth of soil. As the leaching process continued, soluble salts were washed away from soils profile of the agronomy programs and the salinity of the soil surface layer were reduced to a level suitable for cultivation of salt tolerant and semitolerant plants.