فصلنامه فرآیند و کارکرد گیاهی
سال دهم شماره 6 (پیاپی 46، Feb and Mar 2021)

In order to investigate the effects of priming methods on the improvement of seed germination indices and seedling growth of Lallemantia (Lallemantia Iberica) under different salinity levels, two factorial experiment in a randomized complete block design were carried out in the seed technology laboratory of Agricultural Sciences and Natural Resources University of Khuzestan in 2018-2019. In the first experiment, five levels of seed priming including: control, hydropriming (for 24 hours), gibberellic acid (100 mg.l-1 for eight hours), and solutes of potassium nitrate and sodium chloride (NaCl) (50 mg.l-1 for 6 hours) as the first factor and four levels of salinity stress, including 0 (control), 100, 200, and 300 mM of NaCl, as the second factor in four replications were examined. Also, a pot experiment was conducted to determine the effects of the studied treatments on some seedling growth indices in three replications. In general, indices of germination percentage, germination rate, radicle length, plumule length, emergence percentage, emergence rate, contents of chlorophyll a, b, carotenoids, and enzymatic activities of catalase and peroxidase were evaluated in this study. Results revealed that salinity stress, priming, and their interaction had significant effects on most of the studied traits. Also, increasing salinity concentrations led to decreases in all traits (except the activity of antioxidant enzymes). Generally, our findings showed that all seed priming treatments moderated the negative impacts of salinity stress and the application of NaCl could be a suitable treatment to increase the tolerance of Lallemantia seeds against high levels of salinity stress.

Ephedra intermedia is a dioecious plant of the Ephedraceae family whose male and female plants are quite similar in shape, but their biochemical differences are not known. The subject was the TLC and GC-MS study of fatty acids, phenols, essential oils, and alkaloids in male and female shoots of E. intermedia. Male and female shoots were collected from Markazi province in Iran, in spring. Alcoholic extract was obtained by mixing shoot powder with ethanol at 60 ° C. Phenols, fatty acids, and essential oil were separated from the alcoholic extract with ether and alkaloids with chloroform. Male and female ether extracts contained fatty acids, which appear male to be a good source of linolenic acid. The kind and amount of organic acids and phenolic of the two sexes were different. A large quantity of caprylic acid isoamyl ester was present only in females. 2, 6-Di-Tert-4-Methylphenol was much higher in both sexes than in the other compounds. A large number of essential oil compounds were found in the etheric extract of both sexes. The similarity of essential oil compounds between male and female plants was 32.4%. Total essential oils in female and male plants were 9.63 and 11.79 mgg-1DW. Males and females had a large number of alkaloids, but there wasn’t ephedrine and pseudoephedrine. Epherodxan and phendimetrazine in both sexes, ecgonine and aminopyrimidine in the male, and ergotamine and theacrin in the female, were six important medicinal alkaloids. Both sexes of E. intermedia are rich in bioactive compounds, but there was no ephedrine or pseudoephedrine.

Absorption of arsenic (As) by plant root is an essential activity that bridges the soil As concentration and physiological responses which can be monitored soon after exposure to As. In the present study, physiological responses to short exposure to arsenite (AsIII) was compared in two indigenous rice cultivars one adapted to temperate and humid (TH) and the second one to warm and humid (WH) climates.  Twenty days old plants were exposed to 75 µM AsIII, 6h. Expression of certain transporters, antioxidant system, and As detoxifying proteins were noticeable.  The levels of aquaporin transcripts OsNIP 2;1 (Lsi1), OsPIP1;3, and OsPIP2;6 significantly decreased in both cultivars. A more prominent reduction of aquaporin transcripts was observed in the WH cultivar and was accompanied by a lower AsIII uptake as compared to TH. The activity of superoxide dismutase, catalase, ascorbate peroxidase, and glutathione reductase enhanced in both cultivars, indicating the attempts to protect plants against AsIII-induced oxidative damage. These antioxidant responses were more pronounced in the WH cultivar and were accompanied by remarkably enhanced levels of reduced glutathione (a non-protein thiol) and phytochelatin, particularly in shoots. Although both cultivars responsed to AsIII very rapidly, based on the data presented here, it is likely that long-term adaptation of WH cultivar to warm and humid climate has driven genomic changes resulting in AsIII sequestration and other protective strategies against AsIII toxicity.

Haplophyllum virgatum var virgatum (Rutaceae) is a rare or narrow endemic plant, which grows only in one habitat (Geno-Hormozgan Province-Iran). Low distribution of this useful medicinal plant encouraged us to investigate about the micropropagation conditions of the plant. In the present study an efficient and reproducible protocol for multiple shoot induction of Haplophyllum virgatum var. virgatum was developed. Various explants (stem, leaf and root) were obtained from 40 days old axenic seedlings and cultured on B5 medium supplemented with different concentrations of plant growth regulators (Kin, BA, NAA and IAA) to determine the suitable explants and media composition for callus production. BA and Kin were used for multiple shoot induction. Stem explants showed the best results in both callus induction and shoot regeneration. Combination of 0.1 mg L-1 Kin and 5 mg L-1 IAA produced the maximum callus fresh weight. BA at concentration of 2 mg L-1 was the best treatment for shoot induction and regeneration. Embryogenic callus was also observed and the stages of globular and heart embryos were seen on callus culture in B5 medium supplemented with Kin (0.2mg L-1) + IAA (1mg L-1). In conclusion, stem explants and 2 mg L-1 BA regenerated maximum number of shoots.

Experiments were conducted to investigate the role of silicon (Si, 75, 100 mg. L-1 sodium silicate) and selenium (Se, 4, 6 mg. L-1 sodium selenate) in ameliorating the salinity (75 mM NaCl and 75 mM NaHCO3) caused strong detrimental effects on mineral ions uptake and the oxidative damage in cucumber (Cucumis Sativus L.) plants. Salinity and alkalinity stresses reduced macro and micro elements content which were significantly improved by Si and Se supplementation. Further, peroxide hydrogen was more in salinity- alkalinity stressed plants without Si and Se as compared to those supplemented with Si and Se. Si protected cucumber plants from NaCl induced oxidative damage by improving the activity of antioxidant enzymes (glutathione reductase, guaiacol peroxidase, ascorbate peroxidase).  More importantly Si and Se supplementation improved the accumulation of P, Mg, Ca, Fe, Zn, Mn and Cu. In conclusion, Si and Se mitigate the negative effects of NaCl and NaHCO3 in cucumber plants by modifying nutrient uptake and up-regulating antioxidant system.

IIn this study, the effects of paraxanthin on lettuce were investigated. Paraxanthin is a group of purine alkaloids, secondary metabolites of plants. This compound is made up of the caffeine metabolism found in plants such as tea, coffee and cocoa. There have been previous reports of paraxanthine antihypertensive properties.Three different concentrations of paraxanthine as 10, 50 and 100 µg/ml were treated on lettuce seedlings and then some physiological and biochemical parameters were measured at 7 leave stage of the plants. The results showed that seed germination, radicle and plumule growth of lettuce plant decreased at different concentrations of the paraxanthine in a dose dependent manner. At the concentration of 100µg/ml of paraxanthine, all of the growth parameters completely inhibited. Some measured parameters such as wet and dry weights of the shoots, photosynthetic rate, photochemical efficiency of photosystem II, leaf relative content and total protein decreased in the paraxanthine treated plants compared to the control group. However, some other parameters such as proline content, hydrogen peroxide and the activity of polyphenol oxidase, ascorbate peroxidase, catalase and protease in treated plants increased. On the other hand, a significant change in electrophoretic pattern of the plant leaf proteins were observed. As some electrophoretic bands in treated plants with 100µg/ml of paraxanthine removed in comparison than control group. The present study demonstrated that the paraxanthine as an allelochemical causes some physiological and biochemical responses in the lettuce which are much similar to those appears under abiotic stress.

Gracilariopsis persica is one of the most abundant red algae distributed in Persian Gulf, despite increasing use in medicine as a major source for natural biomaterials and bioactive compounds in recent years, the researches on growth parameters of this alga remains limited. The main aim of this research was to study the favorable conditions for G. persica growth. Also it was to find the suitable primary storage density for the establishment of algal thallus in the appropriate depth which causes increase in biomass in the concrete pool of Qeshm Island. Tall of G. persica were grown for 45 days on polyethylene ropes with primary storage weight of 100 and 200 gm-1 in two depths of 1 and 2 m. The effect of environmental factors such as temperature, salinity, pH, and nutrient absorption were investigated for different treatments. Growth rate during the cultivation period increased for both densities of 100 g and 200 g of G. persica at first but decreased then along with the time till sixth week. The highest growth rate (percentage of increase in fresh weight d-1) was obtained for the density of 100 g in 1 m depth in 45 days and the lowest growth rate was observed for the density of 200 g in 2 m depth. Relative growth rate (RGR) was measured weekly based on the changes in fresh weight and showed the highest efficiency in 1 m depth and 100 g density (15.47% d-1). The results showed that nutrients, especially those containing nitrogen and affecting algae growth at low depth, were inversely related (Kendall and Spearman negative correlation coefficients) to growth rate at 1 m depth. At depth 2 m, alga growth showed negative correlation with NO3- and NO2-. Findings provide novel evidence concerning growth and culturing conditions of G. persica, which can aid in the development of cultivating protocols for commercial agar production by this alga.