Iranian Journal of Plant Physiology
Volume:13 Issue: 2, Winter 2023

Climate alteration and population growth have been responsible for the yield decline in crop. Until now, several researchers have been used various physical and chemical factors to stimulate plant growth and development. Static magnetic field (SMF) application has been identified to be a physical technique and useful to control plant diseases and stimulation of biomass yield. Little studies have been made to detection the role of SMF on plant physiological response, defense mechanisms, and plant tolerance against various stress conditions. On the other hand, application of man-made devices producing magnetic field (MF) is also increasing, and more studies are needed on living organisms. This review investigates the impact of MF on induction of seed germination and plant growth. Also, the supportive impact of SMF was investigated on membrane permeability, ion currents, secondary metabolite and antioxidant enzyme activities to suppress oxidative damage. The potential impact of SMF on enzymatic and non-enzymatic antioxidants can cause to increase plant tolerance during adverse conditions of other stresses such as salinity, metal contamination, drought ant etc. This review presents the basic and recent studies about the effect of SMF on plant adaptation to stress environment and emphasizes more research is involved to illuminate how SMF is precepted by cells, and the molecular mechanisms of SMF for plant protection under other stress conditions.

This experiment was conducted to investigate the role of priming in regulating growth and photosynthesis in salt-acclimated canola plants. Salt stress caused a significant decrease in total dry masses, whereas seed priming with hydrogen peroxide (H2O2), nitric oxide (NO) or H2O2+NO mitigated the salt-induced inhibitory effects on the plant growth under acclimated conditions. The adverse effects of salinity on shoot and root lengths were alleviated only by combined H2O2 and NO priming in acclimated canola plants. Under salt-stress conditions, the contents of photosynthetic pigments were reduced in non-acclimated plants, whereas the priming with H2O2+NO alleviated the inhibitory effect of salinity on the chlorophyll a and carotenoids contents. Measuring the chlorophyll a fluorescence parameters indicated that NaCl markedly decreased the maximum quantum yield (Fv/Fm), the quantum yield of electron transport (ΦEo) and the oxygen-evolving complex efficiency of PSII (Fv/Fo) in non-acclimated canola leaves showing photoinhibition of PSII, but the priming with H2O2+NO improved these parameters under salt stress. Our results suggested that priming of canola seeds with H2O2+NO significantly increased photosynthetic pigments accumulation, which was associated with the improvement of the photochemical efficiency, resulting in better plant growth under salt stress.

Roses (Rosa hybrida L.) are prevalent ornamental flowers used as cut and sow flowers. This study aims to examine the effect of gibberellins on the acceleration of flowering of roses planted in pots in Rahma Village, South Lubuklinggau I District, Lubuklinggau City, South Sumatra (-3°018’10”, 102°054’41”) with a height of 110.5 meters above sea level, from September to December 2021. The planting media consisted of Ultisol soil, cow dung, and rice husk (1:1) of 10 kg/pot. Gallica varieties of roses are given gibberellins (GA3) sprayed every 7 days until the plants are 98 days old. Harvesting is done when the flowers are in full bloom. The first harvest is from day 57 to day 116, a total of 17 harvests. The treatment of gibberellin concentration is tested at 6 levels, namely: 0 ppm (Z0), 50 ppm (Z1), 100 ppm (Z2), 150 ppm (Z3), 200 ppm (Z4), and 250 ppm (Z5), with 4 groups and each consists of 3 pots. From the study results, it can be concluded that the administration of gibberellins (GA3) with concentrations between 50 ppm to 200 ppm accelerated flowering time between 2.88 to 10.5 days. Z3 increased the number of flowers by 32.5 buds, and Z2 produced flowers with the largest diameter of 7.16 cm. The length of the stalk and the number of petals on roses cannot be increased by giving gibberellins. For the flowering of roses, it is recommended to administer gibberellin with a concentration of 150 ppm (Z3).

In this study, the possibility of organogenesis of leaves and petioles of two African violet cultivars were evaluated using MS media containing various concentration of plant growth regulators (IAA (1,2 mg/l), BA (0.05, 0.1, 0.2, 0.5 mg/l), NAA (1, 2 mg/l), and TDZ (0.01 mg/l)). All experiments were arranged completely randomized design then data analyzed by one-way ANOVA, and means were separated using Duncan’s new multiple range test (𝑃 ≤ 0.01). Direct and indirect organogenesis from the whole leaf with petiole bases were observed in both cultivars. However, the separated leaf blade and petiole were unable to produce any organs. The organogenesis potential of cultivars was significantly different, although the medium containing BA (0.1 mg/l) + IAA (1 mg/l) showed the highest indirect organogenesis (90 %< in both cultivars). In contrast, the media containing BA 0.05 mg/l + TDZ 0.01 mg/l + IAA 2 mg/l and BA 0.05 mg/l + TDZ 0.01 mg/l + IAA 1 mg /l had more success on the induction of direct organogenesis. Therefore, the level of direct and indirect organogenesis appears to be dependent on the interaction between the PGRs and the explant type having a direct correlation with the genotype.

The effect of day lengths (LD1, LD2, and LD3; natural day length, 1.5 and 2.5 hours light more than the natural day length, respectively) and potassium humate treatment (PH1 as control and PH2: 50% of potassium humate) on photosynthesis traits, chlorophyll fluorescence, carbohydrate and total antioxidant capacity of stevia was studied. Under LD3, the following parameters significantly improved: root/shoot (R/S), leaf water content per unit leaf area (LWCA), and leaf weight rate (LWR), while R/S increased by 16% under PH2. A combined application of LD3 with PH2 increased the morphological parameters including, shoot dry weight (SDW) and root weight rate (RWR). Furthermore, this combination resulted in higher growth compared with the LD1/PH1 combination. Also, an increased day length improved stomatal conductance (gs), transpiration rate (E), WUEi, photosynthesis pigments; chlorophyll fluorescence (Fo, Fm, Fv, Fm/Fv), and antioxidant activity. Besides, regardless of the photoperiod treatment, these parameters improved compared to PH1. The impact of LD3 or PH2 on carbohydrate content tended to be greater than the expected impact of LD2 or PH1. Our results suggest that increasing day length and application of potassium humate, both as individual and combined factors, will change the growth of stevia.

Stevia (stevia rebaudiana) leaves contain valuable sweet compounds, called steviol glycosides (SVglys), which the quantity and quality of these sweet compounds may be changed during the leaf drying process. The present study was conducted to survey the SVglys changes during different leaf drying methods applied for stevia leaves. The stevia leaves were similarly harvested before flowering and dried by different methods including oven (45 and 75 ˚C), shade, infrared, microwave, sun, and freeze-dry, and thereafter the SVglys were assessed. The results showed that the SVglys content and its compositions such as stevioside (Stev) and rebaudioside A (Reb A) were significantly affected by leaf drying methods. The highest content of SVglys and Stev was stabilized using infrared, microwave, sun, and freeze-dry methods while the other methods showed a lower content of SVglys and Reb A. The significant high content of Reb A was recorded by freeze-drying and sun methods. Our results conclusively showed that freeze-dry and sun drying methods were seen more effective than other drying methods in SVglys retention in leaves and recorded the lowest SVglys losses during the drying process.

Chilling stress inhibits yield of rapeseed. Salicylic acid (SA) can improve plants’ resistance to chilling through modification of many physiological mechanisms. In the present study, foliar of SA was investigated on some physiological characteristics of rapeseed under chilling stress in farm. Treatments included sowing date (conventional date, late September, and late 15-day delay, which represents chilling stress) and SA spraying including no spraying, 0, 100, 200, 300, and 400 µM. Findings revealed that conventional sowing date + 100 µM SA resulted in the maximum chlorophyll, anthocyanins, and proline contents while late sowing date+ 100 µM SA resulted in the maximum flavonoids and soluble sugar. The highest catalase activities were recorded for the plants treated with 100 and 400 µM SA, but delayed sowing + 200 µM SA led to the highest activity of superoxide dismutase. Non-application of SA + conventional date showed the highest ion leakage. Applying low concentration of SA to the rapeseed plants sown in the favorable (conventional) sowing date seems to improve their chlorophyll and anthocyanins contents, and increasing the SA in delayed sowing seems to reduce the adverse effects of chilling stress. In the case of flavonoids and soluble sugars, applying 100 µM SA in the delayed sowing group compensated for the negative effects of low temperature compared with the control, improving the plant’s resistance to this stress. In sum, the most favorable performance in most characteristics of the rapeseed was obtained with conventional sowing date along with applying 100 µM SA.

With regard to the high amount of secondary metabolite in Mentha piperita, we evaluated two different methods for total RNA isolation on peppermint leaves. These methods were used to detect the best of all, which provides high-quality RNA. RNX-plus and modified RNX-plus (1-5) methods are used. The visualization of clear 28S RNA and 18S RNA bands on 1% agarose gels was used to check RNA quality. In the changed RNX-plus method (number 2), the purity of 28S and 18S rRNA was highly acceptable when assessed in an agarose denaturing gel. This method was the best one for RNA isolation with good quality. Therefore, this method is helpful for high-quality and quantity RNA isolation from Mentha piperita. The final analysis to get the best RNA isolation methods is gene expression analysis using tubulin primer as an internal gene. The obtained results demonstrated that it is possible to extract total RNA of reasonable quality and quality from Mentha piperita rich in polysaccharides and polyphenols by using modified RNX protocol number 2.

Salinity causes physiological and morphological harmful effects in plants. The present study was conducted to investigate the effect of calcium chloride (CaCl2 0, 50, and 100 mM) and salicylic acid (SA 0, 0.75, and 1.5 mM) on the physiological characteristics of salinity stress (0, 25 and, 75 mM NaCl). The results of this research showed that the adverse effects of salinity were improved by calcium and salicylic acid. Also, root and shoot length, dry and fresh weight, carotenoids, and chlorophylls decreased under salt stress, while proline, inhibition of DPPH radical, malondialdehyde (MDA), and anthocyanine increased. However, calcium and salicylic acid increased dry and fresh weight, the root and shoot length, reducing sugars, carotenoids and chlorophylls, and significantly reduced inhibition of DPPH radical and malondialdehyde in lentils. The present research showed that calcium and salicylic acid promote salinity tolerance, which could be related to regulating antioxidant responses. According to the stated results, it can be suggested that the most appropriate concentrations for improving the physiological parameters of lentils under salt stress are 50 mM calcium concentration and 1.5 mM salicylic acid concentration. Therefore, SA and Ca play this role by regulating the antioxidant system.