Journal of Ornamental Plants
Volume:9 Issue: 4, Autumn 2019

The magnetic field (MF) is considered as a biophysical treatment to change the growth and development parameters. Current research was carried out to evaluate the effect of different intensities of MF (0, 45, 60, 70 and 75 mT) on seed germination and some morphologic and physiologic parameters of Rudbeckia hirta L. in dry and humid conditions for 30 min. Results showed that the MF treatment increased germination percentage of dry seeds more than humid seeds and control. The intensity of 70 mT induced the maximum content of germination of dry seeds (94.5%). The MF decreased the seeds germination rate in both dry and humid conditions, as the control seeds showed the highest germination rate (3.5 days). Investigation of all morphologic traits like plantlet length and vigor index and physiologic (humid and dry weights of plantlet) revealed that the MF caused more induction of growth in these traits than the control. Totally, the use of 70 mT MF on dry seeds for optimum growth and development in Rudbeckia hirta L. is recommended.

Recently, the use of superparamagnetic iron oxide nanoparticles (SPIONS) as a new and promising source of iron in agriculture has been suggested that further investigation is needed before extensive field use. In a greenhouse experiment, the effect of coated magnetite nanoparticles with humic acid (Fe3O4/HA NPs) was investigated on iron deficiency chlorosis and photosynthesis efficiency compared to iron chelates of Fe-EDTA (Fe-Ethylenediaminetetraacetic acid) and Fe-EDDHA [Fe-Ethylene diamine-di (o-hydroxyphenylacetic acid)] as control treatments in chrysanthemum cut flower (Chrysanthemum morifolium) in the open hydroponic cultivation system. The feasibility of absorption and translocation of nanoparticles in the plant was evaluated by vibrating sample magnetometry (VSM). The results of tracing by magnetization measurement was demonstrated that NPs penetrated in root and transferred to the aerial parts of chrysanthemum. The greenhouse experiment demonstrated that the application 20 mg/L Fe3O4/HA NPs in nutrient solution significantly (P<0.001) increased the content of chlorophylls a, b, total and carotenoids in the leaf 14.80, 12.15, 13.90 and 13.98 percent as compared with Fe-EDTA, respectively, but did not with Fe-EDDHA. The equivalent ratio of chlorophyll a/b in all concentrations of nanoparticles with Fe-EDTA and Fe-EDDHA treatments, as traditional sources of iron in growth medium, demonstrated no significant difference in photosynthesis efficiency. Generally, Fe3O4/HA NPs transferred to plant aerial parts, increased the variety of photosynthetic pigments and obviated iron chlorosis.

Water stress is one of the main factors of severe damage and limits of plant production in Iran. In this research, a pot experiment was conducted by using a factorial experiment based on a completely randomized design; there were three replications (each replication contained four pots) to compare physiological and biochemical characteristics of two varieties of tuberose (double- and single- flower) for their tolerance to water stress. Three water stress levels, no stress (W1 = 90 % of FC), moderate stress (W2 = 75 % of FC) and severe stress (W3=60 % of FC), were maintained throughout the experiment.Physiological traits including relative water content (RWC) and electrolyte leakage (EL) were investigated and also were biochemical traits including total chlorophyll (Chl), carotenoid (Car) contents, proline, malondialdehyde (MDA), antioxidant enzymes activity (SOD, APX and CAT), photosynthesis rate (A), transpiration rate (E), and stomatal resistance (rs). Results showed that physiological and biochemical characteristics of tuberose plants were highly affected by the application of water stress. MDA and EL showed a significant correlation with most physiological characteristics. Water stress caused a significant increase of RWC, A, E, rs, Chl, APX, and SOD activities in leaves of single-flower cultivar. CAT, MDA, and proline content in leaves of double-flower cultivar were significantly higher than single-flower cultivar, regardless of water treatments. The results of this study showed that the single-flower cultivar grows better than the double-flower one under stress conditions.

The application of biofertilizers constitutes one of the main components of nutrient management with a fundamental role in sustainable agriculture and the improvement of plant qualitative traits. The present research assessed the effect of various treatments of phosphate solubilizing bacteria including Pantoea agglomerans strain P5 and Pseudomonas putida strain P13 (seed inoculation, the application of biofertilizer 2, 4 and 6 weeks after plant emergence, and no inoculation of seeds as control treatment) and the foliar application of ZnSO4 (at 0, 1, 2, and 3 g L-1 rates), on morphological and biochemical traits of marigolds. It was found that the highest amount in plant height and flower fresh weight were belonged to plants whose seeds were inoculated by biofertilizer and were fertilized by 2 g L-1 ZnSO4 and also, in plants treated by biofertilizer 2 weeks after plant emergence and fertilized with 1 and 2 g L-1 ZnSO4. Also, the highest flower dry weight and anthocyanin content were obtained from the treatments of biofertilizer 2 and 4 weeks after plant emergence supplemented with 1 and 2 g L-1 ZnSO4. The highest P content was seen in the treatments of biofertilizer 4 and 6 weeks after plant emergence × 2 and 1 g L-1 ZnSO4. In addition, the highest Zn content was obtained under conditions including biofertilizer application 6 weeks after plant emergence and in plants fertilized by 3 g L-1 ZnSO4. In contrast, the lowest amount of most parameters was observed at different levels of biofertilizer application without the use of ZnSO4 and with the use of 3 g L-1 ZnSO4. Therefore, the foliar application of ZnSO4 and the soil application of phosphate solubilizing fertilizers can be influenced on the biochemical and morphological traits of marigolds.

The essential oil yield stability of damask rose (Rosa damascena Mill.) as an important medicinal and aromatic plant in different environments has not been well documented. In order to determine appropriate stability parameters, six statistics were studied for essential oil stability of 35 Rosa damascena landraces in seven locations (Sanandaj, Arak, Kashan, Dezful, Stahban, Kerman, and Mashhad) and two years (2007-2008) in Iran, using a randomized complete blocks design with three replications. Significant differences (P<0.01) were observed in essential oil ratio among landraces (G), locations (L), and environments (E) and in landrace × location (GL) and landrace × environment (GE) interactions. The positive correlation of environmental variance (S2), coefficient of variation (CV), and regression coefficient of yield over environments (b) with essential oil suggest that only low-yield landraces develop a similar phenotype over a range of environments and show static stability. Although there were not any stable landraces by b (b ≈ 0) and all of the stable ones by S2 produced very low yields, some of the adaptable ones by CV (e.g. KM1) showed high essential oil ratios and stability simultaneously. The stable landraces according to the dynamic stability concept (b ≈ 1, Sd2 or variance due to deviation from regression ≈ 0) produced moderate essential oil. Superiority index (P) determined some of the highest essential oil as adaptable landraces. The stable landraces with the least variance of the years within places (MSY/P) produced the least essential oil. It could be concluded that a genotype can demonstrates both static and dynamic stability with high essential oil content. In addition, CV, dynamic view statistics (b ≈ 1, Sd2≈ 0), and P are proposed as desirable parameters for the evaluation of essential oil stability with different concepts in damask rose genotypes.

Drought is one of the most important environmental factors limiting the cultivation of ornamental plants in the green space. The effects of spermidine and salicylic acid on hollyhock (Alcea rosea L.)under drought stress were investigated. At first, the plants were sprayed with 3 doses of spermidine and 3 doses of salicylic acid (control, 100, 200 and 400 μM) for three consecutive days, then were subjected to drought stress (40, 60, 80 % FC) for 2 weeks. The results showed that drought stress increase up to 40 % FC increased electrolyte leakage, proline and superoxide dismutase enzyme activity compared to control plants. Also, the application of 100 μM spermidine and salicylic acid in different concentrations of spraying solutions significantly reduced electrolyte leakage and catalase enzyme activity and increased the relative water content (RWC), proline, protein, number of flower, leaf area and superoxide dismutase enzyme activity, but higher concentrations (400 μM) was ineffective or had inhibitive effects. Treated plants with 100 μM spermidine and salicylic acid showed higher tolerance to drought stress (up to 40 % FC) with regard to lower electrolyte leakage (by 5 %) and higher relative water content (by 11 and 9 %), proline content (by 31 and 21 %), SPAD (by 18 and 5 %) and dry weight (by 3 %) compared with non-treated plants under 40 % FC. Hollyhock growth severely suffered by water deficit, but application of spermidine and salicylic acid promoted RWC, proline and protein content under water deficit conditions. Foliar application of spermidine and salicylic acid could be considered as an economical practice for increasing hollyhock performance under water deficit conditions.