recognition of rangeland species with the maximum efficiency and the minimum water usage is very important, since major parts of rangelands in iran are located in arid and semiarid climate. in addition, the rangeland improvement and management on the basis of transpiration rate of rangeland species in different climatic conditions has great importance. the goal of this research is comparison an...

Nutrients can determine the outcome of the competition between different floating plant species. The response of floating plants to current phosphorus levels may be affected by previously experienced phosphorus concentrations because some species have the ability to store excess phosphorus for later use. This might have an impact on their competition. Here, we investigate the effect of previous...

A study to understand the biological effects of samples prepared with lead and the effects of lead were conducted on Lemna minor L. and Spirodela polyrhiza (L.) Schleid. This study was intended to test the hypothesis that nutrient enrichment (P, NO(3) (-)-N and SO(4) (2-)) enhances the metal tolerance of floating macrophytes. The plants were exposed to Pb concentrations 0, 1, 5, 10, 25, and 50 ...

A theoretical model has been built to bypass the equation of titration of the cell wall. This equation, which is an extension of the Henderson-Hasselbach equation, underlines the importance of the exchange constant, the ionic strength as well as the rate of neutralization. The model is restricted to the case when the ionization degree is equal to the neutralization degree. The shape of the titr...

The effects of natural, overwintering conditions on photosystem I and photosystem II activity were examined in isolated thylakoids of periwinkle (Vinca minor L.), an endemic, cold-tolerant, herbaceous evergreen. DCMU-Insensitive photosystem I activity (ascorbate/dichlorophenolindophenol --> methylviologen) exhibited a twofold increase in light-saturated rates upon exposure to low temperature an...

From our theoretical treatment which is an extension of the classical Donnan theory, we have estimated the rational selectivity coefficients of the carboxylic groups of the walls during exchanges of divalent ions against monovalent ones (i.e. calcium and potassium or calcium and sodium ions). These coefficients express the interactions between the different ions, those between the counter-ions ...

Aminooxyacetate, a known inhibitor of transaminase reactions and glycine decarboxylase, promotes rapid depletion of the free pools of serine and aspartate in nitrate grown Lemna minor L. This compound markedly inhibits the methionine sulfoximine-induced accumulation of free ammonium ions and greatly restricts the methionine sulfoximine-induced depletion of amino acids such as glutamate, alanine...

The present study was carried out to examine 6 plants including aquatic and terrestrial plants on food preference and growth of grass carp. 7 experimental treatments with three replicates were considered. The experimental treatments were ponds containing T1: M. spicatum, T2: C. demersum, T3: A. filiculoides, T4: L. minor, T5: C. dactylon, T6: M. sativa and T7: M. Spicatum + C. demersum + A. fil...