Iranian Journal of Plant Physiology
Volume:4 Issue: 4, Summer 2014

The effects of salicylic acid (SA) on growth and metabolism of Brassica oleracea var. Capitata under salt stress was studied in a hydroponic culture. NaCl at 50 mM concentration and SA at 0.5, 1.0, and 1.5mM concentrations were used as treatments. The results showed that salt exhibited inhibitory effects on shoot and root length, fresh and dry weight, and RWC of the seedlings. NaCl at 50 mM concentration significantly decreased the photosynthetic pigments and protein content and nitrate reductase activity. Sugar and proline content was significantly increased under the influence of salinity. The antioxidant enzymes viz. superoxide dismutase, catalase, and peroxidase activities significantly increased under salinity due to oxidative damage. Graded concentrations of SA played protective role against the salt stress. SA significantly ameliorates the oxidative stress caused by NaCl.

In an ongoing research، 24 cultivated and wild cultivars of barley were evaluated for morphological characteristics of grain، pollen، and stomata. Traits of interest included length، width، and area. Results of variance analysis showed that all samples were differed in traits of stomata، grain، and pollen at probability levels of 1 and 5%، suggesting remarkable genetic variation among studied samples. According to cluster analysis، morphological traits of pollen and stomata fell into three cluster and those for grain were categorized in two clusters. Genotypes for arid area like Izeh، Maravetapeh، Kavir، and Nimrooz showed higher levels of stomata densities and area compared to those for cold area like Bahman and A1C84-14. Here، affinity rate of 24 barley cultivars were evaluated using micro and macro-morphological traits as those rare-studied ones.

Ascophyllum nodosum is the most important commercial seaweed. Seaweeds have been applied as soil conditioners in improving plant growth and development in agricultural crops. In current study and for the first time, extracts of brown seaweed A. nodosum improved the growth of Robinia pseudoacasia L., an ornamental tree. This research investigated the effect of cultivation beds (sand, perlite, compost and cocopeat) with different ratios and extracts of brown seaweed A. nodosum on the growth of R. pseudoacasia L. in ex vitro conditions. Concentrations used from extracts of A. nodosum were 0, 1000, 2000, and 3000 mg l-1. The 1000 mg l-1 of extracts of A. nodosum developed optimum plant height, node number, longest root, leaf number, dry weight, fresh weight, and plantlets survival when added to culture bed containing sand + perlite + compost with proportion of 1:1:1. About 75% of the propagated plantlets were established successfully in acclimatization medium. Regenerated plantlets were morphologically identical with mother plants.

Nano-fertilizers are designed in order to gradually release their food contents. They are also manufactured in such a way that the time of their liberation matches with the food product requirement. The use of nano-fertilizers leads to an increase in the efficiency of the consumption of food elements. With regard to the strategic importance of cotton plant and the effects of zinc in increasing plant resistance, the purpose of this research study was comparing the effects of mineral fertilizer of zinc (Mi), chelate of zinc (Ch) and nan-ochelate of zinc (NCh) on the growth and some physiological and biochemical process of the cotton plant. To achieve this goal, the cotton plants in field were cultivated in a completely random design. The first phase of the foliar application of fertilizer was at the square stage or squaring (S) and the second and third stages were squaring-flowering (SF) and a week after flowering (F). Results showed the maximum height, fresh weight, and dry weight were obtained in treatments with nano-chelate and chelate of zinc and there were no significant difference in squaring, squaring-flowering, and flowering application stages. The height, fresh weight, and dry weight of cotton plant increased by application of fertilizers Co, Mi, Ch, and NCh in that order. Chlorophyll a and b increased in nano-chelate and chelate of zinc at squaring and flowering stages. Application of chelate and nano-chelate zinc fertilizer in the present study improved physiological processes in cotton as it increased the amount of chlorophyll and antioxidant activity of peroxidase, catalase, and polyphenol oxidase as a result of increase in fresh and dry weight. Findings suggest that application of zinc chelate and specially the nano-chelate of zinc can improve cotton performance by increasing the number of bolls per plant and mean weight of 20 bolls.

Stored seeds deteriorate over time and must be regenerated to ensure that the benefits of ex situ conservation are realized. Prediction of seed longevity is based on the seed viability equation. This equation has four constants which are species specific. The aim of this project is the estimation of these constants and prediction of regeneration frequency for Elytrigia elongata, Dactylis glomerata, Festuca ovina, Secale cereal, and Secale montanum. Seeds were equilibrated at 20, 40, and 60% RH and their moisture content was determined after equilibration. Seeds were then sealed in nylon pockets and stored at 30, 35, and 40° C. Germination was tested monthly. Seed viability constants (KE, Cw, CH, CQ) were estimated and regeneration time was calculated for each species. High variation in seed longevity was observed both among the genus and species. Elytrigia elongata with KE=6 and Cw=1.64 had the maximum seed longevity ofall species evaluated; seeds stored in an active collection (8% mc, 5° C) would have to be regenerated after 131 years. The minimum seed longevity was obtained for Festuca ovina with KE=4.3 and Cw=0.5; seeds stored in active collections would have to be regenerated after 33 years.

Medicinal plants are the most important sources of life saving drugs for the majority of world''s population. Artichoke is one of the oldest medicinal plants from asteraceae family. In the present study, caffeic acid and chlorogenic acid accumulation of different organs of artichoke callus were studied under in vitro conditions in MS, SH, and B5 media. The experiment was performed based on a completely randomized design with 3 replications. The artichoke seeds were transferred to the sterile Petri dishes containing filter paper immediately after disinfecting under sterile conditions. The obtained seedlings were transferred to half-strength MS medium. Only non-contaminated seedlings were used for preparation of root, leaf, and petiole explants. The SH, MS, and B5 media containing 0.8% agar, 3% sucrose, and 0, 0.5, 0.75, and 1 (mg/l) 2,4-D were used for callus induction. According to the results, caffeic acid accumulation was not found to be statistically different (α<0.05) among various media but maximum amount of chlorogenic acid accumulation between different media was recorded in SH medium containing 0.75 (mg/l) 2,4-D and with the leaf explant. In all culture media callus formation was related to the presence of 2.4,D. Otherwise, no callus formation was observed in hormone-free media.

To study the effects of thyme, savory, mint, and eucalyptus essences on photosynthetic efficiency, chlorophyll fluorescence, changes of transpiration, and leaf temperature of two cultivars of pistachios, namely, Abbasali and Shahpasand, a research was done in one of the commercial gardens of Damghan in 2012. This experiment was implemented in split, split plot as complete randomized block design, by two essences in five levels (4 experimental essences and one control sample). Cultivar type was evaluated at two levels and three replications and effects of treatments on physiological properties of the samples were studied. Type of essence regarding variance analysis table indicates significant effect on the rate of photosynthesis as %1. Also, effects of cultivars, cultivars × essence, concentration of essence, cultivars × concentration of essence, type of essence × concentration of essence and interaction of type and concentration, were not significant. Thyme essence had more pronounced effects on photosynthesis measure than other essences and was at higher rank with average of 12.22 μmolm-2s-1.

In the present study، dormancy and germination requirements were investigated in seeds of Citrullus colocynthis (L.). Seeds were subjected to 10 pretreatments in the present study. These pretreatments included hot water (100° C) followed by the seeds placed between double layered filter paper moistened with 5 ml of distilled water and kept at 28 - 30 °C، sulphuric acid (98% v/v)، for 30 min followed by the seeds placed between double layered filter paper moistened with 5 ml of distilled water and kept at 28 – 30° C، and sulphuric acid (98% v/v)، for 5، 10، 15، and 20 min after which seeds were placed between double layered filter paper moistened with 5 ml of distilled water and kept at alternating temperatures 20 / 25 C (12h / 12h). In the last four pretreatments، Citrullus colocynthis (L.) seeds were subjected to10 and 20 mg/l GA3 followed by moistening with 5 ml of distilled water، 10 mg/l GA3، or 20 mg/l GA3. Concentrated sulphuric acid was partly-successful in dormancy-breaking. Moreover، germination increased at pretreatments and treatments of various levels of gibberellic acid. The highest germination rate and percentage were obtained at concentration of 10 mg/l GA3.