Iranian Journal of Plant Physiology
Volume:2 Issue: 2, Winter 2012

The action of salicylic acid (SA) has been well investigated in plant resistance against pathogen attacks but its role may be extended to a more global anti‐stress plant cell strategy. The expression of defense‐related functions may be also enhanced by elevated hexose levels. To verify if there exists a relation between these two defense programs, SA effect on soluble acid invertase (EC 3.2.1.26) activity was investigated in in vitro grown Pistacia vera plantlets from isolated embryonic axes, at different doses of exogenous sucrose. For this purpose embryonic axes were cultivated on Murashige and Skoog mediumcontaining 10, 20, 30, 40 and 50 g.L‐1 sucrose (control range) with 50 μM SA. After one month of growth, roots and shoots were used for analysis separately. SA treatment significantly enhanced the soluble invertase activity in tissues. The increase was more remarkable in root tissues. Sucrose limitation (10 g.L‐1) SA‐treated plantlets and sucrose osmotic stressed (50 g.L‐1) SA‐treated plantlets have shown very important increases in invertase activity and this was accompanied with a significant raise of total protein in spite of growth reduction. The implication of soluble invertase in the anti‐stress strategy of these tissues seems to be important. It is likely that hexose signaling of defense expression may be related to the action of salicylic acid on soluble invertase activity.

Scarcity of water for irrigation is an alarming issue of Pakistan and the problem is being magnified rapidly with the passage of time. Shortage of water is thus, a limiting factor in increasing per unit area wheat (Triticum aestivum L.) yield that is staple food of most of the people. Eventually, the gap between production and consumption is widening day by day and Pakistan is now suffering from food crisis. Hence, to find out the wheat genotypes having comparatively more drought tolerance, a field experiment was conducted during 2005‐06 and 2006‐07 on 497 wheat genotypes, which were subjected to drought conditions in addition to growing under normal soil moisture conditions. Screening of the genotypes was done on the basis of some Physiological and Agronomic attributes such as, Stomatal Conductance, Net Photosynthetic Rate, Transpiration Rate, Photo Active Radiation, Plant Height, Productive Tillers, Grains per Spike, 1000‐Grain Weight, Biological Yield, Grain Yield per Plant and Harvest Index. Drought stress adversely affected all these parameters, which expressed significant decrease in their values except harvest index, which was significantly increased irrespective of genotypes during both the years of study. The genotypes under study, on the basis of above physiological and agronomic attributes were grouped into high yielding drought sensitive, high yielding drought tolerant, low yielding drought tolerant and low yielding drought sensitive groups, employing cluster analysis. Thus, out of 497 sixteen wheat genotypes were ranked as high yielding drought tolerant which can be successfully grown under drought conditions without substantial decrease in grain yield.

In this study seven plant species were collected from the forest of Arasbaran located in the northwest of Iran. Sampling was conducted in May and August and roots were used for calculating vesicular arbuscular mycorrhizal colonization percentage during the same period. Fine roots were separated, washed and put in FAA solution as a fixative. Through the time, root colonization of all plant species increased significantly. Soil collected from rhizosphere of each plant species was physico-chemically analyzed and spore number was determined. Similar to VAM colonization of roots, spore population per 1 gram rhizosphere soil of all plants except Melilotus officinalis increased through the time. Rhizosphere soils were used for analysis of EC, pH and soil available N, P and K. Soil texture also was analyzed. Soil EC had very high correlation (r = 0.923, p

In this study, the plants of maize (Zea mays L.cv.ksc700) were grown in Hoagland solution containing 1, 3 and 5 mM KH2PO4 or K2HPO4 under controlled conditions. At similar levels of mono and diphosphate, plants supplied with monophosphate have produced higher content of dry matter and characterized with higher total chlorophyll content and longer and well proliferated root system than those treated with similar levels of diphosphate. Plants fed with monophosphate exported more than 50% of the total produced substances toward root system whereas, for the plant supplied with diphosphate, it was less than 20% approximately. In addition, there were a positive and significant correlation between the rate of the uptake and the content of the measured elements such as P, N, Ca, Mg, K, Na and monophosphate level; however, the same elements except for K negatively correlated with diphosphate. In both groups, the major proportion of the absorbed elements was more or less accumulated in leaves in relation to that of other parts of the plants. At the end of experiment, while pH decreased in the root medium supplied with monophosphate, an increase was observed in pH of those containing diphosphate. Differences between means values related to the same parameters in most of the cases were significant at P

Iran is located in a hot and dry region. As a result of low precipitation and a vast area of salty and alkali soil, osmotic pressure is very high in most parts of the country (i.e., osmotic potential is more negative). In the present study four levels of osmotic pressure (‐0.25, ‐0.35, ‐0.45, ‐0.50 MPa) were created artificially, by polyethylene glycol (PEG) and treatment of three seed types, namely, barley, corn and canola. The study aimed at finding the seeds with better germination potential under high osmotic pressure. The seed's germination potential under different levels of osmotic pressure was also investigated. The experiment was conducted with four replications at the Laboratory of Faculty of Agriculture, Islamic Azad University, Saveh Branch, in a completely randomized design. Parameters under study were germination rate and germination percentage. Results showed that germination rate was not affected by osmotic potential. Considering germination percentage, only osmotic potential of ‐0.50 reduced germination percentages of corn seeds. Levels of osmotic potential did not affect seed germination in barley and canola.