IRANIAN JOURNAL OF PLANT PHYSIOLOGY
Year:2015 | Volume:5 | Issue:2|Papers Count:8

The present study reports a factorial greenhouse experiment using a randomized complete block design in 2014 which investigated the effects of salt-pretreated Glomus fasciculatum fungus, salinity, and the interaction effect of these variables on the physiological properties of barley. The first factor was mycorrhiza salinity pretreated with different levels of salt (0, 25, 50 and 100 mM) and the second factor included application of salinity to barley plant at 0, 25, 50, 100 and 200 mM. Mycorrhiza pretreatment with 25 mM salt increased fresh and dry weight in the absence of salinity treatment in the plant but in the presence of salinity, it reduced the dry weight of the plant. Also mycorrhiza pretreatment with salt reduced the leaf area and increased peroxidase, catalase, polyphenols peroxidase enzymes activities and malondialdehyde content. Also by increasing salinity, fresh and dry weight and leaf area decreased and antioxidant enzyme activities, malondialdehyde and proline contents increased.

Olive is one of the most ancient fruit trees and has been cultivated for its oil for thousands of years. A mature olive tree produces about 500, 000 flowers. They are borne on inflorescences termed panicles. The number of flowers and their distribution on the inflorescence are specific for each cultivar but can change from year to year. The flower position on the inflorescence affects its gender and opening day. The flowers are either perfect (hermaphrodite) or staminate (male). Olive flowers are wind-pollinated; however, they are visited by insects. Critical conditions such as strong and dry winds, rain, and high temperature affect pollination and may reduce fruit set. Most olive cultivars are self-incompatible or partially self-compatible and need to be fertilized by compatible pollenisers to ensure acceptable production. Furthermore, some cultivars are cross-incompatible and cannot fertilize each other. The degree of SIin olive is widely influenced by climatic conditions and therefore varies from environment to environment and from year to year. In a year with normal flowering, 1 to 2% of fruit set is enough for a commercial yield. The fruit follows a double sigmoid growth pattern like other drupes and contains quality oil.

In the present study, three rice varieties namely Swarna, Swarna Sub1A, and FR13A were evaluated on the basis of their antioxidative responses to screen submergence tolerance capabilities. Fourteen-day- old seedlings were completely submerged for 7 days and were observed to have a significant variation in reactive oxygen species like H2O2 and O2-. The variety Swarna recorded maximum accumulation of H2O2 and O2- and showed more susceptibility to submergence. On the other hand, chlorophyll content did not show highly significant variation among the varieties thus proving its uncertainty to be a trait under submergence. The activity of superoxide dismutase (SOD) had declined throughout the submergence period irrespective of varieties, being maximum in Swarna Sub1A and minimum in Swarna. Almost similar phenomenon was recorded in other two varieties showing their submergence susceptibility however with insignificant variation in terms of APX and CAT. The results from the present experiment point at the fact of submergence tolerance with the view of oxidative sensitivity in rice varieties and finally their possible roles as screening indices for submergence tolerance are discussed.

Total soluble solid (TSS) content is commercially used as fruit quality index because of its high positive correlation with sugar content. In the present study, The effect of foliar application of naphthalene acetic acid (NAA) with different concentrations (0, 25, 50, and 100 mg.L-1) at 4 true leaf and fruit set stages and plant training (pruning and thinning) on TSS and soluble sugar (i.e. sucrose, glucose and fructose) contents of fruit were evaluated in melon (Cucumis melo L.) cv. Khatooni. Results showed that NAA treatments significantly increased TSS and soluble sugar contents. The highest TSS and soluble sugar contents were observed in 100 mg.L-1 NAA. In contrast, TSS and soluble sugar contents were decreased significantly by plant thinning. In mature fruits, an obvious gradient of TSS and soluble sugar contents was detected, ascending from pedicel to middle and umbilicus part of mesocarp. Also sucrose was dominant sugar in ripening fruit. Results of this work suggest that application of 100 mg.L-1 NAA at fruit set could be used to increase TSS and soluble sugar contents of melon cv. Khatooni.

Aluminum toxicity is one of the most deleterious factors for plant growth in acidic soils because over 50% of the world’s potentially arable lands are acidic. In recent years, considerable research has been conducted to understand the mechanisms of Al toxicity and tolerance in plants. This paper reviews the effects of different concentration of Al on plant shoot, root physiological parameters such as length, fresh and dry weight, pigment content and antioxidant enzyme such as Catalase Ascorbate and Guaiacol peroxidase, malonyldialdehyde content. Maize (Zea mays L.) seeds were sterilized and these seeds were then germinated in Petri dish. The germinated seeds were allowed to grow at 27oC in darkness, and 5 ml of test solution was added to each Petri dish on the second day. The test solution contained 0, 25, 50, 75, 100mM AlCl3. Aluminum toxicity caused reduction in growth in all treatments. The plants exposed to Al exhibited a substantial decline in growth, pigment content, activities of guaiacol peroxidase (GPX), catalase (CAT) and ascorbate peroxidase (APX) and leaf structure. Data show that 50 mM Al caused increased in MDA content.

Seasonal changes in antioxidant enzymes activities, amount of water, ash, proline and soluble sugars were surveyed during this research in four halophyte species of Varamin County, Tehran, Iran: Salsola turcomanica Litwin, Suaeda arcuata Bunge, Tamarix leptopetala Bunge and Cressa cretica L. Plants were collected randomly from their natural habitats in spring and summer. Activity of these enzymes in response to environmental stresses such as salinity increased in shoots of most species from spring (May) to summer (Aug). In T. leptopetala catalase and ascorbate peroxidase activities were high while peroxidase activity was low in comparison to other species. Peroxidase activity in the other three species and catalase activity in all species were high. Thus, high activity of one antioxidant enzyme in stress condition may be accompanied by the low activity of other enzymes. According to this research, water amount in S. arcuata and S. turcomanica shoots were high and by the increase of salinity water potential reduced. The amount of ash in shoots and roots of all species increased from spring to summer but it was the most in S. arcuata and S. turcomanica. This could be the result of ion accumulation (especially Na+and Cl-) in salinity condition in these two species. The amount of proline and especially soluble carbohydrates increased in shoots and roots of most species from May to Aug and it was the most in Tamarix and Suaeda.

To gain a better understanding of molecular and biochemical events involved in light intensity adaptations of Dunaliella salina, we studied the expression of phytoen synthase (psy) gene; pigments, carbohydrates, proteins and lipids accumulation under two light intensities. The cells were pre-cultured under 50 mmol photon m-2s-1 light intensity and then transferred to two different light intensities of 200 and 1000 mmol photon m-2s-1. The psy gene expression in high light (1000 mmol photon m-2s-1) decreased and remained fairly constant until 48 h however, a more decrease was appeared under the low light (200 μmol photon m-2s-1). After 2 weeks cultivation, the high light led to a considerable decrease of Chl a and Chl b contents, and an increase in carotenoids/total chlorophylls and Chl a/Chl b ratios. Total, soluble and non-soluble (starch) carbohydrates; proteins and lipids contents of cells were increased under the high light conditions. The results suggest that D. salina cells can have light intensity dependent adjustments in gene expressions, photosynthesis apparatus function, and structure as well as biochemical cell composition.

In the present study, small segments of cotyledon, apical bud, hypocotyl, and root of 10-day-old seedlings were isolated and transferred to Murashige and Skoog (MS) base medium with different treatments of phytohormones. Two media were used for apical bud culture: MS with indole-3-acetic acid (IAA) and kinetin (Kin) (1 mg/l) and the other medium, MS with double vitamin of MS and 6-benzylaminopurine (BAP) (2 mg/l) and naphthalene acetic acid (NAA) (0.1 mg/l). The findings suggested that capacity of callus generation in BAP and NAA was better than IAA and Kin, but shoot generation and increase of shoot length under IAA and Kin treatment were significant. In BAP and NAA media the callus differentiated in shoot, but generation of shoot and increase in its length was not significant.