IRANIAN JOURNAL OF PLANT PHYSIOLOGY
Year:2016 | Volume:6 | Issue:4|Papers Count:8

Aluminum and silicon are usually abundant in the soil and most plants are affected by them. Therefore, in the present study, the effect of the interaction of Si (0 and 2 mM) and low concentrations of Al (0, 50, 100, and 150 mM) on some physiological parameters of Zea mays var. Merit were investigated and were analyzed by cluster heatmaps for better interpretation of results. Results showed that application of Al increased the fresh and dry weight of maize, and plant growth rate was increased by increasing Al concentration in treatments. However adding Si to Al-treated plants had no effects on the maize plant biomass. Pigments content of plant increased and decreased in Al treatments and Ai + Si treatments, respectively. Also, both Al and Si had negative effect on the activity of antioxidant enzyme and proline content of maize in general. Aluminum treatments mostly enhanced the K and Fe content of plants, but decreased Mg and Ca content. However, adding Si to Al-treated plants reversed this trend. Apparently, Ai and Si have an antagonist effect on the mineral content of the plant. Results of the present study suggested that increasing of the plant pigment content contributes to the enhancing of plant growth rate, and the K content of the shoot in maize has an important role in increasing the plant growth.

In order to understand the response of Lotus corniculatus to salt stress, ions content and some growth factors were analyzed in three varieties of this plant, namely, Ardebil, Karaj, and Jolfa. Lotus corniculatus plants were exposed to 0, 50, 100, and 150 mM NaCl in hydroponic condition. The amounts of anions (Cl-and NO3-) and cations (K+ and Na+) in leaves as well as shoot and root dry weights, stem and root length, leaf area, and number of leaves were analyzed. The amount of Na+ and Cl- significantly increased in all varieties. However, with an increase in NaCl concentration, K+ and No3- content decreased significantly in all varieties (p<0.05). Growth factors (root and shoot length and weight, leaf area, and leaf number) declined significantly with increasing NaCl concentration. Considering alterations in growth factors and ions content, it seems that "Jolfa" and "karaj" have a higher capacity to tolerate salt stress particularly in 100 and 150 mM NaCl compared to "Ardebil".

This research was carried out to study the effect of ageing on antioxidant and biochemical changes of wheat (Triticum aestivum L.) seeds. The experiment laid out in completely randomized design (CRD) with four replications in Islamic Azad University, Boroujerd Branch, Boroujerd, Iran in 2015. The seeds of wheat (cv Sardari) were harvested at maturity and ageing treatments were done at 43oC with 100% relative humidity for 1, 2, 3, 4, and 5 days. After ageing treatments enzymatic antioxidants, non-enzymatic antioxidants, and biochemical characteristics were measured. The results showed that ageing treatment decreased germination percentage. However, electrical conductivity, malondialdehyde content, and H2O2 were increased as the ageing progressed. Soluble sugars and proteins were decreased with an increase in ageing levels, but soluble protein in control treatment was less than that in days 1 and 2 of ageing. Non-enzymatic antioxidants such as ascorbic acid and proline increased until days 1 and 2 of ageing treatments, respectively while they decreased afterwards. Moreover, enzymatic antioxidants such as catalase, peroxidase and ascorbate peroxidase increased until 1, 2 and 3 days of seed ageing decreasing afterwards. The results of this research showed that increasing of hydrogen peroxide under ageing led to increasing of seeds damage. Also, under ageing treatment, enzymatic antioxidants were more efficient than non-enzymatic antioxidants in removing reactive oxygen species.

Tomato (Lycpoersicum esculemtum) belongs to the Solanaceae potato family and is an important crop plant. It is relatively resistant to salinity, but in the saline environment growth and production of the plant significantly reduces. On the other hand, the presence of mycorrhiza fungus can improve the adverse effects of salinity. A factorial experiment in a completely randomized design with three replications was conducted on tomato plants in the Islamic Azad University. The first factor was mycorrhiza treatment with NaCl at 0 (control), 50, and 100 mM, and the second factor included salinity stress at 0 (control), 50, 100, and 200 mM. Based on the obtained results from variance analysis, the effects of mycorrhiza pretreatment with NaCl were significant on the root length. Also, the level of salinity pretreatment of mycorrhiza had a significant effect on proline content (p≤0.05). Moreover, salinity treatment had a significant effect on stem length, leaf area, the inoculation percentage of mycorrhiza, and proline content (p≤0.01) and on stem length (p≤0.05). Moreover, salinity pretreatment of mycorrhiza and salinity treatment reduced root length, the inoculation percentage of mycorrhiza, and proline accumulation. Salinity treatment reduced root length, leaf area, stem length, and the inoculation percentage of mycorrhiza while it increased proline content. Finally, it was found that salinity stress reduced the root length, stem length, leaf area, leaf water content, the inoculation percentage of mycorrhiza, potassium, phosphorous, and nitrogen while it increased the proline content. Finally, mycorrhiza pretreatment with NaCl was found to reduce the negative effects of salinity stress.

This research was conducted with the purpose of appraising the effect of Selenium (Se) and/or amino acid fertilizers (AA) on improving growth, physiology, and biofortification of parsley grown under high EC condition. Plants were foliarly supplemented with four levels of Se (0, 25, 50, 100 mgl-1) and/or two concentrations of AA (0 and 0.2%) three times with a week interval. The significantly increases in the leaf fresh and dry masses as well as improvements in leaf area and stem heights were recorded in Se and/or AA-supplemented plants, as opposed to Se 100. However, the growth inhibiting effects of Se 100 were relieved by AA. In contrast to Se 100, Se 25 AA and Se 50 AA were the most effective treatments to improve the chlorophyll contents. The significant inductions in the activities of antioxidant enzymes, peroxidase, and polyphenol oxidase were observed in Se and/or AA treated plants. The usage of Se and/or AA, especially the combined ones, led to the significant stimulations in the activities of phenylalanine ammonia lyase (PAL). The significantly higher contents of phenolics, a suitable quality indicator with great significance for cardiovascular diseases in humans, were observed in Se and/or AA supplemented plants. The foliar supplementation of amino acids accelerated and/or declined the physiological alterations triggered by Se dependent on the applied concentrations. It could be concluded that the simultaneous supplementation of Se and AA at appropriate levels represents an environmentally friendly way of promoting growth, alleviating stress, and fortifying in parsley.

This study was conducted in order to investigate the effect of drought stress and Azomite fertilizer on some physiological traits of two tomato (Lycopersicon esculentum M.) cultivars (izmir and Izabella). A randomized complete design with factorial arrangement with three replications was used. Treatments consisted of three levels of irrigation including FC (control), 2/3 FC (mild drought stress), and 1/3 FC (severe drought stress)] along with four levels of Azomite (0, 25, 50 and 100g/pot). Results showed that drought stress reduced stem length, plant dry and fresh biomass, relative growth rate (RGR), net assimilation rate (NAR), relative water content (RWC), total chlorophyll, carotenoid, nitrogen, phosphorus and potassium in leaves. Azomite fertilizer increased the stem length, plant dry and fresh biomass, RGR, NAR, RWC, total chlorophyll, carotenoid, nitrogen, phosphorus, and potassium in leaves in comparison with control plants in both cultivars. Interaction effect of drought stress and Azomite had a significant effect on increasing plant fresh biomass, RGR, NAR, RWC, total chlorophyll, carotenoid, nitrogen, phosphorus, and potassium. Interaction effect of drought stress and cultivar showed significant effect on increasing plant fresh biomass, NAR, RWC, total chlorophyll, and phosphorus. Moreover, the results indicated that the interaction effect of Azomite and cultivar had a significant effect on plant fresh biomass, RGR, RWC, and phosphorus in leaves. In general, Azomite was effective on drought stress tolerance of tomato plant.

The aim of this work was to study drought effects on lipid peroxidation, antioxidant compounds, and anti-oxidative enzymes activities in two tolerant (Daric and 92 Zhong), two moderately tolerant (Sabalan and DH-2049-3) and two sensitive (Shark and Tevees) wheat genotypes. Malondialdehyde content and electrolyte leakage increased significantly (P<0.05) in flag leaves under drought. The increase was higher in sensitive genotypes compared to the others. Protective enzymes activities (ascorbate peroxidase, peroxidase, superoxide dismutase, catalase and glutathione reductase) and non- enzymatic antioxidants contents (ascorbate and glutathione) increased under drought stress and this increase was higher in tolerant genotypes. There were significant positive correlations (P<0.05) between anti-oxidative enzyme activities and non- enzymatic antioxidants. It seems that peroxidase and superoxide dismutase - that showed higher increase under stress- had an important role in drought tolerance.

The effects of plant growth regulators were examined in order to optimize the callus induction, regeneration, and proliferation of lisianthus (Eustoma grandiflorum). In vitro leaves provided the explants for callus induction. Explants were cultured on Murashige and Skoog (MS) medium with different concentrations of indole-3-acetic acid (IAA), 1-naphthaleneacetic acid (NAA), and 2,4-dichlorophenoxyacetic acid (2,4-D). Maximum callogenesis was obtained on MS medium supplemented with 100 mM NAA. Calluses were cultured on MS medium containing 6-benzyladenin (BA) (4.4, 13.3 or 22.2 mM) with or without 0.5 mM IAA and NAA for regeneration. The highest number of shoots (12.3 shoots/explant) developed on MS media with 22.2 mM BA plus 0.5 mM NAA. Individual shoots 1 cm in length were excised and multiplied. The maximal shoot proliferation with an average of 10.2 and 11.2 shoots/explant after 4 weeks of culture was achieved when the shoot tips were cultured on MS medium supplemented with 2.2 mM BA with or without 0.5 mM NAA. These results indicate that an efficient callus induction and micropropagation protocol of lisianthus had been established.