modern research physics

---

In the present study, the effects of indole acetic acid (IAA) on certain physiological and biochemical parameters in Glycine max (L.) Merr under aluminum chloride (AlCl₃)stress were studied. Seeds were sterilized and cultured in petri-dishes. Six days old seedlings were transferred to pots, and then they were irrigated with Hoagland solution in a growth chamber (with 16 h light period per 24 h, with day / night temperatures of 25/18 ºC respectively). Twenty days old plants were treated with different concentrations of AlCl₃ (0, 50, 100, 200 and 300 µM) and IAA (0, 50 and 100 µM). Plants were harvested 15 days after treatment. The plants exhibited decline in the relative water content (RWC), protein, soluble sugars, the chlorophylls a and b, carotenoids contents and photosynthetic rate with increase of aluminum chloride concentration, but the respiration rate and CO₂ compensation concentration were increased. With addition of IAA to culture solutions containing aluminum, the plants showed further decrease in the amount of soluble sugars, chlorophylls a and b, carotenoids and photosynthetic rate and further increase in other parameters. With increasing of aluminum concentration to culture solutions with and without IAA unsoluble sugars, proline and lipid peroxidation increased.
 

---

In order to understand some physiological mechanism of chilling and cold sensitivity in plants we investigate the effects of chilling and cold stress on chlorophyll and proline content, lipid peroxidation and variable chlorophyll fluorescence (Fv/Fm) of Arabidopsis (thaliana L.) The four weeks-old plants (WT, and four chilling sensitive mutants [chs2-2], [chs2-1], [chs1-2] and [chs1-1]) were subjected to two different low temperature treatments (control (23^̊ C), chilling (13^̊ C) and cold (4^̊ C)), for one week. Fv/Fm and chlorophyll content changed significantly in all mutants except in WT by chilling stress (13^̊ C), compared with control and 4^̊ C treatments. Two out of four mutants, chs1-1 and chs1-2, had lowest chlorophyll content and Fv/Fm value among the tested genotypes. The proline content increased in all mutant genotypes, as well as in WT by chilling stress and 4^̊ C, compared with control. MDA content of shoots changed dramatically in all mutant genotypes except in WT by chilling stress, compared with control and 4^̊  C treatments. Our findings showed that two mutants, chs1-1 and chs1-2, have had highest chilling sensitivity among the tested genotypes and had the highest proline and MDA contents. It is possible that some damages in photosynthetic systems and/or in proline metabolism via mutation cause these plants more sensitive to chilling and cold stress

---

Effects of various CuCl2 trearments (0, 100, 300, 500 µM) at rosette stage on accumulation of Cu+2, Fe+2, Mg+2, and K+, and proline concentration in root and leaf of two canola (Brassica napus L.) cultivars (PF and Hyola) were studied under greenhouse conditions. In general, in response to copper chloride treatments, significant differences were observed between physiological behaviors of these cultivars. With increasing in CuCl2 concentration, the increases in copper and proline levels and decrease in Fe+2, Mg+2, and K+ concentrations were greater in PF (especially root) than that of Hyola. Thus, it seemed that PF had more ability against heavy metal stress, compared with Hyola. Therefore, from biochemical point of view, PF could be introduced as more tolerant cultivar to heavy metal stress, in comparison to Hyola.

---

The mechanism of soybean(Glycine max L.cv.Gorgan 3) response to drought stress was evaluated. The plants were grown in pots under 23 ± 2°C temperature and 14000 lux light intensity and 14hr photoperiod. When first leaf appeard, three irrigation treatments occurred that consisted as one every day(control), once in three(mild stress) and in five days(sever stress).During 15 days the plants were irrigated an amount of 150 ml. The effect of irrigation treatment on the soluble sugar, total protein, proline, phenolic compound, chlorophyll content and nitrate reductase activity was studied.The results showed that in the root soluble sugar and proline content in mild and sever stress significantly increased while in the stem and the leaf these compound considarably increased under sever stress the total protein ,chlorophyll a,b and nitrate reductase activity in leaf especially decreased in sever stress. Also the decrease phenolic compound in leaf under this condition was significant